Question about meteorology output along trajectory

[Christian813]

Hello,

I have meteorology output along with trajectories, and I can see the values at the exact position in the simple listing. I'm using wrf output as input for hysplit and I was wondering, how hysplit extract meteorology variables at exact height (like 546.4 mts for example) since wrf output use sigma levels? Is Hysplit using some kind of vertical interpolation for this?

Thank you very much

[christopher.loughner]

Yes, the extracted meteorology variables that you see are interpolated WRF fields. HYSPLIT uses a linear interpolation technique. First, HYSPLIT interpolates WRF fields onto HYSPLIT's domain and then interpolates these new meteorology fields onto the trajectory (which is what you see in your output). If you have the source code, you can see how the interpolation is performed from the WRF domain to the HYSPLIT domain in prfsig.f and then onto the path of the trajectory from the subroutines called in advmet.f (adv2nt.f for 2D fields and adv3nt.f for 3D fields).