Refined meteorological services provided during heavy rain process in southern China

During the flood season in 2020, extreme weather events are frequent with rather strong intensity. In particular, southern China has witnessed unusual heavy rain every now and then. The water levels of many rivers have broken records. To help flood control, meteorological departments have pooled resources and provided full-fledged services in terms of monitoring, observation, prediction, early warning and so on.

Refined services for flood control

On July 23, rain reemerged in Hefei, Anhui. Affected by the rain, the water level of Chaohu Lake continued to spike, which is exposed to severe flood control condition. Meteorological departments have made full-fledged stormy wave impact-based prediction. On July 24, Anhui Provincial Meteorological Serviced dispatched 5 emergency support teams to the site. They have added 5 emergency response mobile meteorological stations and 3 emergency response vehicles. They have also carried out real-time observation and prediction services of wind speed, wind direction, wave height on the lake based on real-time monitoring data and radar images.

On July 24, the staff installed emergency response mobile meteorological station in waterfront of Chaohu Lake in spite of the rain Photoed by Yao Hong

At 8:00 a.m. on July 23, Meteorological Observation Center of China Meteorological Administration (CMA) dispatched wind profiling radar team to go to Chaohu, Anhui, to provide wind profiling radar application technical support.

To tackle the rising water level, wind monitoring and prediction in Chaohu is of paramount significance. Anhui provincial meteorological service swiftly pooled strengths, and set up wind power monitoring and prediction platform around Chaohu Lake. Prior to that, the Centre has transferred 7 portable automatic stations to Anhui, which were used for the construction and consolidation of the washout stations.

Staff from Hefei municipal meteorological department briefed on the precipitation condition in the near future in the municipal flood prevention and drought relief headquarters

Meteorological staff members have made all-out efforts to rise to the flood control challenge in Chaohu Lake At 12:00 p.m. on July 25, Anhui provincial flood control and drought relief headquarters declared that relevant regions of the Yangtze River Basin, Huai River Basin, Chaohu Lake Basin entered emergency flood control season. Meteorological practitioners made all-out endeavor and rise to flood control challenge in Chaohu Lake

Location: observation site in Lirong Village, Binhu New Area, Hefei

On July 24, Anhui provincial meteorological service dispatched the technical working group to set up temporary 6-factor automatic observation meteorological station in spite of the rain from 2:00 p.m. on July 24. At 4:00 p.m. that day, they completed the construction of the station and realize the real-time observation data directly available to the CIMISS system. The group also carried out stormy wave observation and refined prediction services in the Chaohu Lake Basin.

The emergency response vehicle from Hefei municipal meteorological department and technical expert team went to the site. The vehicle is capable of video consultation and weather analysis and can realize the consultation with provincial and municipal meteorological observatories.　

Location: observation site in Linhe, Feidong County, Hefei

The automatic meteorological observation station set up by the meteorological staff

Location: observation site in Zhonghan County, Chaohu

In this site, the Service designated the emergency response vehicle to station here. Technical personnel from Huaibei municipal meteorological department and designated technical team members from the provincial Service carried out weather and stormy weather observation and prediction services. The staff was debugging the equipment.

Technical staff carried out wave height monitoring at 3-hour interval and transferred real-time data, which provided support for stormy wave meteorological prediction.

China Meteorological Administration (CMA) dispatched hydrological meteorological prediction expert to help local meteorological technical personnel on Basin prediction operation

On July 23, staff from Chaohu meteorological department distributed meteorological service materials and lightning protection security tip cards to flood control and disaster relief personnel.

Location: observation site in Shuangqiao River, Chaohu

The temporary installed meteorological station

Location: Xibakou of Chaohu

Xibakou with soaring water levels 

Satellite monitoring plays a part

Researchers from National Satellite Meteorological Center (NSMC) have harnessed cloud phase products of Fengyun-4A meteorological satellite and OLR product of FY-3 meteorological satellite, and analyzed the frequency of mixed cloud and ice cloud in the air during the heavy rain in southern China, cloud and atmospheric radiation features like satellite OLR and the change of monitoring figures in the same historical period respectively.

Via the FY satellite, basic information on the cloud and many quantifiable microphysics parameters of the cloud can be obtained and the weather process can be monitored accurately. For instance, satellites can monitor the cloud phase. Furthermore, satellite can monitor OLR. OLR figure have a guiding role in summer convection and precipitation in lower and middle altitude. When the rain emerges, the cloud volume will be quite large. And the cloud top radiation will be quite cold and OLR will be relatively low.　

The combined emergency frequency of mixed cloud and ice cloud from June 10 to July 10 in 2019 (a) and 2020 (b) and the difference of the figure between 2019 and 2020 (c) 

For instance, since July 26, 2020, heavy rain has plagued central Hunan, with the rain mainly converging in Zishui. By 9:00 a.m. on July 28, water in western Dongting Lake and southern parts has receded. However, water levels in eastern parts have witnessed slow rise, with most of the monitoring stations exposed to above warning water levels threshold. 

Monitoring image of the water body in Dongting Lake by radar satellite

True color cloud image and radar base reflectivity rate overlapping image by FY-4A geostationary meteorological satellite (2:00 p.m. on July 28, 2020) Credits: National Satellite Meteorological Center

Ultraviolet enhanced cloud image captured by FY-4A meteorological satellite, at 7:00, 7:30, 8:00, and 8:35 a.m. on July 19, 2020

True color cloud image captured by FY-4A satellite, at 8:35 a.m. on July 19, 2020 and radar base reflectivity overlapped image at 8:30 a.m. on July 19, 2020

On the morning of July 20, Wangjiaba dam discharged flood water and the river flowed to the Mengwa flood storage area. National Satellite Meteorological Center (NSMC) continues to harness radar satellite data of Ganfen-3 to monitor neighboring water body around Mengwa flood storage area of Huaihe River. 

Overlapped image of Mengwa flood storage area of Huaihe River captured by radar satellite (18:23 p.m. on July 20)

Image of water body monitoring of Mengwa flood storage area of Huaihe River captured by radar satellite (July, 20)

Image of water body change of Mengwa flood storage area captured by radar satellite

Multi-channel synchronized image of the Huaihe River Basin captured by Fengyun satellite (12:45, a.m., July, 21)

True color cloud image captured by FY-4A satellite (14:40 p.m. on July, 21)

Radar base reflectivity rate overlapping image (14:36 p.m. on July, 21)

The spirit of meteorological staff exhibited during this “battle”

Meteorological staff carried out sounding radar calibration by harnessing drones, Changsha, Hunan

New technology like “Tianjing” system have played their part in flood prevention services in Wuhan, Hubei

Meteorological staff carried out inspection and maintenance of facilities in Guangzhou meteorological satellite ground station

Meteorological personnel collected accurate data in Huishui, Guizhou　　

Thanks to full-blown deployment and endeavor, meteorological departments have shouldered their responsibilities and given full play to their fighting spirit and further exhibited their contentiousness and sense of accountability in this “battle”. During this year’s flood season, meteorological departments will continue to provide refined monitoring, accurate prediction, and elaborate services.

Editor: Liu Shuqiao