The sensitivity of harp model on atmospheric boundary mixing heights

Abstract

The HARP software had been created and applied as a part of the California Air Resources Board (CARB) to help the Board and industry to evaluate the health based risk assessment from a given activity. The model determines the hourly ground level pollutant concentrations based on the atmospheric dispersion models ISCST3, and simultaneously characterizes human exposure surrounding the facility. A standardized epidemiological exposure-response, and toxicological dose response functions are used to calculate the health based risk impact on the receptors. The height of the atmospheric boundary layer or known as mixing height, serves as one of the inputs in the model. This paper presents the influence of different atmospheric boundary mixing heights on the sensitivity of the HARP, modeled on dioxin-furan emission from a 500kg/hr capacity clinical waste incineration plant. Result showed the mixing height can be represented by a constant value of 500m in local context replacing Holzworth’s mixing height formula as hourly estimates of mixing height with a deviation less than 5%. The influence of different mixing height on the final result to find a stable boundary layer within HARP avoids the complexity of mixing height calculation at the same time obtain a good model result and reduces the impact of mixing height influence on modeling variation.