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Giichi Yamamoto

Abstract

Based on Kaplan's idea that the temperature structure of the upper atmosphere may be inferred from satellite measurements, new methods of estimating the temperature distribution are presented and sample calculations are made assuming observations in four intervals of the 15-micron CO2 band.

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Giichi Yamamoto

Abstract

Based mainly on Howard, Burch and Williams' laboratory absorption data for the near infrared H2O and CO2, bands, and on the solar absorption data for the red and near infrared O2 bands, the direct absorption of solar radiation in near infrared atmospheric bands has been estimated. The estimated absorptivities of the H2O bands in the interval from 0.7 to 2.1 μ are in fair agreement with MeDonald's estimates which are based on Fowle's absorption data. However the absorptivities of the H2O bands from 0.7 to 6.3 μ are larger than McDonald's values. CO2 and O2 absorptions become increasingly important in the upper troposphere and in the stratosphere. Average heating (deg C day−1) was also estimated for London's model atmospheres for clear sky conditions, and compared with the similar estimate made by Roach. For the atmosphere above 300 mb the heating estimated in this paper exceeds that estimated by Roach. Conceivable causes of this discrepancy are pointed out.

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Giichi Yamamoto and Atsushi Shimanuki

Abstract

The three-dimensional equation of diffusion is solved numerically. Vertical diffusivity derived from the turbulent transfer theory is used, as is an assumed form for the lateral diffusivity containing an unknown parameter with respect to stability. The parameter is determined as a function of stability by comparing the theoretical distribution of concentration with observations made during projects Prairie Grass and Green Glow. The dependence on the averaging time of the lateral diffusivity of smoke concentration is also estimated by use of these experiments. The diffusion patterns in different stability and surface conditions are expressed fairly well by the calculations.

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Giichi Yamamoto and Masayuki Tanaka

Abstract

The effect of an increase of particles in the atmosphere on the global albedo and accordingly on the thermal regime of the earth is studied by solving the equation of radiative transfer in model turbid atmospheres.

Realistic model atmospheres with respect to size and vertical distributions of aerosol as well as reflectivity of the earth surface are assumed, and reflectivity at the top of the atmosphere, transniissivity at the earth surface, and absorptivity of turbid atmospheres are calculated as a function of atmospheric turbidity and the complex refractive index of the aerosol. It is shown that the thermal effect of increasing atmospheric turbidity is greatly affected by the imaginary part of the refractive index. Thus, if it takes a small value as is believed so at present, the earth-atmosphere system cools ofF with increase of turbidity, while if its value is large (ni0.05, ni being the imaginary part of the complex refractive index), heating of the earth- atmosphere system is expected due to increasing turbidity.

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Giichi Yamamoto and Gaishi Onishi

Abstract

Absorption of solar radiation by water vapor in the atmosphere has been studied, with use of Fowle's observed results and application of Elsasser's transmission function. The results are compared with those of other workers. Mügge-Möller's absorption curve and Karandikar's are discussed. As a result of calculations, an absorption chart is obtained from which both the absorption of solar radiation by an air column and the rate of heating of the air can be determined. Examples of calculation with the chart are shown with use of London's data for atmospheric conditions, and the results are compared with his.

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Giichi Yamamoto, Masaru Aida, and Susumu Yamamoto

Abstract

This paper presents a method of improving the Curtis-Godson approximation for computing transmission along a non-homogeneous path. The present approximation, as well as those by Curtis-Godson and by Goody, are applied to model atmospheres with typical distributions of three important absorbers, CO2, H2O and O3. Error estimates for each are discussed.

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Giichi Yamamoto, Masayuki Tanaka, and Kazuo Kamitani

Abstract

The equation of radiative transfer as applied to water clouds in the window region near 10 microns is solved numerically by using values of the phase function and albedo for single scattering estimated by Deirmendjian (1964). It is found that for monochromatic radiation of 10 microns the upward intensity at the cloud top shows limb darkening and the downward intensity at the cloud base, limb brightening. For the whole window region from 8 to 12 microns, the upward flux at the cloud top and the downward flux at the cloud base, as well as the emissivity of the cloud, transmissivity at the cloud top and reflectivity at the cloud base are evaluated. When the cloud is thin, the upward flux is mostly dependent on the incident flux corresponding to the earth surface temperature, and when the cloud becomes thick, it approaches the black-body flux at the cloud temperature. The downward flux at the cloud base is very small for a thin cloud, increases with cloud thickness and approaches a constant value which is somewhat larger than the upward flux at the cloud top when the cloud becomes very thick. It is also found that the emissivity, transmissivity and reflectivity change with cloud thickness but are practically independent of both the cloud and earth surface temperatures. Therefore, by using the values of these quantities obtained in this study, one can evaluate the upward and downward fluxes for any combination of cloud and earth surface temperatures and cloud thicknesses.

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Giichi Yamamoto, Masayuki Tanaka, and Shoji Asano

Abstract

The problem of diffuse reflection, transmission and emission of infrared radiation by water clouds is investigated in the wavelength region from 5–50 μ. The drop-size distribution of clouds is assumed to be that of altostratus measured by Diem. The phase function and other optical properties of the clouds are estimated from the value of the refractive index of water proposed by Pontier and Dechambenoy. Radiative processes due to both cloud droplets and water vapor in the cloud are taken into account, and a method of averaging the solution over a spectral interval including a number of absorption lines is developed.

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