Ionospheric Convection Inferred From SuperDARN, LiMIE, and DMSP Observations

L. XU and A. V. KOUSTOV
V. O. PAPITASVILI
University of Michigan, USA.
F. J. RICH
Air Force Research Laboratory, U.S.A.

Recently several studies indicated possible deterioration of the accuracy in the SuperDARN convection measurements at large distances (~3000 km) when the signal is received via the "1 & 1/2 hop" radio wave propagation path. If these signals are echoes from the ionospheric E-region, deterioration should be significant for the strong convection velocities (> 1000 m/s) since, in this case, the phase velocity of irregularities is saturated at the ion-acoustic speed. In this study, the SuperDARN convection observations are compared with direct ion drift observations made by the DMSP satellites over high latitudes to investigate the above-mentioned problem, with the focus on strong convection. Both the "merge" and "fit" radar predictions were considered. A reasonable overall agreement between the DMSP observations and both radar techniques was found though the individual points in some passes show significant differences. The effect of the velocity saturation was not found, but the data show a tendency for the SuperDARN convection vectors to be a little smaller than the DMSP ion drift velocities. The periods of "poor agreement" are considered in terms of the general convection patterns as predicted by the LiMIE model to sort out possible errors in individual patterns.

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