Airflow and air quality simulations over the Western Mountainous region with a four-dimensional data assimilation technique

Abstract We apply a three-dimensional meteorological model with a four-dimensional data assimilation (4-DDA) technique to simulate diurnal variations of wind, temperature, water vapor, and turbulence in a region extending from the west coast to east of the Rockies and from northern Mexico to Wyoming. The wind data taken during the 1985 SCENES ( S ubregional C ooperative E lectric Utility, Dept. of Defense, N ational Park Service, and E nvironmental Protection Agency S tudy on Visibility) field experiments are successfully assimilated into the model through the 4-DDA technique by ‘nudging’ the modeled winds toward the observed winds. The modeled winds and turbulence fields are then used in a Lagrangian random-particle statistical model to investigate how pollutants from potential sources are transported and diffused. Finally, we calculate the ground concentrations through a kernel density estimator. Two scenarios in different weather patterns are investigated with simulation periods up to 6 days. One is associated with the evolution of a surface cold front and the other under a high-pressure stagnant condition. In the frontal case, the impact of air-mass movement on the ground concentrations of pollutants released from the Los Angeles area is well depicted by the model. Also, the pollutants produced from Los Angeles can be transported to the Grand Canyon area within 24 h. However, if we use only the data that were obtained from the regular NWS rawinsonde network, whose temporal and spatial resolutions are coarser than those of the special network, the plume goes north-northeast and never reaches the Grand Canyon area. In the stagnant case, the pollutants meander around the source area and can have significant impact on local air quality.

[1]  J. Weil,et al.  Updating Applied Diffusion Models , 1985 .

[2]  Geoffrey Ingram Taylor,et al.  Diffusion by Continuous Movements , 1922 .

[3]  J. Hoke,et al.  The Initialization of Numerical Models by a Dynamic-Initialization Technique , 1976 .

[4]  Tetsuji Yamada,et al.  Simulations of Nocturnal Drainage Flows by a q2l Turbulence Closure Model , 1983 .

[5]  B. Hicks,et al.  Flux‐gradient relationships in the constant flux layer , 1970 .

[6]  R. McNider.  Investigation of the Impact of Topographic Circulations on the Transport and Dispersion of Air Pollutants. , 1981 .

[7]  Tetsuji Yamada,et al.  A Numerical Simulation of Nocturnal Drainage Flow , 1981 .

[8]  Ying-Hwa Kuo,et al.  The Accuracy of Trajectory Models as Revealed by the Observing System Simulation Experiments , 1985 .

[9]  F. A. Gifford,et al.  Horizontal diffusion in the atmosphere: A Lagrangian-dynamical theory , 1982 .

[10]  Tetsuji Yamada.  The Critical Richardson Number and the Ratio of the Eddy Transport Coefficients Obtained from a Turbulence Closure Model , 1975 .

[11]  G. Mellor,et al.  Development of a turbulence closure model for geophysical fluid problems , 1982 .

[12]  J. P. Mutschlecner,et al.  Atmospheric Transport Models for Complex Terrain , 1984 .

[13]  Tetsuji Yamada,et al.  Simulations of the ASCOT Brush Creek data by a nested-grid, second-moment turbulence-closure model and a kernel concentration estimator , 1987 .

[14]  Takashi Sasamori,et al.  The Radiative Cooling Calculation for Application to General Circulation Experiments , 1968 .

[15]  J. Hoke,et al.  Dynamic Initialization of a Three-Dimensional Primitive-Equation Model of Hurricane Alma of 1962 , 1977 .

[16]  R. Pielke.  Mesoscale Meteorological Modeling , 1984 .

[17]  G. Mellor,et al.  A Hierarchy of Turbulence Closure Models for Planetary Boundary Layers. , 1974 .

[18]  T. Yamada.  Numerical simulations of the night 2 data of the 1980 ASCOT experiments in the California Geysers area , 1985 .

[19]  Richard A. Anthes,et al.  Data Assimilation and Initialization of Hurricane Prediction Models , 1974 .

[20]  Chih-Yue Jim Kao,et al.  Use of the CAPTEX Data for Evaluations of a Long-Range Transport Numerical Model with a Four-Dimensional Data Assimilation Technique , 1988 .