The aurorae are the result of collisions with the atmosphere of energetic particles that have their origin in the solar wind, and reach the atmosphere after having undergone varying degrees of acceleration and redistribution within the Earth's magnetosphere. The global scale phenomenon represented by the aurorae therefore contains considerable information concerning the solar-terrestrial connection. For example, by correctly measuring specific auroral emissions, and with the aid of comprehensive models of the region, we can infer the total energy flux entering the atmosphere and the average energy of the particles causing these emissions. Furthermore, from these auroral emissions we can determine the ionospheric conductances that are part of the closing of the magnetospheric currents through the ionosphere, and from these we can in turn obtain the electric potentials and convective patterns that are an essential element to our understanding of the global magnetosphereionosphere-thermosphere-mesosphere. Simultaneously acquired images of the auroral oval and polar cap not only yield the temporal and spatial morphology from which we can infer activity indices, but in conjunction with simultaneous measurements made on spacecraft at other locations within the magnetosphere, allow us to map the various parts of the oval back to their source regions in the magnetosphere. This paper describes the Ultraviolet Imager for the Global Geospace Sciences portion of the International Solar-Terrestrial Physics program. The instrument operates in the far ultraviolet (FUV) and is capable of imaging the auroral oval regardless of whether it is sunlit or in darkness. The instrument has an 8 ~ circular field of view and is located on a despun platform which

Abstract. Optical measurements of mesospheric winds near South Pole, during August 1996, show the presence of large-scale standing waves with periods of 51.3-hr and 107-hr, respectively. In addition, a 11.6-hr period zonal wavenumber-one oscillation with a westward phase progression was also observed. The direction of the observed mean wind has changed nearly 60 ø westward from the typical wind direction observed during the same month in previous years. The direction of the presently observed mean wind is nearly parallel to wind direction of the 51.3-hr standing oscillation, suggesting an interaction between the mean wind field and the wave during this observation. Based on the simultaneous observation at Scott Base of an uncommon wave with 11.53-hr periodicity with short (-20 km) vertical wavelength of propagation, the 11.6-hr wave observed from South Pole can be identified as a zonal wavenumber one inertio-gravity mode of oscillation. Because of the transience of this wave and its closeness to the inertial period, we also discuss another approach to the interpretation of such waves as possible forced oscillations.In this paper we report uncommon observations of standing waves near South Pole during the period 13 August, 1996UT to 23 August, 1996UT, inclusive. Optical TechniqueThe optical technique and instrumentation used for the meas-

A self‐aligning Fabry‐Perot spectrometer has been installed at Amundsen‐Scott Station, Antarctica (Geographic South Pole) and has been used to determine neutral upper thermosphere winds and temperatures, obtained from the measurement of the Doppler shift and Doppler width of the line profiles of the [OI] 15,867 K (630 nm) line emission, during the austral winter of 1989 (April 1989 to September 1989). These first ground‐based measurements of F‐region neutral dynamics at the South Pole, show a rich variety of dynamic phenomena and strong couplings with the ionospheric plasma. Data for two contrasting days in April 1989 are presented here. The data of April 23 UT illustrate the diurnal variations of winds and temperatures during geomagnetic quiet‐to‐moderate conditions, while the data of April 27 UT illustrate diurnal variations during geomagnetically disturbed periods. These data are compared with the average pattern obtained at a similar geomagnetic latitude and conditions, but in the Northern Hemisphere (Longyearbyen, Spitsbergen) and with predictions of the average dynamics in the South Pole region made by the NCAR thermosphere‐ionosphere general circulation model (TIGCM). The measured winds at the South Pole have a stronger prevailing westward component in its diurnal cycle than is either observed at Longyearbyen (in the Northern Hemisphere) or predicted at South Pole by the TIGCM.

The radiative decay of metastable 1 s 22s '2p 4 ISO atomic oxygen atoms has been shown to proceed at a rate depending linearly on the concentration of argon or xenon present in the gas mixture. With increasing pressure, the IDrISo atomic line at 5577 A becomes accompanied by a broad emission region identified as a band system of a weakly bound rare-gas oxide molecule. Changes in the transition probability as a function of pressure were measured by using the spin-forbidden ) P I_I So transition at 2972 A as a pressure-independent monitor of the 0(' S) concentration. The observed pressure dependence of the emission probability may be described by rate constants for induced emission in argon and xenon atmospheres: (1) for emission in a bandwidth of + 1.6 A centered on the atomic line at 5577 A, k(Ar)=(7±3)XIO-20 em) seC I, k(Xe)=(3±2)XIO-I9 cm 3 sec-I ;and (2) for emission into the entire green band system, k(Ar)=(3.0+.2)XIO-I8 em) sec-I, k(Xe)=(1.7±.2)x 10-15 em) sec-I. Comparison is made with rate constants for deactivation of these metastable atoms by the same rare gases. It appears that substantially all of the collision-induced emission comes from bound rare-gas oxide molecules whose dissociation equilibria provide the observed pressure dependence.