GEOSAT OBSERVATIONS OF SEA-LEVEL RESPONSE TO BAROMETRIC-PRESSURE FORCING

Altimeter and sea level pressure data from the Geosat mission are analyzed for evidence of inverted barometer response of sea level to atmospheric pressure forcing. Estimates of the inverted barometer coefficient are given for a variety of geographic regions and time scales using various orbit error removal strategies. There is some sensitivity to the orbit error removal method, but the estimated coefficients show a clear latitudinal dependence and are generally between -0.5 cm/mbar and -0.9 cm/mbar. The southern oceans respond slightly more like an inverted barometer than the northern oceans for similar latitudes. The regression exhibits significant geographic variability, particularly near major circulation features and in the northern hemisphere. The results suggest that the inverted barometer approximation is reasonable over much of the oceans, but that some sea level variability may be correlated with barometer pressure by means other than the inverted barometer effect.