Longitudinal Variations in Airglow Emission Rate
Beginning with Lord Rayleigh's pioneering airglow observations in the 1920s, large variations in airglow emission rate at a given site, or between observations made at different locations were evident. For centuries before that, many individuals had experienced naked-eye observations of "bright nights", lasting one or several nights in succession. Early satellite observations showed that the airglow exhibited strong longitudinal variations, of wave 1 or wave 2, persisting for a few days at a time. Longitudinally varying observations from space on the same day are characterized by being taken at the same local time. Most of these observations were made for the O(1S), O2 Atm and OH emissions in the upper mesosphere and lower thermosphere, although variations of the O(1D) emission in the thermosphere have also been observed. The WINDII instrument on the UARS also observed longitudinal variations of the wind but the relationship to the airglow emissions varies from event to event. Comparison with TIME-GCM predictions show considerable similarity in the overall patterns of variation. For both the observational and model results the variations are smoothly varying, as for a wave 1, but at times display localized intense regions at specific longitudes. These results are described and discussed.
Temperature Variability in the Stratosphere Obtained from 7 years of Vibrational-Raman- lidar Measurements
The Purple Crow Lidar (PCL) is a large power-aperture product monostatic laser radar located at the Delaware Observatory (42° 52' N, 81° 23' W, 225 m elevation above sea level) near the campus of The University of Western Ontario. It is capable of measuring temperature and wave parameters from 10 to 110 km altitude, as well as water vapor in the troposphere and stratosphere. We use upper tropospheric and stratospheric vibrational Raman N2 backscatter-derived temperatures to form a climatology for the years 1999 to 2007 from 10 to 30 km altitude. The lidar temperatures are validated using coincident radiosondes measurements from Detroit and Buffalo. The measured temperatures show good agreement with the radiosonde soundings. An agreement of ±1 K is found during summer months and ±2.5 K during the winter months, validating the calibration of the lidar to within the geophysical variability of the measurements. Comparison between the PCL measurements and atmospheric models shows the PCL measurements are 5 K or less colder than CIRA-86 below 25 km and 2.5 K warmer above during the summer months. Below 16 km the PCL measurements are 5 K or less colder than the MSIS-90 model, while above this region, the PCL agrees to about ±3.5 K or less. The temperature differences between the PCL measurements and the models are consistent with the differences between the atmospheric models and the Detroit and Buffalo radiosonde measurements. The temperature differences compared to the models are consistent with previous comparisons between other radiosondes and satellite data sets, confirming that these differences with the models are real. We will highlight nights which show significant variations from the long-term averages, and when possible, the evolution of the variations.
Comparisons of neutral thermospheric winds as measured by SOFDI and the Millstone Hill Incoherent Scatter Radar
The Second generation Optimized Fabry-Perot Doppler Imager (SOFDI) has been making continual 24-hour thermospheric horizontal wind observations in upstate New York by measuring the OI 630-nm dayglow emission. In this paper we compare daytime measurements of thermospheric winds with derived neutral winds from the Millstone Hill Incoherent Scatter Radar system located in Westford, MA. We also compare vertical plasma drift measurements to SOFDI neutral winds.
Upper Mesospheric Ozone Density Profile Retrievals from the OSIRIS Instrument
Since 2001 the Canadian built instrument OSIRIS aboard the Odin satellite has been observing the middle atmosphere at wavelengths spanning from near UV to IR. In the upper mesosphere oxygen A-band dayglow observations, at 762 nm, are used to retrieve global ozone density profiles. The retrieval method, results, seasonal variations, and errors are discussed along with cross-validation of OSIRIS ozone profiles with those of the SABER instrument aboard TIMED.