Thermospheric wind field over Mawson and Davis, Antarctica;: simultaneous observations by two Fabry-Perot spectrometers of λ630 nm emission

The thermopheric oxygen lambda 630 nm emission has been observed using high-resolution Fabry-Perot spectrometers at Mawson (67.6 degrees S, 62.9 degrees E) and Davis (68.6 degrees S, 78.0 degrees E), Antarctica. A new technique, combining the results from the two instruments, is used to derive vector wind fields. The technique is described and applied to five nights of simultaneous cardinal point data obtained in 1997. Solar flux was low during this interval, typically F-10.7 = 75. Of the five nights two were magnetically disturbed and three were quiet. The observations for the disturbed nights were compared to a TIEGCM model run and reasonable agreement was found in the first half of the night. On one of the disturbed nights a closed evening circulation cell and cross-polar jet could be identified in our data. On none of the nights was a morning circulation cell evident. Auroral imager data were used to locate the auroral oval. For several hours around magnetic midnight the auroral oval produces doldrums in the thermospheric winds that are not described by the model. Auroral doldrums are also seen on the quiet nights which otherwise maintain a flow approximately consistent with a pressure-gradient driver. (C) 1999 Elsevier Science Ltd. All rights reserved.