Electric fields within noctilucent cloud and polar mesospheric summer echo environments

I present the results of electric field measurements made during the MASS and DROPPS rocket campaigns in Andoya, Norway into noctilucent clouds (NLC) and polar mesospheric summer echoes (PMSE) in 2007 and 1999, respectively. The electric field instrument was similar in both campaigns, and used high input-impedance preamps to measure vertical and horizontal electric fields. Large geophysical electric fields were only detected in the cloud layers during the DROPPS flights, but significant levels of electric field fluctuations were measured on both MASS and DROPPS. Within the cloud layer, the probe potentials relative to the rocket skin were driven negative by incident heavy charged aerosols. The amplitude of spikes caused by probe shadowing were also larger in the NLC/PMSE region. I describe a method for calculating positive ion conductivities using these shadowing spike amplitudes and the density of heavy charged aerosols. Data from the MASS flight is directly compared to the model described by Robertson [2007], with the conclusion that the model is inadequate to fully explain the data.