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Defence Services Branch 50th Anniversary. 


S.J. Caughey and P.W. Davies 
Meteorological Office, Bracknell 

August 1989 
Vol. 118 No. 1405 

OCT 23 1989 

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Summary goles 
In January 1939 Met 06 (then M.O.6) was designated the Meteorological Office Branch responsible for serving 
the Royal Air Force within the United Kingdom. Thus began an association with Defence work which has lasted 50 
years. To mark the occasion this article briefly outlines Meteorological Office activities in support of the Armed 
Forces from the earliest days of military aviation to the major expansion of air power and services during the 
Second World War and, more recently, the Falklands Campaign. An accompanying article (Turton and Caughey 
1989) reviews the current organization for Defence and the services provided and also assesses likely future trends 

and requirements. 

1. Introduction 

Weather has always been a major factor influencing 
the conduct of military operations. There are many 
famous instances throughout history of the tactical use 
of weather by astute military commanders. At Salamis 
in 480 BC, the Greeks relied upon a freshening southerly 
sea-breeze to cause ship-handling difficulties amongst 
larger Persian vessels before attacking them. Julius 
Caesar was severely hampered by strong winds and high 
seas in the Channel during his invasion of Britain in 
54 BC. In more recent times it is well known that the 
invasion of Europe in 1944 was crucially dependent 
upon a suitable ‘weather window’ (Stagg 1971). 

From the few examples quoted above it can be readily 
appreciated that a military commander must have 
access to accurate weather information. This requirement 
becomes particularly important when his forces are 
outnumbered by their opponents or when resources are 
limited. The maximum effectiveness must then be 
extracted from the available resources, and this can 
often be assisted by intelligent tactical use of weather 
information and by being aware of the impact of 
weather on both his own operations and those of his 

As early as 1838, officers of the Royal Engineers on 
detached duty overseas and consuls serving in foreign 
ports had been requested to make meteorological 
observations to build up a climatic database in order to 
assist the provision of meteorological advice to shipping 
(both naval and merchant). The Meteorological Office 
was formed in 1855 as a department within the Board of 
Trade in response to growing unrest over the unsatisfactory 
provision of meteorological information to the fishing 
and merchant fleets. From these earliest days services 
for Defence formed an important part of the work of the 
Office. In this article a brief description is given of the 
growth in services for the military in the early years 
through to the rapid expansion and development which 
took place during the Second World War and until the 
present day. 

2. The early years — pre-1939 

In the earliest years of the Meteorological Office most 
work for Defence was concerned With the supply of 
forecasts and weather information to the Royal Navy, 
which was still using balloons (Fig. 1) and with attempts 
to improve the accuracy of artillery fire. There was, 

Meteorological Magazine, 118, 1989 


however, no satisfactory method of measuring upper-air 
flow and thus in 1881 experiments were conducted into 
the detection of upper-air currents by firing light shells 
vertically. The difficulties of providing a credible 
forecast service can easily be underestimated in today’s 
world of satellites, fast communications and sophistic- 
ated numerical models. All products were generated by 
laborious manual methods and based on limited data of 
variable quality. 

With the introduction of the first military aircraft 
in the early part of this century (circa 1910) the 

Figure 1. 

Meteorological Office appointed (in 1911) J.S. Dines 
as Officer-in-Charge of a Branch Meteorological Office 
at the aircraft factory at South Farnborough. He 
arranged for the provision of weather advice to officers 
of the Air Battalion and also ran the Upper Air 
Experimental Station at Pyrton Hill, near Benson. By 
1913 the Meteorological Office Forecast Division was 
routinely supplying (by telegraph) weather reports and 
forecasts to units of the Royal Flying Corps (Fig. 2), 
Royal Navy Wing at Eastchurch and the Central Flying 
School at Upavon amongst others. The Branch 

6 7 
THe New NAVAL Aursnie, 

Royal Naval Air Service balloons at Farnborough (circa 1912). 

Figure 2. Bristol Scout biplane of the Royal Flying Corps (circa 1915). 

Photographs by courtesy of RAF Museum, Hendon 


Meteorological Magazine, 118, 1989 

Meteorological Office at South Farnborough was made 
permanent in January 1914 and would thus appear to be 
the oldest meteorological office serving Defence. 

With the approach of the First World War the 
expansion of services accelerated with reports and 
forecasts provided for Royal Naval aviation stations, 
and more frequent night-time observations were introduced 
to improve the quality of early-morning forecasts. 
Experiments started with the use of searchlights to 
monitor cloud-base heights. During the First World 
War meteorologists were attached to the Royal Artillery 
for sound ranging and gunnery work and to the Royal 
Engineers to give advice on chemical warfare matters. 
The Meteorological Field Service consisted of about 50 
officers, mainly from the Meteorological Office, up to 
the rank of major. Additionally, large numbers of non- 
commissioned officers (some from the Meteorological 
Office) and other ranks, drawn from the Royal Navy 
and the Royal Engineers were trained for service with 
the various meteorological sections. An example of an 
actual weather chart from this period which was 
prepared by E. Gold is shown in Fig. 3. 

In 1918 the Royal Air Force was formed from the 
Royal Flying Corps and although the Meteorological 
Office initially resisted transfer to the new Air Ministry 
(Meteorological Office 1919) the move went ahead in 
1919. Also in this year the Army Council formally 
requested further civilian support for artillery work and 
new offices were opened at Shoeburyness and Larkhill. 
The growing expertise of the Office in aviation work was 
recognized with the detachment of forecasters to St 

Figure 3. 
to the Battle of Cambrai. 

Surface chart for 0100 GMT on 20 November 1917, prior 

Johns, Newfoundland, to forecast for the first successful 
west-to-east transatlantic flight by Alcock and Brown 
on 14-15 June 1919. 

By 1920 the meteorological organization for Defence 
consisted of the Distributive Services Division (military 
and civil aviation), the Army Services Division and the 
Navy Services Division. All three Divisions received 
their basic guidance from the Forecast Services 
Division. Rapid growth continued through the 1920s so 
that by 1922 the Distributive Services Division (re-titled 
Aviation Services Division) had ten dependent offices. 
The Army Services Division had three offices, at 
Porton, Shoeburyness and Larkhill. Also, 1922 saw the 
opening of an overseas office at Malta, mainly for Royal 
Navy and Royal Air Force work. This was followed by 
eight offices opened in the Middle East during 1926-27 
supporting units of the Royal Air Force engaged in 
pursuance of Trenchard’s policy of aerial policing of 
remote and inhospitable areas. The aircraft in service at 
this time were mostly biplanes such as the Hawker Hart 
and Hawker Hind. Further reorganization and expansion 
took place during the 1930s. 

With the approach of the Second World War a rapid 
expansion of the Armed Forces, particularly the Royal 
Air Force, took place. In 1936 Bomber, Fighter, Coastal 
and Training Commands were set up whilst in 1938 
Balloon and Maintenance Commands were formed. To 
meet the growing capabilities of the Royal Air Force, 
ten new meteorological offices were opened on Royal 
Air Force airfields in the United Kingdom in 1937 alone. 
By contrast, in the same year, responsibility for services 
to the Royal Navy passed from the Meteorological 
Office to the Directorate of Naval Oceanography and 
Meteorology. During the period military aircraft 
increased in sophistication and performance. Also at 
this time the outstations were supplied with information 
direct from the then Central Forecast Office but with the 
approach of war a major organizational change took 
place which paralleled the changes in the Royal Air 
Force. The centralized structure was replaced by 
Command and Group Meteorological Offices, each 
given control over a number of outstations. Staff from 
London were devolved outwards to man these new 
offices and, to mark the event, the Meteorological Office 
Annual Dinner (Fig. 4) on 27 March 1939, included, 
after the Loyal Toast, a toast to “The Decentralized’. 
Some of the legendary meteorological figures who 
played an important part in the Second World War can 
be identified from the photograph. 

Prior to this time the Meteorological Office had been 
organized into a number of rather large Divisions but 
the increasing demands by the Royal Air Force for more 
specialized services could not easily be met by them. 
Smaller, and more manageable, Branches were set up to 
deal with specific service areas. Hence, late in 1938 the 
Director of the Meteorological Office signed a letter 
which authorized the formation of M.0.6 to commence 
work on | January 1939 under the direction of 

Meteorological Magazine, 118, 1989 





R.A. Watson 

Figure 4. Meteorological Office Annual Dinner on 27 March 1939. 

Mr H.W.L. Absalom. Thus, | January 1989 marked the 
50th Anniversary of MetO6 and what is now the 
Defence Services Branch of the Meteorological Office. 

3. The Second World War 

In 1939, as a reaction to European political tension, 
the Armed Forces commenced mobilization. In response 
to that mobilization the Head of M.O.6 issued, by 
teleprinter on 26 August 1939, Emergency Met Instruction 
No 5. This was the War Postings List, part of which is 
reproduced as Fig. 5. It contains some famous names 
such as Eric Evans and Tom Harrower, both of whom 
eventually became Assistant Directors of the Defence 
Services Branch. 

At the start of the Second World War M.O.6 was 
responsible for meeting all Royal Air Force meteorologi- 
cal requirements within the United Kingdom. This 
period, as one can imagine, was a time of enormous 
expansion, rapid change and urgent requirements which 
demanded largely untried products and techniques. By 


R.E. Watson (?) 





