Fig. 4
From: Major upwelling and overturning in the mid-latitude F region ionosphere

Representative images of radar echoes due to coherent scatter from plasma density irregularities in Es layers near 110-km altitude at 2324.5 LT. The brightness of the image pixels specifies the echo signal-to-noise ratio on a decibel scale. The hues reflect Doppler velocity, with red (blue) hues denoting drifts away from (toward) the radar located on St. Croix, USVI