Vaisala GPS station Egyptian Meteorological Authority (EMA) Koubry ELQuobba EMA, Cairo, Egypt, P. BOX : Fax : Abstract Abstract Egyptian Meteorological Authority ( EMA ) will begin a new development technology for Upper air ground stations at jun 2010 by adding new sounding system SR2K2 MODEM with radio sond M2K2-DC from France and new technology for communication of network of the stations. Egyptian Meteorological Authority ( EMA ) will begin a new development technology for Upper air ground stations at jun 2010 by adding new sounding system SR2K2 MODEM with radio sond M2K2-DC from France and new technology for communication of network of the stations. also EMA have 6 upper air stations which used the sounding system of Digicora iii with Radiotidotite RT 20A ( Vaisala ) from fenland. So since 2007 we started to use new development technology with the GPS wind finding system (Vaisala), for three upper air stations in (Matrouh at 2007, Asswan at 2008 and Helwann at 2009 ) to using Digicoraiii with Radiotidotite RT 20A and GPS wind finding system. In this paper We will compare between the different of observations from RDF and GPS system. In this paper We will compare between the different of observations from RDF and GPS system. Also, we will use DigicoraIII dual-mode GPS/RDF wind finding and Modem GPS data Comparison flights executed in Asswan, Marsa Matrouh and Helwan stations, during 2007 to 2010 by the EMA.

2 Global Positioning System (GPS) GPS Signal Path There are two system in upper air stations 1-Upper Air sounding system SR2K2 Modem consists in collecting P,T,U, and wind finding data measured and transmitted from a Radiosonde M2K2-DC during its flight through upper atmosphere layers which used M2K2-DC (Dual Core) GPSonde that is already widespread in the operational SYNOP upper-air network of major and National Met. Services. M2K2 GPSonde successfully participated to the latest WMO inter-comparison of High-Quality Radiosondes, Designation of High-Quality Radiosonde is fully applicable to MODEMs M2K2 GPSonde 2-The DigiCORA® Sounding System MW31 ( Vaisala ) contains :- 2-The DigiCORA® Sounding System MW31 with the Radiotheodolite RT20A and GPS wind finding ( Vaisala ) contains :- A-Radiotheodolite RT20 system Radiotheodolite windfinding is best suited for situations where the balloon elevations remain above about 16°, so we using the stations of Radiotheodolites in the summer season. B-GPS wind finding system portable system with small antennas for 403 MHz telemetry and GPS wind finding RS92-SGP Radiosonde for GPS wind Technology, Major Features All-digital code-correlating GPS Radiosonde Higher level of PTU measurement performance Continuously available, highly accurate wind data code correlating GPS.

2 We compare between the two upper air systems vaisala and Modem :- In the fig (1), (2) and (3) we used system of Modem of upper air sounding system in the 14 jun 2010 we used Modem system and in the fig (4),(5) and (6) the day of 14 jul 2010 we used Vaisala system this data for Marsa matroh, Asswan, and Helwan stations. In the fig (7) it the statistics for data of max height of wind speed from( Dec 2007 to Feb 2008 ) with using vaisala upper air sounding system we found the data of wind speed and direction for all observations reach to about (30-20) kms.

2 Asswan station in Egypt it is one of The Upper-air Network (GUAN) which consists of stations selected from the Global Observing System of the World Weather Watch. Criteria for choice of sites included homogeneity, a history of high quality observations. Asswan station in Egypt it is one of The Upper-air Network (GUAN) which consists of stations selected from the Global Observing System of the World Weather Watch. Criteria for choice of sites included homogeneity, a history of high quality observations.GUAN The data flow for the GUAN begins with national centers that collect and submit the data to the international system. The data flow for the GUAN begins with national centers that collect and submit the data to the international system. The data collected by the network of GUAN stations are transmitted on the GTS in the form of upper-air reports (TEMP and CLIMAT TEMP). International centers perform quality control on the data, prepare data products for users, and archive it for future users. Some of these international centers prepare routine reports on the performance of the system. International centers perform quality control on the data, prepare data products for users, and archive it for future users. Some of these international centers prepare routine reports on the performance of the system. Summary Of GUAN for Asswan Station Summary Of GUAN for Asswan Station Range time WMO STATION OBS LVLS 00Z 12Z AVGPRS >100 >50 >10 TEMPS DPDS WINDS (2007 /8 ) ASSWAN, EGYPT ( Air upper air st.) (2008 /8) ASSWAN, EGYPT ( vaisala upper air st.) (2009 /9) ASSWAN, EGYPT ( vaisala upper air st.) (2009/11-4)( vaisala RDF&GPS upper air) (2009/11-4) ASSWAN, EGYPT ( vaisala RDF&GPS upper air) (2010 /4) ASSWAN, EGYPT ( vaisala RDF upper air st.) We found that seine using Air sounding system we used 500 kg of Metrological balloon which burst at latitude less than 30 km and We found that seine using Air sounding system we used 500 kg of Metrological balloon which burst at latitude less than 30 km and fill with Hydrogen gas by using Sagim system so we found that the number of significant levels for temperature, dew point and wind in fill with Hydrogen gas by using Sagim system so we found that the number of significant levels for temperature, dew point and wind in Air system is less than when used Vaisala system for GPs and RDF system. Air system is less than when used Vaisala system for GPs and RDF system.