Photograph by courtesy of R.K. Pilsbury 

March 1940, and when M.O.6 had been in existence for 
only 15 months, other Branches (M.O.7 and M.O.8) 
were already being created to shoulder some of the 
Royal Air Force burden leaving M.O.6 to deal with 
RAF Bomber, Coastal and Maintenance Commands. 
M.O.7 was responsible for RAF Fighter, Training, 
Balloon and Reserve Commands and M.O.8 for Army 

By December 1942 M.O.6 was directly responsible for 
the meteorological support of Bomber Command, 
Training Command, Coastal Command (except 15 
Group, Liverpool, and 19 Group, Plymouth) and civil 
aviation in the United Kingdom and north-west Europe 
(flights to neutral Sweden, Portugal, etc.). M.O.6 was 
also administratively responsible for the Transferred 
Training Schools although there is no evidence that staff 
were sent to them from the United Kingdom. The 
Transferred Training Schools were Flying Training 
Schools which had been evacuated to the more peaceful 
skies of Canada early in the War. The Branch continued 


Meteorological Magazine, 118, 1989 

BOMBER COMMAND S©==eseessa=e= 
NO 1 GROUP ======s===s== 
C wood 



NO 4 GROUP ======e=s=ce= 
NO 5 GROUP ==s=see=x= 

Figure 5. Part of the teleprinter signal of the War Postings List sent 
at 1821 GMT on 25 August 1939*. 

* The complete list is incorporated in a copy of this article which is 
lodged as a pamphlet in the National Meteorological Library, 

with this extensive commitment until September 1944 
when it was directed to concentrate exclusively on the 
provision of meteorological support for Bomber Command. 
This arrangement continued until the end of the War. 

Bomber Command, and subsequently Strike Command 
into which it was subsumed, has therefore been one of 
the major customers of Met 06. During the Second 
World War M.0.6 maintained a Type | Office (equivalent 
to a Principal Forecasting Office today) at Bomber 
Command Headquarters at High Wycombe. This Office 
was in contact with, and provided general guidance to, 
the other Type | Offices at the various Bomber Group 
Headquarters (1 Group Abingdon, 2 Group Huntingdon, 
3 Group Mildenhall, 4 Group York, 5 Group Grantham 
and 6 Group Norwich). These latter Offices, although 
designated Type |, were basically equivalent to a Main 
Meteorological Office today. The Group Offices, in 
turn, exchanged forecasts and collected observations by 
teleprinter within their own network of Bomber 

The techniques of meteorological observing have 
changed surprisingly little since 1939-45 although the 
code forms and communications are now far superior 
and there are more automatic instruments. The wartime 
observer had no distant-reading thermometers and had 
to visit the enclosure every hour. He (or, in many cases, 
she) had no cloud-base recorder but did have a cloud 
searchlight, and the observation of cloud amounts, 
types and heights at night was made more difficult by the 
lack of reflected urban or industrial lighting due to the 
strict black-out regulations. 

It is in the field of forecasting that the major changes 
have occurred. During the Second World War not only 
were there no numerical products, no satellite imagery 
and no weather radar imagery but operational forecasters 
were just beginning to experiment, in the early part of 
the War, with thickness fields and Sutcliffe development 
ideas (Sutcliffe 1947). The upper-air charts were hand- 
plotted, laboriously hand-drawn and then ‘gridded’ to 
produce the final surface prognosis. 

At this time the Hurricane and Spitfire had proved 
their worth as fighters in the Battle of Britain but the 
Battles, Defiants, Hampdens, Whitleys, Wellingtons 
and Manchesters of Bomber Command were to be 
woefully inadequate as the bomber force until the 
arrival of the Stirlings and Lancasters (Fig.6) in 
sufficient numbers later in the War. Coastal Command’s 
Sunderland flying boats were the only really long-range 
reconnaissance aircraft in the early days until they were 
joined by Liberators and Catalinas on Lend-Lease from 
the USA. These, and the Bomber aircraft, carried out 
long flights with only sketchy forecasts derived from 
sparse information until regular observations, not only 
from our own side but also from interceptions of the 
enemy’s data, improved matters. 

Fighter aircraft could operate from the surface to 30 000 ft, 
whilst photo-reconnaissance aircraft were reaching 
nearly 40000 ft. The night bombing offensive was 

Meteorological Magazine, 118, 1989 


Photograph by courtesy of RAF Museum, Hendon 

Figure 6. Avro Lancasters on a Second World War bombing 
mission (circa 1943). 

mainly carried out at around the 18 000-24 000 ft level 
whilst the daylight interdiction raids might be just above 
the hedge-tops. The long, and often boring, maritime 
reconnaissance flights were usually flown at around 
1500-2000 ft and should be compared with the luxury of 
the (normally) smooth stratospheric flights of the 
modern passenger aircraft. These aircraft also made 
vitally important meteorological observations far out 
over the Atlantic. The perils of carburettor icing, or of 
leaving a condensation trail to mark one’s position in the 
sky, were real problems for wartime aviators. It is 
interesting to note that the ‘mintra’ line on today’s 
tephigram is still the one originally calculated from the 
combustion characteristics of a Spitfire engine! 

The network of upper-air measurements too, was 
rudimentary early in the War and it was only when large 
losses had been suffered by the Bomber Force as a result 
of scattering due to unforseen or badly forecast jet 
streams that an Upper Air Forecast Unit was set up at 
Bomber Command Headquarters. This was to ensure 
that all the airfields used the same flight winds. It meant 
that, even if they were in error, at least the bomber 
streams would stay together and thus be better able to 
defend themselves. On some occasions when different 
winds from different stations had been used by 

navigators of varying abilities the subsequently scattered 
streams of bombers had suffered enormous losses from 
enemy night-fighters. The introduction of the Pathfinder 
Force in 1942, with expert navigators and a single 
controlling ‘Master Bomber’, did much to ameliorate 
the problems and the enormous losses. It is a sobering 
thought, when one views the relative ease with which a 
24-hour numerical wind prognosis can be produced 
today, to remember just what the Bomber Command 
upper-air forecaster was trying to produce, by manual 
methods and with variable data (both in quality and 
quantity). He alone in the Meteorological Office at that 
time, knew the target, but everybody knew that if he 
made an error, the Bomber Force might stray over a 
heavily defended area with the possible consequence of 
high losses. There have always been pressures on 
forecasters but those of the Second World War period 
were, clearly, quite exceptional. 

4. 1945 to the present day 

At the end of the War, some 90% of the Meteorological 
Office staff of 6760 were in uniform. Demobilization 
started almost immediately as did the reorganization of 
the various Branch responsibilities. By May 1946 M.O.5 
was responsible for the Royal Air Force overseas 
(including the British Air Force of Occupation in 
Germany) and M.O.8 dealt with the Army, the Ministry 
of Supply and Training Command, leaving M.O.6 to 
deal with the remainder of the Royal Air Force in the 
United Kingdom. The advent of pure jet fighters 
(Vampire, Venom, Meteor, Hunter and Swift) with their 
relatively short endurances increased the emphasis on 
short-range forecasting. By 1952 M.O.6 was beginning 
to take on something of today’s shape. In that year the 
last piston-engined front-line bombers, a squadron of 
Avro Lincolns (descendants of the wartime Lancasters) 
was detached to Kenya to assist in the control of the 
Mau Mau uprising. Pure jet aircraft were also making 
their mark on endurance flying and on 17 December 
1953 an English Electric Canberra B Mk2 broke the 
London-—Cape Town record by flying 6010 statute miles 
in 12 hours 21 minutes at an average speed of 
486.6 m.p.h. in celebration of the 50th anniversary of the 
Wright Brothers’ first flight. Forecasting for such 
distances was a taste of things to come! January 1955 
heralded the debut of the first of the long-range ‘V’ 
Bombers — the Vickers Valiant — to No. 138 Squadron 
at Gaydon in Warwickshire. 

Further reorganization took place in October 1955 
when the responsibility for the supply of all meteorol- 
ogical information to the Army and the Royal Air Force 
came under the jurisdiction of M.O0.6. M.O.5 then 
became the Communications Branch, while M.O.7 took 
over responsibility for civil aviation and M.O.8 was 
tasked with looking after rainfall matters. There were 
two major military occurrences of note in the mid-1950s. 
Firstly, in October 1956, the Suez Invasion (Operation 
Musketeer) took place and some Meteorological Office 


Meteorological Magazine, 118, 1989 

personnel once again put on Royal Air Force uniforms 
to advise military commanders, in the field, of the 
meteorological aspects of operations. The second was 
the dropping of Britain’s ‘H-bomb’ near Christmas 
Island (Operation Grapple) in May 1957. At the peak of 
activity there were some 31 Meteorological Office 
personnel, under a Principal Scientific Officer, detached 
to the Pacific. There were also frequent trouble-spots in 
the 1960s in various parts of the world (Kuwait, Zambia 
and Borneo) that required some degree of additional 
meteorological support for the military. As a result of 
these, and of Suez in 1956, a review of tactical doctrine 
took place in the Services resulting in an emphasis on 
mobility and reducing the dependence upon fixed bases. 
The formation of the Mobile Meteorological Unit 
(MMU) was a direct consequence of this review. The 
MMU is a small group of Meteorological Office 
volunteers commissioned into the Royal Air Force 
Reserve specifically to provide environmental data and 
advice in forward areas. 

The 1950s and 1960s also saw what was, probably, the 
peak of M.O.6 world-wide activities when there were 
staff from the Branch at many locations. These were in 
Germany, the Mediterranean, the Near East, Africa, the 
Persian Gulf, the Indian Ocean and the Far East. 
However, from then onwards Government policy was to 
progressively concentrate UK forces in support of the 
North Atlantic Treaty Organization. For example, 
Habbaniyah (near Baghdad) closed in May 1959 and a 
Senior Experimental Officer post was established in 
support of | (BR) Corps, Germany in April 1960. Some 
of the fruits of M.O.5’s labours came about in 1962 when 
all the M.O.6 offices in the United Kingdom were 
connected to the national facsimile broadcast (NATFAX) 
for the first time. Confusion had also arisen between the 
abbreviations for the Meteorological Office and for 
Military Operations — both ‘M.O.”. It was therefore 
decreed that the Meteorological Office should be 
shortened to ‘Met O’ — the current ‘Met O 6’ title had 
finally come into existence. 

