How much haze will come again in Chinese reading?

Haze has attracted more and more attention from all walks of life in recent years. In 2013, haze became the keyword of the year. On January 4, 2014, the National Disaster Reduction Office and the Ministry of Civil Affairs included haze weather that was harmful to health into the 2013 natural disasters for the first time. Vocabulary related to it, such as "PM2.5", "explosion", "APEC blue", etc., are almost household names, and Internet jokes such as "hard work in the face of haze" and "self-improvement" are even more popular. At the beginning of 2015, the main urban area of ??Chongqing stopped smoking bacon and firewood turkey in order to control smog, making smog the focus of public opinion.

Looking back on the past year 2014, the haze is undoubtedly a strong part of our memory.

"Haze" is always present on all sides

The "China Climate Bulletin (2014)" released by the China Meteorological Administration shows that in 2014, 13 major storms occurred across the country. The scope and duration of haze weather processes have increased compared with 2013, and are mainly concentrated in January, February, October and November. The occurrence areas are mainly in the Beijing-Tianjin-Hebei and Yangtze River Delta regions.

At the beginning of the new year in 2014, three haze weather events occurred in the central and eastern regions. In January, the national average number of haze days was 11.7, which was significantly more than the same period in normal years. Most areas in central and eastern my country have more than 10 haze days. Among them, most of the Huanghuai River, eastern Jianghuai, central and eastern Jiangnan, western Hebei, southern Shanxi, Beijing, and eastern Guangxi have more than 20 days. Most areas in central and eastern China have more than 20 haze days. It is more than 10 days longer than normal.

The smog in October must have left a deep impression on everyone, and it even spawned an Internet term - "APEC Blue". In October, four large-scale haze weather events occurred across the country. During the first large-scale haze weather in October, persistent haze weather occurred in North China, Huanghuai and other places, covering an area of ??1.51 million square kilometers. In order to ensure air quality during the APEC meeting in Beijing in early November, the Beijing-Tianjin-Hebei region implemented measures such as road restrictions and suspension of polluting companies.

From November 1 to 12, 2014, the air quality in Beijing was at an excellent level, and it coincided with the APEC meeting. Netizens called such blue skies "APEC blue." On December 19, 2014, the annual words of the "Chinese Inventory 2014" sponsored by the National Language Resources Monitoring and Research Center, the Commercial Press, etc. were announced, and "APEC Blue" was promoted to the list as a hot word. "APEC Blue" has also been selected into the top ten weather and climate events of the year, the top ten popular science events of the year, and the hot words of the year in the interactive encyclopedia.

Smog has attracted so much attention, on the one hand, because of its impact and harm on people’s physical and mental health and life. Harmful substances in haze can cause acute upper respiratory tract infection, acute tracheitis, bronchitis, pneumonia, asthma and other diseases, reduce human immune function, and lead to an increase in mortality; in addition, when haze weather occurs, atmospheric visibility is greatly reduced. If it decreases, it is easy to cause flight delays or even cancellations, highway closures, and a series of problems such as blocked sea, land and air traffic and frequent accidents.

On the other hand, it is because haze has become more frequent in recent years. Data show that in 2013, the average number of haze days in central and eastern my country was 36, which was 27 days more than normal and the most since 1961. The Beijing Observatory had 223 haze days in 2013, which was 27 days more than normal and the average of the past 10 years. (58.7 days) and 2012 (124 days) were obviously too long. In 2014, my country's Beijing-Tianjin-Hebei region had 61 haze days, 25 days more than in 2013; the Yangtze River Delta region had 66 days, 7 days more than normal; and the northwest region had 4 days more than 2013.

In 2014, smog occurred not only in our country. In the spring of 2014, France encountered multiple haze weather. On March 12, nearly 1/3 of the country's land area was covered by air rich in respirable particulate matter. The air pollution in the greater Paris area, northern and western provinces, and parts of the central region was relatively serious. PM2 in the air in Paris urban area. 5 and PM10 indexes have seriously exceeded standards for many consecutive days. At the end of April, Paris was hit by smog again. The Eiffel Tower was shrouded in smog and almost "disappeared."

