Study On Sounding PM2.5 With Technique Of Ground

PM2.5 is the fine suspended particles in the atmosphere with diameter less than or equal to 2.5?m.Haze severity is presented by the concentration index of PM2.5.When the GNSS signal passes through the atmosphere,it will be affected by atmospheric water vapor,resulting in signal delay.When fog and haze approaches,the PM2.5 particulate matter increases,the atmospheric water vapor also can change along with it.According to the changes of PM2.5,water vapor and tropospheric delay between the three,explore the relationship model between them,using water vapor for haze monitoring.Haze,a phenomenon of air pollution,has been plaguing us in recent years.If we can get timely fog and haze weather forecast,we can take some appropriate measures to reduce the harm haze bringing to us.Water vapor detection technology based on Ground-based GNSS derived from meteorology and GNSS technology.In recent years,it has gained some achievements in water vapor detection,and become an effective means of detection.It can be used for all-weather observation,without the influence of clouds,rain and other weather,and the existing CORS network can be used to save resources.The inversion results of it are of high precision and incomparable advantages of traditional techniques.The water vapor retrieval process of Ground-based GNSS technology is mainly using troposphere delay generated by the satellite signal propagation in the atmosphere to to calculate the atmospheric water vapor.Atmospheric tropospheric delay includes hydrostatical delay and wet delay.Hydrostatical delay,also known as dry delay,can be calculated by the ground surface temperature and atmospheric pressure and other atmospheric factors through the hydrostatical delay model.The wet delay is affected by the atmospheric water vapor and is very unstable.The wet delay can be obtained by subtracting the hydrostatical delay from the total tropospheric delay.Then through the conversion coefficient,the wet delay is converted to the Atmospheric Precipitable Water.The accuracy of conversion coefficient depends on the weighted average temperature model.The accuracy of weighted average temperature model is compared,and the suitable model of Hongkong area is selected to obtain the relatively high accuracy of Atmospheric Precipitable Water.This research uses the commonly used high-precision data processing software GAMIT.The precipitable water vapor in Hongkong area is calculated from the data of Hongkong satellite positioning reference site.Combining precipitable water vapor,PM2.5 concentration data and Air pollutant data,provided by the environmental protection department of Hongkong,making analysis of the changes of their trend chart,establishing correlation analysis and regression equation monitoring haze.Taking into account the air pollutants under certain conditions will form the before gaseous substances of PM2.5,Carbon monoxide?CO?,nitrogen dioxide?NO₂?,PM10 and other pollutants with atmospheric water vapor,PM2.5 together,further analysis of the relationship between them,and the use of multiple linear regression to establish the relationship model.The main contents are as follows:?1?Comparative analysis Chen Yongqi?2007?,Wang Xiaoying?2011?,Liu Yanxiong?2000?and Bevis?1992?four kinds of T_m model accuracy,select the T_m model suitable for Hongkong area.The water vapor obtained from the four models is compared with the radiosonde data,the result shows that the average deviation of the Wang Xiaoying model is about 0.65 mm,which is obviously better than other models to meet the demand of high precision water vapor in Hongkong area.?2?Correlation analysis between PM2.5 and ZTD,ZWD,ZHD,PWV.The trend maps of zenith total delay?ZTD?,zenith wet delay?ZWD?,zenith hydrostatic delay?ZHD?,Atmospheric Precipitable Water?PWV?and PM2.5 are compareted and analysed.As can be seen from the trend chart,the trend of PM2.5 and ZHD is approximately and opposite of ZTD,ZWD and PWV.In order to better analyze the relationship between them,the correlation analysis was carried out.Through data matching,Tuen Mun?Lam Tei,Kam Tin?Yuen Long,Fanling?Tin Po,Wong shek?Tap Mun,Sha Tin?Sha Tin,stonecutters Island?Sham Shui Po are selected from the Hongkong satellite positioning reference station network and the Hongkong air quality monitoring stations,basically to cover the entire Hongkong region.The results showed that the correlation coefficients of PM2.5 and ZTD,ZWD,ZHD,PWV respectively are: 0.637,0.787,0.617,0.658,which all pass the 0.01 significance test,showing that there is a clear correlation between them.?3?The linear regression of PWV and PM2.5 is carried out,of which equation R2 maximum value is 0.433 and verified with the corresponding site data in 2015.The error analysis of the observed and estimated values is carried out to verify the applicability of the model.This paper describes and analyzes the mutual change between PWV and PM2.5 during the a period of haze in Kam Tin?Yuen Long station in Hongkong area.Water vapor and haze are seasonal,in order to better analyze the relationship between PM2.5 and water vapor,making the correlation analysis of the four seasons.?4?Combined with the atmospheric pollutants carbon monoxide?CO?,nitrogen dioxide?NO₂?,nitrogen oxide?NO_x?,sulfur dioxide?SO₂?,ozone?O3?,PM10 and PWV data,correlation analysis and PM2.5,establish the linear equation between them by using multivariate linear regression.The maximum value of the regression equation R2 was 0.957,which indicated that the regression equation was significant.By January 2015 to Tuen Mun station blue data was verified the accuracy of the model,the correlation coefficient of the true value and predicted value was 0.98,indicating a significant effect of the regression equation for haze monitoring has certain practicability.