Fig. 4From: Tristatic observation of polar mesosphere winter echoes with the EISCAT VHF radar on 8 January 2014: a case study(Right panel) Experimental and fitted spectra for Tromsø at different altitudes at 12:06 UT Spectrum at each altitude are normalised to its maximum. (Left panel) Vertical profile of the logarithm of variable PProxy, proportional to the backscattered power (see the text for more explanations)Back to article page