Wind speed is also derived from the SSM/I microwave sensor. Using a relationship between the roughness of the ocean's surface (what the sensor sees) and the wind speed need to produce that roughness we get that parameter we are interested in.
The behavior of the winds in the Indian Ocean is strongly modulated by the seasonal monsoons focused in the Arabian Sea. The three months with the highest mean wind speeds (all over 7 m/s) occur from June to August (summer monsoon). For this same period the three highest maximum for the Indian Ocean occur in the Arabian Sea (12.3, 11.9 and 11.1 m/s). The calmest month of the year is March with an avearge wind speed of 4.9 m/s. The wind speed in March under the Somalia Jet is only 3-4 m/s. The mean annual wind speed for the IO is 6.2 m/s.
A 4 m/s contour centered at the equator and ~70E, is a unique feature during the summer monsoon, located perpendicular to the maximum wind speed gradient associated with the Somalia Jet. This is something of a pivot point connecting the westerlies of ~10S which then bend at Somalia and add to the jet. In October this 4 m/s contour is still present, but the strong gradient of the Somalia Jet and the connection with the southern westerlies dissapears. For the winter monsoon months of December and January this 4 m/s contour is shifted slightly to the west. This is likely due to the change in wind direction for the winter.
Click here to see an animated movie of wind speed data.
Click here to see an animated movie of 24 years of wind speed data derived
from ship observations. (prosessed by Florida State University)