Research Objectives:1. Define the mean and variable structure of the MLT Our objective here was to define the seasonal, inter-annual, and shorter-term variability of the thermal and wind structures throughout the mesosphere and lower thermosphere (MLT). Some of the relevant questions motivating this study include 1) why is the fall transition (increasing mesopause temperature during August) faster than the spring transition, 2) what are the corresponding mean winds and gravity wave momentum fluxes that account for these differences, 3) why is the summer mesopause temperature so stable (or is it?), 4) what is the morphology of mesospheric inversion layers, are there diurnal variations, and how do they depend on gravity wave forcing, and 5) are the strong shears in the lower thermosphere the source of, or the response to, gravity wave instability and momentum transport? These topics were addressed with long-term measurements of the thermal and wind fields over as full a range of altitudes as the Weber lidar and other ALOMAR instrumentation permit (typically ~10 to 105 km for both winds and temperatures). Though full-column measurements were only possible during comprehensive measurement campaigns, Weber lidar measurements spanned a much greater range of times throughout the years of operation. Define the gravity wave coupling from lower altitudes REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS.

Public reporting burten lor this colteOion of information Is estimated to average 1 hour per response, including the time for reviewing in data needed and completing and reviewing this collection of infomoation. Send comments regarding this burden estimate or any other this burden to Department of Defense, Washington Headquarters Sen/lces, Directorate for Information Operations and Reports (0704-C 4302 Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any i^nalty tw tai-ii vafid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. . AFRL-SR-AR-TR-04- PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)Northwest Research Associates 14508 NE 20*" St. PO Box 3027Bellevue, WA 98009-3027 SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES)