In climate change context, the precipitable water vapour (PW) is key parameter of atmospheric process and dynamics and its variation is very high in space and time. It's accuracy is paramount for any geodetic or climatic study. The main objective of this study is to compute precipitable water vapour from ERA5 reanalysis for 4 stations in Algeria which have different types of climate. We opt for using integration method for different level of pressure with ERA5. The values of water vapour are also compared with radiosondes profiles. The results of this work shows good agreement with a correlation that is not less than not 0.95 and 0.70 compared as radiosondes profiles. The first results are encouraging, in particular for meteorological applications with good hope to introduce another dataset as GNSS to more understand the variation and behavior of water vapour over a long period of observation.
Remote sensing of atmospheric water vapour using GNSS and Satellite data has become an efficient tool in meteorology and climate research. Many satellite data have been increasingly used to measure the content of water vapour in the atmosphere and to characterize its temporal and spatial variations. In this paper, we have used observations from radiosonde data collected from three stations (Algiers, Bechar and Tamanrasset) in Algeria from January to December 2012 to evaluate Moderate Resolution Imaging Spectroradiometer (MODIS) total precipitable water vapour (PWV) products. Results show strong agreement between the total precipitable water contents estimated based on radiosondes observations and the ones measured by the sensor MODIS with the correlation coefficients in the range 0.69 to 0.95 and a mean bias, which does not exceed 1.5.
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<p>Tropospheric delay is one of the important error sources in GNSS positioning and is caused when radio signals broadcasted by GNSS satellites propagate into the neutral atmosphere.</p>
<p>This delay is typically divided into wet and hydrostatic components.&#160; ZTD is described as the sum of the Zenith Hydrostatic Delay (ZHD) and the Zenith Wet Delay (ZWD) and can be combined with surface pressure and temperature to estimate the integrated content of water vapour above GNSS station.</p>
<p>The main objective of this study is to compute the tropospheric zenith delay from ERA 5 reanalysis for 3 stations in Algeria which have different types of climate. We opt for using integration method for different level of pressure with ERA5.</p>
<p>The values of tropospheric delay are also compared with delays obtained from radiosondes profiles.</p>
<p>The results of this work shows good agreement with a mean correlation of 0.70, a mean bias of 3 mm and a RMS of 4 mm. We plan to extend this work for GNSS station recording for long periods.</p>
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