Computer Science – Sound
Scientific paper
Dec 2010
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010agufmsa11a1573g&link_type=abstract
American Geophysical Union, Fall Meeting 2010, abstract #SA11A-1573
Computer Science
Sound
[0350] Atmospheric Composition And Structure / Pressure, Density, And Temperature, [3332] Atmospheric Processes / Mesospheric Dynamics, [3334] Atmospheric Processes / Middle Atmosphere Dynamics, [3360] Atmospheric Processes / Remote Sensing
Scientific paper
A new approach to nadir thermal sounding has the potential to resolve upper atmosphere (10 to 95 km) gravity waves, which are believed to play a major role in high altitude dynamics. It is now possible, using a Doppler modulated gas correlation (DMGC) measurement technique, to overcome three fundamental limitations to such measurements: spectral resolution, signal-to-noise and large emission background. Gas Filter Correlation Radiometry (GFCR) operating near 15 microns can achieve an effective spectral resolution better than 0.002 cm-1. HgCdTe detectors cooled below 50 Kelvin can provide a photon noise limited measurement. Combining those two factors with a 7° modulation of low-earth-orbit (LEO) near-nadir observations produces modulation signals (DMGC signals) strongly dependent on high altitude emission. We present a feasibility study that rigorously quantifies the performance of a hypothetical sensor employing the DMGC approach. Results indicate that the atmospheric temperature structure can be sufficiently resolved and retrieved to detect and quantify dynamically significant gravity wave fields. Derived averaging Kernels show a horizontal resolution of 10 km, combined with vertical resolutions of 4-5 km at the tropopause, expanding to 6-7 km at 65 km and degrading to 12 km at 95 km. Implementation strategies are discussed, such as radiance calibration without an on-board transfer standard, limb observations used to retrieve a priori temperature fields, statistical inter-calibration of limb and nadir measurements, statistical flat-fielding of detector pixels and limb DMGC measurements used for in-orbit calibration of the GFCR CO2 gas cells. Other potential applications of DMGC are mentioned, including possible operation at 4.3 microns. Keywords: Temperature, Gravity Waves, Remote Sensing, Mesosphere Mr. Larry L. Gordley has 35 years of experience in remote sensing measurement design, signal processing and simulations. He wrote the level 1 and 2 processing systems for the Nimbus 7 LIMS instrument. His company, GATS, inc., developed the same for the HALOE instrument on UARS and the SABER instrument now in orbit on the TIMED spacecraft. He was the Principal Investigator for the SOFIE (Solar Occultation For Ice Experiment), developed at the Utah State University Space Dynamics Laboratory for the AIM (Aeronomy of Ice in the Mesosphere) project under the NASA Small Explorer Program.
Fish C. S.
Fritts David C.
Gordley Larry L.,
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