Back trajectories with user entered met data

[kkoz]

Hi,
I'm trying the option allowing user entered surface wind. I've got one month of hourly data - all of January 2018. It seems to convert to the ARL format okay, with all dates and times listed when I view the resulting met file using the "check file" utility. When I try creating back trajectories, I get a maximum of about 8 hours regardless of how many hours I specify, e.g. with a start time of 31st January 2018 and total run time of -24 hours I get endpoints for only 8 hours. Any suggestions why I can't get longer back trajectories? Thanks.

[glenn.rolph]

The issue is that the program that uses the surface observation only creates a 250 x 250 km grid centered over your observation location. It is only designed to be used for very short range simulations since using one surface observation is not representative the farther you are away from the observation.

[kkoz]

Okay. Thanks.