2011 SuperDARN Workshop
Making sense of SuperDARN elevation: Phase offset and variance
P. Ponomarenko , J. Wiid, A. Koustov, and J.-P. St.-Maurice
University of Saskatchewan, Saskatoon, SK, Canada
abstract. The vertical angle of arrival of HF signals contains very important information about the propagation modes and ionospheric conditions. However, despite being routinely registered by SuperDARN radars, elevation angles are rarely utilised. The main reason for that is the apparent unreliability of these data, which frequently appear to be unrealistic. At SuperDARN?2010 we attributed the problem to an inadequate phase calibration that fails to account for certain phase shifts in the radar hardware. However, a following detailed analysis of the experimental data and statistical modelling revealed that the presence of ?strange? elevation components could be fully explained by accounting for the statistical distribution of phase fitting errors. In essence, a combination of this distribution with the very non-linear phase-elevation relationship leads to a two-pi wrap-around of the phase that results in an artificial population of echoes at very high elevation angles.