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Wilford G. Zdunkowski

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Wilford G. Zdunkowski and Frank G. Johnson

Abstract

This paper presents some sample computations of infrared radiative flux divergence due to atmospheric water vapor. These calculations are based upon newly constructed radiation tables which were obtained from the radiometersonde observations of P.M. Kuhn. The results are compared with the findings of other investigators. The importance of the surface-air temperature discontinuity is demonstrated.

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Wilford G. Zdunkowski and David C. Trask

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For a calm night, nocturnal temperature profiles pertaining to various soil types are computed for the entire boundary layer. The mathematical analysis is based upon a numerical solution of the equations of motion, heat conduction and radiative transfer. The effect of radiative temperature change upon the total cooling rate is investigated. Some other interesting quantities associated with the distribution of the exchange coefficient and wind velocity components as a function of height and time are also calculated.

Solutions are presented in graphical format. All results such as temperature profiles, inversion heights and wind spirals seem to be in reasonable agreement with theoretical and observational deductions.

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Jan Paegle, Wilford G. Zdunkowski, and Ronald M. Welch

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The Crank-Nicholson method may not give useful results in detailed prediction of the thermal planetary boundary layer unless tune steps on the order of 10 s are used. In similar problems, lower order time differencing methods give reasonable results with time steps as large as 300 s. The reason for the superior behavior of the lower order schemes relative to straightforward application of the Crank-Nicholson technique is due to a better treatment of short waves which appear to be critically important in nonlinear terms.

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Wilford G. Zdunkowski, Ronald M. Welch, and Jan Paegle

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A dynamic-numerical model is utilized to study the impact of air pollution on the temperature and wind distributions of the planetary boundary layer. The mathematical model uses a rather complete radiative treatment which comprises the entire solar and infrared spectrum ranging from 0.29 to 100 µm. In the solar spectral range, the absorption by water vapor, nitrogen dioxide and industrial haze is fully accounted for in addition to multiple scattering by air molecules and haze particles. In the spectral region of the strong absorption hands of the infrared emission spectrum, the effect of aerosol is very small and is disregarded. The emissivity method is applied here, allowing full treatment of the overlapping effects of water vapor and carbon dioxide. In the window region, however, the effect of aerosol and water vapor absorption and emission is taken into account in addition to multiple scattering by aerosol particles. The radiative treatment accounts for the influence of relative humidity on the particle distribution function and on the complex index of refraction of the aerosol. The spherical harmonic method is used to handle the scattering problem.

The dynamical part of the analysis consists of the numerical solution of a coupled system of partial differential equations comprising the equation of horizontal mean motion, the thermodynamic equations of the air and the soil, and the transport equations of moisture and pollution. Various models of the exchange coefficient are used to study the impact of model assumptions on the computed distributions of temperature, pollutant material and wind. It is found that the choice of the exchange model is not critical but has some effect on the model computations. The present calculations show that the maximum impact of air pollution on the evolution of temperature and wind profiles is highly significant, thus verifying the previous conclusions of Zdunkowski and McQuage (1972).

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