High-Altitude Temperature Sounding (HATS): A Passive Approach for 3D Observation of Upper Atmosphere Dynamics.

The dynamical coupling of lower to upper atmosphere is an active research topic. It is becoming clear that the state of the lower atmosphere is continuously imprinted on the upper atmosphere, mostly by gravity waves that transmit energy and momentum. To date, these waves are largely unobserved on a global scale. Satellite sensors, mostly limb viewers, can detect them, but observations with the few tens of kilometer horizontal resolution required for quantification are limited to mostly ground-based radars. Modern mid-IR FPAs and a spectral scanning technique that uses Doppler shifted gas filters can now fill that observational void. We present a feasibility study that shows how a group of simple nadir viewing gas filtered radiometers can be employed to achieve temperature sounding from cloud-top to nearly 100 km with vertical resolutions previously believed to be limited to tropospheric altitudes. The enabled, highly resolved, 3D images of upper atmosphere dynamics could produce the next major boost in weather forecast skill, both lower atmosphere and near space.