Longitudinal and latitudinal variations in dynamic characteristics of the MLT (70−95km): a study involving the CUJO network

Abstract. The newly-installed MFR (medium frequency radar) at Platteville (40°N, 105°W) has provided the opportunity and impetus to create an operational network of middle- latitude MFRs stretching from 81°W–142°E. CUJO (Canada U.S. Japan Opportunity) comprises systems at London (43°N, 81°W), Platteville (40°N, 105°W), Saskatoon (52°N, 107°W), Wakkanai (45°N, 142°E) and Yamagawa (31°N, 131°E). It offers a significant 7000km longitudinal sector in the North American-Pacific region, and a useful range of latitudes (12–14°) at two longitudes.

Annual climatologies involving both height and frequency versus time contour plots for periods from 8h to 30 days, show that the changes with longitude are very significant and distinctive, often exceeding the local latitudinal variations. Comparisons with models and the recent UARS-HRDI global analysis of tides are discussed. The fits of the horizontal wave numbers of the longer period oscillations are provided in unique frequency versus time contour plots and shown to be consistent with the expected dominant modes. Annual climatologies of planetary waves (16 day, 2 day) and gravity waves reveal strong seasonal and longitudinal variations.

Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides; climatology)