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Implementation of Prognostic Cloud Ice Number Concentrations for the Weather Research and Forecasting (WRF) Double‐Moment 6‐Class (WDM6) Microphysics Scheme.
In: Journal of Advances in Modeling Earth Systems, Jg. 15 (2023-02-01), Heft 2, S. 1-28
Online
academicJournal
Zugriff:
The ice microphysical processes in the Weather Research and Forecasting (WRF) Double‐Moment 6‐class (WDM6) microphysics scheme are treated as a single‐moment approach, in which the number concentration of cloud ice is diagnosed based on its mixing ratio. This study develops the revised WDM6 scheme through the implementation of prognostic cloud ice number concentrations. The effect of the prognostic number concentration on the simulated precipitation is verified through simulations of short‐term winter snowfall cases during International Collaborative Experiments for the Pyeongchang 2018 Olympics and Paralympics (ICE‐POP 2018) winter games and a 1‐month regional climate case during the summer season, July 2009. For all cases, the revised WDM6 simulates higher cloud ice number concentrations and lower cloud ice mixing ratios than the original WDM6. The microphysics budget analysis for the snowfall cases shows that the inefficient deposition and vapor freezing nucleation processes of cloud ice reduce the available cloud ice mixing ratio. Consequently, the accretion processes with cloud ice decrease and the deposition into snow increases due to the surplus water vapor. The revised WDM6 alleviates the positive bias of surface precipitation consisting of snow over the region where the original WDM6 simulates excessive precipitation, compared to the observed data. For the regional climate case, the reduced cloud ice amount strengthens the Western North Pacific high‐pressure system by allowing more solar radiation to reach the surface, leading to simulated precipitation bands and synoptic environments that are more comparable with the observed data. Plain Language Summary: The Weather Research and Forecasting (WRF) Double‐Moment 6‐class (WDM6) scheme has been widely used in research and forecasting areas as one of the cloud microphysics options in the WRF model. However, the WDM6 scheme has a limitation in representing the real cloud and precipitation processes because the scheme does not predict the cloud ice number concentration. We develop the new version of the WDM6 scheme, which can predict the cloud ice number concentration together with its mixing ratio. Therefore, the scheme can represent the more flexible size distribution of cloud ice. The evaluation of the new WDM6 scheme has been conducted for the short‐range winter‐precipitation cases and the regional climate case during summer season. The excess generation of cloud ice mixing ratio, which has been reported as one of the problems of the WDM6 scheme, is considerably alleviated. Furthermore, the new WDM6 scheme improves the precipitation forecasts, relative to the original WDM6, by shifting the major precipitation band location in the regional climate case and reducing the excessive precipitation over the mountainous region for the short‐range winter‐precipitation cases, in which low‐pressure systems located north of the polar jet stream over the Korean peninsula. Key Points: The Weather Research and Forecasting Double‐Moment 6‐class microphysics scheme has been revised with the prognostic cloud ice number concentrationsThe excess generation of cloud ice mixing ratio is alleviated with the revised scheme treating cloud ice as a double‐moment approachThe revised scheme improves the precipitation forecasts by shifting the major precipitation band simulated in the regional climate case [ABSTRACT FROM AUTHOR]
Titel: |
Implementation of Prognostic Cloud Ice Number Concentrations for the Weather Research and Forecasting (WRF) Double‐Moment 6‐Class (WDM6) Microphysics Scheme.
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Autor/in / Beteiligte Person: | Park, Sun‐Young ; Lim, Kyo‐Sun Sunny |
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Zeitschrift: | Journal of Advances in Modeling Earth Systems, Jg. 15 (2023-02-01), Heft 2, S. 1-28 |
Veröffentlichung: | 2023 |
Medientyp: | academicJournal |
ISSN: | 1942-2466 (print) |
DOI: | 10.1029/2022MS003009 |
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