EVOLUTION OF 2 OCEANIC EXTRATROPICAL CYCLONES AS OBSERVED WITH THE SPECIAL SENSOR MICROWAVE IMAGER AND THE GEOSAT AND ERS 1 ALTIMETERS

The evolution of two marine cyclones across the North Atlantic and the North Pacific Oceans is followed with a combination of sequential pas sive and active microwave data. The special sensor microwave/imager (S SM/I) provides estimates of atmospheric parameters: integrated water v apor, precipitation, and ocean surface wind speed. The Geosat and ERS 1 altimeter data are used to derive sea state parameters along the sat ellite tracks: the significant wave height and the ocean surface wind speed. The SSM/I integrated water vapor gradients are used to locate a nd follow the evolution of the atmospheric fronts. In regions of preci pitation, often located behind the atmospheric fronts, the SSM/I surfa ce wind speed cannot be derived, while the Geosat and ERS 1 altimeter wind speed yields estimates of wind speed gradients across the fronts. It is shown that the combination of SSM/I and satellite altimeters pe rmits additional observations of surface fronts with higher resolution both in space and time than those given in the National Meteorologica l Center analyses.