How does HYSPLIT consider the vertical coordinate. If a trajectory meets the surface how does HYSPLIT work?
Posted: July 22nd, 2021, 11:20 am
[Note that the question and the answer below are recreated from a HYSPLIT FAQ site that predates this forum site. The original posting date is unknown.]
Question:
How does HYSPLIT consider the vertical coordinate. If a trajectory meets the surface how does HYSPLIT work? Does it reflect, or use another method to solve it?
Answer:
In the trajectory model, trajectories only move up and down with the vertical velocity field. Trajectories that reach the bottom boundary continue at the surface, trajectories that reach the top boundary terminate.
In the dispersion model, particle trajectories reflect off both the top and bottom boundaries (to conserve pollutant mass).
Roland Draxler
Question:
How does HYSPLIT consider the vertical coordinate. If a trajectory meets the surface how does HYSPLIT work? Does it reflect, or use another method to solve it?
Answer:
In the trajectory model, trajectories only move up and down with the vertical velocity field. Trajectories that reach the bottom boundary continue at the surface, trajectories that reach the top boundary terminate.
In the dispersion model, particle trajectories reflect off both the top and bottom boundaries (to conserve pollutant mass).
Roland Draxler