STARE velocities: 2. Evening westward electron flow
Abstract
Four evening events of joint EISCAT/STARE radar observations (~18 hours in total) are considered to study differences between the STARE line-of-sight velocities and the EISCAT electron drifts along the STARE beams. We show that Finland velocities were persistently smaller than the EISCAT drifts by a factor of 1.5-2 implying stronger differences than reported in the past. The Norway velocities were also smaller than the EISCAT drifts, but the effect was not as significant as for the Finland radar. We show that stronger STARE/EISCAT velocity differences lead to significant STARE total electron drift underestimation not only with the standard merging method but also with the ion-acoustic approach (IAA), especially for slow total electron flows of less than 800-1000 m/s. We test the performance of a new approach recently proposed by Uspensky et al., Ann. Geophys., 2003 (in press). It is based on the assumption that a coherent radar receives signals from all electrojet heights. For this approach, information on the electron density distribution in the E region is required. We demonstrate for one event (February 12, 1999) for which N(h) profiles were known from concurrent EISCAT measurements that STARE predicitons of the electron drift are consistent with the EISCAT drift measurements. This validates the approach for the analysis of evening westward electron flow observations (validation for the morning eastward flows was presented by Uspensky et al., 2003). We also show the "robustness" of the new approach by looking at other 3 evening events for which no information on the electron density was available.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA.....2170U