Mesoscale ionospheric anomalies not associated with space weather

摘要: [1] Using the Austrian network of 10 two-frequency GPS geodetic reference stations, whose location is known with high precision, a study mesoscale anomalies in ionosphere over central Europe has been made (and still progress for following years). From large number individual observations during period from 2000 to 2004, maps small-scale ionospheric behavior (with pixel size 0.5° latitude and longitude) have constructed which local (at an equivalent height 250 km) terms departure model total electron content (TEC) can be recognized. Not all magnetic storms were most common 2000–2002 solar maximum showed effects regional ionosphere, but are not (necessarily) associated space weather also observed up 20% days observation, their highest frequency occurrence winter months (November–February). These typical duration several hours seem traveling disturbances (TIDs) origin could lie gravity waves initiated lower atmosphere. Thus TIDs may play role detected only by virtue dense spatial coverage obtained stations precise positioning. activity background ionization decreased considerably. Since depend on both properties atmospheric level ionization, we smaller absolute TID amplitudes 2003–2004 compared 2000–2001. There indication that relative increased slightly, consistent influence ion drag thermosphere dynamics.