[A-AS03] Large-scale moisture and organized cloud systems

[AAS03-01] Impact of moist thermodynamics expressions on climatological temperature fields represented in a global cloud resolving model

*Tomoki Ohno¹, Shuhei Matsugishi¹ (1.Atmosphere and Ocean Research Institute, The University of Tokyo)

Keywords:the moist thermodynamics, Tropical upper troposphere

The phase change of water is one of the main factors driving the Earth's atmospheric general circulation, and the representation of the thermodynamic system of the moist atmosphere is fundamental to general circulation models. The possibility of condensation and freezing of water complicates thermodynamics, and various approximations are used for meteorological and climatological purposes. For example, the latent heat of vaporization is sometimes assumed to be a constant, or the gas constant or specific heat of water vapor is substituted for that of the dry atmosphere. These simplifications are generally done without considering the mutual consistency of the thermodynamic system, and internal inconsistencies have been recognized as one source of error in numerical models.
This study investigates the impacts of the moist thermodynamics expressions on climatrogical temperature fields represented in a global cloud resolving model. We review two thermodynamic expressions of the mixture of the dry air and water substance examined in this study; one is deveroped considering the consistency and the other is approximated simpler one. It is shown that, in particular, large differences between simulations with two thermodynamic configurations appear in the tropical upper troposphere. Furthermore, based on the notion that the lapse rates are essentially moist adiabatic in the low-latitude region, we investigate what aspects of the thermodynamic configuration cause difference in the temperature structure through the analyses of moist adiabat.