Definition and standard of cold wave

The definition and standard of cold wave are as follows:

Definition: the temperature drops 10 in one day, and the temperature is below 5.

Criteria: The activity intensity of cold air is defined by process cooling and negative temperature anomaly.

Features: the refrigeration range should be large enough and the minimum temperature should be low enough.

Affect the source of cold air in China

1, the Arctic Ocean west of Xindi Island. It comes from this area most (about 40%) and reaches the cold wave intensity the most times.

2. The surface of the Arctic Ocean east of Niigata Island. The amount of cold air coming from this area and affecting China is small (18%), but its intensity is generally strong, and the intensity of cold waves is also more.

3. Atlantic Ocean south of Iceland. There are quite a few people in this area (about 33%), but because of the high temperature, the proportion of cold wave intensity is small.

What is the path of cold air invading China from the key areas of cold wave?

1, Northwest Road (Middle Road): Cold air flows south from key areas through Mongolia to the vicinity of Hetao in China, and directly to the middle and lower reaches of the Yangtze River and the south of the Yangtze River. The cold air coming down this route, the cold wave weather north of the Yangtze River is mainly northerly wind and cooling. After reaching the south of the Yangtze River, it may develop with rain and snow due to the active fluctuation of the south branch.

2. East Road: Cold air passes through Mongolia from key areas to northern North China. While the main cold air continues to move eastward, the low-altitude cold air turns to the southwest, invades North China through the Bohai Sea, and then reaches the two lake basins from the lower reaches of the Yellow River.

3. West Road: Cold air flows southward from key areas, passing through Xinjiang, Qinghai and the southeast of Qinghai-Tibet Plateau, which has a great influence on the northwest, southwest and south of China, but the cooling rate is not great. However, when the fluctuation of the south branch and the fluctuation of the north branch overlap, it can also cause obvious cooling.

4. East Road plus West Road: The cold air in East Road goes south from the lower reaches of Hetao, and the cold air in West Road goes south from the southeast of Qinghai. Two cold air often meet on the east side of the Loess Plateau, between the Yellow River and the Yangtze River, causing a wide range of rain and snow, and then the two cold air merge south, causing strong winds and obvious cooling. The main weather systems forming this cold wave process are polar vortex, polar high, cold wave ground high and cold front.