Research on Retrieval of PWV Based on PPP and NCEP/NCAR Global Reanalysis 1 Data

Abstract

Aimed at lack of temperature and pressure data in retrieving Precipitable Water Vapor (PWV) from Precise Point Positioning (PPP), a Layer Interpolation Method (LIM) used the NCEP/NCAR layer reanalysis data is proposed. 14 IGS stations located at different altitudes are selected to validate the method with its meteorology files. The interpolated temperature and pressure values from the LIM and those from the classical Surface Interpolation Method (SIM) have been compared with the observed data, further for evaluating effect on the derived PWV. The experimental results show that (1) two interpolation methods perform well in pressure at the GPS sites below 2000 m with RMS 1.79 mbar (LIM) and 3.83 mbar (SIM), LIM is better than SIM. While the interpolated temperature values nearly have the same accuracy with RMS 3.63 K (LIM) and 3.69 K (SIM). (2) The LIM and the SIM exist the large pressure errors for the GPS site above 3000 m as LHAZ. The interpolated pressure error reach 8 mbar, which contributes 3 mm PWV error. While the accuracy is still better than the accuracy of PWV without meteorological data, especially for LIM with the improvement from 4.36 to 3.29 mm. (3) The derived PWV accuracy with interpolation data shows obvious positive correlation with the accuracy of the interpolated pressure data, while the accuracy of PWV has no correlation with temperature data, which means the accuracy of retrieving PWV is mainly effected by pressure. (4) The accuracy of the PWV retrieved with the interpolated meteorological data has no obvious coupling relation with altitude and latitude.