Influence of microphysical schemes on atmospheric water in the Weather Research and Forecasting model

Cossu, Federico; Hocke, Klemens (2014). Influence of microphysical schemes on atmospheric water in the Weather Research and Forecasting model. Geoscientific model development (GMD), 7(1), pp. 147-160. Copernicus Publications 10.5194/gmd-7-147-2014

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This study examines how different microphysical parameterization schemes influence orographically induced precipitation and the distributions of hydrometeors and water vapour for midlatitude summer conditions in the Weather Research and Forecasting (WRF) model. A high-resolution two-dimensional idealized simulation is used to assess the differences between the schemes in which a moist air flow is interacting with a bell-shaped 2 km high mountain. Periodic lateral boundary conditions are chosen to recirculate atmospheric water in the domain. It is found that the 13 selected microphysical schemes conserve the water in the model domain. The gain or loss of water is less than 0.81% over a simulation time interval of 61 days. The differences of the microphysical schemes in terms of the distributions of water vapour, hydrometeors and accumulated precipitation are presented and discussed. The Kessler scheme, the only scheme without ice-phase processes, shows final values of cloud liquid water 14 times greater than the other schemes. The differences among the other schemes are not as extreme, but still they differ up to 79% in water vapour, up to 10 times in hydrometeors and up to 64% in accumulated precipitation at the end of the simulation. The microphysical schemes also differ in the surface evaporation rate. The WRF single-moment 3-class scheme has the highest surface evaporation rate compensated by the highest precipitation rate. The different distributions of hydrometeors and water vapour of the microphysical schemes induce differences up to 49 W m−2 in the downwelling shortwave radiation and up to 33 W m−2 in the downwelling longwave radiation.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Applied Physics
10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)

UniBE Contributor:

Cossu, Federico and Hocke, Klemens

Subjects:

600 Technology > 620 Engineering

ISSN:

1991-959X

Publisher:

Copernicus Publications

Language:

English

Submitter:

Monika Wälti-Stampfli

Date Deposited:

06 Oct 2014 12:40

Last Modified:

06 Jul 2017 11:46

Publisher DOI:

10.5194/gmd-7-147-2014

BORIS DOI:

10.7892/boris.57904

URI:

https://boris.unibe.ch/id/eprint/57904

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