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>From: "Fingerhut, William A" <address@hidden> >Organization: Lyndon State College >Keywords: 200405181456.i4IEuttK019619 IDV theta-e mixing ratio Hi Bill- re: Equivalent Potential Temperature (theta-e) calculation >Could it involve units ? (;-) Geez, I should hire you and save myself some time. ;-) I just figured this out, but finding that the units were wrong was quite involved and not obvious. here are the gory details: We calculate theta-e from temperature, pressure and mixing ratio. The latter is derived from temperature and pressure and relative humidity. When we were calculating mixing ratio (w) from saturation mixing ratio (ws) and relative humidity (f) we were doing: w = ws * f/100 (rearranging equation 6-13 of Byers). What we should have been doing is: w = ws*f/100% (left off the units of the 100), so in effect we had w in units of g/kg * %. So, the mixing ratio was off by a factor of 100. I spent most of my time looking at the formula that the IDV uses for calculating theta-e instead of looking at the units. As a side effect, if you plot mixing ratio as contours, the values will be correct now also. Thanks for finding this bug. The fix will be in the next release. Don Murray NOTE: All email exchanges with Unidata User Support are recorded in the Unidata inquiry tracking system and then made publically available through the web. If you do not want to have your interactions made available in this way, you must let us know in each email you send to us.