In Brief

GNSS Meteorology

The Sofia University Atmospheric Data Archive (SUADA) serves as a regional database for atmospheric parameters, specifically for Integrated Water Vapour (IWV), derived using the Global Navigational Satellite Systems (GNSS) Meteorology method. The GNSS Meteorology method is explained in the following animation:

SUADA history

SUADA was born on February 24th 2012. By March 6th the database structure was created on the Sofia University Physics Faculty PHYSON cluster. By the end of March the design of the database was completed and on May 3rd the first IWV for the EUREF GNSS station in Sofia, Bulgaria (SOFI) was uploaded in the database. The SUADA web site design and execution was initiated in April 2012 and by end of July the web site was linked to the SUADA database.


In summer 2011, the SOFI tropospheric files from the first IGS reprocessing campaign (repro1) for the period 2001-2007 were used to derive the Integrated Water Vapour with 3 hourly resolution. In October 2012, this data set was updated with IWV derived from tropospheric products from the CODE analysis centre contribution for the IGS repro2 campaign.

Since November 2011, in the SUADA database are archived tropospheric files from the GNSS network operated by the Zenitgeo company. The company operates 30 GNSS stations on the territory of Bulgaria. In order to derive the IWV with high temporal resolution (15 minutes) for all Zenithgeo stations, currently a numerical weather prediction model is being set up on the PHYSON cluster.

The SUADA database contains tropospheric files and derived IWV data from 6 GNSS stations in Southeast Europe for the period of the 2007 heatwave. The tropospheric files are provided by Prof. Keranka Vasileva from the National Institute of Geophysics, Geodesy and Geography.

In total the data from over 80 GNSS stations in Southeast Europe (32 of which in Bulgaria) are currently available in the SUADA. The ZenitGEO stations are marked in yellow, Balkan processed stations in green, station Sofia in red (processed by EUREF and IGS) and radiosonde station Sofia in blue. The locations of the stations are shown on the map:

SUADA Radiosonde data

The SUADA database also contains radisounde IWV for the period 1995-2012. Only the station in Sofia is currently available in the database.

The envisaged applications of the SUADA database include:

  1. cross-validation of ground-based and satellite observations and derivation of systematic biases;
  2. validation of numerical models used for research and numerical weather prediction (WRFEMS);
  3. study of water vapour distribution in Bulgaria/Southeast Europe;
  4. detection of long term water vapour trends in Bulgaria/Southeast Europe and links to heat waves, droughts and changes in the pathway of the Atlantic Cyclones;
  5. study how well state-of-the-art climate models, notably the one participating in Intergovernmental Panel on Climate Change (IPCC) AR5 assessment, simulate present climate of Bulgaria/Southeast Europe.