Hybrid Single-Particle Lagrangian Integrated Trajectories (HY-SPLIT): Model Description
Roland R. Draxler
NOAA Technical Memorandum ERL ARL-166, September 1988
Abstract - The algorithms and equations used in the development of a long-range transport and dispersion model are presented. The model calculation methods are a hybrid between Eulerian and Lagrangian approaches. A single pollutant particle represents the initial source. Advection and diffusion calculations are made in a Lagrangian framework. However, meteorological input data can either be gridded from rawinsonde observations or archived from the output of an Eulerian primitive equation forecast model. As the dimensions of the initial particle diffuse into regions of different wind direction or speed, the single particle is divided into multiple particles to provide a better representations of the more complex flow field. Air concentrations are calculated on a fixed three-dimensional grid by integrating all particle masses over the sampling time.
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