The seasonal cycles of surface chlorophyll (SCHL) in the Indian Ocean (IO) are regionally described by means of
6 parameters: the timing of the bloom onset and of the bloom peak, and the integrated SCHL value in between
these two extrema for both winter and summer blooms. This description, based on a climatology constructed
from 7 years of SeaWiFS data, provides a regional image of the influence of the two monsoons on phytoplankton
blooms. Over a large part of the basin, the seasonal cycle is characterized by two distinct growth periods, one in
summer during the South West Monsoon (SWM), the other in winter during the North East Monsoon (NEM).
However, in some specific areas such as the southwestern coast of India, there is no maxima during the NEM.
The bloom areas during the SWM and the NEM show totally different regional patterns. Important lags in the
timing of the blooms are identified, and are also associated with distinct regional patterns. The next step in the
understanding of the SCHL seasonal cycles in the IO will be to relate the regional patterns of the timing and
amplitude of the blooms with those of the physics of the IO.