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Abstract
To assess and improve climate models, precise measurements of the climate state are needed that must be as independent from the models as possible. We are addressing these fundamental observational needs as they relate to water vapor, ozone and temperature with a new remote sensing technique called ATOMMS that combines features of GPS Radio Occultations (RO) and NASA’s Microwave Limb Sounder (MLS) by actively probing via satellite-to-satellite occultations the absorption lines that MLS probes passively.
ATOMMS overcomes several limitations of GPSRO by profiling bending angle and absorption to profile water and temperature independent of other observations and climatologies. Probing via occultation offers several advantages over passive emission including an order of magnitude better vertical resolution, simple and unique retrievals, very high SNR and precision to capture variability and signatures of processes, all-weather sampling eliminating clear sky-only biases and self-calibration eliminating long term drift.
ATOMMS profiles of temperature, geopotential height and moisture will extend from the lower troposphere to the mesopause with typical precisions over much of this altitude range of ~0.4 K, 10 m and 1-3%. With additional signal frequencies, other trace constituents can be measured in the upper troposphere and above with similar performance. ATOMMS will also provide profile turbulence.
With NSF funding we are building a prototype instrument to demonstrate the ATOMMS concept and performance using two NASA WB-57F aircraft in late 2009. The long term goal is a microsatellite constellation that will provide full global and diurnal cycle coverage.