Preprints
https://doi.org/10.5194/amt-2016-152
https://doi.org/10.5194/amt-2016-152

  15 Jul 2016

15 Jul 2016

Review status: this preprint was under review for the journal AMT but the revision was not accepted.

Evaluation of IWV from the numerical weather prediction WRF model with PPP GNSS processing for Bulgaria

Tzvetan Simeonov1,a, Dmitry Sidorov2,b, Felix Norman Teferle2, Georgi Milev3, and Guergana Guerova1 Tzvetan Simeonov et al.
  • 1Faculty of Physics, Sofia University "St. Kliment Ohridski", Bulgaria
  • 2Université du Luxembourg, Luxembourg
  • 3Space Research and Technology Center - Bulgarian Academy of Sciences, Bulgaria
  • anow at: GeoForschungsZentrum (GFZ) Potsdam, Germany
  • bnow at: Astronomical Institute University of Bern, Switzerland

Abstract. Global Navigation Satellite Systems (GNSS) meteorology is an established operational service providing hourly updated GNSS tropospheric products to the National Meteorologic Services (NMS) in Europe. In the last decade through the ground-based GNSS network densification and new processing strategies like Precise Point Positioning (PPP) it has become possible to obtain sub-hourly tropospheric products for monitoring severe weather events. In this work one year (January–December 2013) of sub-hourly GNSS tropospheric products (Zenith Total Delay) are computed using the PPP strategy for seven stations in Bulgaria. In order to take advantage of the sub-hourly GNSS data to derive Integrated Water Vapour (IWV) surface pressure and temperature with similar temporal resolution is required. As the surface observations are on 3 hourly basis the first step is to compare the surface pressure and temperature from numerical weather prediction model Weather Forecasting and Research (WRF) with observations at three synoptic stations in Bulgaria. The mean difference between the two data-sets for 1) surface pressure is less than 0.5 hPa and the correlation is over 0.989, 2) temperature the largest mean difference is 1.1 °C and the correlation coefficient is over 0.957 and 3) IWV mean difference is in range 0.1–1.1 mm. The evaluation of WRF on annual bases shows IWV underestimation between 0.5 and 1.5 mm at five stations and overestimation at Varna and Rozhen. Varna and Rozhen have also much smaller correlation 0.9 and 0.76. The study of the monthly IWV variation shows that at those locations the GNSS IWV has unexpected drop in April and March respectively. The reason for this drop is likely problems with station raw data. At the remaining 5 stations a very good agreement between GNSS and WRF is observed with high correlation during the cold part of 2013 i.e. March, October and December (0.95) and low correlation during the warm part of 2013 i.e. April to August (below 0.9). The diurnal cycle of the WRF model shows a dry bias in the range of 0.5-1.5 mm. Between 00 and 01 UTC the GNSS IWV tends to be underestimate IWV which is likely due to the processing window used. The precipitation efficiency from GNSS and WRF show very good agreement on monthly bases with a maximum in May-June and minimum in August–September. The annual precipitation efficiency in 2013 at Lovech and Burgas is about 6 %.

Tzvetan Simeonov et al.

 
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Tzvetan Simeonov et al.

Tzvetan Simeonov et al.

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