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Pi-Huan Wang, Adarsh Deepak, and Siu-Shung Hong

Abstract

Formulas that can be used to determine the optical path between two points along an atmospheric ray path are derived for the case when the local zenith angle of the ray path is larger than 70°. For angles less than 70°, these formulas reduce to the airmass function; viz., the secant of the zenith angle. The formulation presented in this paper is genera] enough to be applicable to a wide variety of atmospheric conditions, such as spherical and nonspherical atmospheres, and vertically and horizontally homogeneous as well as inhomogeneous atmospheres. Formulation for the case when atmospheric refraction is important also is presented here.

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Gail P. Box, Michael A. Box, and Adarsh Deepak

Abstract

This paper describes the retrieval of aerosol size distributions from the measurements of multispectral solar extinction data, by the use of two retrieval methods—a fast approximate method and the numerical nonlinear least-squares (NLLS) method. Comparison of eight sets of results obtained by the two methods, in general, show a good agreement to within 15%. In addition, size distribution results retrieved by the approximate method show that the method is particularly sensitive to the wavelengths used, and differences in the wavelengths used for making observations and for generating the look-up tables can lead to appreciable errors in retrieved results. Thus, one cannot assume a universal data base for use with radiometers with different wavelengths; generation of a separate data base for each set of wavelengths is recommended.

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Pi-Huan Wang, Siu-Shung Hong, Mao-Fou Wu, and Adarsh Deepak

Abstract

The temporal and spatial variations of the zonally-averaged ozone beating rate in the middle atmosphere on a global scale are investigated in detail based on a model study. This study shows that the mean ozone heating rate calculation can be made in a realistic manner by taking advantage of the existing two-dimensional ozone distribution and including the effect of the sphericity of the earth's atmosphere. The obtained ozone heating rates have also been Fourier-analyzed. The common features of the first three harmonic components which correspond respectively to the annual, semiannual and terannual variations are (1) the local maximum amplitudes are located in the altitude regions between 45 and 57 km; (2) local maximum amplitude can be found in the polar region; and (3) maximum horizontal gradients of the beating rate are concentrated in the high latitudes from 60 to 90°. It is also found that the amplitude of the second Fourier component at the pole is about six times greater than that at the equator.

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