Integration and verification of meteorological observations and NWP model data for the local GNSS tomography

摘要

GNSS meteorology applies the Global Navigation Satellite Systems (GNSS) to derive information about the state of the atmosphere (particularly troposphere). The tomography is one of the methods used in GNSS meteorology. The input data of GNSS tomography are the signal troposphere delays, results of GNSS data processing and additionally meteorological observations and Numerical Weather Prediction (NWP) models data. Different types of the input data have heterogeneous character, but give broad spectrum of information. The paper presents the methodology of integration and verification of GNSS, meteorological and NWP data for GNSS tomography. Because of the data inhomogeneity, original methods of meteorological data validation and NWP model calibration are proposed. In order to verify the ground meteorological observations, the differential wavelet method is proposed. The results of analysis show that pressure should be measured as accurately as possible (uncertainty below 1.0 hPa) with homogenous instruments and in the similar conditions. Whereas the temperature could be measured less accurately (uncertainty below 2.4 K), however usage of meteorological radiation shelters (e.g. Stevenson screens) or mathematical algorithms to mitigate the influence of direct insolation is a must. The integration procedure of the COAMPS NWP model shows that the model output parameters are squaring with the meteorological observations from the synoptic stations. The best match is found between pressures from both sources, a good match is also found in case of temperature, whereas relative humidity measurements are less consistent. Moreover, the presented methodology could be used for assimilation of meteorological observations into numerical weather models.