Nowcasting of a Warm‐Sector Rainfall Event in Southern China With the TRAMS Model: Sensitivity to Different Radar Reflectivity Retrieval Methods and Incremental Updating Strategies

Abstract To improve the radar data assimilation scheme for the high‐resolution Tropical Regional Atmospheric Model System (TRAMS) model, this study investigates the sensitivity of simulating a warm‐sector rainfall event in southern China to different radar reflectivity retrieval methods and incremen...

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Main Authors: Xiaoxia Lin, Yerong Feng, Yuntao Jian, Daosheng Xu, Jincan Huang, Haowei Chen, Banglin Zhang
Format: Article
Language:English
Published: American Geophysical Union (AGU) 2025-01-01
Series:Earth and Space Science
Subjects:
Online Access:https://doi.org/10.1029/2024EA003724
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author Xiaoxia Lin
Yerong Feng
Yuntao Jian
Daosheng Xu
Jincan Huang
Haowei Chen
Banglin Zhang
author_facet Xiaoxia Lin
Yerong Feng
Yuntao Jian
Daosheng Xu
Jincan Huang
Haowei Chen
Banglin Zhang
author_sort Xiaoxia Lin
collection DOAJ
description Abstract To improve the radar data assimilation scheme for the high‐resolution Tropical Regional Atmospheric Model System (TRAMS) model, this study investigates the sensitivity of simulating a warm‐sector rainfall event in southern China to different radar reflectivity retrieval methods and incremental updating strategies. The findings indicate that the ice cloud retrieval (ICR) method yields more reasonable cloud hydrometeors. However, the impact of different retrieval methods is minimal without corresponding adjustments to the dynamic field. Further assimilation of the wind field effectively reduced the overestimated south winds and successfully simulated the observed low‐level convergence in northern Guangdong, significantly improving precipitation forecasts. Both incremental analysis update (IAU) and Nudging methods were able to adjust the forecast to better match the observations, with IAU performing slightly better. These findings are beneficial for further improving the forecast accuracy of precipitation intensity. Extending the IAU relaxation time from 4 to 10 min has almost no impact on the actual forecasting. However, prioritizing the adjustment of the wind field through time‐dependent IAU weighting factors, the impact of cloud particle adjustments on the dynamical field can be avoided (e.g., the drag caused by the sinking of cloud particles may offset the upward motion induced by dynamical convergence adjustments). This allows for more realistic low‐level wind convergence and precipitation forecasts to be obtained. Overall, the ICR method for retrieving cloud hydrometeors, combined with the IAU method using time‐dependent distribution weighting factors appears to be a more suitable option for the radar data assimilation scheme in TRAMS model.
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institution Kabale University
issn 2333-5084
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publishDate 2025-01-01
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spelling doaj-art-9ef16ee0662a442395eee967adcd29902025-01-28T11:08:40ZengAmerican Geophysical Union (AGU)Earth and Space Science2333-50842025-01-01121n/an/a10.1029/2024EA003724Nowcasting of a Warm‐Sector Rainfall Event in Southern China With the TRAMS Model: Sensitivity to Different Radar Reflectivity Retrieval Methods and Incremental Updating StrategiesXiaoxia Lin0Yerong Feng1Yuntao Jian2Daosheng Xu3Jincan Huang4Haowei Chen5Banglin Zhang6Guangzhou Institute of Tropical and Marine Meteorology/Guangdong Provincial Key Laboratory of Regional Numerical Weather Prediction China Meteorological Administration Guangzhou ChinaGuangdong‐Hong Kong‐Macao Greater Bay Area Weather Research Center of Monitoring Warning and Forecasting (Shenzhen Institute of Meteorological Innovation) Shenzhen ChinaGuangdong Climate Center Guangzhou ChinaGuangzhou Institute of Tropical and Marine Meteorology/Guangdong Provincial Key Laboratory of Regional Numerical Weather Prediction China Meteorological Administration Guangzhou ChinaFoshan Meteorological Service of Guangdong Province Foshan ChinaShaoguan Meteorology Office Shaoguan ChinaCollege of Meteorology and Oceanography National University of Defense Technology Changsha ChinaAbstract To improve the radar data assimilation scheme for the high‐resolution Tropical Regional Atmospheric Model System (TRAMS) model, this study investigates the sensitivity of simulating a warm‐sector rainfall event in southern China to different radar reflectivity retrieval methods and incremental updating strategies. The findings indicate that the ice cloud retrieval (ICR) method yields more reasonable cloud hydrometeors. However, the impact of different retrieval methods is minimal without corresponding adjustments to the dynamic field. Further assimilation of the wind field effectively reduced the overestimated south winds and successfully simulated the observed low‐level convergence in northern Guangdong, significantly improving precipitation forecasts. Both incremental analysis update (IAU) and Nudging methods were able to adjust the forecast to better match the observations, with IAU performing slightly better. These findings are beneficial for further improving the forecast accuracy of precipitation intensity. Extending the IAU relaxation time from 4 to 10 min has almost no impact on the actual forecasting. However, prioritizing the adjustment of the wind field through time‐dependent IAU weighting factors, the impact of cloud particle adjustments on the dynamical field can be avoided (e.g., the drag caused by the sinking of cloud particles may offset the upward motion induced by dynamical convergence adjustments). This allows for more realistic low‐level wind convergence and precipitation forecasts to be obtained. Overall, the ICR method for retrieving cloud hydrometeors, combined with the IAU method using time‐dependent distribution weighting factors appears to be a more suitable option for the radar data assimilation scheme in TRAMS model.https://doi.org/10.1029/2024EA003724warm‐sector torrential rainfallradar reflectivity retrieval methodsincremental updating strategies
spellingShingle Xiaoxia Lin
Yerong Feng
Yuntao Jian
Daosheng Xu
Jincan Huang
Haowei Chen
Banglin Zhang
Nowcasting of a Warm‐Sector Rainfall Event in Southern China With the TRAMS Model: Sensitivity to Different Radar Reflectivity Retrieval Methods and Incremental Updating Strategies
Earth and Space Science
warm‐sector torrential rainfall
radar reflectivity retrieval methods
incremental updating strategies
title Nowcasting of a Warm‐Sector Rainfall Event in Southern China With the TRAMS Model: Sensitivity to Different Radar Reflectivity Retrieval Methods and Incremental Updating Strategies
title_full Nowcasting of a Warm‐Sector Rainfall Event in Southern China With the TRAMS Model: Sensitivity to Different Radar Reflectivity Retrieval Methods and Incremental Updating Strategies
title_fullStr Nowcasting of a Warm‐Sector Rainfall Event in Southern China With the TRAMS Model: Sensitivity to Different Radar Reflectivity Retrieval Methods and Incremental Updating Strategies
title_full_unstemmed Nowcasting of a Warm‐Sector Rainfall Event in Southern China With the TRAMS Model: Sensitivity to Different Radar Reflectivity Retrieval Methods and Incremental Updating Strategies
title_short Nowcasting of a Warm‐Sector Rainfall Event in Southern China With the TRAMS Model: Sensitivity to Different Radar Reflectivity Retrieval Methods and Incremental Updating Strategies
title_sort nowcasting of a warm sector rainfall event in southern china with the trams model sensitivity to different radar reflectivity retrieval methods and incremental updating strategies
topic warm‐sector torrential rainfall
radar reflectivity retrieval methods
incremental updating strategies
url https://doi.org/10.1029/2024EA003724
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