Figure 2From: Lidar returns from the upper atmosphere of Kamchatka for 2008 to 2014 observationsCritical frequency of the ionospheric F2 layer and lidar signals. (a) Critical frequency of the ionospheric F2 layer (foF2) and (b) lidar signals summed for altitudes of 150 to 200 km and 200 to 300 km.Back to article page