China: New products of FY-4A meteorological satellite improve typhoon path forecast
By Lujian, Liu Shuqiao and Wang Meijue
During this typhoon season, dozens of new remote sensing products of FY-4A meteorological satellite have been put into application. Multi-integrated (space-based, upper-air and ground-based) meteorological observing products have become more abundant, providing important support for accuracy forecast of typhoon, severe precipitation and gale.
Since formation of typhoon Ampil at 8:00 p.m. on July 18, FY-4A always provided 28 new remote sensing products. On July 23, the data from Geosynchronous Interferometric Infrared Sounder (GIIRS) onboard the satellite has rolled into the numerical prediction model, which helps to adjust the typhoon Ampil track forecast and make center position forecast become closer to the real condition. The convective storm products of FY-4A helped forecasters more intuitively to confirm the strong convection position within the typhoon.
In addition, during the typhoon season, the second-generation polar-orbiting meteorological satellite FY-3, geostationary meteorological satellite FY-2 and FY-4 complement each other. The FY-3 satellite Microwave Radiation Imager (MWRI) penetrates the clouds and sees through the typhoon rainfall distribution. FY-2F started the intensive observation with every 6 minutes frequency from 14:00 of July 20 to 08:00 of July 22.
According to statistics, from July 18 to 23, the demand for Fengyun satellite products in the typhoon forecast increased significantly. Within 48 hours before and after the typhoon landfall, the visits of the satellite weather application platform(online version) reached 813, the number of files accessed by the satellite data resource pool exceeded 270000, and the amount of data reached 7 TB.
Liang Haihe, the director of the Data Quality Office of CMA Meteorological Observation Center introduces that the integration of multiple observations such as Fengyun satellite, ground-based weather radar, ground-based lightning locator, offshore buoy, automatic weather stations and wind profile radar are also one of the hightlights of typhoon forecast in this year. Among them, in the ground-based observation, the new-generation weather radar is the most powerful tool for monitoring the weather such as heavy rain, hail, strong winds, etc. Since the network is connected, the three-dimensional structure information of the typhoon is obtained by 3D scanning every 6 minutes. Then the refined degree of spatial resolution has reached 1 km, enable forecasters to quickly estimate convective weather systems. According to statistics, during the typhoon Ampil period, the application amount of CMA integrated observation products system reached more than 250,000 products within 24 hours.
Previously, in the monitoring 8th typhoon Maria, FY-4A has performed very well. At 11:00 on July 10, the CMA launched the global 4D-Var assimilation operation of GRAPES, and assimilated the 15-minute resolution regional intensive observation data of FY-4A GIIRS to the GRAPES global forecast system. Through comparison with actual observations, it shows that the data improved the intensity prediction of typhoon and the forecast of sub-high intensity and position.