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  • Author or Editor: Chandrakant M. Bhumralkar x
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Chandrakant M. Bhumralkar

Abstract

The Rand two-level general circulation model has been integrated to compute ground surface (bare land) temperature by solving: 1) the interface heat balance equation without soil heat flux; 2) the interface heat balance equation by including parameterized soil heat flux; and 3) a prognostic equation which includes the heat capacity of the soil as well as an explicit formulation for soil heat flux.

The integrations were performed for 48 hours for the month of January. A comparison of results shows that the most realistic distribution of the ground surface temperature with respect to the amplitude, diurnal range, and the phase relationship between the ground temperature, solar radiation, and soil heat flux is given by the solution of the prognostic equation.

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Chandrakant M. Bhumralkar

Abstract

This Note describes a method of deriving a modified form of the hydrostatic equation by making allowance for the presence of moisture in an atmospheric column.

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Chandrakant M. Bhumralkar
,
Arthur J. Slemmons
, and
Kenneth C. Nitz

Abstract

A two-dimensional, vertical cross section, numerical atmospheric mesoscale model has been applied to study the potential local/regional atmospheric effects of the installation of a 100 MWe solar thermal central receiver power plant at Barstow, California. Such a plant consists of heliostats (mirrors) which cover a portion of ground surface and reflect sunlight onto a central receiving tower. The model can simulate the changes in surface characteristics associated with the installation of heliostats and other power plant ancillaries, and can simulate the effects of waste heat from cooling towers. The model equations have been integrated to simulate typical summer, and atypical summer.

The results for typical summer conditions at Barstow and the surrounding region show that the power plant has the potential to increase local humidity and wind circulation but cannot induce the formation of clouds or rain. The results for atypical summer conditions show that the solar power plant has the potential to increase the wind circulation and to form clouds and rain. However, the life cycle of such formations is only 2–3 h.

Sensitivity to the type and location of cooling tower has been tested and described. The atmospheric effects of a dry cooling tower located upwind are not as significant and intense as those produced using a wet cooling tower. However, this result is not conclusive and should be researched further. The effect of a wet cooling tower located at the downwind edge of the power plant is not as intense as is the case when the tower is located at the upwind edge of the power plant.

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Nelson L. Seaman
,
Francis L. Ludwig
,
Evelyn G. Donall
,
Thomas T. Warner
, and
Chandrakant M. Bhumralkar

Abstract

The Pennsylvania State University (PSU)/National Center for Atmospheric Research (NCAR) mesoscale model was modified and used to simulate the evolution of meteorological conditions in the vicinity of St. Louis, Missouri, from near sunrise to noon on 25 July 1975. Observations obtained during the METROMEX (Metropolitan Meteorological Experiment) and RAPS (Regional Air Pollution Study) field programs were available for comparison with modeled conditions. The PSU/NCAR model used a nested grid with two-way interaction between the coarse mesh (7.5 km) and the fine mesh (2.5 km), where the fine domain covered the city and its immediate suburban and rural surroundings. Realistic three-dimensionally variable initial and lateral boundary conditions were obtained from the observations so that the numerical experiments could be used for quantitative evaluation of certain urban effects. After simulation of the actual conditions (control experiment), the importance of a number of processes on the urban planetary boundary layer (PBL) structure were investigated. The PBL effects were isolated by using realistic surface parameters as well as those based on the preurban conditions and an expanded urban environment. Sensitivities to surface evaporative fluxes, radiative processes, and different surface roughness associated with urbanization were examined. The control simulations of the temperature, boundary layer depth, specific humidity and wind fields exhibited essentially the same behavior as observed in the urban PBL throughout the morning forecast period. Unlike many other documented cases that displayed strong urban-induced low-level convergence, the confluence on this morning was relatively weak, with the center of the heat island displaced (in both the simulation and the observations) downwind (south) of the city. A relative minimum in windspeed was associated with the center of the displaced heat island. The sensitivity experiments clearly demonstrated and maintenance of the urban PBL perturbation.

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