Fig. 2
From: Major upwelling and overturning in the mid-latitude F region ionosphere
Enhanced version of the topside ionospheric irregularities from the latter portion of the event. A low-pass filter (Gaussian with a standard deviation of 100 pixels) was applied to the original image, and the difference between the filtered and unfiltered images was then plotted. Despite having units of per cubic meter, the quantity being plotted is not strictly electron density, and the grayscale is arbitrary
