Remotely sensed chlorophyll pigment concentrations from the Coastal Zone Color Scanner (CZCS) are used to estimate biological heating rate and investigate the biological modulation of the sea surface temperature (SST) in a bulk mixed layer model, embedded in the ocean isopycnal general circulation model (OPYC). A higher abundance of chlorophyll in October than in April in the Arabian Sea increases absorption of solar irradiance and heating rate in the upper ocean, resulting in decreasing the mixed layer thickness and lowering temperatures in the layers below the mixed layer than they would be under clear water condition. These changes in the model mixed layer were consistent with Joint Global Ocean Flux Study (JGOFS) observations during the 1994--1995 Arabian Sea experiment. ¿ 2000 American Geophysical Union