In the late 1960s and early 1970s there were a number 
of organizational changes as the military withdrawal 
from east of Suez took place. The meteorological offices 
in Aden and Borneo were closed in 1967, El Adem in 
1970, Sharjah in 1971, Gan in 1976 and Malta in 1978. In 
1968 Transport Command became Air Support Command, 
Bomber and Fighter Commands became Strike Command, 
and Flying and Technical Training Commands amalgam- 
ated to form Training Command. Coastal Command 
was eventually subsumed into Strike Command in 1969. 
All these changes had to be mirrored by consequent 
changes in Met O 6. There were, similarly, a significant 
number of closures of UK meteorological offices as cuts 
in the Defence Forces began to bite. For example, 
Manby was closed in 1974, Abingdon in 1975, West 
Raynham (for a second time), Andover, Little Rissington, 
Ternhill and Thorney Island all in 1976, and Pershore 
and Fairford in 1977. 

Simultaneously there were communications develop- 
ments with the introduction of a number of dedicated 
military meteorological broadcasts such as the Strike 
Command facsimile broadcast (STRIFAX), the Strike 
Command teleprinter meteorological broadcast (STRI- 
MET), the RAF Strike Command Weather Aciual 
System (STCWAS) and the Transport Command 
meteorological facsimile broadcast (TRANFAX). 
Numerical weather prediction products of increasing 
sophistication were being introduced on the Meteorological 
Office national facsimile programmes at this time. 

Also during this period a number of events took place 
which can be seen as bringing the history of Met O 6 up 
to the present day. In July 1974 Turkey invaded Cyprus. 
Quite coincidentally, a detachment of the MMU was on 
exercise on the island and was able to provide additional 
support to the ex-patriot staff after the locally employed 
staff had experienced difficulties in being able to report 
for duty. A sad occasion took place at Akrotiri in 
December 1977 when an aircraft crashed on to the 
meteorological office causing a number of fatalities and 
serious injuries. However, such was the resilience of the 
remaining staff (both UK based and locally employed) 
that a meteorological service was resumed to the 
military authorities within a few hours. 

Easter 1982 saw the start of events in the South 
Atlantic which culminated in the Falklands Campaign 
(Operation Corporate) and the subsequent demanding 
meteorological requirements on the Falkland Island 
and Ascension Island. Met O06 was involved within 
hours of the Argentine invasion. A vast amount of rapid 
organization was required and provided (Pothecary and 
Marsh 1983). It is fair to say that the experience at all 
levels in MetO6 (and much of the rest of the 
Meteorological Office) in world-wide meteorological 
tasks over many years allowed not only a valuable and 
rapid response to the requirements of the military 
(Fig. 7) but also the comment that, meteorologically 
speaking, the South Atlantic was just another place! The 
MMU played an invaluable role in this operation, 
setting up makeshift meteorological offices and working 
in very demanding conditions, both on Ascension Island 
and, eventually, at Port Stanley Airfield. This expert 
and immediate response by the Office was recognized by 
a number of awards and decorations. 

For some years the abilities of the meteorologist to 
assist the military non-aviator had gone largely 
untapped. Over the years, however, the military 
appreciation of good environmental support has 
increased sharply. Warfare, both in the air and on the 
ground, is becoming daily more scientific and the 
requests placed before the meteorologists today will 
require increased skill and ingenuity if they are to be 
properly met. Several decades ago a major challenge 
was the accurate forecasting of upper-level winds — 
today it is the forecasting of very low cloud and visibility 
and the provision of expert advice concerning the 
impact of the weather on the operation of electro-optical 

Meteorological Magazine, 118, 1989 


Photograph by courtesy of RAF Museum, Hendon 

Figure 7. Avro Vulcans of the type used on the Port Stanley 
Airfield raids in 1982. 

systems such as infra-red weapon sights and night-vision 
goggles. In all cases the meteorologist is working at the 
extremes of meteorological knowledge and capabilities. 
Life for the meteorologist serving the military is never 
dull and does not look as if it ever will be. 


The assistance of both present and retired members of 
the Meteorological Office in compiling this article is 
gratefully acknowledged. 


Meteorological Office, 1919: Annual Report of the Meteorological 
Committee. London, HMSO. 

Pothecary, I.J.W. and Marsh, J., 1983: Meteorological and oceano- 
graphic support during the Falklands conflict. Jn Conference 
proceedings No. 344, Space system applications to tactical operations. 
Neuilly sur Seine, France, NATO AGARD. 

Stagg, J.M., 1971: The Forecast for Overlord. Shepperton, Surrey, 
lan Allen Ltd. : 

Sutcliffe, R.C., 1947: A contribution to the problems of development. 
QJ R Meteorol Soc, 73, 370-383. 

Turton, J.D. and Caughey, S.J., 1989: Defence Services Branch 50th 
Anniversary. Part II: Current commitments and the future. 
Meteorol Mag, 118, 168-175. 


Defence Services Branch 50th Anniversary. 
Part Il: Current commitments and the future 

J.D. Turton and S.J. Caughey 
Meteorological Office, Bracknell 


This paper describes the services currently provided by the Meteorological Office Defence Services Branch to the 
Armed Forces, Ministry of Defence (Procurement Executive) and other government departments, with emphasis 
on developments in advice for the use of new technologies employed by the Forces and civil emergency services. The 
meteorological response to chemical and nuclear emergencies is also discussed. 

1. Introduction 

In the accompanying article (Caughey and Davies 
1989) a brief history of services for the Armed Forces is 
given. This paper describes those services currently 
provided by the Meteorological Office Defence Services 
Branch (Met O 6) for the Armed Forces, Ministry of 
Defence (Procurement Executive) (MOD(PE)) and 
other government departments. Support for the Armed 

Forces is given primarily to the Royal Air Force (RAF) 
and the Army, although the Royal Navy also relies on 
the Meteorological Office for basic meteorological 
information. In recent years there has been an increasing 
emphasis on the MOD(PE) range activities, in developing 
advice for the new technology employed by the Forces 
and in the area of civil emergency planning. These 


Meteorological Magazine, 118, 1989 

services currently account for about 40% of the total 
cost of the Meteorological Office and employ around 
25% of its manpower. 

2. Services for the RAF 

Services for the RAF currently involve personnel 
based at over 50 stations in the United Kingdom, 
Federal Republic of Germany, the Mediterranean and 
the South Atlantic. On-site forecasters are established to 
provide meteorological advice for both operational and 
non-operational activities. The operational activities 
include air defence, reconnaissance, air transport and 
air training tasks for which forecasts, warnings, and 
information on the actual weather are required. In 
particular, short-period forecasts of detailed boundary- 
layer conditions, especially cloud and visibility, are 
crucial for the increasing volume of low-level flying 
undertaken by the RAF. This entails regular briefings to 
aircrew, of which over 200 000 were given during 1988. 
Forecasts are also provided for other RAF units such as 
radar stations, weapons ranges and signals units. 

The Principal Forecasting Office (PFO) at Headquarters 
Strike Command (HQSTC) provides technical forecasting 
advice to most Met 06 offices. The PFO prepares 
specialized flight documentation (e.g. low-level significant 
weather and wind charts) and guidance on broad-scale 
developments. Recently the PFO was relocated into the 
newly constructed Primary War Headquarters (PWHQ) 
at HQSTC. Within the United Kingdom there are three 
Main Meteorological Offices (MMOs) who, with the 
PFO, are responsible for the forecasting offices at RAF 
airfields. At a number of these airfields, facilities known 
as Wing Operations Centres (WOCs) have been built. 
Each WOC includes a Meteorological Cell which is 
manned by Meteorological Office staff during exercises. 

Similar facilities also exist for Meteorological Office 
staff at RAF stations in the Federal Republic of 
Germany. A Mobile Forecasting Unit (MFU), staffed 
by Meteorological Office personnel, is also established 
to support the Harrier Force there (Fig. 1). 

Overseas there are MMOs at Gibraltar and in Cyprus, 
to provide meteorological advice for operations in the 
Mediterranean. In 1986 a permanent forecasting office 
(an MMO) was established at RAF Mount Pleasant, 
Falkland Islands (Fig. 2). This office now provides the 
meteorological information required by all three 
Services for operations in the South Atlantic theatre. 

The Mobile Meteorological Unit (MMU) forms part 
of the RAF Tactical Communications Wing and its 
purpose is to provide forecasts and meteorological 
advice for exercises in areas where there is no nearby 
meteorological service. The MMU is manned by 
volunteers from the Meteorological Office who hold 
active Civil Conditions Commissions in the RAF 
Reserve, and may be deployed anywhere in the world in 
support of the Armed Forces. The MMU was deployed 
during the Falklands conflict, as described in Caughey 
and Davies (1989). 

On the non-operational side, Met 06 staff provide 
basic training in meteorology to RAF personnel at the 
Flying Training Schools. Some 3700 hours a year are 
involved in teaching, and the setting and marking of 
examination papers, for students who may end up as 
pilots of fast jets, transport aircraft, helicopters, or as 
navigators or air engineers. The subjects taught cover 
those relevant to flying, such as the characteristics of air 
masses, visibility, thunderstorms and icing. Also some 
training in observational techniques is given to air traffic 
control staff, who may be required to make observations 
at stations where there is no meteorological office. The 
initial training is given at the Meteorological Office 
College, Shinfield Park followed by practical experience 
on an operational airfield before the student is awarded 
a certificate of competence. 

3. Services for the Army 

The Army Air Corps (AAC), which operates 
helicopters and light aircraft, also has a requirement for 
close meteorological support. In particular it has a 
growing need for advice relating to the use of various 
weapon systems and night-vision aids. Support for the 
AAC is provided at its UK airfields and at Detmold in 
the Federal Republic of Germany, where the Staff 
Meteorological Officer (SMO) for 1(BR) Corps is 
established. The SMO deploys with the Corps on field 
exercises and is supported by an MFU. This involves 
adopting a somewhat ‘outdoor’ life-style — most staff 
agree that Army food has improved over the years! 

