What is the difference between 20 13 and "7 19" in 2007?

From 0: 00/kloc-0: 00 on July 9 to 08: 00 on July 20, the strongest rainfall occurred in Beijing since the flood season this year. At the same time, large-scale heavy rainfall occurred in North China, Huanghuai, Jianghan and other places, with a rainstorm area of more than 50 mm reaching 635,000 square kilometers, in which heavy rains of more than 250 mm occurred in Hebei, Henan, Hubei and other places, and the daily rainfall in Shanxi, Hebei, Hubei and other places 17 counties and cities exceeded historical extremes.

"This is the first time that such a large-scale heavy rainfall process has occurred in the northern region since the flood season this year." Ma Xuekuan, chief forecaster of the Central Meteorological Observatory, said, "The main reason for this rainfall is that the subtropical high belt in the western Pacific Ocean has strengthened and lifted northward."

Ma Xuekuan said that the updraft prevails at the edge of the subtropical high, and the convection is strong, which is easy to cause heavy rain; In addition, the southwest warm and humid airflow at the edge of subtropical high can continuously transport water vapor, and it meets with cold air violently in North China and Huanghuai area, forming "Huanghuai cyclone", which leads to the occurrence and development of heavy precipitation weather. "Huang-Huai cyclone" is usually regarded by meteorologists as a "lighthouse" for heavy rain in the north. It is like a "water pump", which is conducive to the influx and accumulation of surrounding water vapor.

Comparing the "July 21"torrential rain in 20 12 with the two heavy rainfall weather processes in July19 this year, they all have the common characteristics of heavy rainfall, long duration, wide influence range and high social concern. However, the weather systems affecting these two rainfalls have different "routes", different intensities and different precipitation characteristics.

According to the influence system, "7.2 1" is due to the eastward movement of the cold vortex, and this "7. 19" is due to the northward movement of the Huanghuai cyclone. According to statistics, "7. 19" rainstorm is weaker than "7.2 1" four years ago, and the rainfall intensity is relatively small, which is 56.8 mm/h, but the rainfall lasts for a long time.

"The low vortex (Huanghuai cyclone) moves slowly, causing this stable and continuous precipitation." Zhu Dingjun, a senior engineer of the Public Meteorological Service Center of China Meteorological Administration, said in an interview with the reporter of China Science News. As of 20th 14, the rainfall in Beijing has reached 3 1 hour and will continue, far exceeding the 17 hour of "7.2 1" in 20 12 years.

The "July 2 1" of 20 12 was caused by the eastward movement of cold air, which was mainly affected by a cold air process from west to east. There are warm area precipitation and cold front precipitation at the same time, and the short-term precipitation is strong, reaching100.3 mm/h.

"Generally speaking, the influence of summer cold front is stronger, and strong convection will be more obvious. The influence of the easterly airflow moving from south to north is relatively weaker than that of the cold front, so the degree of this strong convection is not as obvious as "7.2 1". " Zhu dingjun said.

Guo Yingchun, chief service officer of Hebei Meteorological Bureau, told the reporter of China Science News that the rainfall process had a great impact on southwest Hebei, showing the characteristics of strong locality and heavy rainfall intensity. "In the early stage, soil moisture in some areas of Hebei was still poor. After this rain, we should pay attention to the impact of drought and flood transformation. "

In Henan, the meteorological department has sent disaster investigation teams to Linzhou and other places. Niu Shufen, chief forecaster of Henan Meteorological Observatory, said that compared with the memorable heavy rainfall process in Xinxiang, Henan Province on July 8-9, this process had a greater impact, with more accumulated rainfall and similar hourly rainfall intensity. Except Sanmenxia, southeast Xinyang and south Nanyang, most areas in the province have precipitation above the magnitude of rainstorm.

Ma Xuekuan said that compared with the southern region, there are great differences in drainage facilities, urban construction characteristics and water storage capacity of urban rivers and lakes in northern cities, and more attention should be paid to urban waterlogging caused by short-term heavy rainfall. At the same time, Taihang Mountain and Tongbai Mountain should pay special attention to prevent geological disasters caused by heavy rainfall.