Diagnostic Wind Model Research Articles

Modeling sulfur dioxide concentrations in Mt. Rainier area during prevent

The MATHEW/ADPIC models (a diagnostic wind model and a particle model) which were developed at Lawrence Livermore National Laboratory, were used to compute SO 2 concentrations in the Mt Rainier area during PREVENT (Pacific Northwest Regional Visibility Experiment Using Natural Tracers, June to September 1990). The modeled concentrations were compared to measured concentrations at two sampling locations (Tahoma Woods and Paradise near Mt Rainier) which are located in a valley. The SO 2 sources considered are located along the Puget Sound (Everett, Seattle and Tacoma area) and south of it. New formulations were included in the models for the oxidation of SO 2 and the interpolation of the wind field. Because of the paucity of the meteorological data near the sampling points, an estimation was made of the wind values in the valley, based on the phenomena of wind channeling, mountain and valley winds, and historical wind observations near Mt Rainier. The models were run for several non-rainy days during the PREVENT period when large SO 2 concentrations were observed, and for other special cases. Out of 14 days for which the emissions of the previous night were taken into account, for 12 days the ratio of the modeled to the measured SO 2 concentrations at Tahoma Woods during the daytime, was in the interval 0.45–2.00, considered a good agreement. However, the agreement at Tahoma Woods during the night, and at Paradise during the day and the night, were not as good. It seems that the wind flow near Tahoma Woods under the stable conditions at night, and near the steep terrain of Paradise, were not modeled correctly, with the limited input of available meteorological observations.

Synoptic Classification and Physical Model Experiments to Guide Field Studies in Complex Terrain

Abstract Synoptic classification is used to identify meteorological conditions characteristic of high-pollution periods at Nogales, Arizona. Low surface winds determined by local surface cooling at night with little vertical mixing were found to be most important. This condition was simulated in a 0.79-m-square box filled with water with the lower surface made to model a 12-km-square region of the surface topography of the United States-Mexico border at Nogales. The aluminum base was cooled to induce the downslope flows. Photographs of dye initially placed on the surface at many locations were used to obtain a set of surface velocities that formed the input to the Diagnostic Wind Model (DWM). The DWM provided hourly velocity data with grids of 500- and 250-m spacings. The similarity arguments used to analyze the relationship of the physical model to the atmosphere are discussed. Although the magnitude of the wind vectors in the physical model cannot be matched to the atmosphere, the directions can be used...

The interaction of katabatic winds and the formation of blue-ice areas in East Antarctica

AbstractBlue-ice areas (BIAs) are an extreme example of a local mass-balance gradient and are furthermore reasonably stable in time and space owing to local feed-back mechanisms. A meteorological experiment, performed in and around a blue-ice area in Dronning Maud Land. East Antarctica, showed that during drifting-snow conditions surface wind speed over the blue ice behind the mountain barrier is equal to that away from the mountains, when corrected for surface roughness and stability. This implies that use of diagnostic katabatic wind models to estimate divergence of drifting snow can be extended to the situation where nunataks are involved in preventing the drifting snow from passing, which is the case for most BIAs. A diagnostic model is tested for a two-dimensional profile in Terre Adélie. after which it is applied to entire East Antarctica. The present order-of-magnitude estimate shows that areas sensitive to blue-ice formation appear where precipitation is low and mean annual wind speed is high, i.e. in Dronning Maud Land and the drainage basin of Lambert Glacier. The results appeared to be especially sensitive to a change in inversion strength: a decrease in inversion strength weakens the katabatic flow, and thus the amount of snowdrift transport, reducing the area where BIAs can develop.

The interaction of katabatic winds and the formation of blue-ice areas in East Antarctica

AbstractBlue-ice areas (BIAs) are an extreme example of a local mass-balance gradient and are furthermore reasonably stable in time and space owing to local feed-back mechanisms. A meteorological experiment, performed in and around a blue-ice area in Dronning Maud Land. East Antarctica, showed that during drifting-snow conditions surface wind speed over the blue ice behind the mountain barrier is equal to that away from the mountains, when corrected for surface roughness and stability. This implies that use of diagnostic katabatic wind models to estimate divergence of drifting snow can be extended to the situation where nunataks are involved in preventing the drifting snow from passing, which is the case for most BIAs. A diagnostic model is tested for a two-dimensional profile in Terre Adélie. after which it is applied to entire East Antarctica. The present order-of-magnitude estimate shows that areas sensitive to blue-ice formation appear where precipitation is low and mean annual wind speed is high, i.e. in Dronning Maud Land and the drainage basin of Lambert Glacier. The results appeared to be especially sensitive to a change in inversion strength: a decrease in inversion strength weakens the katabatic flow, and thus the amount of snowdrift transport, reducing the area where BIAs can develop.

