Modeling the diurnal cycle over tropical oceans using the weak 1 temperature gradient approximation

Abstract

4 We investigate the extent to which precipitation over tropical oceans is modulated by the 5 diurnal variations in the thermodynamic environment. Tropical precipitation is modeled 6 using a cloud system resolving model with the large scale parameterized using the weak 7 temperature gradient (WTG) approximation. In WTG, convection responds to specified 8 potential temperature and humidity profiles. By imposing diurnal variations observed during 9 the 2001 EPIC field program to the reference profiles of potential temperature and mixing 10 ratio, we assess the extent to which convection responds to these changes and accounts 11 for the diurnal variability in precipitation observed during EPIC. Remarkably, the WTG 12 approximation is able to reproduce a precipitation maximum near the observed time, despite 13 an imperfect reproduction of the diurnal variability in saturation fraction. The ability of the 14 model to capture the diurnal variability relies heavily on a strict enforcement of the WTG 15 approximation and the lateral entrainment of moisture into the model domain resulting from 16 this enforcement. 17

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Cite this paper

@inproceedings{Sessions2013ModelingTD, title={Modeling the diurnal cycle over tropical oceans using the weak 1 temperature gradient approximation}, author={Sharon L. Sessions and Leah A. Lindsey and Carlos L{\'o}pez Carrillo and David Raymond}, year={2013} }