Comparison of Large- and Small-Scale Gravity Waves Over Halley, Antarctica and Petrolina, Brazil

Investigations of small-scale mesospheric gravity waves have been made from a number of sites around the globe. The Center for Atmospheric Space Sciences at Utah State University has operated all-sky CCD imagers at Petrolina (9°S), Brazil and Halley (76°S), Antarctica, to capture images of gravity waves in the OH airglow emission (altitude `87km). A recently proven method utilizing "Keograms" has been used to analyze larger-scale gravity waves (e.g. Taylor et. al, 2009). Keograms were initially developed to study auroral motions at high-latitudes. Using the same technique we have investigated the characteristics, such as horizontal wavelength, phase speed, and the observed period, at high-latitude and the equatorial region of both the larger- and small-scale gravity waves. Further analysis using this method will be applied to other available data sets to develop a better understanding of the characteristics and variability of larger-scale mesospheric gravity waves.