How did the weather in most parts of the country compare with previous years on September 20 this year?

Since the autumn of this year, the temperature in most parts of China has been higher than normal, and there has been a warm autumn phenomenon. So does this mean?

It means that from 1986, after 15 years of continuous winter high temperature in most parts of the country, another warm winter is coming.

Coming? Meteorologists at the National Climate Center are also working intensively to reach a conclusion as soon as possible.

In fact, warm winter and cold winter are a climate concept, which is compared with the average climate. General winter (12

The average temperature in most parts of China is obviously higher than normal, which is called "warm winter". Warm winter doesn't mean

The whole winter is very warm, and alternating cold and warm is the general law of climate change, and cold and warm exchanges often occur in warm winter.

Substitution phenomenon, but warm is dominant, that is, warm time is longer than cold time, and warm range is larger than cold range.

On the contrary, it's winter.

Reasons for the formation of warm winter

China has been enjoying a warm winter climate since the mid-1980s, but the winter temperatures in 2000 and 1999 dropped again.

Obviously reduced, warm winter characteristics are not obvious. So what are the main factors that restrict warm winter and cold winter?

First, with the intensification of the greenhouse effect, the increase of greenhouse gases such as carbon dioxide in the atmosphere is global warming.

Important reasons. Before the industrialization of the world, the content of carbon dioxide in the atmosphere was relatively stable, but since industrialization,

Due to the burning of a large number of fossil fuels and deforestation, the content of greenhouse gases such as carbon dioxide in the atmosphere has increased rapidly.

At the same time, the global temperature has obviously increased, which has increased by more than 0.6℃ in the past 100 years.

However, the increase of carbon dioxide in the atmosphere rises linearly, while the rise of temperature fluctuates alternately between cold and warm.

Dynamic characteristics. There was a cold cycle before the 1920s, a warm cycle of about 30 years from the 20s to the 40s, and a warm cycle from the 1950s to the 1950s.

The 1970s was a cold cycle of about 30 years, and it turned into a warm cycle in 1980s. This shows that when the climate gets warmer,

But it is also restricted by other factors.

In addition, volcanic activity is also a reason. When a large volcano on the earth erupts, it will spew a lot of volcanic ash.

Rise to the sky, form an "aerosol" layer, reflect solar radiation, reduce solar radiation reaching the earth's surface, and make

When the temperature drops, this phenomenon is called "parasol effect". This shows that volcanic activity is frequent and the temperature is easy to drop; volcano

With the decrease of activity, the temperature tends to rise. According to statistics, the strong volcanic eruption in warm cycle is less than half of that in cold cycle. 80 years

Since the 1970s, the number of major volcanic eruptions in the world has obviously decreased, which may also be one of the reasons for climate warming.

Then there is the El Nino phenomenon. El Nino and La Nina are abnormal warming and seawater anomalies in the equatorial eastern Pacific.

The occurrence and development of two kinds of constant temperature cooling phenomena often lead to abnormal winter climate in China. On the whole, Earl

The occurrence of Nino phenomenon often leads to the rise of winter temperature in China, forming a warm winter climate. It happened 195 14 times since 0.

El Nino phenomenon, China has a 13 warm winter climate. Since 1980s, the SST in the equatorial eastern Pacific has been low.

High pressure and El Nino occur frequently, and China continues to be warmer. However, the occurrence of La Nina phenomenon often leads to winter in China.

The temperature drops, resulting in a cold winter climate. There have been eight La Nina events since 195 1, and there have been six cold events in China.

winter 1999 and in the winter of 2000, the persistent influence of La Nina phenomenon may be the winter temperature ratio in most parts of China.

An important reason for the obvious decline in previous years.

Snow in Eurasia. Winter snowfall in the middle and high latitudes of Europe and Asia is also an important factor affecting winter temperature in China. ordinary

In this case, the large-scale snowfall in Eurasia in winter is beneficial to the development and southward movement of Mongolian cold air mass that often appears in China.

The winter climate is cold; However, if the snow area in Eurasia is small in winter, it will not be conducive to the strengthening of Mongolian cold air mass and its southward invasion.

China's cold air force is weakened, and it is prone to warm winters.

The influence of winter wind. The intensity of winter wind is the direct cause of temperature and warmth changes. Generally speaking, the wind in winter is weak and pleasant.

