The investigators will conduct comprehensive experimental studies aimed at quantifying gravity wave (GW) momentum transport and the GW instability dynamics that drive energy and momentum deposition and energy transfers in the mesosphere and lower thermosphere (MLT). GWs having small horizontal scales and large amplitudes and momentum fluxes provide the majority of the mean and variable forcing in the MLT, and these vary significantly in space and time. Understanding of this forcing and variability is highly uncertain, but it is extremely important for parameterization of such dynamics in large-scale modeling of the MLT, and throughout the atmosphere. The same parameterization needs are also critical for general circulation models (GCMs), climate models, and numerical weather prediction (NWP) models in related fields. To quantify these GW and instability dynamics and their mean and variable forcing as fully as possible, the investigators will employ instrument suites at the only two sites able to define these dynamics in the most complete and quantitative manner. Low-latitude measurements will use the comprehensive instrumentation of the new Cerro Pachon Observatory in Chile (30°S); high-latitude measurements will employ the even more extensive suite of instrumentation at the ALOMAR observatory in northern Norway (69°N).
These instrument suites permit the most complete, and redundant, specification of the GW, instability, and mean parameters needed to quantify GW amplitudes, momentum fluxes, and instability dynamics at any site. The recognized role of GWs in driving the mean and variable structure of the MLT makes an understanding of their various contributions, and an ability to model their effects, a high priority. These dynamics also influence a wide range of other processes ranging from tidal and planetary wave structures and dynamics to minor species transport. The need to describe such effects accurately also has broader implications for modeling climate change, responses to variable solar forcing, and Space Weather.
