This true-color <a HREF="http://modis.gsfc.nasa.gov" target="outlink">Moderate Resolution Imaging Spectroradiometer</a> (MODIS) image from October 4 was shows what is likely to be the impact of the southwest monsoon season on the biological productivity of the waters of the Arabian Sea. During the southwest, or summer, monsoon season, winds blow steadily from the southwest along the coast of Oman, setting up an ocean current that flows northeast. As the warm surface waters are pushed along by the winds, cold, nutrient-rich water from deep in the ocean wells up to the surface. This nutrient-laden water supports and abundance of marine plant life, and may be responsible for the colorful swirls seen in the ocean in this image.The monsoon reaches its peak in July, and tapers off toward the end of the year. Around December or January, the monsoon winds begin to blow from the northeast, but not as strongly as the southwest monsoon. Therefore, the surface waters of the ocean respond less strongly, and the weaker ocean currents that result are often not powerful enough to create upwelling. This difference in monsoon wind strength means that the waters of the Arabian Sea and northern Indian Ocean experience extremes of biological productivity’with half the year having abundant marine plant and animal life, while productivity in the other half of the year declines markedly. This region exhibits one of the sharpest seasonal contrasts in biological productivity in the world. Sensor: Terra/MODIS. Data Start Date: 10/4/02. Data End Date: 10/4/02.