The Study of Fengyun4a Temperature Profile Data Assimilation in a Southwest Vortex Heavy Rainfall Case

25 Pages Posted: 24 Jun 2022

See all articles by Kuo Zhou

Kuo Zhou

affiliation not provided to SSRN

Lingkun Ran

affiliation not provided to SSRN

Libo Zhou

affiliation not provided to SSRN

Tianbao Zhao

affiliation not provided to SSRN

Lei Chen

affiliation not provided to SSRN

Abstract

A rapid updating cycle assimilation and forecasting system is built for improving precipitation forecasting effect and ensuring operational safety along the Sichuan-Tibet Railway. The Fengyun4A satellite (FY-4A) temperature profile data quality control and assimilation are carried out in a heavy rainfall event in Sichuan Province during June 25~27, 2020. The results show that the data quality of the FY-4A temperature profile in clear sky area is better than that in cloudy area. The temperature and water vapor biases in the analysis field are reduced after the clear sky FY-4A temperature profile assimilation with cloud detection, and the 48 h precipitation forecast TS score is improved effectively. Based on that, the observation error of FY-4A temperature profile in clear sky is obtained using the sounding observation. After using the FY-4A temperature profile observation error to correct the original static temperature observation error, the temperature and water vapor biases in the assimilation analysis field are further reduced, and the precipitation forecast TS score is significantly improved. The southwest vortex (SWV) is the main weather system affecting the precipitation process. The analysis field from observation error correction assimilation has the effects of warming, humidifying and enhancing the southwesterly wind on the 700 hPa environmental field. After assimilation, the near-surface stratification tends to be unstable, and the positive vorticity at 700 hPa increases in the Sichuan Basin. The assimilation analysis field provides favorable dynamic and thermal conditions for the development of the SWV and precipitation, and the development of the SWV is enhanced and causes precipitation. In contrast, the original FY-4A temperature profile assimilation is drastic for temperature, humidity and wind field adjustments. The adjusted environmental field is not conducive to the development of the SWV and precipitation, so the assimilation of the original FY-4A temperature profile is not optimal for the precipitation forecasting improvement.

Keywords: FY-4A temperature profile, cloud detection, observation error, southwest vortex, precipitation forecasting

Suggested Citation

Zhou, Kuo and Ran, Lingkun and Zhou, Libo and Zhao, Tianbao and Chen, Lei, The Study of Fengyun4a Temperature Profile Data Assimilation in a Southwest Vortex Heavy Rainfall Case. Available at SSRN: https://ssrn.com/abstract=4145237 or http://dx.doi.org/10.2139/ssrn.4145237

Kuo Zhou (Contact Author)

affiliation not provided to SSRN ( email )

No Address Available

Lingkun Ran

affiliation not provided to SSRN ( email )

No Address Available

Libo Zhou

affiliation not provided to SSRN ( email )

No Address Available

Tianbao Zhao

affiliation not provided to SSRN ( email )

No Address Available

Lei Chen

affiliation not provided to SSRN ( email )

No Address Available

Do you have negative results from your research you’d like to share?

Paper statistics

Downloads
22
Abstract Views
96
PlumX Metrics