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heimbach |
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A Global Comparison of Ekman Pumping From Satellite Scatterometers and |
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Ocean Data Assimilation Estimates |
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Paulo Polito^1, Tong Lee^2, and Ichiro Fukumori^2 |
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1. Inst. Nac. de Pesquisas Espaciais, Sao Paulo, Brazil |
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2. Jet Propulsion Laboratory, California Institute of Technology |
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Ekman pumping, a form of wind-driven upwelling, plays important |
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roles in upper-ocean dynamics, thermodynamics, and biology as well as |
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in boundary-layer meteorology. Inverse models, such as those of |
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ECCO (Estimation of the Circulation and Climate of the Ocean, |
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http://www.ecco-group.org/), estimate wind forcing through |
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ocean data assimilation. Scatterometer data provide a stringent test |
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of the skill of the assimilation in estimating wind. Ekman pumping |
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obtained from various scaterometers are compared with those |
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derived from ECCO model which assimilate TOPEX-derived sea level |
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anomalies using the adjoint and Kalman filter/smoother methods. |
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Differences in Ekman pumping between scatterometer and assimilation |
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estimates are quantified in terms of the mean, standard deviation, and |
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correlation. Change in Ekman pumping due to the assimilation is |
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analyzed to identify the spectral (frequency-wavelength) space over |
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which the assimilation has significant impact. The comparison also |
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highlights aspects where the ECCO model and assimilation schemes need |
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improvement. |
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