The Army artillery is also very dependent upon 
meteorology, and the forecasting office at the Royal 
School of Artillery (RSA) Larkhill provides ballistic 
forecasts for the Army training camps in the United 
Kingdom. Larkhill also produces acoustic forecasts 
to predict gun noise, so as to help minimize noise 
disturbance to the community living around the ranges, 
as discussed more fully later. Since 1986 a forecaster has 
been based at the Royal Artillery range, Hebrides. This 
forecaster has a vital job in the planning and execution 
of trials, both near to the shore and out into the Atlantic. 
The trials include test firings of ground-to-ground 
missiles (Fig. 3) and warship training against approaching 
anti-ship missiles. 

4. Services for the Royal Navy 

Since 1937 meteorological services for the Royal 
Navy have been provided by the Directorate of Naval 
Oceanography and Meteorology (DNOM). Close liaison 
between Met O06 and the Royal Navy, in particular 
between the PFO at HQSTC and the Fleet Weather and 
Oceanographic Centre (FWOC), Northwood, is main- 
tained. The Royal Navy, however, relies on the 
Meteorological Office for routine forecast information 
from the operational numerical models and other more 
specialized support, e.g. wave charts and surface 
evaporation-duct forecasts (Turton, Bennetts and Farmer 

Meteorological Magazine, 118, 1989 


Figure 1. 

RAF Harrier on exercise in Germany. 

Figure 2. 

5. Services for MOD(PE) 

A number of forecasting offices are situated at MOD 
trials establishments. The role of these stations is to give 
the meteorological input needed for decision making 
relating to the safety and success of trials, and to provide 
the relevant meteorological data for post-trial analysis. 
The offices at the Proof and Experimental Establishment 
(P&EE) ranges at Shoeburyness and Eskmeals provide 
the meteorological information needed for proof testing 
of ammunition. Shoeburyness also gives support to the 
Atomic Weapons Establishment (AWE) explosives 
testing ground at Foulness. The office at the Royal 
Aerospace Establishment (RAE), Aberporth provides 
meteorological advice for the various trials held on the 
range in Cardigan Bay and at the nearby P&EE range, 

The Main Meteorological Office at Mount Pleasant Airport, Falkland Islands. 

Pendine. Here some specialized facilities are needed, for 
example accurate monitoring of rainfall is required in 
trials of weapon fuse mechanisms (Hewston and Sweet 
1989). The office at RSA Larkhill, in addition to giving 
meteorological assistance to the Army, also provides 
support to RAE Larkhill and the Chemical Defence 
Establishment (CDE), Porton for its various trials. Full 
upper-air sounding facilities are established at the 
Eskmeals, Shoeburyness, Aberporth and Larkhill offices. 

One of the tasks of these stations is the provision of 
acoustic forecasts to predict the levels of noise, resulting 
from explosions or gunfire, around the ranges (Turton, 
Bennetts and Nazer 1988). This is important to minimize 
public disturbance and to avoid complaints, whilst 


Meteorological Magazine, 118, 1989 

Reg ot 
spp eae 
ee? : 
ae ee 
> : mee - 0 
* i 
; PP ii 
‘ pa # 
<4 5 
P > 
IE 4 
- i 
| : \ 
+4 ; 

Figure 3. Rocket firing in trials at the Royal Artillery range, 

maximizing the use of the range facilities. Fig. 4 shows 
an example of an acoustic forecast for gun noise from 
Larkhill. An unusual feature in this case was that the 
reports of noise occurred in an upwind direction from 
the guns and were due to focusing rather than the more 
usual downwind noise enhancement. However, the 
relation between the predicted and reported sound 
patterns is seen to be reasonably good in the upwind 

Met O 6is currently collaborating with the University 
of Salford and CDE Porton in a research programme 
sponsored by MOD(PE) Safety Services Organization 
to develop improved methods for predicting impulsive 
noise. The programme includes the development of a 
new acoustic model, based on more realistic acoustic 
and meteorological theory, for operational use at the 
ranges. Also, instrumentation for remote monitoring of 
the noise levels around the ranges is being developed. 
Attention is also turning to the prediction of sound from 
continuous noise sources such as aircraft. 

Figure 4. Acoustic forecast showing predicted noise levels in 
decibels. The shaded and hatched regions indicate areas where the 
gunfire was reported to be ‘very loud’ and ‘loud’ respectively. 

6. Services for the United Kingdom 
Warning and Monitoring Organization 

The UKWMO, which is part of the Home Office, is 
responsible for providing warning of an air attack and 
monitoring any subsequent nuclear fall-out. Knowledge 
of the meteorology is essential for the prediction of the 
spread and intensity of the fall-out. The Meteorological 
Office provides forecasters for the UKWMO sector 
controls, each of which has responsibility for a 
particular region. Regular exercises to test the network 
are held, for which Met 06 provides meteorological 
data from which a fall-out pattern is determined. 

7. Emergency planning 

The Defence Services Branch is responsible for 
formulating the meteorological response to nuclear and 
chemical emergencies. These are considered according 
to the location of the incident and the nature of the 
hazardous material involved. 

7.1 Nuclear accidents within the United 

The Department of Energy is responsible for co- 
ordinating the national response to a civil nuclear 
accident within the United Kingdom. The Ministry of 
Defence is responsible for co-ordinating the response to 
any nuclear accident which may occur at a Defence 
establishment or base, or to nuclear powered warships 
or to Defence nuclear weapons, reactor or materials 
whilst being transported. The spread of debris from such 
an accident is highly dependent on the meteorological 
conditions and Met O 6 was responsible for developing 

Meteorological Magazine, 118, 1989 


the procedures known as PACRAM (Procedures And 
Communications in the event of a release of RadioActive 
Material) to ensure that the appropriate meteorological 
advice is available. Each nuclear establishment is 
associated with a designated Meteorological Office, 
where arrangements for the provision of advice on 
weather conditions and the movement and dispersal of 
released material have been agreed. This involves an 
initial forecast by the designated Meteorological Office 
of those factors (e.g. wind speed, mixed-layer depth and 
stability) which are used to define the initial spread of 
the plume. The Central Forecasting Office at Bracknell 
would then be notified and a forecast forward trajectory 
computed from the fine-mesh model. 

7.2 Nuclear accidents overseas 

Foliowing the reactor accident at Chernobyl, the 
Office has played a significant role in the development 
of the Government’s National Response Plan (NRP) 
which arranges for departments and agencies to react to 
international nuclear incidents. Her Majesty’s Inspectorate 
of Pollution (HMIP), part of the Department of the 
Environment which has responsibility for co-ordinating 
the response to an overseas accident, has equipped 46 
Meteorological Office observing sites with gamma 
radiation monitors (HMIP 1989). This network (Fig. 5) 
is known as the Radioactive Incident Monitoring 
NETwork (RIMNET). The gamma radiation measure- 
ments are made by Office staff and passed hourly to 
Bracknell where they are automatically sorted and re- 
transmitted to HMIP’s computer databases in London 
and Lancaster. 

In order to ensure rapid notification of any future 
accident internationally the World Meteorological 
Organization (WMO) and the International Atomic 
Energy Authority have agreed that the WMO Global 
Telecommunication System may be used to provide 
initial warning and information. This message would be 
received at Bracknell, HMIP alerted and the NRP 
activated if appropriate. A Technical Co-ordination 
Centre staffed by officials from various government 
departments, including the National Radiological Protect- 
ion Board and the Meteorological Office, would assess 
the effects of the incident on the United Kingdom, assist 
ministers and keep the public and media informed. 

The Meteorological Office would also run a nuclear 
accident response model which would draw on meteor- 
ological and radiological data to predict the movement 
of radioactive material across the United Kingdom and 
the pattern of both wet and dry deposition. This model 
includes those factors that were found to be significant 
following the Chernobyl accident (Smith 1988). 

7.3 Chemical emergency 

Hazardous volatile chemicals are stored at thousands 
of sites throughout the country. In the event of a spillage 
or leak, meteorological factors will play a large part in 
determining the area affected. Detailed procedures 

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Figure 5. Locations of the RIMNET sites. 

(CHEMET — CHEmical METeorology) have been 
developed to help cope with the handling of chemical 
accidents. Each MMO (and some Weather Centres) is 
allocated an area of the United Kingdom; if the office 
receives notification that an accident has occurred 
within this area then the CHEMET procedure is 
activated. The essence of the CHEMET service is the 
provision of timely advice on the dispersal and track of 
released chemicals to the Police, who will pass this 
information to the other emergency services (Fire and 
Ambulance) so that appropriate action can be taken. 

