| Accurately determining the content of atmospheric precipitable water vapor and its changes are of great significance for the development of meteorological forecasting,climate change,hydrological monitoring,resource remote sensing,and geodetic survey.Compared with the traditional atmospheric precipitable water vapor detection method,the ground-based GNSS inversion of atmospheric precipitable water vapor has the advantages of real-time monitoring,high monitoring accuracy,high temporal and spatial resolution,and less interference with weather conditions.The inversion and application of regional atmospheric precipitable water vapor is one of the main research hotspots of GNSS remote sensing application technology.At present,the existing literature on the inversion and application of atmospheric precipitable water vapor has gradually matured,but there are still some problems,mainly reflected in:(1)Many scholars have chosen the sounding data of different time periods to establish weighted average temperature models for Hong Kong,but its applicability to near-real-time atmospheric precipitable water vapor inversion needs to be tested.(2)When using high-precision GNSS data processing software —— GAMIT software for atmospheric precipitable water vapor inversion,how to choose the solution strategy to make the solution result the best.(3)Many scholars have analyzed the temporal and spatial distribution characteristics of atmospheric precipitation in China's local areas,but there are few related studies on Hong Kong.(4)Analyze the relationship between atmospheric precipitable water vapor and actual rainfall,and judge whether it can be used for short-term forecast during the occurrence of heavy rainfall.(5)With the continuous update of the GAMIT software version,it has become possible to solve BDS data.The accuracy of the atmospheric precipitable water vapor inversion by combining GAMIT software with BDS data needs to be tested.In view of the above problems,this paper uses the sounding data,Hong Kong satellite positioning reference station network data,real rainfall data in Hong Kong and Australian multi-GNSS experiment data as the basis for research data,and using GAMIT software,MATLAB software,Python software to process the related data and analyze the data processing results.The main research contents and conclusions of this paper are as follows:(1)The annual,seasonal and monthly weighted average temperature models of Hong Kong were constructed and the accuracy test was carried out using the weighted average temperature model already applicable to Hong Kong.The accuracy of annual,seasonal and monthly weighted average temperature models in Hong Kong is better than that of existing models.The accuracy of inversion of atmospheric precipitable water vapor is higher than that of existing models.It has important practical application value.(2)Systematic analysis of the influencing factors of atmospheric precipitable water vapor inversion,and determine the best solution strategy.Under certain conditions,fast precise ephemeris or ultra-fast precise ephemeris can be selected to replace the final precision ephemeris for atmospheric precipitable water vapor inversion.The reversal results of RELAX and BASELINE data processing methods are comparable,but the BASELINE method is faster and requires less time.The accuracy of NMF mapping function inversion results is the lowest,GMF and VMF1 have the same precision and high precision,and usually adopt VMF1.Adding the tide model in the offshore area can improve the inversion accuracy.If there is no real-time meteorological data corresponding to the station,the GPT model can be used for inversion,and the inversion accuracy can also be satisfied with the weather needs.It provides a basis for the analysis of the characteristics of atmospheric precipitable water vapor,the spatial and temporal distribution characteristics and the monitoring of heavy rainfall in Hong Kong.(3)Analysis of the temporal and spatial distribution of atmospheric precipitable water vapor in Hong Kong using atmospheric precipitable water vapor data obtained from ground-based GPS data inversion.The atmospheric precipitable water vapor in Hong Kong is the highest in summer,the smallest in winter,the spring and autumn tends to be between the two,and the autumn is slightly higher than the spring.The atmospheric precipitable water vapor is the smallest in February,the largest in July and August,and the monthly change shows a single-peak curve.The average daily change in January is characterized by “double peaks and double valleys”,and the average daily change in July is “single peak and single valley”.The spatial variation characteristics were obvious,and the distribution trend remained basically the same.(4)Systematic analysis of the relationship between atmospheric precipitable water vapor and actual rainfall during a heavy rain event in Hong Kong.Before the rainstorm occurs,the atmospheric precipitable water vapor can continue to rise until the atmospheric precipitable water vapor can rise rapidly and reach the maximum peak in a small period before the heavy rain.When the atmospheric precipitable water vapor reaches a peak,it will last for a short period of time,and then it will begin to suddenly drop,and a sudden drop will occur after a certain period of time.With the occurrence of heavy rain,the atmospheric precipitable water vapor can show a gradual decline.Until the end of the heavy rain,the atmospheric precipitable water vapor can reach the lowest value and tend to be stable.(5)A method for atmospheric precipitable water vapor of BDS data based on GAMIT software was proposed,and the accuracy of the sounding data calculation results and GPS data inversion results were verified.The results show that the average relative error and root mean square error between the atmospheric precipitable water vapor and the sounding data calculated by BDS inversion are less than 2 mm,and the correlation coefficient is greater than 0.98.The average relative error and root mean square error are less than 4 mm between the GPS inversion results and the GPS inversion results,and the correlation coefficient is greater than 0.90.The BDS inversion results are highly accurate and can meet the meteorological needs. |
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