oa Investigating The Dynamics Of The Earth’S Middle Atmosphere Using The Cedar Mesospheric Temperature Mapper

The CEDAR Mesospheric Temperature Mapper (MTM) is a versatile CCD imager that<br>was designed to investigate the properties of short period (<1hour) atmospheric gravity<br>waves as they propagate through the earth’s upper mesosphere. The imager samples two<br>selected emission lines in the hydroxyl OH M (6,2) band emission (peak altitude ~87 km)<br>to determine nocturnal temperature and wave-induced intensity and temperature<br>perturbations with high precision. In addition the MTM has also proven to be<br>exceptionally capable of studying much larger scale wave perturbations of tidal and<br>planetary wave origin. To date, observations have been made at mid-latitudes alongside<br>two powerful Na lidar systems: at Ft. Collins, CO (June 1997-May-1998) and at the<br>Starfire Optical Range, NM (November 1998 – January 2000). However, an enhanced<br>MTM system will shortly be deployed at Haleakala Crater, Maui, HI for low-latitude<br>studies as part of the MAUI-MALT program. The potential of this imaging system for<br>investigating short-term, wave-induced, and seasonal dynamics within the Mesosphere<br>and Lower Thermosphere (MLT) region (~80-100 km) will be discussed with reference<br>to recent measurements of terdiurnal (8-hr) tidal oscillations in OH intensity and<br>rotational temperature and the unexpected detection of a large-scale, recurrent<br>perturbation in mesospheric temperature around the autumnal equinox period associated<br>with the penetration of planetary wave energy from the troposphere into the mesosphere.<br>Plans for coordinated ground-based measurements using the MTM (and other<br>instrumentation) during the forthcoming NASA TIMED satellite mission will also be<br>discussed.