Evaluating and understanding the accuracy of cloud microphysical(MP) schemes in numerical weather prediction(NWP) models is crucial for assimilating satellite radiance data under cloudy conditions. This study leverage...Evaluating and understanding the accuracy of cloud microphysical(MP) schemes in numerical weather prediction(NWP) models is crucial for assimilating satellite radiance data under cloudy conditions. This study leverages surface observations, radar reflectivity data, and Himawari-8 satellite radiance data from both water vapor and window channels to assess the performance of four prevalent cloud MP schemes: WSM6, WDM6, Thompson, and Morrison, as implemented in the Weather Research and Forecasting(WRF) model. The assessment focuses on two typical heavy rain events in South China: a warm-sector torrential rainfall(WSTR) event and a squall line(SL) event. The findings reveal that the cloud MP schemes exhibit varying levels of accuracy across the two events. Notably, for the WSTR event, the WDM6scheme shows the closest alignment with observed rainfall in terms of precipitation forecast. In contrast, the Thompson scheme outperforms the others during the SL event. The simulation of infrared(IR) radiance data from cloud and rain areas remains a significant challenge, particularly for ice clouds, which exhibit greater forecast uncertainty compared to water clouds. Identifying the optimal scheme for describing the full cloud process during rainfall events remains challenging among the evaluated MP schemes. Specifically, the WDM6 scheme stands out in forecasting clear skies and water clouds,while the Morrison and Thompson schemes are found to be more adept at predicting ice clouds. The discrepancies observed between the accuracy of precipitation forecast and cloud prediction highlight the need for further research to identify an MP scheme that effectively balances precipitation forecast with accurate cloudy radiative transfer(RT) simulation for data assimilation(DA). This research offers valuable insights into the selection of cloud microphysics parameterization schemes for all-sky radiance assimilation, particularly under diverse rainfall processes.展开更多
A new scheme that separates convective-stratiform rainfall is developed using threshold values of liquid water path(LWP) and ice water path(IWP).These cloud contents can be predicted with radiances at the Advanced Mic...A new scheme that separates convective-stratiform rainfall is developed using threshold values of liquid water path(LWP) and ice water path(IWP).These cloud contents can be predicted with radiances at the Advanced Microwave Sounding Unit(AMSU) channels(23.8,31.4,89,and 150 GHz) through linear regression models.The scheme is demonstrated by an analysis of a two-dimensional cloud resolving model simulation that is imposed by a forcing derived from the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment(TOGA COARE).The rainfall is considered convective if associated LWP is larger than 1.91 mm or IWP is larger than1.70 mm.Otherwise,the rainfall is stratiform.The analysis of surface rainfall budget demonstrates that this new scheme is physically meaningful.展开更多
基金Guangdong Province Natural Science Foundation Youth Science Fund (2021A1515110944)。
文摘Evaluating and understanding the accuracy of cloud microphysical(MP) schemes in numerical weather prediction(NWP) models is crucial for assimilating satellite radiance data under cloudy conditions. This study leverages surface observations, radar reflectivity data, and Himawari-8 satellite radiance data from both water vapor and window channels to assess the performance of four prevalent cloud MP schemes: WSM6, WDM6, Thompson, and Morrison, as implemented in the Weather Research and Forecasting(WRF) model. The assessment focuses on two typical heavy rain events in South China: a warm-sector torrential rainfall(WSTR) event and a squall line(SL) event. The findings reveal that the cloud MP schemes exhibit varying levels of accuracy across the two events. Notably, for the WSTR event, the WDM6scheme shows the closest alignment with observed rainfall in terms of precipitation forecast. In contrast, the Thompson scheme outperforms the others during the SL event. The simulation of infrared(IR) radiance data from cloud and rain areas remains a significant challenge, particularly for ice clouds, which exhibit greater forecast uncertainty compared to water clouds. Identifying the optimal scheme for describing the full cloud process during rainfall events remains challenging among the evaluated MP schemes. Specifically, the WDM6 scheme stands out in forecasting clear skies and water clouds,while the Morrison and Thompson schemes are found to be more adept at predicting ice clouds. The discrepancies observed between the accuracy of precipitation forecast and cloud prediction highlight the need for further research to identify an MP scheme that effectively balances precipitation forecast with accurate cloudy radiative transfer(RT) simulation for data assimilation(DA). This research offers valuable insights into the selection of cloud microphysics parameterization schemes for all-sky radiance assimilation, particularly under diverse rainfall processes.
基金National Key Basic Research and Development Project of China(2013CB430103,2015CB453201)National Natural Science Foundation of China(41475039,41375058,41530427)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘A new scheme that separates convective-stratiform rainfall is developed using threshold values of liquid water path(LWP) and ice water path(IWP).These cloud contents can be predicted with radiances at the Advanced Microwave Sounding Unit(AMSU) channels(23.8,31.4,89,and 150 GHz) through linear regression models.The scheme is demonstrated by an analysis of a two-dimensional cloud resolving model simulation that is imposed by a forcing derived from the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment(TOGA COARE).The rainfall is considered convective if associated LWP is larger than 1.91 mm or IWP is larger than1.70 mm.Otherwise,the rainfall is stratiform.The analysis of surface rainfall budget demonstrates that this new scheme is physically meaningful.
