Ionospheric Observations from Formation Flying Spacecraft

The equatorial ionosphere exhibits remarkable variability on a variety of spatial and temporal scales. While numerical models are able to capture the larger-scale climatological features of this region, and simulate many of the processes that produce smaller-scale structures, they are unable to accurately predict the low latitude ionospheric density on any given day. For that reason, observations of this region remain critical. Remote sensing from the ground offer an opportunity to get high resolution observations, but only at a few locations. Remote sensing from space offers the possibility of characterizing the region on a global-scale but can miss some of the smaller-scale features. In situ observations from space capture the smallest scales, but only at the location of the spacecraft. Here we utilize a time period in which 2 spacecraft were flying in formation - maintaining approximately the same relative position of less than a few hundred km separation for several days. Using in situ samples from both, we are able to capture small scale features, and identify their spatial gradients, and coherence over these intermediate scales.