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William R. Yueh and William L. Chameides

-, indicating the rapidconvergence of our perturbation scheme for typicalatmospheric conditions. Our calculations indicatethat aerosols contribute a net heating to the atmosphere in the infrared region. The effects of aerosolattenuation of radiation can be seen by comparingthe H- terms, which do not include the scatteringeffects, for the three calculations. Table 1 indicatesthat for the HHM, as compared to CM, aerosolattenuation leads to about 15% and 5% more heating at 0 and 1 km, respectively. Similarly

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Irving F. Hand

SUMMARY

Immediately before and during the passage of a smoke cloud from forest fires, simultaneous measurements were made of total normal incidence solar radiation and that portion of the solar spectrum longer than 0.7μ. Calculations made of the relative amount of radiation that should be received for both the total and limited components checked closely with the ratios between measurements with a smoke-free atmosphere but showed variance with ratios obtained in the presence of smoke. The range between the maximum and minimum values of total radiation during a ten-minute period in the presence of smoke was 2.3 times as great as the range between the maximum and minimum values of infrared radiation; from which we conclude, as theory implies, that long-wave radiation passes much more freely through an atmosphere containing particles slightly less than one micron in diameter than does the shorter, or visible and ultraviolet radiation.

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Starley L. Thompson and Stephen G. Warren

DECEMBER 1982 STARLEY L. THOMPSON AND STEPHEN G. WARREN 2667Parameterization of Outgoing Infrared Radiation Derived from Detailed Radiative Calculations STARLEY L. THOMPSONNational Center for Atmospheric Research~, Boulder, CO 80307 STEPHEN G. WARREN2Cooperative Institute for Research in Environmental Sciences, University of Colorado, Bo~lder 80309(Manuscript received 8 January

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J. J. Stephens and J. R. Gerhardt

] to drawlimited conclusions about drop absorption in the infrared. Havard [4] has shown absorption cross-sectionsfor nine wavelengths in the region of maximum emission of the terrestrial spectrum. Absorption crosssections for various wavelengths of the terrestrialspectrum are presented here along with a comparisonof I-larvard's data for corresponding wavelengths.2, Absorption cross-sectionelectromagnetic radiation may be defined as [SIThe absorption cross-section that a drop presents towhere Pabs

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Jean-Louis Dufresne, Vincent Eymet, Cyril Crevoisier, and Jean-Yves Grandpeix

temperature T a of the atmosphere is also fundamental. If the increase of CO 2 concentration has little impact on absorptivity, it has a significant impact on T a . When the CO 2 increases, the infrared radiation that escapes toward space is emitted by the atmosphere at a higher altitude. As most of the radiation is emitted by the troposphere, higher altitude means lower emission temperature, a lower value of the Planck function, a lower value of the radiation emitted toward space, and therefore a

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R. S. Quiroz

Abstract

Radiance measurements made by the Satellite Infrared Spectrometers (SIRS A and B) and Vertical Temperature Profile Radiometers (VTPR) in 1969–74 comprise a basically uniform observational data source, in view of the similarity of the transmittance weighting functions for the stratospheric channels of these instruments. Hemispheric radiance maps of measurements in the 669 and 678 cm−1 channels are used to depict the evolution of major stratospheric warmings in the 1969–70, 1970–71 and 1972–73 winters. These warnings are indicated to have arisen from the interaction of eastward-travelling thermal waves with a standing wave in eastern Siberia. Sudden warming in the Arctic was related to the poleward migration of the resultant thermal systems. In these events the arctic mean stratospheric temperature increased by about 30°C in 8 days, but local increases were at least twice as great in the upper (196–70 and 1970–71) or middle (1972–73) stratosphere. The polar vortex breakdown is illustrated with the aid of conventional 10-mb map analyses and 2-mb data based on isobaric layer thicknesses derived from the radiance maps. A preliminary description of a late winter warming in 1973–74 is also given. Radiance patterns associated with minor and major events are distinguished, and during the 1973–74 winter both types are described within the context of repeating oscillations in the thermal structure. In all cases observed, major warmings were associated with the occurrence of horizontal radiance gradients of 15 mW (m2sr cm−1) (10°lat)−1 in both radiation channels.

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Sidney C. Stern and Frederick Schwartzmann

338JOURNAL OF METEOROLOGYVOLUME 11CORRESPONDENCEAn infrared detector for measurement of the back radiation from the sky By SIDNEY C. STERN and FREDERICK SCHWARTZMANN Chemical Corps Biological Laboratories, Camp Detrick, Frederick, Maryland 9 June 1954With reference to the above-titled article which appeared in the April 1954 issue ofthe JOURNAL, we wish to take this opportunity to acknowledge with thanks the priorefforts of Lt. Cmdr. Leo C. Clarke, USNR. Working as a

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S. K. Dutta, L. Garand, and S. Heilliette

radiation scheme. It turns out that for the latter the emissivity is set to unity in infrared spectral bands ( Li and Barker 2005 ) while the broadband emissivity assumed in the surface analysis scheme and forecasts is set to 0.95, except over snow and sea ice where it is set to 0.99. Such a simplification may lead to significant biases in the predicted T s . Future work is currently planned that aims toward achieving consistency using the spectral emissivity database used in this work. There exist

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Sungwook Hong, Inchul Shin, and Mi-Lim Ou

1. Introduction The infrared (IR) spectral emissivity of the earth’s surface is now recognized to be a key factor in radiative transfer forward modeling. Since the oceans cover 70% of the earth’s surface, a high degree of accuracy is generally necessary for sea surface skin temperature (SST) determination ( Nalli et al. 2006 ). Considerable progress has been made toward modeling the spectral IR emissivity of wind-roughened water surfaces. Existing emissivity models explicitly calculate the

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Odran Sourdeval, Gérard Brogniez, Jacques Pelon, Laurent C.-Labonnote, Philippe Dubuisson, Frédéric Parol, Damien Josset, Anne Garnier, Michaël Faivre, and Andreas Minikin

/DIRAC 2001 . Atmos. Res. , 72 , 425 – 452 . Brogniez, G. , Legrand M. , Damiri B. , Behnert I. , and Buis J.-P. , 2005 : Multi-channel ground based and airborne infrared radiometers. NEWRAD Proc. Ninth Int. Conf. on New Developments and Applications in Optical Radiometry , Davos, Switzerland, Physikalisch- Meteorologisches Observatorium Davos, World Radiation Center, 173–174 . Chepfer, H. , Brogniez G. , Sauvage L. , Flamant P. H. , Trouillet V. , and Pelon J. , 1999 : Remote

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