Fig. 1From: Geomagnetic activity dependence and dawn-dusk asymmetry of thermospheric winds from 9-year measurements with a Fabry–Perot interferometer in Tromsø, NorwayPower density function (PDF) of SME from January 23, 2009 to September 22, 2017 under the Kp selection from Kp = 0 to Kp < 4. The Kp level is depicted by color as illustrated in the boxBack to article page