National Permanent GNSS (Global Navigation Satellite Systems) Network

It consists of more than 20 permanent GPS/GNSS stations which data are archived, proceeded and analyzed in Center for procession and analysis. The procession and analysis of the measurements permits to carry out a monitoring of the current crustal motions in Bulgaria and Balkan Peninsula and, along with the seismic information, to evaluate the seismic risk.

Center for procession and analysis of GPS/GNSS measurements

The Center was established in 2002-2003 in connection with the obligations of the Department of Geodesy in the building and maintaining of the (new) State GPS network of the Republic of Bulgaria. Equipped with high technology computer techniques and possessing modern software for processing and analysis of GPS/GNSS measurements as: GAMIT/GLOBK, elaborated in the Massachusetts Technological Institute; Bernese 5.2, of the Astronomical Institute of the University of Bern, software packages QOCA, FONDA, DYNAPG.

In the Center are archived, proceeded and analyzed the measurements from the permanent GPS/GNSS stations on the territory of Bulgaria, Balkan Peninsula and Europe.

In Fig.1 are shown the permanent stations on the country’s territory which are proceeded regularly in the Center for analysis.

Fig.1

In the Figure with squares are marked the principal Hemus-NET permanent stations; with triangles the stations of the National GPS/GNSS Permanent Network of the National Institute of Geophysics, Geodesy and Geography (NIGGG) including the stations maintained together with NAVITEK Network; with lozenges are noted permanent stations of the NAVITEK Network; with stars are made EUREF permanent stations.

The first permanent stations of the National Permanent Network are settled in the mid of 2007 in the framework of the Project, financed in the Science for peace NATO program, “Monitoring of the deformation of the Earth’s crust in the Central-Western Bulgaria and Northern Greece with the Global positioning GPS – Hemus-NET.

The main permanent network Hemus-NET consists of 8 GPS/GNSS stations – 6 on Bulgarian territory and 2 on the territory of Greece:

• Dragoman (DRAN), meteorological station Dragoman;
• Kustendil(KUST), meteorological station Kyustendil;
• Sandanski (SAND), meteorological station Sandanski;
• Sofia (SOFA), roof of the Agency for Geodesy, Cartography and Cadastre, Sofia;
• Pazardjik (PAZA), meteorological station Pazardzhik;
• Yundola (YUND), roof of the research base of the University of Forestry, Sofia;
• Kato Nevrokopi, Greece (NEVR);
• Lemnos island, Greece (LEMN).

The permanent GPS/GNSS stations are stabilized on the reinforced concrete posts.

Data from the permanent GPS/GNSS stations of the main permanent network Hemus-NET have free access at:

• Bulgaria – at anonymous ftp server ftp://195.96.249.3;
• Greece – via web server http://egelados.gein.noa.gr/services/GPS/GPS_DATA/.

During the time from 2007 up to now NIGGG has installed considerable number of new permanent stations (see Fig. 1), united in a National Permanent GPS/GNSS Network – Hemus-NET.
The settled stations of the National network at the moment are:

• Plana (PLA1), National Geodetic Observatory in Plana;
• Panagyurishte (PANG), National Magnetic Observatory in Panagyurishte;
• Valandovo (VALA), Republic of Macedonia;
• Vidin (VIDI);
• Oryahovo (ORIA);
• Pleven (PLEV);
• Troyan (TROY), Military-geographic service of Bulgarian Army;
• Rakovski (RAKO);
• Kardzhali (KARJ), Station of the National Seismological Network of NIGGG;
• Harmanli (HARM);
• Elhovo (ELHO);
• Rozhen (ROZE), National Astronomical Observatory in Rozhen;
• Varna (VARN), Astronomical Observatory in Varna;
• Provadia (PROV), Station of the National Seismological Network of NIGGG;
• Varna (VTAG), permanent GPS/GNSS station in the mareographic station in Varna of the National Mareographic Network.
• In the near future will be installed permanent GPS/GNSS stations in Tran and Pernik in the framework of the Project „MONITORING AND INFORMATION SYSTEM FOR CURRENT CRUSTAL MOTIONS AND THE SEISMIC RISK VIA THE NATIONAL GNSS, SEISMIC AND ACCELEROMETRIC NETWORKS”, sponsored by Scientific Research Fund, by agreement ДФНИ ИО1/4 – 27. 11 2012.

Additionally will be installed a receiver in the mareographic station in Burgas from the National Mareographic Network.

With the intended three new stations in Tran and Pernik and the mareographic station in Burgas the total number of the permanent GPS/GNSS stations from the National Permanent GPS/GNSS Network – Hemus-NET is 26.

The permanent GPS/GNSS stations in Vidin, Oryahovo, Pleven, Kardzhali, Harmanli, Elhovo and Rakovski are installed and operated jointly with the permanent network NAVITEK, possession of SB Group. The data from all permanent GPS/GNSS stations of the network NAVITEK are given to NIGGG, according a binding contract, and are used for the research purposes of the National Institute (see Fig. 1).