The influence of El Nino on 20 15 northern winter!

Since entering the flood season in June this year, due to many rainfall processes and strong rainstorm intensity, the "continuous rainy" mode has been launched in many places in China. Not only has the precipitation in the middle and lower reaches of the Yangtze River reached a new high in the same period since 2000 since the flood season this year, but there have been 32 rainy weather processes in Beijing within 5 1 day, which is a rare phenomenon in meteorological history.

How much impact did the El Nino event that started last year have on the "continuous rain" pattern in China? What is the impact of excessive precipitation in some areas?

Turn on the "continuous rain" mode in many places.

From June this year 1, Beijing started the "continuous rainy" mode, and there were 32 rainy weather processes on May1day. /kloc-Since July 0/5, continuous precipitation has occurred, which is also rare in the meteorological history of Beijing.

Compared with Beijing, there has been continuous heavy rainfall in the southern region since the flood season this year. Among them, a heavy rainfall from June 26 to 28 covered Taihu Lake, the lower reaches of the Yangtze River and the Huaihe River Basin. The average rainfall in Taihu Lake Basin reaches 1 12mm, and the maximum rainfall is 456mm in Jiangyin, Jiangsu and 400mm in Jinzhai, Anhui.

Sun, a senior engineer in the Climate Monitoring Office of the National Climate Center, told the reporter that from June 1 day to July 20 since the flood season of 20 15, the precipitation in the northern part of the Yangtze River and the Jianghuai area was 20% to 2 times higher than normal, and the precipitation in southern Jiangsu was more than 2 times higher than normal.

Regarding the obviously excessive precipitation, Sun said that the precipitation in the middle and lower reaches of the Yangtze River since the flood season this year has set a record for the same period since the new century.

The data show that from the flood season to July 20th this year, the accumulated precipitation in the middle and lower reaches of the Yangtze River was 398.4 mm, which was more than the normal period 19.5%, the highest value since 2000, and even slightly higher than the 1998 where the catastrophic flood occurred.

The situation announced by the National Defense General in early July showed that many small and medium-sized rivers exceeded the warning water level during the flood season this year, and the flood magnitude was large. Among them, there are 57 rivers with floods exceeding the warning water level 197, more than the same period since 2000, 33 rivers with floods exceeding the guaranteed water level, and 4 rivers with extraordinary floods in 50 years.

How big is the impact of El Nino?

In view of the fact that the rainfall in the south this year is obviously higher than that in previous years, Wang Hao, a water resource expert and academician of China Academy of Engineering, told reporters that this year is the "El Ni? o Year" and there is a great possibility of floods in the south.

When it comes to El Nino events, people will naturally think of the "super El Nino" that happened from 1997 to 1998. The impact of that El Ni? o event spread all over the world, and it also brought more rainfall, which led to flooding in the Yangtze River, Songhua River and Nenjiang River basins in China. Therefore, people from all walks of life have speculated whether the risk of floods in these basins is increasing this year.

In this regard, the real-time rolling monitoring of the National Climate Center shows that El Ni? o continues to develop, and the SST in the equatorial Middle East Pacific presents a wide range of warmer characteristics, with the central intensity exceeding 3.0℃.

Zhou Bing, a senior engineer in the Climate Monitoring Office of the National Climate Center, believes that the El Ni? o events since May 2065438+2004 have had an important impact on China's climate. The recent performance is that the precipitation in South China is less in the spring of 20 15, and the flood season in South China is late, and the heavy precipitation has been frequent since the flood season in South China.

Many experts from the National Climate Center predict that El Ni? o events will continue to develop in the next six months, but the intensity should not be higher than 1997 to 1998.

Ding, an academician of China Academy of Engineering, recently pointed out that unlike the El Ni? o from 1997 to 1998, this round of El Ni? o was "greatly weakened" due to the rising temperature last spring and summer and this spring. Most scientists believe that its intensity should be the standard of strong El Nino, that is, it is difficult to reach the "super" level. However, Ding suggested that for the northeast region, we should be prepared for possible heavy precipitation.

The south needs flood control, but the north still "does not quench its thirst"

Despite the heavy rainfall in many places in the south, the continuous rain in Beijing has not stopped, but many areas in North China are currently "thirsty". There are still moderate meteorological droughts in southeastern Tianjin and eastern Hebei, and the central and western Shandong Peninsula, not far from Beijing, is suffering from severe meteorological drought.

In this regard, experts from Beijing Water Affairs Bureau told reporters that although many people feel that there is much rain in Beijing this year, statistics show that so far, the precipitation in Beijing this year is not more than that in the same period of history, and many areas in the north are still "not quenching their thirst".

According to the data obtained by the reporter, from June 5438+1 October1day to 8: 00 on July 20 this year, the accumulated precipitation in Beijing was 263.4 mm, which was significantly higher than the 224.8 mm in the same period last year, but basically the same as the average annual precipitation of 259.8 mm in the same period.

"Everyone feels rainy, mainly because the rainfall in Beijing is mainly concentrated in the main flood season from July 20 to August 10. There are many thunderstorms and heavy rains in the main flood season, and the instantaneous rainfall is large, which will give everyone a feeling of rain. " Wang Hao said.

However, according to statistics for many years, due to the extremely uneven distribution of precipitation in Beijing, especially in the main flood season, it is easy to have a sharp turn of drought and flood or alternating drought and flood. Due to the dense precipitation this year, it has been suggested that Beijing may have passed the dry season. However, experts from Wang Hao and Beijing Water Affairs Bureau believe that the above conclusions cannot be drawn based on hydrological cycle change and model prediction.

Experts said that water-deficient cities in the north should speed up the construction of "sponge cities", increase precipitation to replenish groundwater and prevent precipitation from flowing away in vain. Zack Zhang, director of the Urban Water Management Office of the Ministry of Housing and Urban-Rural Development, said that all urban floors are facing the problem of "hard coverage", especially in the urbanization stage with rapid population growth. In the past, 90% of rainwater could seep effectively, but now less than 30% of water can seep to replenish groundwater, and the rest will soon gather on the road surface, causing waterlogging and flowing into the sewer.

In addition to predicting that more precipitation in Beijing and other places will replenish groundwater, experts say that more rainfall in the south this year will also play a positive role in ensuring that the South-to-North Water Transfer Project will transfer water to several northern provinces and cities.

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