Why is it becoming more frequent?

After seeing the above data, many people may ask: Why has haze become more and more frequent in recent years? We know that pollutant emissions and calm weather are important factors in the formation and maintenance of smog. The formation of smog is the result of the simultaneous interaction of man-made and natural factors. The increase in smog is closely related to changes in these two aspects.

First of all, the emission of atmospheric pollutants is definitely increasing year by year. Regarding this point, the "Green Paper on Climate Change: Report on Response to Climate Change (2013)" pointed out that in the past 50 years, my country's haze weather has generally shown an increasing trend, and the sustained haze process has increased significantly. The main reason is that social The emissions of air pollutants caused by the increase in fossil energy consumption are increasing year by year. The main sources of these pollutions are thermal power emissions, industry, especially heavy chemical production, vehicle exhaust, winter heating, residential life (cooking, hot water) and ground dust.

Taking Beijing as an example, according to the research results of the Chinese Academy of Sciences, there are six important sources of PM2.5 in Beijing, namely soil dust, coal burning, biomass burning, vehicle exhaust and garbage incineration, industrial pollution and secondary inorganic aerosols (generally composed of (converted from automobile exhaust and coal-fired emissions), their average contributions are 15%, 18%, 12%, 4%, 25% and 26% respectively.

Secondly, in addition to human emissions, meteorological conditions conducive to the occurrence of haze frequently occur, becoming an "accomplice" to the increase in haze weather. These include an increase in calm weather, a decrease in average wind speed, and a decrease in the number of precipitation days.

Still weather usually refers to a low-level atmospheric characteristic with low wind speed near the surface and stable atmosphere. The atmosphere continues to be stable, resulting in poor diffusion ability, causing pollutants to accumulate near the ground, making it easier to form haze weather. The meteorological department has designed a static and stable weather index based on a large amount of research work. It is an index that can quantitatively reflect the degree of atmospheric stability. The greater the index, the greater the possibility of air pollution occurring or maintaining, and the higher the degree of air pollution. . In 2014, my country's static weather index averaged 9.72, which was nearly 5% higher than the 9.30 in 2013.

In the context of global climate change, the decrease in average wind speed and the number of precipitation days have been supported by relevant data. Rainfall and snowfall can clear and wash away haze in the atmosphere. Judging from the number of precipitation days, the number of precipitation days nationwide decreased significantly from 1961 to 2013, with a decrease of 10% in the past 50 years. The number of precipitation days in eastern Northwest China, Jianghuai, North China, and western Northeast China decreases by 0.5 to 1 day per year.

Strong winds are helpful in dispersing smog. The 2013 "China Climate Change Monitoring Bulletin" shows that from 1961 to 2013, my country's average wind speed showed a decreasing trend, with an average annual decrease of 0.01 to 0.05 meters/second, and the average annual wind speed in some areas decreased by more than 0.05 meters/second. Judging from the number of calm and gentle wind days, from 1961 to 2013, there was a significant increase in the number of calm and gentle wind days in my country. The number of calm wind days increased significantly in the Yangtze River Basin, with an increase of more than 1.5 days per year. In 2014, it was also in line with the above trend. The national average wind speed was 1.9 meters/second, which was 5% lower than that in 2013. The number of light wind days was 230 days, which was 2% higher than the average in 2013. The overall meteorological conditions are conducive to the elimination of air pollution. Poor.

In 2014, the seawater temperature in the equatorial Pacific Ocean continued to be high, and reached the standard of a weak El Ni?o event in October. Ding Yihui, an academician of the Chinese Academy of Engineering, pointed out that this will further increase the risk of haze. Under the El Ni?o state, the East Asian winter monsoon is weak, which will cause the air transport and diffusion capabilities to weaken. The air will remain stationary and stable. At the same time, the stability of stratification will also increase. The air will be colder at the bottom and warmer at the top, and the fluidity will become worse. Conducive to the formation of haze. "Weak monsoons bring dirty air", this is what they say.