Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 17, 15037-15043, 2017
https://doi.org/10.5194/acp-17-15037-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Technical note
19 Dec 2017
Technical note: A noniterative approach to modelling moist thermodynamics
Nadya Moisseeva and Roland Stull Dept. of Earth, Ocean and Atmospheric Sciences, University of British Columbia, 2020-2207 Main Mall Vancouver, BC, V6T 1Z4, Canada
Abstract. Formulation of noniterative mathematical expressions for moist thermodynamics presents a challenge for both numerical and theoretical modellers. This technical note offers a simple and efficient tool for approximating two common thermodynamic relationships: temperature, T, at a given pressure, P, along a saturated adiabat, T(P, θw), as well as its corresponding inverse form θw(P, T), where θw is wet-bulb potential temperature. Our method allows direct calculation of T(P, θw) and θw(P, T) on a thermodynamic domain bounded by −70 ≤ θw < 40 °C, P > 1 kPa and −100 ≤ T < 40 °C, P > 1 kPa, respectively. The proposed parameterizations offer high accuracy (mean absolute errors of 0.016 and 0.002 °C for T(P, θw) and θw(P, T), respectively) on a notably larger thermodynamic region than previously studied. The paper includes a method summary and a ready-to-use tool to aid atmospheric physicists in their practical applications.

Citation: Moisseeva, N. and Stull, R.: Technical note: A noniterative approach to modelling moist thermodynamics, Atmos. Chem. Phys., 17, 15037-15043, https://doi.org/10.5194/acp-17-15037-2017, 2017.
Publications Copernicus
Download
Short summary
This technical note presents simple noniterative approximations for two common thermodynamic relationships used for moist convection. The method offers roughly 2 orders of magnitude improvement in accuracy over the only existing noniterative solution. The proposed approach alleviates the need for costly numerical integration of saturated thermodynamic equations within numerical weather prediction models and in theoretical studies.
This technical note presents simple noniterative approximations for two common thermodynamic...
Share