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Titre du document / Document title

Outgoing Longwave Radiation due to Directly Transmitted Surface Emission

Auteur(s) / Author(s)

COSTA S. M. S. (1) ; SHINE K. P. (2) ;

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

(1) Center for Weather Forecasts and Climate Studies, National Institute for Space Research, Cachoeira Paulista, BRESIL
(2) Department of Meteorology, University of Reading, Reading, ROYAUME-UNI

Résumé / Abstract

A frequently used diagram summarizing the annual- and global-mean energy budget of the earth and atmosphere indicates that the irradiance reaching the top of the atmosphere from the surface, through the midinfrared atmospheric window, is 40 W m-2; this can be compared to the total outgoing longwave radiation (OLR) of about 235 W m-2. The value of 40 W m-2 was estimated in an ad hoc manner. A more detailed calculation of this component, termed here the surface transmitted irradiance (STI), is presented, using a line-by-line radiation code and 3D climatologies of temperature, humidity, cloudiness, etc. No assumption is made as to the wavelengths at which radiation from the surface can reach the top of the atmosphere. The role of the water vapor continuum is highlighted. In clear skies, if the continuum is excluded, the global- and annual-mean STI is calculated to be about 100 W m-2 with a broad maximum throughout the tropics and subtropics. When the continuum is included, the clear-sky STI is reduced to 66 W m-2, with a distinctly different geographic distribution, with a minimum in the tropics and local peaks over subtropical deserts. The inclusion of clouds reduces the STI to about 22 W m-2. The actual value is likely somewhat smaller due to processes neglected here, and an STI value of 20 W m-2 (with an estimated uncertainty of about ±20%) is suggested to be much more realistic than the previous estimate of 40 W m-2. This indicates that less than one-tenth of the OLR originates directly from the surface.

Revue / Journal Title

Journal of the atmospheric sciences    ISSN  0022-4928   CODEN JAHSAK 

Source / Source

2012, vol. 69, no6, pp. 1865-1870 [6 page(s) (article)] (3/4 p.)

Langue / Language

Anglais

Editeur / Publisher

American Meteorological Society, Boston, MA, ETATS-UNIS  (1962) (Revue)

Mots-clés anglais / English Keywords

uncertainties

;

clouds

;

deserts

;

Geographic distribution

;

Clear sky

;

subtropical zone

;

tropical zone

;

water vapor

;

Cloudiness

;

Climatology

;

three-dimensional models

;

Total radiation

;

Atmospheric window

;

irradiance

;

energy balance

;

Outgoing longwave radiation

;

Mots-clés français / French Keywords

Incertitude

;

Nuage

;

Désert

;

Répartition géographique

;

Ciel serein

;

Zone subtropicale

;

Zone tropicale

;

Vapeur eau

;

Nébulosité

;

Climatologie

;

Modèle 3 dimensions

;

Rayonnement total

;

Fenêtre atmosphérique

;

Eclairement énergétique

;

Bilan énergie

;

Rayonnement sortant grande longueur onde

;

Mots-clés espagnols / Spanish Keywords

Nube

;

Desierto

;

Distribución geográfica

;

Cielo sereno

;

Zona subtropical

;

Zona tropical

;

Vapor agua

;

Nebulosidad

;

Climatología

;

Modelo 3 dimensiones

;

Radiación total

;

Ventana atmosférica

;

Radiación saliente onda larga

;

Localisation / Location

INIST-CNRS, Cote INIST : 6498, 35400050777334.0070

Nº notice refdoc (ud4) : 25968751



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