AN INVERSION ALGORITHM FOR DETERMINING AREA-SOURCE EMISSIONS FROM DOWNWIND CONCENTRATION MEASUREMENTS

Measuring emissions from nonuniform area sources, such as waste reposi tory sites, has been a difficult problem. A simple but reliable method is not available. An objective method of inverting downwind concentra tion measurements, utilizing an assumed form of atmospheric dispersion to reconstruct total emission rate and distribution, is described in this study. The Gaussian dispersion model is compared to a more realis tic model based on K-theory and similarity expressions. A sensitivity analysis is presented indicating the atmospheric conditions under whic h a successful application of the method could be anticipated. Field r eleases of sulfur hexafluoride (SF6) from a simulated area source in f lat terrain were conducted to check the method, ability to reconstruct source distribution, and total emission rate. The sensitivity analysi s and the field study confirm that a few ground-level concentration me asurements and a simple determination of the atmospheric dispersion ch aracteristics are sufficient, under neutral to stable conditions, to o btain the total emission rate accurately. Reconstruction of the spatia l pattern of the source is possible by utilizing concentration informa tion from samplers located on two separate ground-level receptor lines , if a shift in the wind direction occurs and if it can be assumed tha t the total emission rate is time invariant. A method of cross-checkin g the accuracy of the reconstruction, using a simultaneous tracer rele ase, is presented.