Evaporation and solar irradiance as regulators of sea surface temperature in annual and interannual changes

Abstract

Seven years of net surface solar irradiance (S) derived from cloud information provided by the International Satellite Cloud Climatology Project and 4 years of surface latent heat flux (E) derived from observations of the special sensor microwave imager were used to examine the relation between surface heat fluxes and sea surface temperature (Ts) in their global geographical distribution, seasonal cycle, and interannual variation. The relations of seasonal changes imply that evaporation cooling is significant over most of the ocean and that solar heating is the main drive for the change of T s away from the equatorial wave guide where ocean dynamics may be more important. However, T s is not the most direct and significant factor in the seasonal changes of S and E over most of the ocean; the solar incident angle may be more important to S, and wind speed and air humidity are found to correlate better with E. Significant local correlations between anomalies of T s and S and between anomalies of T s and E are found in the central equatorial Pacific; both types of correlation are negative. In this area, organized deep convection overlies the warm ocean, forms high clouds, and reduces $, while the low wind speed and high humidity that result from surface convergence reduce E. The negative correlation is not present in the surrounding areas where equally warm water and strong T s anomalies are found under a subsiding atmosphere without similarly strong S and E anomalies. Correlation between anomalies of temperature tendency and the fluxes is weak, indicating that other factors are more influential in changing upper ocean heat balance during E1 Nifio. The result shows that the relations between Ts and the flux components, in annual and interannual timescales, are not universal and not consistent with the local negative feedback postulations which require that an increase in Ts would result in an increase in local evaporative cooling and a decrease in local solar heating of the ocean. Largescale atmospheric circulation changes clouds, winds, and humidity; they, in turn, influence the fluxes significantly. The influence of ocean dynamics in changing T s in the tropical ocean can not be ignored. 1Now at Paper number 94JC00604. 0148-0227/94/94JC-00604505.00 carried by evaporation and net solar irradiance from the sun (S), using satellite data. Their studies were confined to the central and eastern tropical Pacific, because the microwave radiometer data available at that time had geographically dependent errors and the geostationary Satellite GOES W had only limited coverage. The interest in the relation between surface heat fluxes and Ts, however, is not confined to the tropical ocean [e.g., Cayan, 1992]. Recent availability of satellite data from the International Satellite Cloud Climatology Project (ISCCP) and from the special sensor microwave imager (SSMI) on the operational spacecraft of the Defense Meteorological Space Program make it possible to derive E and $ with adequate duration to study annual and interannual ch...

Southern Hemisphere forcing of Pliocene δ18O and the evolution of Indo‐Asian monsoons

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Relationship between downwelling surface shortwave radiative fluxes and sea surface temperature over the tropical Pacific: AMIP II models versus satellite estimates

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Acknowledging contributions

“…This is a somewhat surprising result considering that on larger, basin scales, the correlation is often negative (Mantua et al 1997;Okumura et al 2001, Liu et al 1994 which is interpreted as evidence that the atmosphere is driving an ocean response. In the large scale scenario, intensified winds cool the ocean surface through evaporation, as well as possibly increasing the entrainment of upper-thermocline cool waters into the mixed layer.…”