8. North Atlantic Treaty Organization 

Met O 6 staff represent the United Kingdom on the 
NATO Military Committee Meteorology Group(MCMG) 
and the Supreme Headquarters of the Allied Powers in 
Europe (SHAPE) Meteorological Committee. These 
groups co-ordinate the provision of meteorological 
support to NATO forces in peacetime and develop 
appropriate contingency arrangements for crisis situat- 
ions. The needs of major NATO commanders are 
considered against the facilities and services provided by 
the nations of the Alliance. The MCMG also provides a 
forum for those concerned with the provision of 


Meteorological Magazine, 118, 1989 

meteorological support to the Armed Forces to meet 
and discuss advances in techniques and facilities 
developed by any one nation, leading to benefits for 

In addition, Met O 6 represents the United Kingdom 
on the NATO Armies Armaments Group (NAAG) 
Independent Special Working Group No. 3) (ISWG. 3) 
on Meteorology, the Target Area Meteorology Instru- 
mentation and Analysis (TAMIA) and the Civil 
Defence Committee (CDC) groups. ISWG. 3 is concerned 
with the provision of meteorological data to the Alliance 
Armies for a wide range of uses, e.g. to provide ballistic 
messages for the use of artillery in the field. The TAMIA 
group is addressing the problems of the acquisition, 
processing and use of meteorological data from the 
battlefield. These data will be required for use in new 
Tactical Decision Aids (TDAs) which are being 
introduced. The CDC is involved with defining the 
areas at risk from the use of chemical (or biological) 

9. New developments 

In recent years the Defence Services forecaster has 
had access to a wider variety of products as improvements 
in the forecast models and communication systems have 
been made. A new communication and information 
system — the Weather Information System (WIS) — 
which will provide high-speed digital links to forecasting 
offices is under development. A simplified form of this 
facility, known as Outstation Display System (ODS), 
where stations are being equipped with microcomputers 
to give them rapid access to processed data and forecast 
products is under way (Cluley and Hills 1988). This is 
enabling them to provide more accurate and detailed 
weather information and forecasts. The improvement in 
the meteorological service, due to more rapid access to 
observational data, has been very significant indeed. To 
date, some 18 offices have had ODS installed; it is 
expected that all offices should have the full WIS by the 
early 1990s. 

As this new equipment is being introduced the 
Defence Services forecasters are at last getting timely 
access to basic meteorological data, of a range and 
quality that enables them to carry out the demanding 
and time-critical local forecasting task. However, as new 
technology and equipment are being introduced by the 
Services, the role of the forecaster is expanding. No 
longer are they required just to give information on the 
general weather characteristics, but increasingly they 
are being asked to provide advice on how weather will 
affect the new technology being employed by the Armed 
Forces. These new developments demand that meteor- 
ologists have a good understanding of the new 
technology and that they combine this knowledge with 
accurate meteorological forecasts and data to provide 
the most useful advice to Force Commanders. 

In particular, the effects of weather on radar 
propagation, electro-optic systems and the movement of 

troops and equipment are areas currently being studied. 
Forecasters are being asked to provide detailed 
assessments of the impact of meteorological conditions 
on the performance of these systems and the movement 
of resources. To assist them, computer programs and 
models are being tested and developed. These TDAs 
provide the military commanders with the specific 
information which is needed to assist in tactical 

For example, electro-optic imaging and ranging 
devices are becoming more widely used as they 
overcome many of the problems associated with night 
flying, especially in poor weather conditions. Both the 
RAF and the AAC use night-vision goggles (NVGs) for 
night flying, but these devices will only work when the 
ambient light exceeds a certain threshold level. The light 
incident at the top of the atmosphere depends upon the 
positions of the sun and moon relative to the earth. 
However, the amount of light that actually reaches the 
surface is reduced because of scattering and absorption 
by aerosol and water particles in the atmosphere, in 
particular by cioud and rain. The ambient light-level 
also includes a contribution due to ‘cultural’ lighting; 
this is light from towns and cities which is reflected back 
by clouds. Fig. 6 shows an example of how the light 
levels during a night can be affected by the passage of a 
frontal system when the light level remains low until the 
frontal cloud cleared by 0100, after which time the light 
increased. Consequently the use of NVGs would have 
been, at best, marginal until this time. 

Thermal-imaging devices are also being fitted to 
many aircraft; although these also provide ‘night vision’ 
they do not have an all-weather capability. Cloud and 
rain can obscure the image and reduce the range at 
which targets can be detected to an unacceptable limit. 
Computer models which combine the characteristics of 
such sights with the relevant weather information and 
then predict the performance parameters for such 
devices (e.g. target detection and lock-on ranges) are 
currently being evaluated by Met O 6. 

80 - 

Sky clears 


50 F / 
Moonrise / 

Clear-sky ¥ 
levels 7 

40 + 


Ilumination (mix) 

20 / 

10 fe 

* - 
——- ° 

0 = os 
17 18 19 20 21 

22 23 00 01 O02 O03 
Time (hours) 

04 05 06 

Figure 6. An example of the way in which the passage of a frontal 
system can alter the natural illumination levels at night; for 
comparison the clear-sky levels are also shown. A moon phase of 75% 
was specified with moonrise at 1930 and a front clearing by 0100. 

Meteorological Magazine, 118, 1989 


Radars are employed on a wide variety of tasks and 
platforms by the Armed Forces. It is well known that the 
coverage of radar systems can be severely affected by the 
atmospheric conditions (Turton, Bennetts and Farmer 
1988). Under some circumstances part of the radar beam 
can be trapped, forming a duct with coverage out to 
exceptionally long range. However, above the duct there 
is a region where less radar energy penetrates, such that 
targets may escape detection. This is illustrated in Fig. 7, 
where a radar coverage in ducting conditions is shown 
alongside the ‘normal’ coverage of the same radar; here 
the differences are due solely to the atmospheric 

Weather also affects the mobility of Army ground 
forces. Previously, assessments of manoeuvrability were 
made manually by Force Commanders using all the 
information available to them. This is a formidable task 
and is well suited to computerized techniques. Detailed 
databases for evaluating the military options are being 
developed in the Army TERAS (TERrain Analysis 
System) programme. TERAS will consist of a detailed 
topographic database and climate information, together 
with environmental and battlefield data. The environ- 
mental data, which includes meteorology, is a vital part 
of TERAS and will require the forecaster to regularly 
update and amend the meteorological input. It is 
expected that the various TDAs as discussed above will 
eventually be incorporated into TERAS. 

10. Concluding remarks 

Part I (Caughey and Davies 1989) of this article gave a 
description of the way in which services for Defence 
have developed in the Meteorological Office, since its 
inception to the present day. Major developments in 
these services occurred in order to meet the demands of 
the military during the two World Wars. Just before the 
Second World War, the Defence Services Branch was 

Height (feet) 

Range (nautical miles) 



formed. Since then, the Branch has been involved in 
providing meteorological assistance to the Forces 

This paper has discussed the wide range of services 
currently provided for the Armed Forces, MOD and 
other government departments. In recent years advances 
in computer technology have changed the face of 
operational meteorology. As forecast models have 
become ever more sophisticated with higher resolutions, 
the accuracy of their predictions has improved signific- 
antly. High-speed communications (e.g. WIS) are 
already giving outstation forecasters rapid access to a 
wider array of observational data and forecast products, 
enabling them to give much more accurate meteorolog- 
ical advice. 

Another development that is likely to prove important 
in forecasting is the development of artificial intelligence 
and expert systems. The latter are computer programs 
which can apply reasoning and judgement to a 
particular problem. Already, pilot projects on expert 
systems for predicting precipitation and thunderstorms 
are under way at the Meteorological Office (Conway 
1989). Such techniques are potentially of great benefit to 
the Defence Services forecaster. 

New technology is also being employed by the 
Services (e.g. electro-optic imaging and ranging devices). 
However, the performance of such equipment is weather 
sensitive, and the forecaster is being asked to give advice 
on the use of this equipment. Computer programs and 
models (TDAs) are being introduced to assist the 
forecaster in this area. Another key area of current 
concern is the acquisition of meteorological information 
from data-sparse or battlefield areas, required as input 
to the meteorological forecast models, the TDAs and 

Given improved observational data, better numerical 
forecast models, forecasting algorithms and artificial 

5000= - — _ 

40004 ~ — _ 

30004 — ~ 

2000 + 

Height (feet) 

Range (nautical miles) 

Figure 7. Radar coverage diagrams in (a) normal and (b) ducting conditions, where a surface-based duct 1000 ft deep was specified with the 

radar at 750 ft height. 


Meteorological Magazine, 118, 1989 

intelligence systems, the demanding local forecasting 
task of the Defence Services forecaster will become 
more tractable. However, there is an increasingly 
important need for advice relating to the impact of 
meteorology on military equipment and operations. The 
preparation and dissemination of this type of advice will 
demand the adoption of new skills and computer 
techniques. The most effective presentation of these new 
products to the user will require excellent links between 
Meteorological Office (WIS) and military automatic 
data processing facilities. As far as one can judge, the 
outstation meteorologist will continue to have an 
expanding and important role in support of the Forces, 
assisting them to conduct vital operations and exercises 
in the years ahead. 


Caughey, S.J. and Davies, P.W., 1989: Defence Services Branch 50th 
anniversary. Part I: Historical aspects. Meteorol Mag, 118, 

Cluley, A.P. and Hills, T.S., 1988: Meteorological Office Outstation 
Display System: from concept to reality. Meteorol Mag, 117, 1-12. 

Conway, B.J., 1989: Expert systems and weather forecasting. 
Meteorol Mag, 118, 23-30. 

Hewston, C.M. and Sweet, S.H., 1989: Trials use of a weighing 
tipping-bucket rain-gauge. Meteorol Mag, 118, 132-134. 

HMIP, 1989: The National Response Plan and Radioactive 
Incident Monitoring Network (RIMNET). Phase I. Nuclear 
accidents overseas. Department of the Environment, HMSO. 

Smith, F.B., 1988: Lessons from the dispersion and deposition of 
debris from Chernobyl. Meteorol Mag, 117, 310-317. 

Turton, J.D., Bennetts, D.A. and Farmer, S.F.G., 1988: An 
introduction to radio ducting. Meteorol Mag, 117, 245-254. 

Turton, J.D., Bennetts, D.A. and Nazer, D.J.W., 1988: The Larkhill 
noise assessment model. Part I: Theory and formulation. Meteorol 
Mag, 117, 145-154. 


Westward-moving disturbances in the South 
Atlantic coinciding with heavy rainfall events at 

Ascension Island 

B.A. Hall 
London Weather Centre 


Easterly atmospheric waves in the northern hemisphere have been well documented but much less is known about 
similar features in the southern hemisphere. A study of upper-wind time cross-sections maintained at Ascension 
Island during the early part of 1986 suggests that features with similar characteristics to easterly waves affected the 
island, probably triggering several heavy rainfalls which occurred during that time. Some evidence is produced that 
the 15-level model of the Meteorological Office is able to reproduce these disturbances. 

