Influence of La Nina Year

In the first half of the year, the national climate showed a diversified trend. After research and analysis, climate experts initially believe that La Nina phenomenon is the main reason that affects China's climate in the first half of the year.

Zhao Zhenguo, a researcher at the National Climate Center, believes that this year, due to the La Ni? a phenomenon, the water temperature in the equatorial eastern Pacific is low and the meridional circulation in East Asia is abnormal, resulting in the northerly airflow prevailing in northern China since the spring, while the warm and humid airflow in the southeast is relatively weak. It leads to frequent strong cold waves and strong winds in the north, but the rainfall continues to be less and the temperature remains high.

According to statistics, sandstorms occurred frequently in northern China this spring. From March to April, a large-scale sandstorm 12 occurred, affecting northwest, north, northeast, Huanghuai and even Jianghuai areas. In May, there were three regional or local sandstorms in northwest China, which were rare in the same period of nearly 50 years. Chen Yu, a climate expert, said that in the past 50 years, the frequency of dusty weather in northwest China has increased year by year.

Lu, a senior engineer of the National Climate Center, said that since 300 AD, there have been five frequent sandstorms in China, each lasting about 90 years. In the past 10 years, sandstorms have shown a significant increase trend.

Talking about the causes of sandstorms, Chen Yu believes that the formation and scale of sandstorms depend on two factors: environment and climate. From the environmental point of view, the increasingly serious desertification problem can not be ignored. However, "there is no smoke without fire". From the climate point of view, the temperature in the northern region has risen rapidly since February this year, with a high range of 2 to 3 degrees Celsius, which led to the early thawing of soil and the emergence of a large number of dry soil layers. At this time, the rainy season has not yet arrived. Affected by La Ni? a phenomenon, windy weather occurred continuously in the northern region, and the gale immediately formed a sandstorm.

High temperature and little rain in the north are also hot topics. From March to May this year, the national average temperature reached 196 1, which was the highest in the same period, especially in the north. Since February, there has been less precipitation in most areas north of the Yangtze River. For four consecutive months, the total precipitation was less than 100 mm, and less than 50 mm in North China and Northwest China, which was more than 50% less than normal. Especially from February to April, the average precipitation in the northern region was only 23 mm, which was the least since the founding of the People's Republic of China. The combined effect of high temperature and little rain led to the rapid decline of soil water content in the northern region, and the worst spring drought occurred since the 1990s.

Zhao Zhenguo said that since 1992, except 1998, the precipitation in North China from February to April in other years was lower than the multi-year average, especially since June last year, the precipitation in North China has been less and the soil moisture has been very poor. At this time, under the influence of La Nina phenomenon, the northerly airflow prevails in northern China, while the warm and humid airflow in the southeast is relatively weak. Coupled with the unfavorable cooperation of cold and warm air, the ideal rainfall conditions in the northern region have not been formed, resulting in continuous lack of rain and drought.

During the drought-resistant period in the north, heavy rains occurred frequently in some areas south of the Yangtze River. In this regard, Lu pointed out that the heavy rain in the south is the result of local strong convective weather, and the precipitation is normal in a wide range of river basins.

When talking about the overall climate characteristics and development trend of China, Lu said that from the global climate change trend in recent years, the overall trend is diversified, which is mainly the result of the alternating effects of El Ni? o and La Ni? a phenomena under the background of global warming. In this environment, China cannot be a peaceful "Xanadu". He said that the national meteorological department is paying close attention to the future atmospheric climate changes and making timely forecasts to minimize the losses caused by disastrous climate.

Relationship between Climate Anomaly and La Nina in 2008

In 2008, it was in La Nina state, that is, the SST in the equatorial eastern Pacific was 0.5 degrees lower than normal, which had a very obvious impact on China's climate. Under the influence of La Nina phenomenon, the meridional circulation in East Asia is abnormal, which is very beneficial to the southward movement of cold air in northern China. It has given us a cold winter, so we can see that this cold winter has already appeared this year.

Rani, that's just one of the reasons. Another reason for the heavy snow is as follows:

Since 2008, the high pressure in Asia has been very active, forming a cold air mass in the south, affecting China and causing large-scale gale and cooling weather. However, due to the active warm air mass in the south this year, a large number of warm and humid air currents from the Pacific Ocean and the Indian Ocean frequently patronize the southern region. When the powerful cold air mass from Mongolia and Siberia quickly moved south to meet the warm and humid air mass, the cold and warm air just merged into one. Affected by these two air currents, there have been more rainy and snowy weather recently, especially in the Yangtze River basin, and the low temperature weather has lasted for a long time. If there is only a strong cold air mass without a large amount of water vapor provided by warm and humid air mass, there will only be strong winds and cool weather in the south; If there is only a large amount of water vapor provided by warm and humid air masses, there will be no disastrous weather at all without the arrival of cold air masses. When both are ready, disaster comes.

