Correlation of GSO satellite anomalies with space weather data

This work summarizes the main results of our studies at the ISRO cell of IIT-Mumbai, on the relationship between space weather and geostationary satellite anomalies. We point out that the essence of the problem is to understand quantitatively the relationships between changes in space weather at the Sun (S) and the dayside Lagrangian point (L1) on the one hand, and on the other hand the electron/proton fluxes and magnetic field changes at the geostationary altitude (G). Electromagnetic and cosmic ray changes at the Earth surface (E) are also related to the field and particle changes observed at G. We have evolved prediction programs for satellite anomalies based on proton events on the Sun, the solar wind speeds measured at L1, and the 2MeV electron flux enhancements observed at G. The probabilities and time lags of the occurrence of satellite anomalies are also governed by whether the ‘shock’ in solar wind and IMF parameters detected at L1 is of a ‘sharp’ or a ‘diffuse’ type. From a comparative study of the two years 2005 and 2006 with very different space weather conditions, we find that the type and number of anomalies is (1) clearly governed by the magnitude of the interplanetary electric field Esw, and hence by the IMF B and (2) by the number of proton events on the Sun. We are currently exploring the role played by the ratio of 2MeV electrons to the >1MeV protons, both at G, in the occurrence of satellite anomalies.