Title

Reduced Horizontal Sea Surface Temperature Gradients Under Conditions of Clear Skies and Weak Winds

Document Type

Article

Publication Date

8-2005

Publication Title

Boundary-Layer Meteorology

Keywords

Air-sea fluxes, Diurnal warming, Oceanic horizontal temperature gradients, Remote sensing, Sea surface temperature

ISSN

0006-8314

Volume

116

Issue/No.

2

First Page

175

Last Page

185

Abstract

Consideration of the dependence of various components of the sea-surface heat and momentum fluxes on sea surface temperature (SST) leads to an explanation for the observed reduction in the horizontal temperature gradients in the uppermost layer of the ocean (a few to 10 m in depth). Horizontal temperature gradients within the mixed layer can be masked by a near-surface layer of warm water. This camouflage of horizontal temperature gradients has importance for the remote sensing of SST used by the fishing industry, for the estimation of acoustic transmission, and for the forecasting of hurricane development, among many uses of SST data. Diurnal warming conditions in the Straits of Florida are examined by a simulation calculation and by analysis of observations obtained on moorings deployed on the south-east Florida shelf. When there is net heating (i.e., the solar input is stronger than the combined latent, sensible and longwave radiative heat losses) the originally warmer water experiences less heating than the colder water, leading to a weakening of the horizontal SST gradients as seen by surface buoys or satellites. The warmer water also experiences more mixing and therefore less increase in temperature. The strongest effect of the diurnal heating on wind stress occurs when the SST starts out cooler than the air temperature and the atmosphere is stably stratified. Diurnal warming can then rapidly increase the SST above the air temperature because of reduced wind stress and reduced upper-ocean mixing. After that the wind stress increases as convectively driven turbulence contributes to the atmospheric exchange.

Comments

©Springer 2005

The final publication is available at Springer via http://dx.doi.org/10.1007/s10546-004-2421-4

Additional Comments

ONR grant #s: N00014-98-1-0861, N00014-02-1-0950

ORCID ID

0000-0001-6519-1547

DOI

10.1007/s10546-004-2421-4

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Peer Reviewed

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