1. Introduction 

Ascension Island is situated at 8°S, 14° W in the 
South Atlantic (Fig. 1). It is a small isolated island, 
1450km from Africa, over 1600km from South 
America and | 100 km north-west of its nearest neighbour 
and mother colony, the island of St Helena. In recent 
years Ascension Island has played an important role as a 
staging post between the United Kingdom and the 
Falkland Islands. 

All available literature about the climate of Ascension 
Island (see Hodges (1985) for a comprehensive list of 
references) and the experience of Meteorological Office 
staff based on the island (Brenchley 1986) indicates that 
Ascension Island has a very pleasant tropical climate. It 
is predominantely dry, apart from (in some years) spells 
of ‘drizzly’ showers, sometimes several such spells 
occurring over a period of a month or more. However, 
in some years there are infrequent rainstorms occurring 
mostly in March and April. Table I shows some of the 
heavy rainfalls reported on Ascension Island. It should 

- Equator 
Rio de Janeiro 
Buenos Aires 
0 1000 2000 3000 
Kilometres 0 
Figure 1. Location of Ascension Island. 

Meteorological Magazine, 118, 1989 


Table |. Heavy rainfall reported on Ascension Island 
Year Month Event 
(if known) 

1831 _ ‘Dampier’s tank**’ damaged by heavy rains. 

1859 June ‘Great rains’, 9 inches (229 mm) in a day 
with damage to roads and crops. 20 inches 
(508 mm) fell in June and 108 inches 
(2743 mm) were recorded in the year at 
Green Mountain (see Farm Site Fig. 2). 

1864 April Very heavy rainfall, thunder and lightning. 

1887 April Great damage to roads. Yearly total 56 
inches (1422 mm) at Green Mountain. 

1896 _ ‘Unusual thunderstorm’, Capt. Napier’s 
Japanese steward ‘revived by a good 
brandy’ after being struck down when the 
overhead telephone wire was hit by 

1899 May Heavy rainfall. 

1909 April Heavy rainfall. 

1924 April ‘Freak’ rains; 5.62 inches (143 mm) fell at 
Georgetown during the month. Waist-high 
grass over low ground and a plague of 

1934 April Torrential rains, an ‘astonishing 
cloudburst’ —209.6 mm fell in 12 hours 
29/30 April at Georgetown. 

1950 March 75 mm of rain during the month at 

1963 March ‘Great rainstorm’; 96.5 mm fell on 
29 March at Georgetown. Extensive 
damage to roads, cemetery flooded, 

1964 April 95 mm of rain during the month at 

1974 March 90 mm of rain fell during the month at 

1978 -- Annual rainfall total at Two Boats village 
48.5 inches (1232 mm). 

1979 April 80 mm of rain fell during the month at the 
Pan Am site at Wideawake Airfield. 

1984 March 317 mm of rain during the month at the 
RAF base at Wideawake Airfield. Runway 
closed on 4 March due to erosion and 
boulders; road damage. 

1985 April 538 mm of rain measured at Traveller’s Hill 
during the month; 145 mm fell at the RAF 
base in one day on 7 April. 

1986 April 67 mm of rain fell at Traveller’s Hill on 

9 April; ‘spectacular lightning display’. 

* Two large stone water tanks built by the famous buccaneer, explorer 
and Admiralty hydrographer, William Dampier, on the lower slopes 
of Green Mountain can still be seen today. 

—_ > 2 

¢ oister's Peak 


Lady Hille329m x Two BOATS 
TRAVELLER'S HILL 514 me White — 

Red Hill e544 m 

UK Met. Office 


Figure 2. Ascension Island, including the locations of places 
mentioned in the text. 

be noted that records are probably only reasonably 
reliable since 1924 when regular readings were started at 
Georgetown (Fig. 2). Not every heavy rainfall event is 
included in the Table, only those of interest. 

In 1984, 1985 and 1986 heavy rainfall occurred on the 
island — some falls heavy enough to cause flooding, soil 
erosion and road damage. These events also had serious 
consequences for aviation. For example, George (1984) 
described how the pilot of an RAF Hercules aircraft 
returning from the Falklands had great difficulty in 
landing his aircraft at Ascension Island (Wideawake) 
airfield owing to a severe storm on 4 March 1984. The 
pilot was considering ‘ditching’ when the navigator 
spotted the rock-strewn runway through a gap in the 
cloud; the pilot managed to land the aircraft safely with 
only 30 minutes of fuel remaining. In another incident, 
on 15 October 1985, a Boeing 747 was diverted to 
Abidjan, Ivory Coast, because of low stratus associated 
with frequent showers. These, and several other less 
serious incidents, warranted an investigation into the 
possible causes of such poor weather. 

It is important to point out that, as the local 
investigation proceeded, it became clear that the lighter 
‘drizzly’ showers are usually associated with very 
shallow low-level instability (cloud tops often limited to 
5000 feet under the inversion of the sub-tropical high). 
Patchy low stratus beneath these showers is a significant 
hazard to aircraft on descent into Ascension, but is an 
entirely different forecasting problem. This occurs with 
the greatest frequency from August through to January 
with much year-to-year variation and some problem- 
free years. Here consideration is given to the possible 
causes of the heavier, deeper instability-controlled 
showers which occur mainly during March and April 
and may be associated with easterly waves. 

2. Investigation 
The heavy rainfall events in 1984, 1985 and 1986 
appeared to be linked with the passage of westward- 


Meteorological Magazine, 118, 1989 

moving disturbances rather than local or diurnal 
convective development (Johnson 1978, Ross 1985). 
Studies of the satellite picture sequences leading up to 
the heavy rainfall events revealed that the origin of the 
disturbances was Africa, probably over the Congo basin 
in Central Africa. This suggests similarities with the 
easterly waves in the North Atlantic which originate 
over West Africa (Albignat and Reed 1980). The 
subsequent investigation had three objectives: 

(a) To devise some forecasting rules for predicting 

heavy rainfall on Ascension Island in the South 


(b) To establish whether such heavy falls are 

associated with easterly waves. 

(c) To examine examples of 15-level model analyses 

to see whether they are capable of reproducing the 

changing wind-field profiles associated with the 

passage of these disturbances. 

Before describing the results it is important to state 
the limitations of the investigation: 

(a) Little success has been achieved locally at 
Ascension Island in using temperature and humidity 
soundings to confirm or predict changes in instability. 
Vertical motion can only be inferred from known 
changes in upper-wind profiles derived from once- 
daily soundings (American radiosonde data are 
available for 1200 GMT only, Monday-Friday 

(b) Cross-sections of the variation of upper winds 
with time were only available for the period 
20 January—30 April 1986 but model wind-field 
analyses (including vertical profiles) were available, 
for the 3 years 1984-86. 

fang 2 > 
con ‘ 


on oa 


Height (km) 
No observations over weekend 

. = ia 

a 4 

P i? oF ty 
a \ ra 
1 a | ie —Z l ‘es ~/ 
a a A nd a Ot 
20 21 22 3 24 25 26 27 28 29 
January 1986 
Figure 3. 

(c) To enable direct comparison between radar 
winds and model wind fields, the investigation has 
been deliberately limited to horizontal wind compon- 

(d) Although Ascension Island covers an area of 
only approximately 35 square miles, it is quite 
common for downpours to affect one part of the 
island whilst other regions remain virtually dry. The 
heavy falls noted in Table I were recorded at a 
number of different sites (Fig. 2). 

3. An example of the changing upper-wind 

In order to study temporal changes in vertical wind- 
structure at isolated locations where radar-wind inform- 
ation is available, vertical wind-profiles can be plotted 
as time cross-sections. This method was introduced at 
Ascension Island early in 1986 and produced some 
interesting results. In January 1986, a heavy rainfall 
event occurred after a marked change in vertical wind- 
profile (Fig. 3). On 21 January the strongest winds were 
at a level of 5 km — north-easterly 25 kn. By 24 January, 
as indicated by the 25 kn isotach on the profile, the 
zone of strongest winds had lowered to between 3 
and 4 km and veered* to easterly. During the weekend 
25-26 January, no upper-air data were available but by 
Monday 27 January it was evident that the lower-level 
winds had veered to around 140° (from the usual 110°) 
and the strong middle-level easterlies had ceased. Over 
40 mm of rain was recorded at Traveller’s Hill (Fig. 2) 
on 28 January and by 29 January the winds between 
levels of 5 and 6 km had backed to 070° whilst at low- 
levels they had returned to their normal direction and 
rainfall had ceased. Some kind of ‘disturbance’ can 

40 - (b) 

Wideawake RAF base 

[_] Traveller's Hill 

20 F 

Rainfall (mm) 

10 - Weekend 


ce oe | 
20 21 22 23 24 25 26 
January 1986 

(a) Variation of upper-air winds with time, and isotachs added for clarity, for the period 20-29 January 1986 at Ascension Island. 

The wind arrows indicate horizontal wind speed and direction as in conventional weather symbol plotting. The bold arrows also indicate 
horizontal wind direction but, only approximately, speed; they are shown to emphasize the significant changes of wind, and (b) daily rainfall at 

two sites for the same period. 

*In this article veering indicates the wind direction increasing in azimuth (measured N-E-S—W) and vice versa for backing. Among forecasters 

the opposite convention is used in the southern hemisphere. 

