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>From: "John H.E. Clark" <address@hidden> >Organization: Penn State University >Keywords: 199906081528.JAA26160 >Could you help with a GEMPAK problem? I have been trying to run the >following code in GDCROSS. It cannot evaluate GFUNC, which is horizontal >potential vorticity advection. I have successfully contoured potential >vorticity. Also I have successfully displayed GRAD(pvor(thes,geo)) in >GVECT. > >Thanks for your consideration, >John Clark > >CXSTNS = 43.3;-81.0>38.9;-74.9 > GDATTIM = f15 > GVCORD = pres > GFUNC = adv(pvor(thes,geo),geo) > GVECT = wnd > GDFILE = /home/clark/models/gemmm5_971230_00-06 > WIND = bm1 > REFVEC = > PTYPE = LOG > YAXIS = 1000/300 > CINT = 2 > SCALE = > LINE = 2/-2/1 > BORDER = 1 > TITLE = 1/-3/ | > CLEAR = yes > DEVICE = XW > TEXT = 0.5 > PANEL = ul > CLRBAR = > CONTUR = 2 / 2 > FINT = > FLINE = 10-20 > CTYPE = C > John, The trouble you are having is that PVOR is a layer quantity, while GEO is calculated at a single level. The result is an error message stating GEO can not be found for a layer. In order to do the above calculation, you can use the advection of PVOR by the layer average geostrophic wind, eg: gfunc = adv(pvor(thes,geo),vlav(geo)) Now the vertical cooordinate and levels for both terms of the advection will match. Steve Chiswell