A Further Study on Estimating Surface Evaporation Using Monthly Mean Data: Comparison of Bulk Formulations

Abstract

This study further examines the errors in estimating surface evaporation using monthly mean surface atmospheric variables from the moored buoys in the equatorial Pacific. Results from two significantly different bulk aerodynamic formulas are compared. It is shown that for both formulas the errors are within 2?3 W m?2 on average, representing a relative error of less than 3% in the equatorial Pacific. Although small, this error varies systematically across the equatorial Pacific and depends on the bulk formula used. It is also demonstrated that the individual nonlinear contributions associated with the strong dependence of exchange coefficient on surface wind to monthly mean surface evaporation are significant. However, they largely cancel each other, leaving small net effect.