Fig. 37
From: Review of the accomplishments of mid-latitude Super Dual Auroral Radar Network (SuperDARN) HF radars
A histogram of significant frequencies in the TIG data set. A three-point smoothing is applied to the data and is shown by the curve with the slightly darker black line superimposed on the histogram. The vertical lines identify peaks of the smoothed curve showing certain frequencies at 1.3, 1.6, 2.1, 2.9, and 3.3 mHz which appear to have higher spectral power than the neighboring frequencies. The frequency resolution is 0.1 mHz. Reproduced from Fig. 7 of Norouzi-Sedeh et al. (2015)