Development of Climate Zones for DARWin-ME

The Enhanced Integrated Climatic Model (EICM) integrated in the DARWin-ME design procedure allows users to select adjacent weather stations to generate a virtual weather station (VWS), whose data are further used to predict environmental impact on pavement performance. The DARWin-ME approach doesn't fully consider the potential spatial variations among these adjacent stations. Therefore, developing climate zones within a state may be necessary to account for the different climatic patterns and improve the accuracy of generated climate data. In this paper, using climate data from the National Climatic Data Center (NCDC), a cluster analysis technique is applied to develop climate zones for the State of Oklahoma. Consequently, climatic data from NCDC, DARWin-ME site-specific weather station, DARWin-ME interpolation approach using adjacent stations, and interpolation using stations within the same climate zone are obtained and compared. It is anticipated that the virtual weather data generated from the approach developed in this paper will provide more accurate data than those using the built-in DARWin-ME database and approach. However, due to the fact that Oklahoma is one of the most geographically flat states in the US and the spatial variations within the states are insignificant, only minor improvements are obtained using the proposed technique in the DARWin-ME analyses. It is identified in the paper that selecting 5 to 10-year period of climate history data provided in DARWin-ME to generate climate data for a 20 to 40-year pavement design is inadequate. It is recommended that further work needs to be conducted in the states where substantial spatial variations are present.