USING OF MODIS HIGH RESOLUTION DATA FOR STUDY OF ATMOSHERIC PROCESSES BY THEIR IMPRINT ON THE SEA SURFACE

USING OF MODIS HIGH RESOLUTION DATA FOR STUDY OF ATMOSHERIC PROCESSES BY THEIR IMPRINT ON THE SEA SURFACE

Marina A. Evdoshenko
Institute of Oceanology Russian Academy of Sciences
36 Nakhimovsky Prospect, Moscow, Russia
maarsio@bk.ru

Moderate Resolution Imaging Spectroradiometers (MODIS) high resolution (HIRES) of 250 m data were used to study atmospheric events occurring in the marine atmospheric boundary layer (MABL) by their imprint on the sea surface. Atmospheric events by their lower boundary modulate a local wind nearby the sea surface which in turn changes the surface roughness and effecting on backscatter radiance signal. In present time Synthetic Aperture Radar (SAR) images are widely used for the same aims, but they are obtained with a repeat interval of several days and are rather expensive, whereas MODIS scanners installed on AQUA and TERRA supply with data images of the same water area at least twice a day and the data are completely free. Normalized water leaving radiance (Lwn) of level L2 (after the atmospheric correction) at 859 nm, providing by MODIS, is forming in the upper several centimeter layer and well reflects atmospheric processes by their signature. The same atmospheric event by their upper boundary may simultaneously modulate the wind speed at the upper boundary of the MABL producing resembling imprints in cloudy layer visible by level L1 radiance return (without an atmospheric correction).at 859 nm. Data processing was realized with SeaDAS program packet, image contrast was slightly enhanced to display atmospheric traces. In the work were analyzed signatures of atmospheric solitary waves spreading in upstream direction in the Bering Sea, lee waves and roll vortices in the Black Sea, rolls, lee, and gravity waves and also solitary waves spreading down the wind in the Caspian Sea. Revealed prolongation of atmospheric traces on L1 image of the cloudy layer on one side of a cloudy boundary, to those displayed simultaneously on L2 image of free sea surface corresponding to opposite side of the cloudy boundary was an evidence of vertical spreading of atmospheric process in the MABL. On the whole HIRES scanner return at 859 nm seems to be attractive for study of in principle invisible atmospheric processes by their traces. Such study promises to be particularly successful if we consider air stratum area with intermittent cloudiness when atmospheric event signatures on the sea surface and in cloudy layer for adjacent vertical parts impressed at the same time is possible to obtain.