Initial Millstone Hill, Sondrestrom, and Hilat Observations of Thermospheric Temperatures and Frictional Heating

Elevation scan observations made by the millstone Hill and Sondrestrom incoherent scatter radars are combined to provide extended latitudinal coverage of thermospheric measurements. Maps of the latitudinal and temporal structure of the exospheric temperature are presented for two 24-hour periods over the latitude range 45 to 72 degrees north. On the magnetically quiet June day the millstone and Sondrestrom data formed a consistent picture of thermospheric structure. On the disturbed July day the two radars observed very different behavior, with Millstone Hill observing strong, long-lived ion frictional heating events but Sondrestrom observing more quiescent behavior. Comparison with HILAT satellite data recorded on the July day suggest that the two radars were observing different ionospheric regions separated by a bright auroral arc with a very turbulent ionosphere to the south of the arc but smooth flow to the north. (reprint)