NARAC's Atmospheric Data Assimilation and Parameterization Tool (ADAPT) constructs 3-D meteorological fields for use in LODI dispersion calculations. ADAPT outputs fields of key parameters including winds, temperature, pressure, humidity, and precipitation derived from meteorological observations and/or numerical weather prediction model output. Turbulence variables are determined from meteorological and land-surface data using similarity-theory turbulence scaling relationships and surface energy budget methods.
Weather observations are collected in real-time to provide input to ADAPT. These observations are acquired from world-wide surface, tower, balloon sounding, and profiler measurement stations provided by the National Oceanic and Atmospheric Administration (NOAA), the Department of Defense, Kennedy Space Center, AWS Convergence Technologies, Inc. (WeatherBug), and an expanding set of meteorological networks ("mesonets"). The ADAPT model also ingests gridded forecast and analysis field made available by the NOAA, the Air Force Weather Agency, and the Fleet Numerical Meteorology and Oceanography Center (FNMOC), or produced using NARAC's in-house NWP model WRF.
ADAPT produces non-divergent wind fields using an adjustment procedure based on the variational principle and a finite-element discretization. The finite element method provides an effective approach for treating complex terrain and dealing with variable resolution grids. The solution is obtained via a choice of conjugate gradient solvers and the use of a stabilization matrix to improve computational efficiency.