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Air moisture control on ocean surface temperature, hidden key to the warm bias enigma
Author(s) -
Hourdin Frédéric,
GăinusăBogdan Alina,
Braconnot Pascale,
Dufresne JeanLouis,
Traore AboulKhadre,
Rio Catherine
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2015gl066764
Subject(s) - atmospheric sciences , environmental science , sea surface temperature , evaporation , humidity , relative humidity , atmosphere (unit) , moisture , climatology , radiative cooling , evaporative cooler , meteorology , geology , geography
The systematic overestimation by climate models of the surface temperature over the eastern tropical oceans is generally attributed to an insufficient oceanic cooling or to an underestimation of stratocumulus clouds. We show that surface evaporation contributes as much as clouds to the dispersion of the warm bias intensity in a multimodel simulations ensemble. The models with the largest warm biases are those with the highest surface heating by radiation and lowest evaporative cooling in atmospheric simulations with prescribed sea surface temperatures. Surface evaporation also controls the amplitude of the surface temperature response to this overestimated heating, when the atmosphere is coupled to an ocean. Evaporation increases with temperature both because of increasing saturation humidity and of an unexpected drying of the near‐surface air. Both the origin of the bias and this temperature adjustment point to the key role of near‐surface relative humidity and its control by the atmospheric model.