High altitude thermal sounding using doppler modulated gas correlation

A measurement technique is presented that demonstrates the ability to thermally sound the atmosphere from cloud-top in the troposphere to the upper mesosphere with nadir observations using a Doppler modulated gas correlation (DMGC) approach. It is shown that DMGC measurements of CO₂ emission at 15 μm can achieve an effective spectral resolution of <;0.002 cm^-1, which can be used to generate averaging kernels from nadir observations with 4-12 km vertical resolution to 95 km. The S/N required for such measurements is achievable with adequately cooled (≤ 50 K) HgCdTe (MCT) detector arrays. A High Altitude Thermal Sounder (HATS) using this approach could provide global temperature fields with the information content necessary to observe and quantify gravity waves throughout the stratosphere and mesosphere.