Cutting-edge technologies help forecast heavy rain

China Meteorological Administration

Recently, many parts of the world have been subjected to extreme weather events like heavy rain or heat wave. While in mid-late July, heavy rains have battered large portions of North China and Huanghuai Region. During the response to the heavy rain, multiple cutting-edge forecasting technologies and modernization results have been harnessed by China Meteorological Administration (CMA).

Advanced forecasting technologies

According to the figure by World Meteorological Centre Beijing (WMC-BJ), from 8:00 a.m. on July 17 to 8:00 a.m. on July 23, cumulative rainfall registered 200-450mm in central-northern and southwestern Henan, central and southwestern Hebei, and southeastern Shanxi. Portions of Zhengzhou, Xuchang, Pingdingshan, Xinxiang, Jiaozuo, Hebi, and Anyang witnessed 500-700 cumulative rainfall.Some regions like Xinjiang and Anyang in Henan was walloped by over 800 mm cumulative rainfall. This extreme process was characterized by heavy cumulative rainfall,strong short range rain intensity, and extreme feature.

Precipitation extremes forecasting technology

In tackling heavy rain from July 16 to 19, National Meteorological Centre (NMC) of CMA fully utilized multi-model self-adapting integrated quantitative objective forecasting technology, precipitation extremes forecasting technology, minute-scale precipitation forecasting technology updated from time to time, multi-source quantitative precipitation forecasting integrated technology based on similar grid point, and subjective and objective integrated QPF platform optimum weight integrated products. These products have been incorporated into MICAPS platform, integrated analysis platform, and forecasting verification and assessment platform, which has elevated the operational efficiency.

In the meanwhile, during tackling the heavy rain from July 11 to July 12, WMC-BJ has conducted analysis and provided refined services.

Regarding this extreme event, the grid point forecasting products by NMC of CMA accurately grasped the scope, intensity and evolution characteristics of the heavy rainfall. Threat Score (TS) of the torrential rain forecast on July 11 and July 12 reached 0.53 and 0.45 respectively, both exceeding the forecasting results of various raw global models. In addition, NMC's daily extreme precipitation forecasting products also performed well for this extreme precipitation event.

Meteorological satellite products help

During tackling the two large-scale heavy rain during mid-July, National Satellite Meteorological Center (NSMC) of CMA has generated high temporal resolution satellite products like cloud top brightness temperature, and precipitation estimation.

NSMC have conducted smart monitoring and early warning services of parameters with myriad features for provinces and cities that the cloud system traverses and is going to exert impacts on during the latter process.

NSMC activated 1-minute frequency regional observation model of the rapid scanner of FY-4B meteorological satellite after harnessing the location of severe convection derived from weather prediction result. Via FY-4B cloud image animation with 250 meter resolution within 2000×2000 kilometer scale, the volatile and detailed process can be explicitly seen. The cloud image can help forecasters capture the relationship of roughness of cloud system texture and heavy rain in heavy rain regions.

t has leveraged cloud top height and cloud top temperature products of FY-4A satellite to judge if severe convection cloud cluster reach severe convection scale. Convective initiation products provide estimated precipitation within the monitoring scope of satellites and help forecasters grasp rain condition intensity. In the meanwhile, the assimilation of atmospheric vertical parameters derived from geostationary meteorological satellite and polar-orbiting meteorological satellite observation into numerical weather prediction (NWP) models can ramp up NWP accuracy.

NSMC has provided technical support for tackling the heavy rain in places in Henan via monitoring by multiple products. From July 20, NSMC activated 1-minute frequency regional observation of the rapid imager of FY-4 satellite as soon as possible, and carried out real-time monitoring of rain conditions in Henan. In the meanwhile, NSMC has harnessed myriad products to monitor the torrential downpour in Henan, such as true color images of geostationary FY-4 satellites and polar-orbiting meteorological satellites, infrared water vapor, convection quantitative products, and rainstorm risk indicator.

The newly developed indicator, rainstorm risk indicator by NSMC has leveraged satellite reversion precipitation products of meteorological satellites, combine data on terrain, river system, demography, and economy, and construct monitoring models of this indicator, including a few rainstorm disaster-inducing factors, hazard inducing environment, and hazard-affected body information.

Refined observation services provided

Targeted at extreme heavy rain weather in places like Henan, Meteorological Observation Center (MOC) of CMA is closely monitoring the observing facilities in Henan and adjacent regions, to ensure stable and reliable operation of observing stations. It has harnessed Tianheng and Tianyan system to conduct the accuracy validation of observation extremes in Zhengzhou, Kaifeng, and other relevant stations, and provide data support for forecasters.

By 7:00 p.m. on July 21, integrated meteorological observation station network in Henan was in stable operation. 9 weather radars, 3 sounding radars, 31 GNSS/MET water vapor stations were operating smoothly. Observation facilities like automatic meteorological stations and radar stations were in stable operation. The real-time operational platform of MOC has released monitoring texts covering 256 people, and provided 7 for provincial facilities departments.

It has also carried out observation data quality control and assessment for Henan. The real-time operational platform has conducted electromagnetic interference quality control with 224 frequency. Besides, cloud radar products and vertical observation products developed by MOC has provided first-hand data for judging precipitation time, intensity, and duration, and so on.

MOC will soon roll out Radar Mosaic product. The internal structure of the echo can be seen in more detail and the refined level of rainstorm prediction can be elevated.

Besides,the rapid refined experiment and alpine model observation experiment are being conducted in 2021. Alpine model observation experiment can detect the emergence of precipitation in faraway regions at an earlier time. Rapid refined experiment helps elevate resolution, in order to rapidly obtain more refined internal structure of severe convection monosome.

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