DINEZIO, P. N., RSMAS/CIMAS, Miami, USA, pdinezio@rsmas.miami.edu
GONI, G. J., NOAA/AOML, Miami, USA, gustavo.goni@noaa.gov
LUMPKIN, C. F., NOAA/AOML, Miami, USA, rick.lumpkin@noaa.gov

GLOBAL COMPARISON OF SEA SURFACE CURRENTS DERIVED FROM DRIFTER AND ALTIMETRY OBSERVATIONS

A global comparison of sea surface currents derived from drifter observations and alongtrack altimetry observations is performed. The altimetry-derived alongtrack sea height anomaly data are grouped together with the drifter-derived velocities for every intersection between a drifter track and a satellite ground track within a one day-window. The drifter-derived velocities are decomposed into time-mean and time-varying components. Additionally, the Ekman component is removed to obtain an estimate of the drifter-derived geostrophic velocity anomaly. The alongtrack sea height anomaly gradients and all components of the acrosstrack drifter-derived velocity are linearly regressed for every set of coincident observations. Global fields of regression parameters are presented. Results obtained here indicate that the altimetry-derived estimates of the geostrophic anomalies overestimate drifter-derived geostrophic anomalies. A hypothesis based on different time and space filtering in the processing of both datasets is provided to explain this discrepancy. The decomposition into time-mean and anomaly of drifter-derived velocities is evaluated through the regression bias. Results obtained from this work will allow complementing the ocean observing system by providing velocity estimates derived from altimetry where drifter coverage is not adequate.

Oral presentation

Presentation is given by student: Yes
Session #:006
Date: 03-05-2008
Time: 14:00