HYSPLIT Forum: hysplitbbs.arl.noaa.gov

I have used hysplit for some time and recently was messing around with generating hourly relative humidity data for specific locations. What I was getting was highly variable at times and other times somewhat respectable numbers (meaning that the were what I expected not necessarily what actually occurs). I have not done an exhaustive search but could not find any quick explanations of how the data is generated within the model. Any help out there?

Are you referring to the ability of HYSPLIT to output meteorological variables along a trajectory? Or are you referring to how is RH calculated in HYSPLIT from the meteorological fields and used in chemistry routines in the model?

I was generating RH values above a single spot on a bi-hourly basis and they seemed at times to be highly variable. The variability went against what i expected, however I must admit that there may be nothing wrong with it. That is why I asked about how the calculations were made.

Cheers

Could you tell me please what is the download size of the data required to run HYSPLIT ? Also are subsequent periodic or ad hoc downloads or updates required ?