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Paul Halpern and Kinsell L. Coulson

Abstract

This study is aimed at evaluating shortwave effects of aerosol pollutants in the lower troposphere (surface to 2 km). We have solved the radiative transfer equation for a plane-parallel atmosphere of infinite extent in the horizontal but inhomogeneous and of finite extent in the vertical. The vertical inhomogeneity is due to the presence of a non-uniform aerosol distribution, and a non-uniform concentration distribution of absorbing gases. The shortwave spectrum is divided into a sufficient number of intervals to simulate absorption characteristics of various atmospheric gases. The equation of radiative transfer is solved for these spectral intervals taking into account all orders of scattering.

Simulations have been made, using several representative vertical distributions of aerosols, typical aerosol values of refractive indices, and various size distribution functions. The analyses of these results indicate that the spectrally integrated flux divergence in the lower troposphere is highly dependent on solar zenith angle, the imaginary part of the refractive index, and the height and size distributions of the aerosol. The effect of gaseous absorption, however, has a smaller influence on the flux divergence.

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Hsuan-Heng Wang and Paul Halpern

Abstract

Twelve and 24-hr 500-mb forecasts have been made using a hemispheric dependent, limited-area, fine-mesh prediction model. The model is barotropic and makes use of the primitive equations. Boundary conditions are obtained via a coarse-mesh hemispheric model, and are imposed during the subsequent integration of the fine-mesh model. Two methods of initializing the fine-mesh simulation are presented. Comparison between the coarse- and fine-mesh results are shown. The quality of the fine-mesh predictions indicates the validity of the approach.

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Paul Halpern, Conrad Simon, and Larry Randall

Abstract

Sulfur dioxide concentrations (in ambient air), obtained from helicopter soundings and traverses, together with wind data from pibals, were used in a kinematic box model to determine hourly average three-dimensional fluxes of SO2 for the New York City area. Continuous dry-bulb temperature and pressure height records were obtained concurrently and utilized in the analysis and interpretation of the flux data.

The SO2 fluxes were compared to degree-day-dependent emissions from residential, industrial and utility sources. Results indicate that the vertical structure of the fluxes is related to diurnal variations of the temperature lapse rates. Furthermore, the emission rates determined from the measurement of flux in 13 tests agree with those derived from the New York City sulfur dioxide emission inventory within limits which have been considered acceptable for use in air pollution modeling.

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HSUAN-HENG WANG, PAUL HALPERN, JIM DOUGLAS JR., and TODD DUPONT

Abstract

The Galerkin method is applied to a pair of linear and then nonlinear primitive (wave) equations. This results in a system of ordinary differential equations. Procedures are included for generating the coefficient matrices of the system of ordinary differential equations when piecewise Hermite cubic functions are used as basis functions. It is demonstrated that this system can be efficiently solved by an implicit method. Numerical examples show that integration using the Galerkin method is more efficient than the corresponding finite-difference method with central differences in space.

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