Observing and Studying Extreme Low Pressure Events with Altimetry

Type Article
Date 2009-03
Language English
Author(s) Carrere Loren1, Mertz Francoise1, Dorandeu Joel1, Quilfen Yves2, Patoux Jerome3
Affiliation(s) 1 : CLS, F-31520 Ramonville St Agne, France.
2 : IFREMER, F-29280 Plouzane, France.
3 : Univ Washington, Seattle, WA 98195 USA.
Source Sensors (1424-8220) (Molecular Diversity Preservation International), 2009-03 , Vol. 9 , N. 3 , P. 1306-1329
DOI 10.3390/s90301306
WOS© Times Cited 1
Keyword(s) Barotropic model, Sea level pressure, Extra tropical depressions, Tropical cyclones, Detection, Altimetry
Abstract The ability of altimetry to detect extreme low pressure events and the relationship between sea level pressure and sea level anomalies during extra-tropical depressions have been investigated. Specific altimeter treatments have been developed for tropical cyclones and applied to obtain a relevant along-track sea surface height (SSH) signal: the case of tropical cyclone Isabel is presented here. The S- and C-band measurements are used because they are less impacted by rain than the Ku-band, and new sea state bias (SSB) and wet troposphere corrections are proposed. More accurate strong altimeter wind speeds are computed thanks to the Young algorithm. Ocean signals not related to atmospheric pressure can be removed with accuracy, even within a Near Real Time context, by removing the maps of sea level anomaly (SLA) provided by SSALTO/Duacs. In the case of Extra-Tropical Depressions, the classical altimeter processing can be used. Ocean signal not related to atmospheric pressure is along-track filtered. The sea level pressure (SLP)-SLA relationship is investigated for the North Atlantic, North Pacific and Indian oceans; three regression models are proposed allowing restoring an altimeter SLP with a mean error of 5 hPa if compared to ECMWF or buoys SLP. The analysis of barotropic simulation outputs points out the regional variability of the SLP/Model Sea Level relationship and the wind effects.
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