Figure 3: Ion densities of the entry plasmas.
From: Solar wind entry into the high-latitude terrestrial magnetosphere during geomagnetically quiet times
(a) Ion densities for the events versus the corresponding solar wind density. Black markers indicate the events, whereas red stars are the average value for each 3-SW density bin with more than 3 points. (Two extreme events that exhibited densities of greater than 1 are not shown here.) The positive relationship between the average density and solar wind density strongly indicates that the entry plasmas are originated from the (compressed) solar wind. Mean ion density values along (b) the y-direction and (c) the x-direction for each 1-Re-bin, respectively. The density was higher near the mid-night sector and, therefore, the contribution of K-H instability25,26 and gradient drift processes27 at low latitudes can be excluded.
