Statistical analysis of echo power, Doppler velocity and spectral width obtained with the Syowa South HF radar

摘要

Statistical analyses are made of the physical parameters (echo power, Doppler velocity and spectral width) of Doppler spectra obtained in September 1995 with the Syowa South HF radar. We present time and range distributions and histograms of the parameters and cross-correlations among them. With K index at Syowa Station the distributions and histograms vary slightly but the correlations do not change so much. The most noticeable feature is that there is a positive correlation between the absolute values of Doppler velocity and echo power. This relationship can be interpreted in terms of the gradient-drift instability which is the most probable cause to generate decameter-scale irregularities in the F-region ionosphere.