Douw Steyn

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Three statistical models that estimate daily maximum ozone (03) concentrations in the lower Fraser Valley of British Columbia (BC) are specified using measured concentrations from two monitoring stations during the time period 1978-1985. The three models are (I) a univariate deterministic/stochastic model, (2) a univariate autoregressive integrated moving(More)
Genetic variation within the HLA-B locus has the strongest impact on HIV disease progression of any polymorphisms within the human genome. However, identifying the exact mechanism involved is complicated by several factors. HLA-Bw4 alleles provide ligands for NK cells and for CD8 T cells, and strong linkage disequilibrium between HLA class I alleles(More)
* Authors are members of EPA/AMS Regional Model Evaluation Workshop Steering Committee, and are listed in alphabetical order. Abstract This work provides a comprehensive view of the process of evaluating regional-scale (~200-2000 km) three-dimensional numerical photochemical air quality modeling systems, including meteorological, emissions, and air quality(More)
We discuss the ways in which atmospheric numerical models can be shown to have both predictive and explanatory value. This argument rests largely on the established predictive value of numerical weather forecasts, and can be extended to atmospheric models at larger-and smaller scales. We demonstrate that atmospheric modellers have not been particularly(More)
A scaling analysis has been used to capture the integrated behaviour of several photochemical mechanisms for a wide range of precursor concentrations and a variety of environmental conditions. The Buckingham Pi method of dimensional analysis was used to express the relevant variables in terms of dimensionless groups. These grouping show maximum ozone,(More)
Probabilistic forecasts are often employed to estimate the potential for high pollutant concentrations. To develop a probabilistic forecast of ozone concentrations, we suggest that use be made of the inherent properties of seasonality and autocorrelation in 0, time series. A non-stationary, autocorrelated stochastic process is used to simulate a conditional(More)
Water-tank models of meso-scale atmospheric processes often show good qualitative agreement of bulk quantities and flow characteristics and good quantitative agreement of turbulence quantities with field observations. However, it was demonstrated in the first part of this two-part communication that the similarity of velocities of thermally driven upslope(More)
Introduction Conclusions References Tables Figures Back Close Abstract Introduction Conclusions References Tables Figures Back Close Full Screen / Esc Print Version Interactive Discussion EGU Abstract A scaling analysis has been used to capture the integrated behaviour of several pho-tochemical mechanisms for a wide range of precursor concentrations and a(More)
Introduction Conclusions References Tables Figures Back Close Abstract Introduction Conclusions References Tables Figures Back Close Abstract The similarity relationship for maximum ozone concentration as a function of initial precursor concentrations developed in the first article of this 2-part series exhibits a scale break, most easily seen after a(More)
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