Refinement Of Regional Tropospheric Delay Model

Tropospheric delay is one of the research directions of modern space measurement technology.In the practical application,the model method is usually used to reduce the influence of tropospheric delay.Due to the time variability and spatial difference of meteorological factors,the model value and the actual value have errors when solving tropospheric delay in a global or a large range with the same model.Therefore,the corresponding tropospheric delay model should be established for solving in a small range.By calculating the measured data,this paper visualized the calculated data of different stations and different time scales,and explored the relationship between the spatial position and time scale and the delay change of troposphere.Based on the theory of tropospheric delay correction,the atmospheric stratification model,atmospheric refraction index and two mapping functions are studied.Based on the theory of NMF(Neill Mapping Function)model,a tropospheric delay refinement model with constant dry term coefficient,time list of wet term coefficient and increase of ground height correction is established in a small range(the different of latitude<15°).Finally,the application of tropospheric delay on the hourly scale is discussed.The conclusions are as follows:(1)GAMIT software was used to solve and visualize the data on different time scales of the same measuring station and data on different measuring stations at the same time.It was found that the annual variation trend of tropospheric delay of the same measuring station with different time spans was consistent,and the monthly variation pattern was different.There is no correlation between the tropospheric delay curve of remote stations in small time scale,and the time interval of the same station is one year.By calculating the measured data from two stations in Hong Kong in July 2016,it is found that the delay change rules of the troposphere are basically the same,and that the short-term delay change rules of the troposphere in a small region are consistent.(2)With a small scale,tropospheric delay calculating data with real-time meteorological data,can reduce the representative error of meteorological elements,high density calculating tropospheric delay prediction accuracy can be improved,so based on the Python language for calculating the tropospheric delay,data processing,a key to implement efficient visualization(has applied for a patent for invention),compared to Excel,visual time by about 9.6 h to within 5 min,analysis efficiency is improved.(3)The tropospheric delay model with the relationship between meteorological elements.Regional scale elaboration model is put forward based on NMF model,of which dry coefficient is invariant in the region,the damp coefficient with time list,and adding the altitude correction.using HKSL station data of 50 days,through the elaboration model,Saastamoinen(SA)model,NMF model results and the true value(the data during the same period from IGS data center)is compared,the elaboration model consistency with the true value is stronger.(4)Application of short-time tropospheric delay.Using hour-scale tropospheric delay data predicts short-term PM_2.5 concentration change.The result shows that,under the test condition of 95%confidence,the hourly tropospheric delay data can accurately predict the short-term PM_2.5 concentration change.