Meteorological Characteristics Of Typical Haze Processes In Xi'an Based On Multi-source Data Analysis

With the rapid development of the economy and society,the problem of air pollution is becoming more and more serious,especially in auumn and winter,The haze disasters in various parts of the world frequently occur,which have a great influence on people's travel,life and health.The haze process is closely related to certain meteorological conditions.Therefore,it is of great scientific significance and application value to study the meteorological characteristics of the haze process.This thesis uses the visibility date,AQI(Air Quality Index)data,NCEP(National Centers for Environmental Prediction)data,Xi'an University of Technology automatic weather station monitoring data,and Lidar data to use a comprehensive diagnosis method.Aiming at the meteorological characteristics of the two typical haze processes conducted in Xi'an area,the physical model of haze in Xi'an area was initially established and the reference indices for haze forecast were proposed.Finally,a preliminary verification of the forecast reference indicators was conducted through another haze process.The main conclusions of this paper are as follows:(1)Six forecast reference indicators of haze formation are proposed,including two main indicators:The emergence of warm high-pressure,high-pressure ridges,temperature ridges and wet tongue weather systems at 850 hpa,and the appearance of typical weather systems with high-pressure ridges and temperature ridges at 700 hpa;500hpa wind speed reduction?7m/s.(2)Four forecast reference indicators of haze maintenance are proposed,including two.main indicators:The lower layer weakly divergence decreases,the upper layer weakly converges the upward movement airflow;The wind speed is maintained between 0 and 1 levels.(3)Nine forecast reference indicators of haze dissipation are proposed,including two main indicators The emergence of typical weather systems with cold ridges and cold tongues at 850hpa and 700hpa;500hpa wind speed increase?15m/s.(4)The preliminary verification of the forecast index are completed.The forcast ind-exes were verified by a haze process in January 2018.The results show that the chara-cteristics of the meteorological elements in the haze process are basically in line with the reference index.To some extent,the research shows that the results including the conceptual model and the forecast indicator have the value for forecasting the haze in Xi'an.