Three-dimensional observations from MODIS and CALIPSO for ocean responses to cyclone Nargis in the Gulf of Martaban

Satellites measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS) on Aqua and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) are used to study physical, optical, and biological changes in the Gulf of Martaban following the passage of cyclone Nargis during early May of 2008. The shortwave infrared (SWIR) atmospheric correction algorithm has been used to derive ocean optical and biological properties from MODIS. Following the passage of cyclone Nargis, a significant increase of surface sediment concentration is observed with considerably enhanced normalized water-leaving radiance at the red and near-infrared (NIR) wavelengths in the Gulf of Martaban and along the mouths of the Ayeyarwady River. It is estimated that, before and after cyclone Nargis, the average total suspended matter (TSM) in the Gulf of Martaban increased from 24 mg/l to 31 mg/l, while the TSM value nearly tripled from 12 mg/l to 34 mg/l along the mouths of the Ayeyarwady River. The CALIPSO measurements also show that, before cyclone Nargis, the sediment concentration in the region increases with depth in the water column, while after cyclone Nargis the sediment vertical profile becomes relatively uniform in the upper 50 m depth due to wind-driven vertical mixing and entrainment. Citation: Shi, W., and M. Wang (2008), Three-dimensional observations from MODIS and CALIPSO for ocean responses to cyclone Nargis in the Gulf of Martaban, Geophys. Res. Lett., 35, L21603, doi: 10.1029/2008GL035279.