Meteorological Magazine, 118, 1989 


readily be seen to have passed westwards over Ascension 

4. The onset and duration of heavy rain 

A careful analysis of a number of case studies from 
early 1986 indicated that the structure of the disturbances 
associated with heavy rain was similar to that of the 
easterly waves found in the North Atlantic. Fig. 4 shows 
schematically the low-level structure of the disturbances 
associated with heavy rainfall found in the southern 
hemisphere, and their vertical structure is given in 

Fig. 5. In most cases, small pressure changes (of the 
order 0.5 to 1.0 mb) occurred over and above the normal 
diurnal variation. Generally, veering surface winds were 
associated with pressure falls and backing winds with 
pressure rises. Vertical motion could be inferred from 
cloud behaviour near to the rainfall event: ascent, by 
towering cumulus or cumulonimbus clouds, increasing 
both in height and extent prior to the falls, and 
subsidence by clouds decaying rapidly after the trough 
or wave. In each case studied the trough or wave axis 
exhibited a slope with height, a similar finding to that of 





tig I Se = tl hemisphere 


Figure 4. Schematic diagram of an easterly wave in the southern hemisphere (horizontal structure at low levels). The bold arrows are as in 
Fig. 3 and the hollow arrows give some indication of the direction and magnitude of the associated vertical motion. 




Pressure (mb) 




Wave moves west 

348 8 


1000 : 
= 3 to 6 days- — —>l< — —-—2 to 4 days -— — —>> 
<_------- §to 0.days-—— > 

Figure 5. Schematic diagram of an easterly wave in the tropical southern hemisphere (vertical structure). The symbols are as in Figs 3 and 4. 
The horizontal scale shows the approximate time that the wave takes to travel across the longitude of Ascension Island. 


Meteorological Magazine, 118, 1989 

Albignat and Reed (1980) who concluded that easterly 
waves sometimes show a tilt characteristic of baroclinic 

In late summer (January and early February) in the 
vicinity of Ascension Island, as a result of strong 
westerlies aloft, marked wind shear usually exists at 

v , A 
12 - 
10 F 
& 8+ 
6 fF o 
-*° | 
2 re) 
i > 
wa if 
0 —/ = Tia es at of Mag 
1 l 4 1 n l — 
7 8 9 10 11 12 13 14 
March 1986 
Wideawake RAF base = 
[_] Traveller's Hill ry 
30 F 
20+ Ek 
10 F 
0 l an ‘1 L Bes oo 8 ei 
7 8 9 10 11 12 13 14 15 
March 1986 

Figure 6. As Fig. 3 but for 7-14 March 1986. 

around 10km, thus limiting vertical stability and 
allowing isolated moderate to heavy showers rather 
than violent downpours. However, as autumn approaches 
and upper winds reverse to easterlies, deep convective 
clouds can form with cloud tops reaching 12-15 km. It is 
possible that it is easterly waves which trigger the storms 
over Ascension Island. A study of the lengths of showery 
periods during 1986 revealed a strong link between these 
and the rapidity of onset and lowering of the zone of 
stronger easterly winds aloft. Prior to short showery 
periods of only a day or so, the onset of strengthening 
easterlies was quick (only apparent | or 2 days before the 
showers). However, when the easterlies strengthened to 
25-35 kn over a greater depth, say 4-5 km, and over a 
period of 3 or 4 days, then an unsettled period lasting 3 
or 4days followed. The cessation of showery activity 
coincided with the return of middle-level easterly wind 
speeds to the normal values of 10-15 kn. 

Fig. 6 shows an example of a time cross-section of the 
upper winds associated with heavy rainfall. The marked 
‘slopes’ indicated by the 25kn isotach indicate the 
lowering and subsequent retreat of the stronger 
easterlies very wel: This example confirms the lowering 
of stronger upper easterly winds prior to a period of 
heavy rainfall and shows evidence of one or more 
weather troughs at low level (rainfall was not continuous 
during this period but comprised heavy, showery 
bursts). In this instance, lowering of the 25 kn isotach 
took 3-4days with the subsequent showery periods 
lasting also 3-4 days. 

5. Analyses from a global model 

Divergence and convergence clearly play an important 
role in controlling the degree of vertical motion 
involved. Preliminary study of the operational analyses 
from the global model of the Meteorological Office 
(Bell and Dickinson 1987) has shown that the model is 
capable of indicating middle-level (700-500 mb about 
3.5-5.5km height) divergence and low-level (900— 
850 mb about 1.5km height) convergence coinciding 
with rainfall events. An example for 4 March 1986, has 
been chosen because (unlike the one given in section 4 
covering 7-14 March) a short period of heavy rain only 
was involved with no interruption of radiosonde data, 
enabling comparison of measured with model winds. On 
this particular occasion, changes in low-level winds were 
minimal but at 6-7 km (500-400 mb) both measured 
wind profile (Fig. 7) and spatial model wind-field 
(available for 500 mb, about 5.5 km height — Fig. 8) 
indicate divergence near, or moving away west from 

A month or so later, during the night of 9/10 April 
1986, spectacular displays of lightning, thunderstorms 
and torrential rain occurred over Ascension Island. The 
event was different from those observed previously, in 
that it was preceded by an increase in upper westerly 
winds at heights between 9 and 15 km. The ability of the 
model to depict very accurately the changes in wind 

Meteorological Magazine, 118, 1989 


Figure 7. 

Figure 8. 



Height (km) 

oe oe ee 


ems nf wy = 


OE ee: Sed Sal Sd 

3 4 5 6 

March 1986 
Upper-air winds 

Wideawake RAF base 
Traveller's Hill 

ry a 
T 1 


Rainfall (mm) 

March 1986 

As for Fig. 3 but for 3-6 March 1986. 

<a “Ss Pie 
Area of divergence 
™~ * 

5 ih a 

500 mb horizontal wind-field for 00 GMT 3 March 1986 
showing area of divergence west of Ascension Island and the 20 kn 

4 / 
O~ RLS tm @r 
we ~ A pen la~ or 
> 50kn4 
a iver ae 
10 g— A\\ An. — 
25 kn 
£ os ie | . 
~ 8F / > 
ro wee > oy? 
sb 2 Fun 
2r J —~/ a nl 3 
7 8 9 10 11 
April 1986 
Upper winds 
(b) Wideawake RAF base 
80 F [__] Traveller's Hill 
3 Daily rainfall 
20 + 
\ i 

April 1986 

Figure 9. As for Fig. 3 but for 7-11 April 1986. 

profile which took place is demonstrated by comparison 
of Figs 9 and 10. 

6. Concluding remarks 

A careful study of satellite picture sequences, linked 
with use of a time cross-section of upper-wind profile 
changes, can give useful indications of the approach of 
disturbances likely to give severe weather at Ascension 
Island. The following are forecast rules based on the 

(a) On the vertical time cross-section, look for 

lowering of strong wind zones, combined with a 

veering of middle-level winds. Initially, strong 


Meteorological Magazine, 118, 1989 

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Figure 10. (a) Variation with longitude of the vertical profile of horizontal wind at the latitude of Ascension (8° S) for 12 GMT on7 April 1986 
from the Meteorological Office global model analysis, and (b) as (a) but for 12 GMT on 10 April 1986. The longitude of Ascension Island is 


middle- to upper-level winds will tend to inhibit 
shower activity but once the strongest winds have 
propagated downstream of the station and the height 
of the 25 kn isotach (for example) starts to increase, 
heavy showers are likely to develop as wind shear 

(b) A slow lowering of the upper strong wind zone 
will lead to longer unsettled periods, roughly equal to 
the number of days that the 25 kn isotach takes to 
lower. This is simply because the larger the scale of 
the disturbance, the greater the period of passage 
over any one point. 

It has been found that the disturbances which affect 
Ascension Island from time to time have the character- 
istics of the well-documented easterly waves of the 
North Atlantic. By study of satellite pictures, their 
origin is almost certainly central equatorial Africa, and 
rainfall and climate records confirm that March and 
April are the months of maximum activity. Also, 
retrospective inspection of the Meteorological Office 
archive of global operational analyses, using horizontal 
wind components, has provided encouraging evidence 
of the ability of the global model’s analyses to depict 
upper-air disturbances affecting Ascension Island, 
which have the characteristics of easterly waves. 

The scope of this paper has been limited by 
circumstances to model analyses. However, there is a 
good case for taking the next step in seeing if the global 
model can forecast the development and movement of 
easterly waves. If proved successful, then output in a 
form similar to the examples given should be made 

available to forecasters at remote locations such as 
Ascension Island in order to enhance forecasting 


To R.M. Morris, DrR.A. Bromley and DrR.W. 
Riddaway for their constructive comments, to forecaster 
colleagues at Ascension Island for their co-operation 
during my 6-month detachment, especially the late 
J. Bush, and to S. Ineson for her help in accessing the 
analyses from the Meteorological Office global model. 


Albignat, J.P. and Reed, R.J., 1980: The origin of African wave 
disturbances during phase III of GATE. Mon Weather Rev, 108, 

Bell, R.S. and Dickinson, A., 1987: The Meteorological Office operational 
numerical weather prediction system. Sci Pap, Meteorol Off, 
No. 41. 

Brenchley, H.E., 1986: The Mobile Meteorological Unit in the South 
Atlantic 1982-86. Meteorol Mag, 115, 257-263. 

George, D.J., 1984: Request for information about heavy rains. Jn 
The Islander, 13 April 1984. Georgetown, Ascension Island, 
Islander Office. 

Hodges, A., 1985: An investigation into the rainfall characteristics of 
Ascension Island and their environmental implications. (Unpublished, 
copy available in the Department of Geography, University of 

Johnson, R.H., 1978: Cumulus transports in a tropical wave 
composite for phase III of GATE. J Atmos Sci, 35, 484-494. 

Ross, R.S., 1985: Diagnostic studies of African easterly waves 
observed during GATE. Millersville University, Pennsylvania, 
Department of Earth Science, MSF Grant No. ATM-7825857. 

