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Meteorol Atmos Phys (2012) 116:6379 DOI 10.1007/s00703-012-0182-z
ORIGINAL PAPER
An upgraded version of the Eta model
Fedor Mesinger Sin Chan Chou Jorge L. Gomes Dusan Jovic
Paulo Bastos Josiane F. Bustamante Lazar Lazic Andr A. Lyra
Sandra Morelli Ivan Ristic Katarina Veljovic
Received: 28 July 2011 / Accepted: 8 January 2012 / Published online: 26 February 2012 The Author(s) 2012. This article is published with open access at Springerlink.com
Abstract Upgrades implemented over a number of years in an open source version of the Eta model, posted at the CPTEC web site http://etamodel.cptec.inpe.br/
Web End =http://etamodel.cptec.inpe.br/ , are summarized and examples of benets are shown. The version originates from the NCEPs Workstation Eta code posted on the NCEP web site http://www.emc.ncep.noaa.gov/mmb/wrkstn_eta
Web End =http://www.emc.ncep.noaa.gov/ http://www.emc.ncep.noaa.gov/mmb/wrkstn_eta
Web End =mmb/wrkstn_eta , which differs from the NCEPs latest operational Eta by having the WRF-NMM nonhydrostatic
option included. Most of the upgrades made resulted from attention paid to less than satisfactory performance noted in several Eta results, and identication of the reasons for the problem. Others came from simple expectation that including a feature that is physically justied but is missing in the code should help. The most notable of the upgrades are the introduction of the so-called sloping steps, or discretized shaved cells topography; piecewise-linear nite-volume vertical advection of dynamic variables; vapor and hydrometeor loading in the hydrostatic equation, and changes aimed at rening the convection schemes available in the Eta. Several other modications have to do with the calculation of exchange coefcients, conservation in the vertical diffusion, and diagnostic calculation of 10-m winds. Several examples showing improved performance resulting from the dynamics changes are given. One includes a case of unrealistically low temperatures in several mountain basins generated by a centered vertical advection difference schemes unphysical advection from below ground, removed by its replacement with a nite-volume scheme. Another is that of increased katabatic winds in the Terra Nova Bay Antarctica region. Successful forecast of the severe downslope zonda wind case in the lee of the highest peaks of the Andes is also shown, and some of the recent successful verication results of the use of the upgraded model are pointed out. The code is used at numerous places, and along with setup information it is...