HYSPLIT Forum: hysplitbbs.arl.noaa.gov

Hi everyone,

I have been running HYSPLIT4 in batch mode with ARL generate from ERA5 data, converted using the gribtoarl.exe. It seems to work well but I would like to verify if there are any issues in using gribtoarl for era5. I know there is the script era52arl but I have some problem to compile it.
I ran hysplit to generate trajectories over the Antarctica. At first, it did not always calculate the full length of back trajectories, without indicating any error messages (in certain case few hours, in others almost the entire trajectories).
The problem seemed to be in correspondence of the passage between -180/180; I downloaded the era5 grib files for the domain -40/-180/-90/180. So, as second attempt, I tried to download again the gribs but indicating the area =-40/0/-90/360. Running again hysplit, it calculated the new trajectories without truncations.
I wonder if you can give me some information about that.

Thanks,
Virginia

HYSPLIT only applies the cyclic boundary conditions to global data.
So in your first dataset it sees the 'edge' of the dataset at -180 and 180.
In your second data set the edges are now at 0 and 360.
You will still have truncations with the 0-360 data, just in a different place.
Currently the only way to fix this without editing the code is to download ERA5 as a global dataset.