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Particle Pollution Designations

HYSPLIT Trajectory Endpoint Data

These columns are found in the trajectory data tables:

  • trajnum - A simple counter to allow keeping track of individual trajectories. Each file has four different valies for trajnum. The lowest value corresponds to trajectories with a terminating height of 10 merets above ground level. The next value corresponds to trajectories with a terminating height 25% of the boundary layer height. The next value corresponds to trajectories with a terminating height 50% of the boundary layer height. And the highest trajnum value corresponds to trajectories with a terminating height 75% of the boundary layer height.
  • year, month, day, hour - Correspond to the time and sdate the air parcel is found at the coordinates.
  • age - The length of time between the point and the start of the trajectory. An age of 7 means the point is 7 hourw away from arriving at the trajectory end point. Keep in mind trajectories move backward in space and time.
  • lat, lon - Coordinates of the data point corresponding to the location of the parcel of air at the date and time.
  • pressure - atmospheric pressure of the point in three-dimensional space.
  • rain - Anount of any recipitation calculated at the data point.
  • mixing - The mixing height calculated at the data and time. The mixing height (boundary layer height) used to setermine the endpoints of the 4 trajectories is the mixing height at age = 0 for the trajectory.
  • rdate - The date for the start of the trajectory.
  • shour - The hour of the start of the trajectory. this should equal the hour column when age = 0.
  • sheight - End point height for the trajectory.
  • siteid - AQS id for the end point fo the trajectory, corresponds to a PM 2.5 monitor location.