Impact of Satellite-Derived Diffuse Attenuation Coefficient on Upper Ocean Simulation Using High-Resolution Numerical Ocean Model: Case Study for the Bay of Bengal

• Published in: Marine geodesy 2019-11, Vol.42 (6), p.535-557
• Main Authors: Mallick, Subrat Kumar, Agarwal, Neeraj, Sharma, Rashmi, Prasad, K.V.S.R., Weller, Robert A.
• Format: Article
• Language: English
• Subjects: Attenuation; Attenuation coefficients; Barrier layers; Bay of Bengal; Buoys; Climatology; Computer simulation; Depth; diffuse attenuation coefficient; Downwelling; Extinction coefficient; Mathematical models; Mixed layer depth; Ocean currents; Ocean dynamics; Ocean models; Oceans; Parameter sensitivity; Radiation; Satellites; Sea surface; Sea surface temperature; Short wave radiation; shortwave attenuation depth; Spatial distribution; Spatial variability; Spatial variations; Surface temperature; Thickness; Type-I water; Upper ocean; Water depth
• ISSN: 0149-0419; 1521-060X
• DOI: 10.1080/01490419.2019.1664677

Impact of satellite-derived shortwave attenuation depth and its spatial variability on the upper ocean dynamics has been studied using a numerical ocean model over the Bay of Bengal. We conducted two simulations, differing in the spatial distribution of shortwave attenuation depth for the period 2014-2015. The control run use a constant attenuation depth of 23 m (the default case for Type-I water) while the experimental run (ER) use spatially varying attenuation depths derived from daily climatology of the diffuse attenuation coefficient ( ). Simulated parameters like sea surface temperature (SST) and mixed-layer depth (MLD) are sensitive to that limits the penetration of downwelling shortwave radiation into the ocean. It has been found that alters the upper ocean thermodynamics significantly. Validation has been performed using satellite, moored-buoy and profile data, for the year 2015. During spring, the errors in SST in the ER are reduced up to 35% at buoy location. The impact of improving shortwave attenuation depth is found to be maximum in the upper ocean (50-150 m). Error in simulated temperature at 100 m depth is reduced by 15% in the ER. MLD, barrier layer thickness, and the depth of 26 °C isotherm also show significant improvements in the ER.