Accession Number : AD1004433

Title :   Using Enthalpy as a Prognostic Variable in Atmospheric Modelling with Variable Composition

Descriptive Note : Journal Article

Corporate Author : University of Colorado Boulder United States

Personal Author(s) : Akmaev,R A ; Juang,H H

Full Text :

Report Date : 14 Apr 2016

Pagination or Media Count : 5

Abstract : Specific enthalpy emerges from a general form of the internal energy equation as a convenient prognostic thermodynamic variable for atmospheric modelling with variable composition, including models of moist air. This choice presents a general and flexible alternative to the common formalism of virtual temperature employed in most numerical weather prediction and climate models to account for the presence of water vapour and other constituents. The new approach eliminates the need for additional terms in the energy equation, resulting from composition variations along the air-parcel trajectories and routinely neglected in models. This note presents a derivation of relevant equations from first principles and outlines the changes to existing model codes necessary to accommodate the new formulation.

Descriptors :   enthalpy , entrophy , atmospheric models , temperature

Distribution Statement : APPROVED FOR PUBLIC RELEASE