Turbulence structure of the atmosphere in a region of complex terrain and near to a major industrial installation

The Sellafield nuclear reprocessing plant in Cumbria discharges a variety of pollutants to both the marine environment and the atmosphere. Understanding the dispersion of this effluence is of prime importance for the industry, which must demonstrate safety to national regulatory bodies. Accurate modelling of the air flow in the region is one of the key ingredients towards correct prediction of the ground level concentrations of emissions. Work is being carried out to assess the suitability of the computer code FLOWSTAR for the task of predicting the atmospheric flow. Its predictions include means of the turbulent statistics within the boundary layer of the atmosphere. This paper will concentrate on the comparison of the predictions of these turbulence statistics at key points with the values measured by sonic anemometry. It is the turbulence, quantified by the standard deviations σu, σv and σw of the wind vector's components that is responsible for the local dispersion of pollution and for inducing many other boundary layer changes. The high frequency variation in the wind vector brings about the necessity for rapid response equipment such as the sonic anemometer