| Atmospheric aerosol optical properties are a fundamental research in atmospheric sciences,and they have unparalleled significance for understanding climate effects.As a typical arid region in the world,Central Asia annually transports a large amount of sand and dust particles to the surrounding and even across the ocean as a source of sand / salt storms.The impact of aerosols on climate change along the “One belt,one road” is of great significance.Based on the observation data of AERONET,SONET and self-designed stations,we analyzed the AOD and Angstrom wavelength index(α)of different typical regions in the arid region of Central Asia,the optical properties of long time series are expected to try to get a more realistic overall situation of atmospheric aerosols in Central Asia.The main conclusions are as follows:(1)The annual average value of atmospheric aerosol AOD in Kashi City is about 0.488;the four-season average is ranked as follows: spring(0.702)> winter(0.478)> autumn(0.430)> summer(0.354);monthly average value is about 0.487.Corresponding to the annual average value of α for many years is 0.460;the ranking of its four-season average is approximately: winter(0.853)> autumn(0.464)> summer(0.345)> spring(0.140);monthly average is about 0.440.Analysis of the probability distribution characteristics of the highest frequency interval of all samples of AOD and α in each season,and it is concluded that Kashi City has three typical seasons of dust and aerosols in spring,summer and autumn,and the input of large-sized particles is the main reason for the high value of AOD outbreaks.Winter is a city-industrial aerosol type,and its main control aerosol mode is stable.Although the proportion of fine particles far exceeds other seasons,it is still dominated by coarse particles.(2)The annual average value of AOD in Dushanbe is about 0.242;the ranking of the four-season average is about: summer(0.316)> autumn(0.261)> winter(0.197)> spring(0.171);monthly average value is about 0.245.The annual average is about 0.844;the ranking of the four-season average is about winter(1.342)> autumn(0.810)> spring(0.755)> summer(0.519);and the monthly average is about 0.831.Analysis of the probability distribution characteristics of the highest frequency interval of all seasons of the entire sample of AOD and α shows that the large-size particles with a coarse mode mainly in the spring,summer and autumn in Dushanbe city have a more prominent vertical extinction effect on aerosols,while the main effect in winter The controlled mode is dominated by fine particles.Summer aerosols are a mixture of sand-dust aerosols and continental aerosols,and vice versa in spring and autumn.In winter,they are mainly urban-industrial aerosols.(3)The annual average AOD value of Lake Issyk is 0.117;the ranking of the four-season average is: spring(0.155)> summer(0.122)> autumn(0.106)> winter(0.091);the monthly average is about 0.117.The annual average is about 1.132,and the multi-year four-year average is ranked as follows: winter(1.408)> autumn(1.137)> summer(1.190)> spring(1.132);the monthly average is about 0.831.Analysis of the probability distribution characteristics of the highest frequency interval of all samples of AOD and α in each season,and it is concluded that the atmospheric aerosols of Lake Issyk are mainly sea-salt-like aerosols in spring,summer,autumn and autumn,and biomass burning aerosols in winter and four seasons aerosols They are mainly composed of fine modal particles.(4)The impact of sand and dust in Jinghe County is much higher than that of Wusu City.It is likely that there are other sources in Wusu City besides Aibi Lake Salt Dust.Jinghe County will be more affected by sand and dust in spring,while Wusu City Summer is even stronger.AOD and α in Jinghe County are mainly negatively correlated.The intra-day peak of AOD has a clear synergy with the human activity cycle,indicating that the change in particle size is mainly responsible for the fluctuation of AOD.The highest value of AOD is July(about 0.262),the lowest value is June(about 0.142),and the monthly average value is about 0.185;1.226.The summer mean values of AOD and α are: 0.200 and 1.346,and the mean values of autumn are: 0.219 and 1.115,respectively.The type of aerosol in summer is complex,and in autumn it should be a mixture of sea-salt-like aerosol and urban-industrial aerosol.The air quality in both seasons is good.Analyzing the frequency distribution characteristics of AOD and α from June to October,it is concluded that the fine aerosol particles in June-September of Jinghe Station are mainly fine-grained particles,and in October,they are mainly coarse-grained particles.(5)The average values of AOD and α in Shihezi City in May are about 0.348 and 0.482,the maximum value of AOD is about 3.328,and the minimum value of α is about-0.680.The coefficients of variation of the two are 89.908% and 74.338%,respectively.The high value of AOD during the day is mainly concentrated in the daily rush hour.Part of the aerosol is mainly sand and dust aerosol,and the rest is mainly aerosol produced by human industrial and agricultural activities.The average monthly AOD of Urumqi was the highest in February(about 3.335).The highest frequency range of AOD is 0.1-0.2,accounting for 27.648%.The frequency distribution of α is characterized by three peaks,and the aerosol types at the three peaks are: urban-industrial aerosol,continental aerosol and sand aerosol.Urumqi AOD is formed by the combination of coarse dust particles and atmospheric smoke and dust produced by man-made industrial and agricultural activities.Among them,dust particles are mainly responsible for the high value of Urumqi AOD explosion.(6)Atmospheric aerosols in Central Asia are heavily affected by sand and dust weather,and the AOD extreme value varies greatly.Spring is the most active stage of sand and dust particles,and coarse-grained aerosols dominate the whole year.The air quality is declining rapidly,and the atmospheric condition of the natural environment is the best.The aerosols in Kashi and Jinghe areas with dust sources nearby have extremely obvious source characteristics.The more concentrated the aerosol types of cities in Central Asia,the more concentrated the urban-industrial aerosols are,but sand and dust are still the main pollution factors that affect the deterioration of the urban atmospheric environment.In the scale of aerosol particles in large cities,the large dust particles account for a relatively small amount,and the response of the atmospheric conditions of small cities to the influence of dust is extremely strong.The AOD in southeastern Central Asia is the highest,and it is a dust aerosol;the second is the northeast,and its aerosol type is complex;the other is the southwest;the middle is the lowest. |
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