Atmospheric Fronts Using RISAT-1 SAR Data: Case Studies for Shear Lines.

Atmospheric fronts are an important feature of the marine atmospheric boundary layer. In this paper, India's first synthetic aperture radar (SAR) mission, RISAT-1, is used to detect the atmospheric fronts especially shear lines over the Indian Ocean by studying their imprints on the sea surface using backscatter radar echo. For this study, a multitude of SAR images were analyzed for detecting potential front structure over the Arabian Sea, Bay of Bengal, and South Indian Ocean. Frontal identification, analysis, and characterization are carried with the help of an ancillary satellite and atmospheric model data as provided by the sea-surface temperature, lower tropospheric stability, vertical wind shear, etc. The computation of the thermal front parameter and front points derived from them along with the associated wind speed exhibit a discernible demarcation at the frontal boundary, with the wind speed difference in the range of 2–4 m/s. The study is first of its kind over the Indian Ocean (IO), where separate zones of the IO are explored to emphasize different frontogenesis mechanisms, based on ocean–atmosphere coupling. [ABSTRACT FROM AUTHOR]