Meteorological Magazine, 118, 1989 


Notes and news 

The Meteorological Office celebrates Worid 
Meteorological Day 1989 

On 22 March this year the Meteorological Office at 
Bracknell entertained about 50 representatives of the 
civil aviation industry, as the UK contribution to the 
celebration of World Meteorological Day (strictly 
23 March), and the theme for the year, ‘Meteorology in 
the Service of Aviation’. The visitors represented a wide 
range of the aspects of aviation — carriers, operations, 
ground support, technical developments, controlling 
bodies — and several journalists from aviation publications 
also attended. Staff from Branches of the Office 
responsible for Marketing, and for Forecasting, acted as 

The guests first assembled in a room containing a 
series of display boards showing the development of 
meteorological services to both civil and military 
aviation. The boards commenced with the crude 
weather information made available to early balloonists, 
including a European surface chart for 22 March 1889, 
exactly 100 years previously, and ended with an example 
of a flight briefing chart for the same area for 22 March 

1© Day ||| « office LI win 
| ; The Met. Office 

Services t 
Military A: 

Mr Ken Pollard (right), Director of Aviation Services, Meteorological 
Office, Bracknell and Mr Tim Guest, Manager of Flight Crew Briefing 
for British Airways, in front of one of the display boards. 

The visitors were then welcomed by the Office’s 
director of Marketing Services, Mr Francis Hayes, who 
introduced Mr Ken Pollard, the Office’s Director of 
Aviation Services. In his address, Mr Pollard started by 
mentioning the Office’s role in aviation meteorology as a 
World Area Forecast Centre (WAFC), Regional Area 
Forecast Centre (RAFC) and as a National Forecast 
Centre. As a WAFC the Office uses its sophisticated 
15-level numerical forecast model, supported by powerful 
computer capability to produce global grid-point 
forecast fields of relevant meteorological variables. 
These are issued to RAFCs, with a back-up procedure 
involving the other WAFC at Washington to guard 
against rare cases of system failure. As an RAFC the 
Office uses the grid-point data to produce regional 
charts and significant weather charts, and these three 
types of data are interchanged with neighbouring 
RAFCs. Finally as a National Centre, RAFC-produced 
charts, low-level weather and wind charts, TAFs, 
trends, SIGMETs and aerodrome warnings are issued. 
The provision of equivalent tail-wind components also 
contributes to the support of general services to aviation. 

The method of disseminating weather information to 
the aviation industry was next described; it was stressed 
that information transfer often used technologies which 
were becoming obsolete in contrast to the rapid 
developments in forecasting, and that this was a 
handicap for many aviation customers. 

Mr Pollard went on to describe other meteorological 
products which would be of value to aviation operators 
but which at present were not available because of 
limitations in communications. These included weather 
radar and satellite images giving information about 
rainfall at airfields, forecasts of surface temperature, 
detailed wind forecasts for Air Traffic Controllers and 
objective forecasts of significant weather. Finally he 
spoke briefly about new methods of disseminating 
information for briefings, operations and flight planning. 

The visitors were then shown around the Central 
Forecasting Office (CFO) where several demonstrations 
had been organized. These included: 

Mr Martin Morris, Head of the Central Forecasting Office, Bracknell talking to visitors to the CFO. 


Meteorological Magazine, 118, 1989 

MARS — the Met and AIS Retrieval System (AIS — 
Aerodrome Information System) being developed by 
the UK Civil Aviation Authority and due to become 
operational during 1989. This is an interactive system in 
which pilots can receive flight weather briefings, 
aerodrome information or other relevant data via visual 
display units linked to a central computer at London 
(Heathrow) Airport. It is planned that the terminals will 
be installed at all the larger airports in the United 
Kingdom and that this will become the standard briefing 

Air Data — a commercial micro-computer-based 
system developed by Air Data Limited, a British 
company, for use by airline operators required to make 
operational decisions concerning the distribution of 
flight plans, evaluation of aircraft and route costs, and 
the management of aircrew. The occasion was used to 
promote their flight planning system which uses 
equivalent tail-wind components, calculated at Bracknell 
from all the forecast wind data available. This system 
reduces the errors introduced by interpolation from the 
standard coarse grid of data, inherent in all other flight 
planning systems. 

The visitors were also shown a demonstration of the 
use of document facsimile for transmitting briefing 
charts (a system which is believed to have considerable 
potential with the steadily reducing costs of facsimile 
machines). Users could dial into the facility and 
automatically receive a pre-determined set of charts or 
other information. The use of the FRONTIERS 
weather radar system for producing 6-hour forecasts of 
rainfall over the United Kingdom and the general work 
of aviation forecasters were also explained. 

The visitors were given copies of the literature from 
Geneva specially prepared for this important day in the 
WMO’s calendar, including the interesting document 
WMO-No. 206 by J. Kastelein (President, WMO Com- 
mission for Aeronautical Meteorology) which describes 
the development of meteorological services for aviation. 

The 3rd Workshop on Operational 
Meteorology, 2-4 May 1990, Montreal, 
Québec, Canada 

The 3rd Workshop on Operational Meteorology, 
sponsored by the Atmospheric Environment Service of 
Environment Canada and the Canadian Meteorological 
and Oceanographic Society, will be held on 2-4 May 
1990 at L’Université du Québec a Montréal. The 
principal theme of the workshop will be ‘Weather 
Services of the Future’. A number of other topics in 
operational meteorology will also be included. 

The Program Committee wishes to solicit papers on 
the following topics: 

Short-term forecasting and meso-meteorology (observ- 

ations, analysis, diagnostics, forecast techniques and 


Bridging the gap between research and operations 
User requirements 
Tomorrow’s weather offices. 

The format will consist of submitted papers, invited 
papers, panel discussions, and poster and demonstration 
sessions as well as 1- and 2-hour laboratory sessions. A 
brief introduction of each poster presentation will be 
given in an appropriate oral session. 

Titles and reviewers’ abstracts of 400-1000 words 
should be sent by | November 1989 to: 

Stan Siok 

Program Committee Co-chairman 

Atmospheric Environment Service 

3rd Floor 

100 Alexis Nihon Blvd 

Ville St-Laurent 

Québec H4M 2N8 


Authors should indicate their preference for presenting 
their paper orally, in a poster session, as a demonstration, 
or inashort laboratory session (1 hour). Preferences will 
be considered to the extent possible. Abstracts will be 
evaluated on their relevance to the theme as well as on 
their quality. Papers not related to operational meteorology 
will not be accepted. Authors will be notified by 
15 December 1989 with respect to both the acceptance 
of their abstract and instructions on the format of their 

Complete camera-ready papers of no more than eight 
pages, including diagrams, must be received by the 
program co-chairmen no later than | March 1990. A 
preprint volume will be prepared and distributed to 
workshop registrants. Papers and abstracts may be in 
either English or Fiench. For additional information 
contact either Stan Siok (514-283-1139) or Peter Zwack 
(514-282-3304), Program Committee Co-chairmen. 

Books received 

The listing of books under this heading does not preclude a review in 
the Meteorological Magazine at a later date. 

Weather sensitivity and services in Scotland, 
edited by S.J. Harrison and K. Smith (Edinburgh, Scottish 
Academic Press, 1989. £25.00) is the outcome of a 
conference held at the University of Stirling in February 
1988. It is an example of the benefits which can be derived 
from the effective use of weather and climate information, 
which could be a model to policy-makers world-wide. 


Meteorological Magazine, June 1989, p. 126, caption 
to Fig. 10. The section in brackets should have read: 
‘(2123 GMT on 25 April 1986 to 0000 GMT on 27 April 

Meteorological Magazine, 118, 1989 


Satellite and radar photographs — 
1800 GMT 

24 May 1989 at 1200 and 

ntl r= 

ree) an - a Sf) 12:00. 24-05-89 

Thunderstorms affected many inland areas of England 
and Wales on 24 May 1989, and were locally severe with 
large hailstones, and causing flash flooding. South 
Farnborough in Hampshire recorded 56 mm of rainfall 
between 1200 and 1330 GMT. 

The development and organization of the storms 
could be monitored by means of the frequent 
(‘2-hourly) images from Meteosat and the UK weather 
radar network. Shown above are images for 1200 GMT 
— in the early development phase of the thunderstorm 
complex to the west of London, and 1800 GMT — by 
which time the combined anvil cirrus shield of the 
mature complex covered much of central England. The 
surface chart for 1200 GMT is included for reference. In 
the infra-red images, the colour sequence: black, yellow, 
green, cyan, blue, magenta, red and white represents the 

transition from warm to cold. The radar colour 
sequence: blue, green, yellow, pink, red and cyan 
represents progressively increasing rainfall rates. 

/ | 1010 
1200 GMT 24 May 1989’ 


Meteorological Magazine, 118, 1989 



Articles on all aspects of meteorology are welcomed, particularly those which describe results of research in 
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Editor: B.R. May 
Editorial Board: R.J. Allam, R. Kershaw, W.H. Moores, P.R.S. Salter 


Defence Services Branch 50th Anniversary. Part |: Historical 


Caughey and P.W. Davies qe sus tek as 

Defence Services Branch 50th Anniversary. Part Il: Current 
commitments and the future. J.D. Turton and $.J:Caughey <= «ne 

Westward-moving disturbances in the South Atlantic coinciding 
with heavy rainfall events at Ascension Island. BA.Hall ... ... ... ... ... 175 

Notes and news 

The Meteoro 

Books receive 

Satellite and 

Contrit ns. 
Ofiice m 
guiac vel 
artic ett 
lor t ns 

Subacr s. 

ogical Office celebrates World Meteorological Day 1989... ... 182 

rkshop on Operational a 2-4 May 1990, Montreai, 
anada et snot As s.r 

- 183 
teat ce + wae eee «se #*. wee eae eee vee te eee eae eee eee 

«ee oe. “+ see wee wee eee eee “of ose one eee 183 

adar photographs — 24 May 1989 at 1200 and 1800 GMT 184 

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989. First published 1989