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Patrick, OABSND will interpolate the levels of each sounding to your list of levels input. See: $GEMPAK/source/gemlib/pc/pccmvr.f, pccmdt.f The interpolation is possible if your coord is PRES, HGHT, or THTA. Since you are on pressure levels, the interpolation will be done with respect to log pressure: pcintp.f Steve Chiswell Unidata User Support >From: "Market, Patrick S." <address@hidden> >Organization: UCAR/Unidata >Keywords: 200201311916.g0VJGWx27073 >Hello. > >I am writing to inquire how GEMPAK does an objective analysis of sounding file > s at non-mandatory levels. > >Our current work requires us to maintain the best possible vertical resolution > in our gridded files from the RAOB data. For the first time, I set > >LEVELS=0;1000;950;900;850;800;750;700... etc. > >and saw that even at non-mandatory levels (e.g., 750 mb) the full suite of sta > tions was accounted for. I did not know this was possible. For years I had > labored under the impression that doing so would yield incomplete/invalid fie > lds at non-mandatory levels. > >Have I been wrong? If so, how does GEMPAK achieve data representation on leve > ls like 750 mb? Does it interpolate for each station to the unobserved level > and then Barnes that result? If not, then what am I getting at levels like > 750? And do I need to write my own interpolation routine? I'd like to know > before I OABSND the next 123 cases... > >Thanks. > >Pat > >Dr. Patrick S. Market >University of Missouri-Columbia >Dept. of Atmospheric Science >203 Gentry Hall >Columbia, MO 65211 >(573)882-1496 Web: http://web.missouri.edu/~marketp >