Beijing: the number of days without effective precipitation breaks a record
"whether or not the record is an effective precipitation day, Beijing takes the southern suburb observatory as the representative station, rather than the city's average situation. Beijing's first snow did come this winter," said Yang Jie, chief forecaster of the meteorological services at the Beijing Meteorological Observatory.
Because of the poor water vapor conditions, this winter, the snow in Beijing is hard to find. Despite the high altitude mountain times "ground see white snow, plain area is only the night of January 21st, big range of snow, but the snow marks light.
"Yanqing, Huairou, Miyun, Pinggu, Mentougou, Changping and other places of snow are relatively obvious, for small snow. The city and the southeast, including the southern suburbs of observation stations, all trace of snow, with precipitation less than 0.1 mm." Yang Jie said.
In accordance with the "definition" of the first snow in Beijing, meet the first snowfall in one of the following conditions for "the first snow": Beijing city's 20 artificial station more than 10 stations to have snow phenomenon; urban 5 station (Chaoyang, Haidian, Fengtai, Shijingshan, the Observatory) were observed in 3 snow phenomenon; one or more stations 5 stations in the snow, and at least 1 station snowfall is greater than or equal to 0.1 mm.
"The city's 20 artificial station in 17 stations observed snowfall in Beijing has reached the standard of" snow "." Yang Jie said, however, according to standard meteorological observation, a meteorological observation station of daily precipitation is greater than or equal to 0.1 mm, denoted as a "effective precipitation days, daily precipitation in Southern Observatory station is less than 0.1 mm, so in the statistics of" effective precipitation days ", it is" no".
The southern suburbs of Beijing Observatory "the longest days no effective precipitation" is 114 days. In the last ten years, the longest "no effective precipitation" is 108 days. In October 23rd last year to February 7th this year, Southern Observatory continuous "no effective precipitation has reached 108 days, and is expected to rewrite the two record.
It is reported that the southern suburb observatory, which was established in 1912, is a national meteorological observation station and a representative station in Beijing, which participates in the exchange of global conventional meteorological data. In the analysis of climate data in Beijing, the station is generally used as a representative to carry out historical comparisons.
Water vapor, power lift, temperature: snowfall conditions in Beijing "three lack of two"
Since this year, the snow scenery of the whole country has been covered by the WeChat circle of friends and the snow in Beijing. Why is it difficult to find a trace?
In meteorology, water vapor, dynamic uplift and temperature are the three conditions for snowfall. Guo Jianxing, a senior engineer of Beijing professional meteorological observatory, said that the cold air in Beijing is frequent this winter, but there is not enough water vapor condition and dynamic condition is not enough.
Expert introduction, since November 2017, the central and eastern equatorial Pacific SST in the "La Nina" state, under the influence of Siberia high pressure stage is strong, the East Asian trough is stronger and stronger cold air forces, the Beijing Tianjin Hebei region is mainly affected by the northwest wind control; at the same time, the Western Pacific subtropical high, South West was not. To warm air and cold air North South transport from the north of the intersection in Beijing, so it is difficult to form a wide range of significant snowfall in Beijing.
"Snow, cold air and warm air interaction, from Siberia cold air is very strong, but the South warm moist air flow to Beijing no channels, no intersection, hard into the snow." Shi Hongbo, the climate center of the Beijing Climate Center, said.
According to reports, Beijing perennial snow on November 29th, "late" occurred in the winter of 2010 to February 10th of next year to the drag; "early" have also occurred, 2009 snow in November 1st, they are not the beginning of winter.
It's so cold in winter because of the "Arctic warming"
The snow lurched you, not necessarily think, this winter cold, is because - the north pole is warm. Scientific research shows that the warming caused by global climate change, especially in the summer and autumn seasons, is higher than the annual temperature, affecting the temperature of the ocean in high latitudes.
The ocean analysis data released by the Chinese Academy of Sciences in mid January showed that in 2017, the hottest year of the ocean since the modern ocean observation records, the ocean warming has occurred in most of the waters. The Atlantic and the Southern Ocean are the most rapidly warming sea areas.
The temperature in the North Pacific and the North Atlantic increases, and the atmospheric temperature near the polar region is affected by water vapor exchange. Therefore, the atmospheric circulation is disturbed, and the Arctic vortex is always squeezed to the south. Zhu Jiang, director of the atmospheric Institute of the Chinese Academy of Sciences, said that in winter, once the Arctic vortex has found a gap, the cold air in the polar region will go south, which is like opening the door of the refrigerator.
The vortex of the Arctic is called the "polar vortex". It exists perennial, like a huge pot cover, the cold air pressure in the Arctic, so that the northern hemisphere winter, not as cold.
At the beginning of January this year, the United States once again encountered the south polar vortex, multiple blizzard. 1 months late, the polar vortex at East Asia, Russia and Siberia minus 50 degree centigrade, Northeast China also suffered extreme cold, Heilongjiang of Harbin Province, northeastern the Inner Mongolia Autonomous Region Jinhe, have Yitulihe, close to an all-time low temperature extreme record, East China suffered a blizzard......
Experts pointed out that the north is menacing the "polar vortex", with the cold air southward; the south is ready "webtisr", guides the warm moist air flow, Everfount northward transport. The two forces met in the eastern and central part of China, where cold and warm currents intersect -- the right temperature and abundant water vapor, and the long and heavy snowfall and low temperature weather happened.