The Research Of Water Vapor Variation Over Hong Kong Region During Typhoon

The social economy and people's livelihood in Hong Kong have been seriously affected by the severe weather brought by typhoons every year.As the most active part of the atmosphere,water vapor acts as a medium for energy transmission during the formation and dissipation of typhoons.On the one hand,the study of water vapor variation over Hong Kong region during typhoon will help to correct the tropospheric delay of GNSS satellite signals,and on the other hand,the research achievement will help relevant departments to make loss estimates,formulate disaster prevention and mitigation strategies,and reduce the impact of typhoon on people's lives.The water vapor inversion based on GNSS has the advantages of all-weather application,low cost,high accuracy,high spatial-temporal resolution,etc.,to meet the various needs of water vapor detection.Based on the above,the main work and research results are as follows:(1)For the inversion of precipitable water vapor and the three-dimensional water vapor tomography,zenith troposphere delay of GNSS ground observation stations has been extracted by processing GNSS observation data during the period of severe tropical storm"Talas" and tropical storm "Roke" in Precise Point Positioning method.(2)The two-dimensional distribution of water vapor over Hong Kong region during typhoon has been analyzed by using the PWV data over each station and rainfall data.The results show that the influence of the typhoon on the water vapor distribution over Hong Kong region has an overall correlation;water vapor accumulation is the precondition of heavy rainfall,and there is a positive correlation between the cumulative time of PWV greater than 60mm and the cumulative rainfall when water vapor accumulations are similar;the influence range(specifically reflected in the area where the PWV value is greater than 65mm),the influence time and the influence degree of typhoon on water vapor plane distribution are related to its grade;typhoon track has certain influence on local water vapor distribution.(3)The three-dimensional distribution of water vapor over Hong Kong region during typhoon has been analyzed by using the water vapor density obtained by tomography technology and rainfall data.The results show that:the overall change of water vapor is consistent with the typhoon information,larger variation occur in the water vapor density in the middle area and lower area;the impact of "Talas" on water vapor density is greater than that of "Roke" in the area below 1.6km,but the contrary is the case in the area of 1.6km-3.2km;on the day of heavy rainfall,the water vapor density is obviously decreased in the area below 1.6km,but there is not a quantitative relationship between the amount of decline and the daily precipitation;the impact of typhoon on the distribution of water vapor in the lower and upper areas is unconspicuous,but significant in the middle area.