STARE velocities: 3. Double-pulse and multi-pulse measurements
Abstract
The STARE coherent radars are a powerfull instrument for studying the auroral zone electrodynamics, first of all with respect to plasma convection. For decades, the radars have been using the double-pulse (DP) technique to measure the velocity. Recently, the multi-pulse (MP) scheme has been implemented. The detailed comparisons (Uspensky et al., 2003, 2004) between EISCAT and STARE MP measurements showed a good performance of the MP scheme for convection estimates, contrary to the known difficulties of the DP method. In the present study we consider differences in the velocity estimates by the MP and DP schemes in order to evaluate the uncertainties of the convection predictions by the DP scheme. We confirm previous warnings by Schlegel et al. (1986) and Schlegel and Thomas (1988) that the STARE DP scheme with fixed pulse separation can give a systematic error in the velocity estimate. We show that the DP velocities are typically smaller than the MP velocities, especially for large flow angle observations in the afternoon/evening sector. We also report occasional cases of small DP velocity overestimations. It is argued that the observed differences between DP and MP velocities originate from a minor, but not negligible, correlation between the signals coming from the main and aliasing volumes of the DP scheme particularly under the condition of broad backscatter spectra.
- Publication:
-
35th COSPAR Scientific Assembly
- Pub Date:
- 2004
- Bibcode:
- 2004cosp...35.1410U