scholarly journals On the inclusion of GPS precipitable water vapour in the nowcasting of rainfall

2015 ◽  
Vol 3 (6) ◽  
pp. 3861-3895 ◽  
Author(s):  
P. Benevides ◽  
J. Catalao ◽  
P. M. A. Miranda

Abstract. The temporal behaviour of Precipitable Water Vapour (PWV) retrieved from GPS delay data is analysed in a number of case studies of intense precipitation in the Lisbon area, in the period 2010–2012, and in a continuous annual cycle of 2012 observations. Such behaviour is found to correlate positively with the probability of precipitation, especially in cases of severe rainfall. The evolution of the GPS PWV in a few stations is analysed by a least-squares fitting of a broken line tendency, made by a temporal sequence of ascents and descents over the data. It is found that most severe rainfall event occurs in descending trends after a long ascending period, and that the most intense events occur after steep ascents in PWV. A simple algorithm, forecasting rain in the 6 h after a steep ascent of the GPS PWV in a single station is found to produce reasonable forecasts of the occurrence of precipitation in the nearby region, without significant misses in what concerns larger rain events, but with a substantial amount of false alarms. It is suggested that this method could be improved by the analysis of 2-D or 3-D time varying GPS PWV fields, or by its joint use with other meteorological data relevant to nowcast precipitation.

2015 ◽  
Vol 15 (12) ◽  
pp. 2605-2616 ◽  
Author(s):  
P. Benevides ◽  
J. Catalao ◽  
P. M. A. Miranda

Abstract. The temporal behaviour of precipitable water vapour (PWV) retrieved from GPS delay data is analysed in a number of case studies of intense precipitation in the Lisbon area, in the period 2010–2012 and in a continuous annual cycle of 2012 observations. Such behaviour is found to correlate positively with the probability of precipitation, especially in cases of severe rainfall. The evolution of the GPS PWV in a few stations is analysed by a least-squares fitting of a broken line tendency, made by a temporal sequence of ascents and descents over the data. It is found that most severe rainfall events occur in descending trends after a long ascending period and that the most intense events occur after steep ascents in PWV. A simple algorithm, forecasting rain in the 6 h after a steep ascent of the GPS PWV in a single station, is found to produce reasonable forecasts of the occurrence of precipitation in the nearby region, without significant misses in what concerns larger rain events, but with a substantial amount of false alarms. It is suggested that this method could be improved by the analysis of 2-D or 3-D time-varying GPS PWV fields or by its joint use with other meteorological data relevant to nowcast precipitation.


2017 ◽  
Vol 28 (2) ◽  
pp. 19-29 ◽  
Author(s):  
Oladiran J. Abimbola ◽  
◽  
Oluwasesan A. Falaiye ◽  
Joseph Omojola ◽  
◽  
...  

Author(s):  
Richard Cliffe Ssenyunzi ◽  
Bosco Oruru ◽  
Florence Mutonyi D’ujanga

Currently, the East African tropical region has limited information about Precipitable Water Vapour (PWV) data and yet the region has a high potential for its utilization. This is on the grounds that the East African tropical region is profoundly prone to climate change and fluctuation. Existing studies need data on the detailing and performance evaluation of precipitable water vapour models within East Africa. This has been so as a result of the scattered Global Positioning System (GPS) networks and other alternative water vapour measuring equipments, enormous information gaps and the absence of surface meteorological data. The accessibility and precision of surface meteorological estimations is crucial in deriving accurate GPS PWV data. In this study, the daily average, PWV, pressure, temperature and weighted mean temperature () models have been developed utilizing one year (2013) GPS PWV and European Centre for Medium-Range Weather Forecasts (ECMWF) 5th Re- Analysis PWV (ERA5 PWV), total column water vapour (TCWV), surface pressure and 2 meter (2m) temperature data. The purpose of the developed models is to predict PWV over regions with data gaps where the computation of GPS Zenith Tropospheric Delays (ZTD) is impossible and in cases of station outages. In addition, the models will provide meteorological parameter where meteorological sensors are missing. The GPS PWV accuracy obtained with the developed models shows an average RMSE of 1.54 mm and MnB of 0.32 mm in comparison to the measured GPS PWV data. The ERA5 PWV accuracy obtained with the developed models shows an average RMSE of 0.33 mm and MnB of 0.01 mm in comparison to the measured ERA5 PWV data. Based on the RMSE, it was observed that the site-specific models developed can be utilized to provide estimates of nearly a similar degree of precision compared to the measured values at the thirteen stations.


2021 ◽  
Author(s):  
Eshetu Erkihune ◽  
Addisu Hunegnaw ◽  
Felix Norman Teferle

<p>As one of the most important components of the global hydrologic cycle, atmospheric water vapor shows significant variability in both space and time over a large range of scales. This variability results from the interactions of many different factors, including topography and the presence of specific atmospheric processes. One of the key regions for affecting global climatic variations lies in the sub-Antarctic zone over the Southern Ocean with its Antarctic Circumpolar Current and the associated Antarctic Convergence. There, in this cold and maritime region, lies South Georgia Island with its weather and climate being largely affected by both the dominating ocean currents and the westerly winds in this zone. While the island forms an important outpost for various surface observations in this largely under sampled and extremely remote region, it also forms a barrier for these winds due to its high topography. This, in turn, leads to various local meteorological phenomena, such as warm Foehn winds, which have a significant impact on the near-surface meteorology and contribute to the accelerated glacier retreat observed for the northeast of the island.</p><p>Surface meteorological data have been available for several stations near King Edward Point (KEP) in South Georgia for much of the 20<sup>th</sup> century. Since 2013 and 2014, Global Navigation Satellite System (GNSS) data have been available at five locations around the periphery of the island. In this study, we investigate the consistency between the different surface meteorological data sets and along with GNSS Precipitable Water Vapour we use these to analyse historic Foehn events.</p><p> </p>


Author(s):  
Houaria Namaoui ◽  
Salem Kahlouche ◽  
Ahmed Hafidh Belbachir

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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