The centerpiece of this project is the continuation of year-round operations and calibration of a high resolution Fabry-Perot spectrometer at the University of Canterbury's Mount John Astronomical Observatory, NZ (44 deg S) that the PI has been conducting for the last 14 years. These observations will lay the foundation for the derivation of a statistically meaningful long-term mesospheric and lower thermospheric climatology including both winds and temperatures for the Mid-latitude Southern hemisphere atmosphere. Comparison between Mount John (southern hemisphere) and Fritz Peak (northern hemisphere) wind and temperature climatologies will be used to investigate inter-hemispherical differences in atmospheric dynamical behavior. Additional objectives that will be explored as part of this project include: comparison between simultaneous common volume observations of winds with the optical technique and both meteor and MF radar techniques at and near Mount John; combining radar and optical techniques to determine and characterize airglow altitude dependencies; and comparison with planned optical imager investigations at Mount John to investigate short-periodicity wind and temperature oscillations that have recently been discovered in the observations.
The planned activities will be conducted as part of an established U.S.-New Zealand international cooperative project. In addition, through international cooperation and collaboration under the aegis of the Antarctic Aeronomy Consortium the observations in New Zealand (Mount John, Birdlings Flat) will be combined with observations in Australia (Adelaide, Beveridge), Argentina (El Leoncito, Buenos Aires) and Antarctica (Scott Base, Arrival Heights, Mawson, Davis, South Pole) to extend the climatological studies of planetary-scale and tidal wave activity to cover large fractions of both the midlatitude and high-latitude Southern Hemisphere. Collaboration with a theoretical modeling scientist to further interpret and investigate the implications of the observational findings has also been established. Graduate and undergraduate students will participate both in the observational and data analysis parts of the planned research program. Knowledge of atmospheric behavior at Southern Hemisphere latitudes is an important ingredient in fully understanding Global Climate Change and its human implications.
Investigation of the Southern Hemisphere's mid-latitude upper atmosphere is part and parcel for our understanding the Earth's atmosphere. Although it has been tempting to perceive the Southern Hemisphere as a mirror image of the Northern Hemisphere, it is becoming clear this is not the case. The existence of the Southern polar vortex has been shown to affect the behavior of this hemisphere's atmospheric region. The sparseness of land at the Southern Hemisphere midlatitude has limited long-term investigations there; New Zealand's strategic location provides a unique opportunity such long-term midlatitude atmospheric investigations and, with the collaboration of our New Zealand colleagues, we have been carrying an in-depth long-term study of upper atmosphere. Our specific studies in New Zealand have consisted of the determination of the optical Doppler shifts (winds) and Doppler widths (kinetic temperature) of the naturally occurring neutral particle emissions of the night sky, from which we can study the dynamical and thermodynamical behavior of the atmosphere. Our rugged and nearly-autonomous instrumentation (located at the University of Canterbury's Mount John Observatory) has been shown to be stable to better than one part per billion per year (ppb/yr) for decades, thus providing known quality measurements over the long term. Our investigations over the years have attracted (graduate) students interested in hands-on unique experimental work, with results whose interpretation have advanced knowledge in the field. These 11 students have received Ph.D and MS degrees. The already existing complementary, University of Canterbury operated, medium-frequency (MF) and astronomical meteor radars (the latter being adaptable to atmospheric motion studies) have provided a unique opportunity for an international collaboration, now extending for over two decades, to study both the motions and thermal behavior of the Southern midlatitude atmosphere at 44$degree$S. Among our earlier combined studies, the three ground-based instruments showed the motions measured by them to be the same (within the uncertainties of measurement) as well as to provide a determination of the height of emission for the optically derived motion measurements. The optical height of emission was also determined independently by comparison with the WINDII instrument on the UARS satellite. One of the notable findings of our NZ studies has been the observed cooling of the mesosphere and lower-thermosphere (MALT) both earlier than and during solar activity maximum. This result applies regardless whether sunspot number or the F10.7 index is used to denote solar activity. This effect is shown in Figure 1 for the yearly averages at Mount John for both the lower thermosphere (nominally at 95 km altitude and denoted by the measured emission of atomic oxygen OI) and the mesosphere (nominally at 87 km altitude and denoted by the measured emission of molecular hydroxil OH). Figure 2 illustrates the Mount John mesospheric OH daily temperature (935 points) data for the same period as Figure 1 and solar activity as a scatter plot showing a (statistically) significant negative dependence of the mesospheric temperature with solar activity. This negative dependence was reported earlier in the 1970s by us and by a Sodium lidar study at the Northern Hemisphere. Other studies, albeit not as long as the ones mentioned here, have reported a positive temperature dependence with solar activity. A detailed report on our findings including the data shown here) and their interpretation is in preparation. The recent installation of a Boston University all-sky imager, at the same location as our instrumentation, has enlarged the scope of our studies to include the investigation of the relation between the apparent motion of brightness features observed by the imager and the mass motions (wind) determined from Doppler shifts by our equipment. This new direction has been the driving force for the recent installation (March 2013) of another of our instruments at Mount John in order to determine the wind and kinetic temperature of the upper thermosphere (nominally 250 km altitude).
