| As the world’s highest continent in terms of average altitude,Antarctica has the coldest,driest and windiest climate;it is also the main source of cold in the global atmospheric circulation and plays an important role in global heat exchange,momentum exchange,moisture exchange and atmospheric circulation and other climate changes,making it a key area for studying global climate change.This paper integrates GNSS(Global Navigation Satellite System)and ERA5(Medium-Range Weather Forecasts Reanalysis 5)data to invert Precipitable Water Vapor(PWV)at high spatial and temporal resolution to analysis the spatial and temporal characteristics of atmospheric water vapor and its impact on global climate change in the Antarctic region in recent years.(1)The accuracy of ERA5 reanalysis data in the Antarctic region was evaluated for ground meteorological elements such as barometric pressure,air temperature,relative humidity,and Zenith Tropospheric Delay(ZTD).Compared with the ground meteorological elements from the sounding station,the root mean square error(RMSE)of ERA5 air pressure is 0.81～1.08 h Pa and the RMSE of temperature is 2.35～3.90℃,indicating that the ERA5 meteorological data can be used in the atmospheric precipitable inversion.The accuracy of the ZTD of ERA5 inversion was compared with that of the ZTD monitored by the IGS site,in which the RMSE solved by the Saastamoinen model is 10.34～11.20 mm,and the RMSE using the integral method inversion is 6.59～8.73 mm,indicating that the integral method has higher calculation accuracy than the model method.(2)A spatially weighted and temporally corrected GNSS-PWV and ERA5-PWV time-series fusion method(Inverse Distance Weighted ERA5 Month Bias,IEMB)is proposed and its accuracy is evaluated.The method combines the advantages of ERA5time-series stability and spatial integrity with GNSS high accuracy and temporal resolution,and applies inverse distance-weighted horizontal interpolation to ERA5-PWV in space and height adjustment in vertical direction according to the vertical correction model of South Pole PWV to obtain ERA5-PWV at GNSS stations;in time,the sliding monthly average deviation of ERA5-PWV from GNSS-PWV at the missing moment is obtained.The spatial adjustment and temporal correction are combined to complete the missing GNSS-PWV data and obtain the atmospheric water vapor data with continuous temporal and high spatial resolution.The accuracy of GNSS-ERA5-PWV obtained based on the IEMB method is significantly higher than that of the Linear Interpolation(LI)method for different missing intervals and missing lengths,and the RMSE is improved by 43.88% and 54.35%,respectively.(3)The results of Theil-Sen method analysis and Fourier series modeling analysis of the GNSS-ERA5-PWV time series after time series fusion using the IEMB method show that the atmospheric water vapor content and temperature in the Antarctic region are both decreasing from 2012 to 2021,which is related to the Antarctic Oscillation(AO),and its enhancement will cause high pressure in the Antarctic region near 40°S and low pressure in the Antarctic region near 65°S.This is related to the Antarctic Oscillation(AO),which causes high pressure in the Antarctic region near 40°S and low pressure in the region near 65°S,thus strengthening the southerly winds blowing from the Antarctic continent and causing a decrease in temperature.The seasonal mean and inter-seasonal difference of ERA5-PWV in Antarctic region and the spatial characteristics analysis show that the atmospheric water vapor content is higher in the Antarctic continental margin and lower in the inland area,but the spatial difference is small.The inter-seasonal variation of atmospheric water vapor content is higher in the outer seas and lower in the interior,and the gradient of PWV variation is larger in the steep topography of the east and west sides of Antarctica. |
PDF Full Text Request