Backward trajectories starting point: height issue

[coutre]

Hello,

I am running backward trajectories on Hysplit with a high altitude starting point (Chacaltaya, Bolivian Andes; latitude 16° 20' 47'' S, longitude 68° 07' 44'' W, height according to Google Earth ~5350m). I plotted terrain height along trajectory with the vertical plot height units in Meters AGL, and surprisingly the resulting plot outputs a starting point at 3200m ASL. This questioned me: how does Hysplit determine the ground level on which are based the model's altitude outputs? I am hoping that could help me understand the ~2000 m altitude difference at the trajectory starting point.

Thank you for any answer!

[ariel.stein]

HYSPLIT can use heights above ground level (AGL) or above sea level (ASL). The default is AGL. When using ASL, HYSPLIT determines the terraing height from the input meteorological data.