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Representation of the autoconversion from cloud to rain using a weighted ensemble approach: a case study using WRF v4.1.3

Authors :
J. Yin
X. Liang
H. Wang
H. Xue
Source :
Geoscientific Model Development, Vol 15, Pp 771-786 (2022)
Publication Year :
2022
Publisher :
Copernicus Publications, 2022.

Abstract

Cloud and precipitation processes remain among the largest sources of uncertainties in weather and climate modelling, and considerable attention has been paid to improving the representation of the cloud and precipitation processes in numerical models in the last several decades. In this study, we develop a weighted ensemble (named EN) scheme by employing several widely used autoconversion (ATC) schemes to represent the ATC from cloud water to rainwater. One unique feature of the EN approach is that the ATC rate is a weighted mean value based on the calculations from several ATC schemes within a microphysics scheme with a negligible increase in computation cost. The EN scheme is compared with the several commonly used ATC schemes by performing real case simulations. In terms of accumulated rainfall and extreme hourly rainfall rate, the EN scheme provides better simulations than by using the single Berry–Reinhardt scheme, which was originally used in the Thompson scheme. It is worth emphasizing, in the present study, that we only pay attention to the ATC process from cloud water into rainwater with the purpose of improving the modelling of the extreme rainfall events over southern China. Actually, any (source and sink) term in a cloud microphysics scheme can be treated with the same approach. The ensemble method proposed herein appears to have important implications for developing cloud microphysics schemes in numerical models, especially for the models with variable grid resolution, which would be expected to improve the representation of cloud microphysical processes in the weather and climate models.

Subjects

Subjects :
Geology
QE1-996.5

Details

Language :
English
ISSN :
1991959X and 19919603
Volume :
15
Database :
Directory of Open Access Journals
Journal :
Geoscientific Model Development
Publication Type :
Academic Journal
Accession number :
edsdoj.4a04cd882a694a52b2a8edeca4220cd8
Document Type :
article
Full Text :
https://doi.org/10.5194/gmd-15-771-2022