Analysis And Forecasting Research Of Fog And Haze Environment Meteorological Parameters In Heilongjiang Typical Area Based On NCEP Reanalysis Data

As a weather phenomenon,fog and haze has existed since ancient times.The visibility and air pollution caused by fog and haze in modern society have seriously affected human activities.This paper makes use of the data of four?02,08,14 and 20hours?ground observations and the data of 08 and 20 hours high altitude observations of the four high-altitude stations in Heilongjiang Province from 2000 to 2014,6-hour NCEP reanalysis data.Statistics on environmental indicators,such as visibility at the time of fog and haze,vertical wind shear between 500hPa and 850hPa at 08,vertical difference of?_sebetween 850hPa and 1000hPa at 08,Ki at 08,Ai at 08,T-T_d at925hPa at 08,reverse temperature intensity at 08,height of mixing layer at 08,Ri at 08,ventilation coefficient at 08.The threshold range of major environmental conditions at different levels of fog and haze is summarized.The results were as follows:?1?Statistics were performed on the meteorological conditions at the time of fog and haze occurrence,and 9 environmental parameters were selected that could pass the relevant significant test of the relevant level=0.1.Surface wind speed is below6m/s,Ri is above 0.3,the reverse temperature intensity is greater than-0.9?/100m,the vertical difference of?_sebetween 850hPa and 1000hPa is greater than 3?,the height of mixing layer is less than 1000m,the Ki and the Ai are lower than the empirical threshold when convective weather occurs,the atmospheric vertical and horizontal direction are not conducive to the diffusion of pollutants and the generation and maintenance of fog and haze.?2?At the same time of the distribution characteristics of the meteorological conditions of the haze,the differences between the data of the station and the data of the reanalysis were compared.The distribution of the two data elements outside the extreme value is basically the same,among which the inverse temperature index,Ri,the height of the mixing layer and the diffusion coefficient are the same and the highest.Further more,the correlation coefficient analysis shows that the correlation between the calculated results of both data for all nine indices can pass the relevant significant test=0.001 level.The reanalysis data can be used instead ofthe station observation data for statistical analysis of environmental parameter distribution and threshold.?3?Statistics on meteorological conditions during fog occurrence,in addition to9 environmental parameters in haze analysis,the difference of T-T_d at 925hPa,which represents the saturation of near-surface atmosphere,is related to the degree of visibility and is related to the occurrence of fog.The wind speed of local surface is below 6 m/s,the Ri is more than 0.25,the inverse temperature intensity is greater than-0.8?/100m,the vertical difference of?_sebetween 850hPa and 925hPa is greater than-6?,T-T_d at 925hPa is less than 8?,and the mixing layer is not higher than600M.The range of Ki and Ai at 30-9?and 20-26?respectively,is favorable to maintain and strengthen the fog.?4?According to the statistical results of 5 environmental factors which have great influence on visibility,fog and haze mainly occur in the background of high atmospheric thermal and dynamic stability.When fog occurs,reverse temperature intensity is below-0.9?/100m,the Ri is more than 0.25,the mixing layer height is less than 900m,the wind speed of near surface is less than 5m/s;Haze occurs when the index requirements are lower than fog,the Ri is less than 0.25,the mixing layer height between 1100-900m,the wind speed of near surface between 8-5m/s still in the case of haze.?5?According to the statistical results of fog and haze,the requirements of fog to the thermal and dynamic stability of the atmosphere are higher than those of haze.Moreover,the relative degree of visibility and the index was higher than the haze at the time of fog occurrence.All passed the relevant significant test=0.01 level.With the increase of fog forecast and early warning level,all the threshold of the index changes in the direction of the improvement.