Variations in the Ionosphere and Thermosphere observed by C/NOFS CINDI in the equatorial region.

Abstract:

During the latter part of the Communications/Navigation Outage Forecast System (C/NOFS) mission the Coupled Ion Neutral Dynamics Investigation (CINDI) instruments observed simultaneous variations in plasma and neutral density motions and temperature in the equatorial region. Large-scale variations in the neutral density compare well with thermospheric models. But the most significant variations are seen during periods of magnetic activity when even very modest storms produce enhancements in the thermospheric temperature and density that are seen at the equator. Increases in the neutral density are consistent with increases in the neutral atmosphere scale height associated with a global increase in the neutral temperature apparently produced by high latitude energy inputs that influence low latitudes through a disturbance that propagates rapidly to low latitudes. Variations in the neutral density are also seen during quiet times. These variations are longitudinally dependent and coupled through the ion drag force to similar variations in plasma density induced by transport associated with electric fields.