Using spaceborne synthetic aperture radar to improve marine surface analyses

The ever-changing weather and lack of in situ data in the Bering Sea warran ts experimentation with new meteorological observing systems for this regio n. Spaceborne synthetic aperture radar (SAR) is well suited for observing t he sea surface footprints of marine meteorological phenomena because its ra diation is sensitive to centimeter-scale sea surface roughness, regardless of the time of day or cloud conditions. The near-surface wind field generat es this sea surface roughness. Therefore, the sea surface footprints of met eorological phenomena are often revealed by SAR imagery when the main modul ator of sea surface roughness is the wind. These attributes, in addition to the relatively high resolution of SAR products, make this instrument an ex cellent candidate for filling the meteorological observing needs over the B ering Sea. This study demonstrates the potential usefulness of SAR for observing Berin g Sea meteorology by focusing on its ability to image the sea surface footp rints of polar mesoscale cyclones (PMCs). These storms can form unexpectedl y and are threatening to maritime interests. In this demonstration, a veter an meteorologist at the Anchorage National Weather Service Forecast Office is asked to produce a surface reanalysis for three separate archived cases when SAR imaged a PMC but the original analysis, produced without the aid o f SAR data, did not display it. The results show that in these three cases the inclusion of SAR data in the analysis procedure leads to large differen ces between the original surface analysis and the reanalysis. Of particular interest is that, in each case, the PMC is added into the reanalysis. It i s argued that the reanalyses more accurately portray the near-surface meteo rology for each case.