2011 SuperDARN Workshop       

SuperDARN and EISCAT observations of SPEAR (Space Plasma Exploration by Active Radar) induced sporadic E-region heating at 78°N

L.J. Baddeley (1) and I. Haggstrom (2)
(1) University Centre in Svalbard, Norway
(2) EISCAT Scientific Association, Kiruna, Sweden

abstract. We present the 1st high resolution observations of sporadic E-layer heating at high latitudes (78?N) using the SPEAR heating facility, the EISCAT Svalbard Radar (ESR) the SuperDARN HF radars. During the experiment the SPEAR heating facility was transmitting with O-mode polarization in a field aligned direction. Results from the co-located ESR show distinct heating enhancements in the plasma line spectra, corresponding to the SPEAR heater frequency of 4.45MHz. High spatial resolution (100m) plasma line data indicate simultaneous enhancements at both the top and bottom side of the layer respectively (located at ~107.5 and 109km altitude respectively). The observed enhancements disappear completely during a SPEAR on period, during which time the SuperDARN radars observe a patch of artificial field aligned irregularities (AFAIs) co-located with the SPEAR system. It is postulated that the results represent evidence of O to Z-mode conversion of the heater wave occurring at the bottom of the E-layer, allowing propagation through the layer resulting in simultaneous topside enhancements. When this layer disappeared completely it allowed the beam to propagate to a higher altitude, reaching the F-region, where conditions were suitable for the generation of AFAI?s.

Sakaguchi KaoriNICT Japan