Plasmapause location under quiet geomagnetic conditions (Kp ≤ 1): THEMIS observations

We statistically examined the plasmapause location (L-pp) under quiet geomagnetic conditions (Kp1) using the electron density inferred from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft potential for 2year period (2008 and 2009). Five hundred forty-three L-pp samples were identified under steady quiet conditions with Kp values 1 during 12h prior to the plasmapause crossing. From our large data set, we determined the medians and means of L-pp in L and magnetic local time (MLT). They are located near geosynchronous orbit and nearly circular. The L-pp medians show a slight bulge located in postdusk sector. Comparing with previous models, our median or mean L-pp is extended approximate to 1-2L from the Earth than the model L-pp along the local time from 0800 to 2400 MLT. That is, L-pp locations in the previous models are underestimated during quiet geomagnetic conditions.