HYSPLIT Forum: hysplitbbs.arl.noaa.gov

I've been scratching my head trying to figure out why the values I'm seeing coming out of the 3-km NAM CONUS and 2.5 km HI grid files (e.g. hysplit.t00z.namsf00.CONUS and hysplit.t00z.namsf.HI) seem to have specific humidity values at model levels 2 and 10 that appear to be much higher than the values in the neighboring levels. I went back and looked at some older files and found this was not the case before the 21 Mar 2017 NAM upgrade (https://www.weather.gov/media/notificat ... pdates.pdf), so I suspect that changed something. I don't see any issues with any of the other variables at those levels, only specific humidity (SPHU). I'm thinking that perhaps model level 2 and 10 somehow got mixed up with heights of 2 and 10 meters and that those are what are written out into the files, based on how close the values are to the first model level. I don't think the issue affects the model itself, only what is written out into these HYSPLIT files, as if the 10th model level were biased high, I would expect that to bleed over into levels 9 and 11, but I'm not seeing that.

I'm using a custom file reader I wrote in Matlab, so I want to make sure this isn't some mistake I made with my reader and was wondering if anyone else could confirm what I'm seeing.

I realize this is not a bug in the HYSPLIT software itself, so I apologize it this is the wrong place to post this.

Thanks for any assistance!

We are working on an operational fix, then will need to fix the archived files. This applies to all the "nams" files.