It means that the cold air mass in the north is inactive, and the cold air invading China is less and weaker, and the temperature is high and easy to be warmer.

winter On the contrary, the strong wind in winter means that the cold air mass in the north is active, and the cold air invading China is frequent and powerful.

The temperature is low and it is prone to cold winter.

The intensity of subtropical high. The western Pacific subtropical high located in the southeast of China is a warm high.

Its strength also directly affects the cold and warm weather in winter in China. Generally speaking, when the high pressure is strong, it is beneficial to warm air in the south.

Flowing to China, it is easy to have warm winter; Weak time is not conducive to the transportation of warm air from the south to China.

The temperature in China is often very low in winter, which makes it very cold in winter. Since 1980s, the subtropical high in the western Pacific has been strong, which is beneficial.

Maintain the warm winter climate in China. 1999 and in the winter of 2000, the subtropical high in the western Pacific weakened obviously, which made China bigger.

The temperature has dropped significantly in most areas.

Characteristics of Warm Winter in China

What are the characteristics of warm winter climate in China since 1986? First of all, from the perspective of spatial distribution, this time

Global warming is more obvious in the northern hemisphere than in the southern hemisphere, and the middle and high latitudes in the northern hemisphere are more obvious than the low latitudes. The northern part of China is warming up.

Obviously, it is not obvious in the south, and it is getting colder and colder in the southwest and other places. Secondly, from the perspective of seasonal changes, the temperature rise in winter and autumn is the most obvious.

Season and spring take the second place, and the trend of warming in summer is not very clear. Third, from the daily variation, the lowest temperature is the night air.

The temperature rise is obvious, but the maximum temperature is not obvious during the day. Finally, compared with the historical period, from one hundred years to

Looking at the past changes, the warmest1940s since the 20th century, the longest continuous warm winter is 8 years, and this time it has lasted 15 years.

Rare in the 20th century. The average temperature of 1998 exceeded the warmest 1946 in the 1940s, making it one of the warmest years in this century.

A few years. Judging from the changes since the Millennium, from 5000 to 3000 BC, the temperature was about 3℃ higher than it is now, which is legendary.

"Dayu's water control" happened at that time. At that time, there were subtropical animals and fish such as elk and bamboo rat in Guanzhong area of Shaanxi Province.

A large number of aquatic animals exist, and this period is called "climate suitable period"; At the peak of the Tang Dynasty, the Chinese nation was brilliant for thousands of years.

During this period, the temperature was also about 65438 0℃ higher than now. In some years in Xi 'an, there is no ice and snow, and citrus can be planted. At this time,

The period is called "small warm period"; So this temperature rise can't keep up with that time.

The influence of warm winter

At present, warm winter is not good for energy saving, transportation, irrigation and water conservancy construction and people's outdoor work.

Often beneficial. However, warm winter also has its disadvantages. First, warm winter promotes the vigorous growth of wheat and reduces its cold resistance to catch up with spring.

Low temperature is vulnerable to freezing injury, so pay attention to prevent freezing injury; Secondly, warm winter will breed and spread pests and diseases, which should be strengthened.

Prevention and control of pests and diseases; There is also the high temperature in warm winter and the increase of evaporation, which aggravates the drought and has a negative impact on the growth of winter wheat and spring sowing.

Spring ploughing is unfavorable, so it is necessary to strengthen the work of drought resistance and moisture conservation; In addition, warm and dry weather, coupled with strong winds, is prone to forest fires.

Forest fire prevention must be strengthened.

On a longer time scale, the global sea level may rise due to climate warming. Due to the global changes in the past century

Warm, the sea level has risen by about 10- 15 cm. Rising sea level may lead to flooding of coastal lowlands and damage to coasts and beaches.

Erosion, land salinization, seawater intrusion, damage to ports and coastal buildings and their impact on shipping and aquaculture.

Wait a minute. At the same time, it can also cause the climate zone to move. First of all, global warming will cause the temperature zone to move northward, generally at 20-80 north latitude.

Between degrees, about every 10 latitude, the temperature difference is 7℃. If the global average warming is 3.5℃, the temperature zone can move northward.

Five latitudes make the originally cold area warm. Secondly, it may also cause changes in the precipitation zone, which turned out to be dry.

The place may get wet, and the original wet place may dry; In addition, the seasonal distribution of precipitation will also change.

In some places, precipitation may decrease in summer and increase in winter. This will make agriculture, forestry, animal husbandry,

The fishery layout is affected. Of course, this change is a long process.