At the same time, when China was severely hit by a snowstorm, the temperature in the central United States dropped by 20 degrees Celsius, and snowstorms appeared from time to time (2008+0); Central Asia, which has not snowed for a hundred years, suddenly snowed 10mm, setting a new record for Baghdad 100 (2007+02). In the summer of 2007, the floods in western Europe were serious, and Britain and France suffered huge losses (summer of 2007). Since the beginning of winter, the temperature in the northern edge of Russia has hit a new low, once reaching MINUS 50 degrees Celsius ... La Nina is still not over, and the situation is still very grim. ...

The weather is the most extreme in 10 years. Experts say the culprit is La Nina.

According to the news of China Meteorological Bureau, the weather and climate characteristics of China in June 20 10 were slightly higher temperature and more precipitation. The national average temperature is -3.5℃, which is 0.2℃ higher than the normal period of -3.7℃. The national average precipitation is17.2mm, which is more than the normal period (8.3mm) 1. 1 times, and it is the third highest since 196 1 year.

Chen Zhenlin, Director of Emergency Disaster Reduction and Public Service Department of China Meteorological Bureau, said that this year is the year with the largest frequency, intensity and impact of extreme weather and climate events in China 10, and the number of stations with extreme precipitation events in the whole year is the highest in 10.

Chen Zhenlin said that since July 20 10, the SST in the equatorial Middle East Pacific has been cold for five months, and the comprehensive intensity has reached the standard of "La Nina", which means that the surface of the equatorial Middle East Pacific is unusually cold in a large area. The analysis of historical events shows that La Nina is beneficial to the strong wind in winter in China, which leads to the overall cold climate in winter, dry in North China and South China, and possible staged extreme low temperature events.

Chen Zhenlin said that according to the forecast of the weather in China this winter and next spring, the possibility of four consecutive low-temperature rain, snow and freezing disasters in 2008 is still low. However, due to many factors such as La Nina incident, the possibility of a very strong cooling process cannot be ruled out.

Song Lianchun, director of the National Climate Center, said that the scientific basis for La Nina's "Millennium Extreme Cold" is very inadequate. It is even more "irrelevant" to connect La Nina with the Gulf Stream, because they belong to different time scales. La Nina is an interannual scale, which fluctuates greatly every year. However, the Atlantic warm current is relatively stable, mainly showing a long-term change of 10 years or more. Observations in recent decades show that the Atlantic warm current has only a weak decreasing trend.

The cold weather in Guilin will continue, and the three-level emergency response has started.

Since the strong cold air from the north entered Guilin on New Year's Day, the temperature in our city has dropped continuously, with light rain and sleet weather. Compared with the average temperature of 20 10 during New Year's Day 123 degrees Celsius, the weather at 20 1 1 can be described as "freezing in the cold".

654381October 4th, it was learned from the Municipal Meteorological Observatory that the cold weather will not change in the next few days. Affected by cold air and low-level warm and humid airflow, Guilin will continue to have a low temperature before 1 9. Class III emergency response has been initiated. According to meteorological data, 20 1 1. 1.2 The resources in Guilin and Quanzhou are frozen below 0℃. The urban area and 10 county have successively issued yellow warning signals for road icing. On the 3rd and 4th, urban areas and several counties continued to issue yellow warning signals for road icing. The municipal meteorological department predicts that the lowest possible temperature in northern Guilin will be -2℃-3℃ before 1 July 7, with -4℃-0℃ in the alpine mountainous area. In view of this situation, the emergency office, reference station, agricultural gas station, information center, logistics service center and other departments of Guilin Meteorological Bureau and the 12 County Meteorological Bureau entered the level III emergency response state of major meteorological disasters. The main person in charge of the above units implements the foreman system, strictly implements the 24-hour emergency duty system, and all business positions do their best to do real-time monitoring, timely warning, business monitoring, information security and so on. "Freezing" is far from 2008. The ice and snow disaster in 2008 is fresh in people's memory. This year, like 2008, is in the year of "La Nina" (La Nina refers to the phenomenon that the sea surface temperature in the eastern and central equatorial Pacific Ocean continues to be abnormally cold, which is just the opposite of the El Ni? o phenomenon), which makes citizens worry that the ice and snow disaster will happen again. Ren Fumin, chief expert of the National Climate Center, said in a related article that the current situation of atmospheric circulation is very different from that during the freezing rain and snow disaster in 2008. In the next few days, if the subtropical high responds positively to La Nina and begins to weaken from strong to weak, then China is likely to have a cold winter. Judging from the situation in Guilin, as of 8: 00 am on the 4th, there were different degrees of freezing and sleet in the area north of lingchuan county. In the urban area, heavy rain also appeared in parts of the north of the city. However, meteorologists said that at present, citizens do not have to worry too much about serious freezing disasters like those in 2008. In 2008, the freezing days reached more than 30 days, causing serious consequences; The freezing in the northern county of Guilin started from 1 month 1 2, and the days were only about 4 days, which was not very serious. As the current low temperature and cold conditions will continue for some time, the meteorological department said that it will pay close attention to the latest weather changes and timely and accurately convey the weather conditions to the public.