As the latest generation of Chinese Geostationary Weather Satellites, Fengyun-4 carries the Advanced Geosynchronous Radiation Imager (AGRI), which has more spectral bands and higher temporal and spatial resolution than the Visible Infrared Spin-Scan Radiometer (VISSR) onboard geostationary satellite FY-2. Direct assimilation of the FY-4A AGRI datasets has been proved to be an efficient way to improve heavy rainfall simulation. We aim to assess the joint assimilation of AGRI infrared radiance and ground-based MWR (Microwave Radiometer) data on short-duration heavy rainfall prediction. RTTOV (Radiative Transfer for the TIROS Operational Vertical Sounder) is used as the observational operator for FY-4A AGRI data assimilation. The data assimilation interface is built in WRFDA 4.3 to achieve direct assimilation of FY4A AGRI radiance. The forecasting effectiveness of the joint assimilation for a typical heavy rainfall event over northern China is analyzed with four simulation experiments. The main conclusions are: 1) Assimilating MWR data can improve the initial humidity condition in the middle-lower layers, while AGRI radiance assimilation favors the initial humidity correction in the middle-upper layers. The joint assimilation of two datasets can remarkably improve the initial humidity condition in the entire column. 2) Data assimilation effectively improves the 6-h accumulated rainfall simulation. The joint assimilation of AGRI radiance and MWR data is superior to assimilating either of them. The joint assimilation significantly improves the rainfall forecast over the Beijing area, where the seven MWRs are distributed. 3) Data assimilation experiments present similar effects on predicted and initial humidity conditions. The MWR_DA experiment (only assimilate MWR data) markedly improves the humidity forecast in the middle-lower layers, while AGRI_DA (only assimilate AGRI data) is effective in the middle-upper layers. The joint assimilation of AGRI radiance and MWR data could skillfully correct the humidity distribution in the entire layers, allowing for more accurate heavy rainfall prediction. This paper provides a valuable basis for further improving the application of FY-4A AGRI radiance in numerical weather models.
In this paper, ERA5 reanalysis data from the European Center for Medium-Range Weather Forecasts and the Weather Research and Forecasting (WRF) mesoscale model are used to compare and simulate a topographic gravity wave event that occurred over the Tibetan Plateau between 18:00 on 3 May 2014 and 00:00 on 4 May 2014. The stratosphere-troposphere exchange (STE) process and its detailed characteristics during the gravity wave event are presented. The response of the upper troposphere and lower stratosphere (UTLS) ozone to the gravity wave is discovered from the perspective of the gravity wave dynamic process. The results show that the gravity wave structure between 90 • E and 100 • E had a westward tilt with height. From 19:00 to 21:00 the gravity waves decayed and from 22:00 to 23:00 their shape gradually blurred. Meanwhile, there was a response of the ozone mixing ratio in the UTLS over the Tibetan Plateau to the gravity waves breaking. After 21:00, this wave process caused the STE, as air from the stratosphere with a greater ozone concentration was injected into the upper troposphere, leading to rapidly increased ozone concentration there.
Abstract. Two types of temperature profile products from the FY-3 (FengYun-3) satellite system, using GNOS and VASS, together with AIRS operational Level 2 data, are used to compare and analyze gravity wave parameters. The advantages and disadvantages of these three types of temperature profile data for gravity wave parameter extraction are determined, based on three extraction methods: vertical sliding average, double-filter and single-filter. By comparing the three methods, the conditions under which each dataset can be applied are obtained. Accurate gravity wave disturbance profiles cannot be obtained using the vertical sliding average method. The double-filter method can extract gravity waves in a vertical wavelength range from 2 to 10 km. The single-filter method can obtain gravity wave disturbances with vertical wavelengths less than 8 km. For all three gravity wave parameter extraction methods, the GNOS temperature profile product performs better in the lower layer of 5–35 km. From 35 to 65 km the AIRS temperature profile product is better than GNOS. Using the single-filter method, GNOS and AIRS filter out the vertical linear trend in the disturbance profile well, reflecting the advantages of a single filter. The vertical resolution of VASS is lower, but larger vertical scale components are retained.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.