Total electron content models and their use in ionosphere monitoring

摘要: At L band frequencies used in Global Navigation Satellite Systems (GNSS), the ionosphere causes signal delays that correspond with link related range errors of up to about 100 meters. In a first order approximation error is proportional integral electron density along ray path (Total Electron Content - TEC). Whereas this can be corrected dual frequency measurements by simple linear combination L1 and L2 phases, single need additional information for mitigating ionospheric error. This provided TEC maps deduced from corresponding GNSS or model values. In talk we discuss development use background models reconstructing reliable distributed via an operational space weather data service (http://swaciweb.dlr.de ) international community,. To reconstruct over selected region assimilate observation into specific TEC. approach has advantage case only few even total loss input data, maintained providing Since ground based are often uneven distributed, inclusion reconstruction helps overcome such gaps which naturally occur oceans. The Neustrelitz Model (NTCM) basic family regional global models. The approximates variations depending on location, local time solar activity. coefficients calibrated least squares methods. European NTCM-EU polynomial 60 coefficients. monitoring modelling activities started 1995, cover more than full cycle, thus forming set needed developing cycle model. Reported also both polar areas as well All these serve assimilated. Operational primarily IGS EUREF area available SWACI at update rate 5 minutes. Accuracy various obtained after assimilation compared other reconstructions Klobuchar NeQuick maps.