Windii redline observations of conjugate low-latitude red aurora during the February 26, 1992 geomagnetic storm

The WIND Imaging Interferometer (WINDII) was launched on-board the Upper Atmosphere Research Satellite (UARS) in September 1991. The global coverage of the WINDII nighttime redline (OI 630nm) emission rate, winds and temperature profiles are analyzed to investigate the spatial and temporal response of thermosphere/ionosphere during the February 26, 1992 (WINDII day 0168) geomagnetic storm (SSC at 1657 UT, Σ Kp=39, Ap=65, with | Dst|_max=174 nT between 2200--2300 UT). Near-simultaneous measurements (electron temperature, ion density, particle flux and horizontal drift) by the Defense Meteorological Satellite Program (DMSP) F10 (∼ 800 km altitude) are also presented. The WINDII redline observations on the geomagnetically disturbed day are compared with those obtained on February 16, 1992 (WINDII day 0158), a quiet day (Σ Kp = 9-, Ap = 4). During the main phase of the geomagnetic storm, the OI 630nm nighttime observations detected low-latitude red aurora, intruding to about +/-25° latitude regions in the conjugate hemispheres. The low-latitude aurora was possibly excited by heavy ions or energetic neutral precipitation from the ring current. In addition to high levels of emission intensities in the low-latitude red aurora regions (up to about 1-2 kR), the observations showed high thermospheric temperature ( up to about 3000 K) and strong equatorward meridional (up to about 500 m/s) wind in both the hemispheres. The strong zonal (up to about 500 m/s) wind was eastward in the northern hemisphere whereas westward in the southern hemisphere. The difference in the storm-time zonal wind flow direction between the hemispheres may be due to different longitude of energy input. The DMSP observations of the westward component of plasma velocity by ion drift meter indicate evidence of subauroral polarization streams (SAPS) close to the low-latitude aurora regions in both the hemispheres.