Rapid computation of spectrally integrated non-LTE limb emission

Conference · Sat Dec 31 04:00:00 EST 1994

OSTI ID:227971

Mlynczak, M G; Russell, III, J M ^[1]; Olander, D S ^[2]; Lopez-Puertas, M ^[3]; Gordley, L L ^[4]

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1. NASA Langley Research Center, Hampton, VA (United States)
2. Univ. of Wisconsin, Madison, WI (United States)
3. CSIC, Granada (Spain). Inst. de Astrofisica de Andalucia
4. GATS Technical Software, Hampton, VA (United States)

The interpretation of infrared radiance measurements made by satellite-borne limb scanning broadband radiometers requires accurate and computationally fast techniques with which to evaluate the equation of radiative transfer. This requirement is made even more stringent when analyzing measurements of non-LTE emission from the terrestrial mesosphere and lower thermosphere. In principle, line-by-line calculations which explicitly account for the departure from thermodynamic equilibrium in both the source functions and the transmittances are necessary. In this paper the authors extend the emissivity growth approximation (EGA) techniques developed for LTE conditions to the non-LTE environment. Computations of the non-LTE spectrally integrated limb radiance for the molecular oxygen airglow (1.27 {micro}m and 762 nm), ozone and carbon dioxide in the 9--11 {micro}m spectral interval, carbon monoxide (4.6 {micro}m), nitric oxide (5.3 {micro}m), and carbon dioxide (15 {micro}m) are presented. Using the non-LTE form of the EGA, the spectrally integrated limb emission is calculated for 35 tangent heights in the mesosphere and lower thermosphere (requiring a total of 1,200 atmospheric layers) with line-by-line accuracy in only {approximately}0.25 sec of CPU time on readily available desktop computer hardware, while the corresponding line-by-line calculations may require tens of minutes. The non-LTE EGA technique will allow minor constituent retrieval algorithms to readily include non-LTE effects limited only by the a priori knowledge of the departure from LTE in the observed bands.

• OSTI ID: 227971
• Report Number(s): CONF-940723--; ISBN 0-8194-1590-1
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
AIRGLOW
CARBON DIOXIDE
CARBON MONOXIDE
DATA
DATA ANALYSIS
DATA PROCESSING
INFRARED RADIATION
MESOSPHERE
NITRIC OXIDE
OZONE
RADIATION TRANSPORT
RADIOMETERS
REMOTE SENSING