Summary of Abstract Submission

Abstract Submission No. IO50-06-0017PresentationOral

IMPACT OF CHLOROPHYLL ON SST,MLD,SSS AND SURFACE CURRENTS IN THE TROPICAL INDIAN OCEAN USING NEMO SIMULATIONS

Anitha Gera*1, Mitra A K2, Mohapatra D K2, Imran Ali2, Rajagopal E N2

1 NCMRWF,ESSO,MoES,NOIDA, India
2 NCMRWF, India

ABSTRACT :

Chlorophyll concentration in the upper ocean is known to influence the Sea Surface Temperature (SST) by absorbing the solar radiation in the top few surface layers. The Mixed Layer Depth (MLD) is thereby modified due to re-stratification. In this study, we analyse the seasonal impact of chlorophyll through shortwave radiation penetration depth estimation on sea surface temperature (SST) and mixed layer temperature depth (MLD) using the Nucleus for European Modelling of the Ocean (NEMO) over the Tropical Indian Ocean (TIO). Results of model experiments with parameterizations that use chlorophyll concentration and do not use chlorophyll concentration for shortwave radiation penetration depth estimation indicate that using chlorophyll concentration produces better representation of MLD and SST than when not. Increased SST and decreased MLD are observed when using chlorophyll concentration. The largest impact is noticed over the Arabian Sea and the Bay of Bengal during spring and fall. The maximum of change in SST in the two experiments is 0.4deg C and in MLD is 10m. Interestingly, during July and August cooler SST was observed over the Arabian Sea while using chlorophyll. This is may be attributed to the upwelling of cooler sub-surface waters dominating the warmer SSTs. The maximum change in Sea Surface Salinity is observed over the head bay of Bengal followed by Arabian Sea. These changes in surface salinity are associated with corresponding changes in surface currents. However the changes in salinity are small in magnitude. A case study for 2010 using seaWIFS chlorophyll data is also performed.