Fig. 17
From: Review of the accomplishments of mid-latitude Super Dual Auroral Radar Network (SuperDARN) HF radars
The association of quiet-time sub-auroral irregularities with gradients in ionospheric electron density and temperature. The top panel shows time series of the electron density and electron temperature gradients measured by the Millstone Hill incoherent scatter radar. The pink triangle marks the time that the gradient in electron temperature reversed from poleward to equatorward, establishing favorable conditions for the TGI. The bottom panel shows a time series of backscatter power from one beam of the Wallops radar and the increase in backscatter power that followed the reversal. Adapted from Fig. 1 of Greenwald et al. (2006)