Large- and Small-Scale Dynamics and Comprehensive Meteor Studies with the Southern Argentina Agile MEteor Radar (SAAMER)

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This study is based on observations made by the Southern Argentina Agile MEteor Radar (SAAMER), which was installed at Rio Grande on Tierra del Fuego (53.8oS) in May 2008. Since its installation, SAAMER has performed routine measurements of large-scale dynamics of the middle atmosphere, determined the monthly-mean momentum fluxes due to smaller-scale gravity waves (GWs), and characterized meteor head echoes and non-specular meteor trails in a routine measurement mode. Previously, routine GW momentum flux measurements were only possible with large (and expensive) radars, while meteor head echo and non-specular trail studies were only possible with "high-power, large-aperture" (HPLA) radars that are likewise large, very expensive, and used only intermittently for such studies. When employed for experimental studies viewing vertically with different transmitter phasing, SAAMER promises to contribute significantly to meteoroid head echo, non-specular trail, and trajectory studies, as well as to Polar Mesospheric Summer Echoes (PMSE) and related microphysics studies. SAAMER was installed on Tierra del Fuego (TdF) to provide sensitivity to the large-scale dynamics, especially the semidiurnal tide, in a latitude band expected to exhibit large semidiurnal tide amplitudes, but devoid of other instrumentation. Its location on TdF was also motivated by the occurrence of the major "hotspot" of GW activity on Earth centered over the Southern Andes, Drake Passage, and Antarctic Peninsula. This hotspot is due, apparently, to the major GW sources in this region, believed to include high mountains, strong jet streams, and vigorous frontal systems. These sources are expected to yield large GWs and momentum fluxes and strong interactions with the large-scale motion field in the mesosphere and lower thermosphere (MLT), and SAAMER analyses to date confirm expectations that the fluxes in this region can be very large. This research addresses topics that are of high current interest and relevant to diverse communities. MLT dynamics studies, especially quantification of GW dynamics, momentum transport, and its deposition, are central needs in defining more accurate parameterizations of these small-scale dynamics in general circulation, numerical weather prediction, climate, and space weather modeling. Measurements of large-scale dynamics likewise serve to constrain models of these dynamics that are missing key inputs, especially at high southern latitudes. Meteoroid trajectory studies may provide clues to potential meteor impact risks. SAAMER is also utilized as an educational and training tool through various NSF programs devoted to promoting international collaborative activities between U.S. and S. American researchers and students, including extensive exchanges between the U.S., Argentina, and Brazil to date, with active collaborations arising from these.