Analysis of Tracer Data Collected during the SCCCAMP 1985 Intensive Measurement Periods

Abstract This paper contains an analysis of data obtained from measurements of the concentration of tracer gases released during the four intensive measurement periods of the 1985 South-Central Coast Cooperative Air Monitoring Program (SCCCAMP). These tracer experiments were designed to document mesoscale circulation patterns in the coastal region of Santa Barbara and Ventura counties in southern California. Analyses of these concentration data are aimed at evaluating the design of the experiments, describing the movement of the tracers and comparing transport patterns to measured winds, and evaluating the ability of trajectory calculations, which are based on winds from a diagnostic wind model to reproduce those patterns of transport. The study concludes that patterns of recirculation over the 2-day period of the tests are successfully documented, revealing transport in the Santa Barbara Channel that is consistent with the circulation about the midchannel eddy, and diurnal patterns of onshore–offshore fl...

Identification and Tracking of Polluted Air Masses in the South-Central Coast Air Basin

Abstract Canister samples of air taken during the South-Central Coast Cooperative Air Monitoring Program (SCCCAMP) 1985 field study program were analyzed for concentrations of over 50 hydrocarbons as well as chlorofluorocarbons (CFCs), carbon monoxide, hydrogen, and methane. Additional evidence of location and timing of airmass origin was obtained by utilizing long-lived halocarbons such as F-12 as “tracers of opportunity” in conjunction with known source profiles. Wind trajectories were developed from hourly gridded wind fields produced by a diagnostic wind model utilizing observed wind data. These wind trajectories were used to determine how pollutants from major source areas might be transported to sampling sites. Particulate lidar height–distance traverses were made from aircraft that provided a view of pollutant layering. Mixing height and vertical pollutant concentration distributions were obtained in order to determine if observed pollutant concentrations were consistent with the degree of stagnati...

A refined diagnostic wind model

Diagnostic wind models provide mass-consistent wind velocity fields over complex orography on the basis of sparse measured data. For this purpose the model presented in this paper solves an elliptic differential equation to obtain wind fields satisfying the discrete formulation of the continuity equation. A proper parameterization allows to account for the influence of atmospheric stability on the resulting wind fields. The solution procedure is based on the Conjugate Gradient Method and an efficient direct elliptic solver using FFT. Calculated mass-consistent wind fields in the Athens basin reveal the typical diurnal variation of sea breeze circulation. Detailed results allow a discussion of the major model features.

Application of Atmospheric Transport Models for Complex Terrain

Numerical modeling techniques are applied to several diverse situations to study mesoscale transport of effluents in the earth's atmosphere. Simulations of a tracer release in complex terrain are compared with experiments carried out in the Northern California Geysers area during a period when nighttime drainage flow was the dominant feature. In addition, we study two situations, the Idaho National Engineering Laboratory and the Savannah River Laboratory, for which the terrain is assumed to not be a factor. These involve larger modeling areas and in one case, time periods extending over more than two diurnal cycles. These model simulations indicate that a diagnostic wind model utilizing terrain-following coordinates gives reasonable agreement with observations obtained over simple as well as complex terrain. In order to increase the accuracy in simulations of pollutant concentration distribution, much more refinement in wind measurements in space and time is needed since small differences in wind direction, for example, can produce a large difference in computed and measured concentration sufficiently downwind of a source.

Siting of Wind Turbine Generators in Complex Terrain

Accurate determination of wind distributions in the atmospheric surface layer is a prerequisite for the successful siting and design of wind turbine generators. A general methodology which combines a climatological approach and a diagnostic wind model is proposed for selecting optimum wind power sites in complex terrain. The development of the diagnostic wind model, which is based upon the numerical solution of the threedimensional mass continuity equation with the appropriate physical processes parameterized, is delineated. To demonstrate its utility, the proposed methodology is applied to the island of Maui in Hawaii. The predicted wind field appears to retrieve quantitatively the essential features of the measured wind flows; additionally, the areas identified as potential wind power application sites correspond to those determined earlier via field studies.