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Titre du document / Document title

Initial data from the Mars Global Surveyor thermal emission spectrometer experiment : Observations of the Earth

Auteur(s) / Author(s)

CHRISTENSEN P. R. (1) ; PEARL J. C. (2) ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

(1) Department of Goelogy, Arizona State University, Tempe, ETATS-UNIS
(2) Goddard Space Flight Center, Greenbelt, Maryland, ETATS-UNIS

Résumé / Abstract

The thermal emission spectrometer (TES) on the Mars Global Surveyor spacecraft acquired observations of the Earth from a distance of 4.7 million km for instrument performance characterization on November 24, 1996. The data were calibrated using an internal reference surface and deep space in a manner identical to that which will be used in Mars orbit, and scaled to account for the fact the Earth filled only 9.3% of the field of view. These first, calibrated, in-flight spectra from the TES confirm the expected instrument performance and radiometric accuracy and precision. The data provide the first known whole-disk thermal infrared spectral observations of the Earth. These spectra represent how an Earth-like planet would appear during a search for extrasolar planets. Spectral features in the Earth's atmosphere are readily apparent; CO2 (centered at 668 cm-1), ozone (1000-1075 cm-1), and water vapor (200-550 and 1260-1650 cm-1) absorptions are evident. Radiation at the center of the CO2 hand arises mainly from the lower stratosphere; near 650 and 700 cm-1 from near the tropopause; and further into the band wings from the troposphere and surface. Thus, in the disk-averaged sense, the spectrum indicates a warm stratosphere above a tropopause somewhat colder than 215 K, in good agreement with results from similar instruments previously flown in low Earth orbit. The atmospheric window between approximately 800 and 1200 cm-1 is relatively featureless, as expected, given the observing geometry centered over the Pacific Ocean and the partial obscuration by clouds. The derived window brightness temperature, assuming an emissivity of unity, is 270 K, a reasonable average temperature of the ocean surface, the polar regions, and the cloud tops, especially given the uncertainties in the exact scaling to account for the fact that the Earth did not fill the field of view.

Revue / Journal Title

Journal of geophysical research    ISSN  0148-0227 

Source / Source

1997, vol. 102, noE5, pp. 10875-10880 (9 ref.)

Langue / Language

Anglais

Editeur / Publisher

American Geophysical Union, Washington, DC, ETATS-UNIS  (1949) (Revue)

Mots-clés anglais / English Keywords

Earth planet

;

Planetary atmosphere

;

Space probe observation

;

Calibration

;

Performance

;

Emission spectrometry

;

Infrared spectrum

;

Spaceborne instruments

;

Mots-clés français / French Keywords

Planète Terre

;

Atmosphère planétaire

;

Observation par sonde spatiale

;

Etalonnage

;

Performance

;

Spectrométrie émission

;

Spectre IR

;

Instrument spatial

;

Mots-clés espagnols / Spanish Keywords

Planeta tierra

;

Atmósfera planetaria

;

Observación por sonda espacial

;

Contraste

;

Rendimiento

;

Espectrometría emisión

;

Espectro IR

;

Localisation / Location

INIST-CNRS, Cote INIST : 3144, 35400006160916.0010

Nº notice refdoc (ud4) : 2675257



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