Date: Mon, 09 Jun 2003 13:56:04 -0600 From: "Stan Benjamin" To: Geoffrey Manikin Subject: Hourly RUC BUFR files question]] (fwd)] hi Bob and ER folks, Geoff Manikin had asked me to look into this issue quite a while ago and I apologize that I let it drift into the netherworld of un-wellread email in my inbox (don't ask more about that -- it's too ugly). The answer to the RUC BUFR question is simple: The RUC 2-m T/Td values use the 'minimum topography' (topomini) elevation, which is different from the lowest model level. This is described in the RUC20 TPB, on p. 21-22 (note esp. Table 6 on p. 22 in the FSL pdf version, off the RUC web site at ruc.fsl.noaa.gov). It uses local lapse rates from the model native levels, constrained in various ways considering dry adiabatic, isothermal, and near-sfc superadiabatic conditions. Let us know if you have an opinion about this technique. No other NCEP model has a similar reduction in the post-processing but it does help with the accuracy of the 2-m values, no question Interestingly, the reduction to the different topomini is exactly what should be done in GFE (but isn't, since the full native data isn't available in AWIPS). Maybe this should be publicized more through COMET/Jascourt/Bua or through SOO-Talk. It gets discussed through seminar and email questions intermittently but here it is again, and admittedly, it is a more obscure 'feature' (hopefully in the real sense) of the RUC Please also write any other questions. I promise to answer more quickly this time. The simplicity of the answer makes me feel even more stupid I let this sit around without answering -- my apologies again. Stan -----------------------------------------------------------------------------