Typical Day Meteorological Data in Support of ATD Modeling

Atmospheric Transport and Dispersion (ATD) models demand meteorological input that is both representative of a particular time and place and physically realistic. Statistically summarized climatological mean data lacks these characteristics. The objective of this project was to develop the necessary data and applications that will provide the ATD community with self-consistent 4D data sets of climatologically significant environmental modes, or typical days (TDs). The data sets produced during this project are modal in the statistical sense. Our methodology could be extended to provide data sets in response to requests for meteorological fields with user defined characteristics. As part of our approach we have developed a robust and extensible software capability through the reuse of technology from the Environmental Scenario Generator (ESG). This paper outlines the theoretical basis of the TD algorithm and its implementation. We will also describe how we addressed the practical challenge of providing the TD data to ATD users in a portable, easy to use format.