AMISR as a tool for studying the generation and propagation of gravity waves at high latitudes

Nicolls, M.1, Heinselman, C.1, Vadas, S.2 and Kelly, J.1

1 SRI International, Menlo Park, CA, USA
2 NWRA/CoRA Divison, Boulder, CO, USA

The tracers of atmospheric gravity waves (AGWs) are observed frequently at high latitudes by examining fluctuations in ionospheric parameters measured by incoherent scatter radars, ionosondes, or HF radars (e.g., SuperDARN), and have been studied for decades. These waves are in general thought to be associated with auroral electrojet activity, which impart momentum and energy into the neutral gas through Lorentz forcing and/or Joule heating. Tropospheric sources may also be a major source of a certain subset of AGWs that reach ionospheric altitudes. The Advanced Modular Incoherent Scatter Radar (AMISR) is a unique tool allowing for the study of the propagation characteristics and source region identification of AGWs. Multi-position measurements with AMISR allow for the direct and nearly unambiguous extraction of AGW parameters, including period, horizontal and vertical wavelengths, and propagation direction and speed. This allows for the explicit evaluation of a recently derived AGW dispersion relation [Vadas and Fritts, 2005] that includes the role of kinematic viscosity and thermal diffusivity, important effects in the upper atmosphere, without assumption about horizontal wavelengths. In addition, AMISR studies will allow for source region identification using observed AGW amplitudes and wavelengths, which could shed light on the major sources of AGWs at high latitudes. We will show some case studies where AMISR data have been used to extract AGW properties and discuss how AMISR can be used, in combination with other instruments, to better understand AGW generation, propagation, and interaction with the ionosphere.