Spectral Characteristics of High Frequency (HF) Backscatter for High Latitude Ionospheric Irregularities: Preliminary Analysis of Statistical Properties

摘要

OTH-B radar signals backscattered from ionospheric irregularities can be very intense, and any effort to mitigate against their influence requires knowledge of at least the Doppler shift and spread that they introduce in the backscattered signals. This report presents the Doppler spectral characteristics of HF signals backscattered from F-region ionospheric irregularities at high latitudes. The report will show that the variability in spread of the Doppler returns make it difficult to discriminate against ionospheric clutter by Doppler techniques alone. The data presented have been obtained with the Johns Hopkins University/Applied Physics Laboratory (APL) HF radar located at Goose Bay, Labrador. This is an auroral site and signals from the radar are subjected to ionospheric clutter from magnetic-field-aligned irregularities at high latitudes. The report discusses the various procedures that may be used for spectral and/or autocorrelation analysis of backscattered radar signals, the method by which these autocorrelation functions are obtained to remove contributions from ground backscatter and unwanted signal sources. The autocorrelation functions are analyzed to determine their decorrelation time and finally, the parameters are converted to Doppler velocity width and shift. (rh)