[Wrf-users] how to set sigma values

[Eric Altshuler]

Jesse,

You need many more levels between 0.95 and 0.0, you have only 3 levels above the boundary layer! The model was never designed to run with such a strange distribution of vertical levels.

The intervals 0.95 - 0.8, 0.8 - 0.5, and 0.5 - 0.0 (the last interval contains half the mass of the atmosphere!) are much too big. You need to fill in these gaps with many more eta values, probably a total of at least 40. Perhaps you can use something like this (46 levels):

1.000, 0.9992, 0.9983, 0.9945, 0.9917, 0.9889, 0.9778, 0.950, 0.925, 0.9,
0.875, 0.85, 0.825, 0.8, 0.775, 0.75, 0.725, 0.7,
0.675, 0.65, 0.625, 0.6, 0.575, 0.55, 0.525, 0.5,
0.475, 0.45, 0.425, 0.4, 0.375, 0.35, 0.325, 0.3,
0.275, 0.25, 0.225, 0.2, 0.175, 0.15, 0.125, 0.1,
0.075, 0.05, 0.025, 0.0

This is just a suggestion; other users may have different ideas on how to choose the placement of vertical levels.

Best regards,

Eric L. Altshuler
Assistant Research Scientist
Center for Ocean-Land-Atmosphere Studies
4041 Powder Mill Road, Suite 302
Calverton, MD 20705-3106
USA

E-mail: ela at cola.iges.org
Phone: (301) 902-1257
Fax: (301) 595-9793

----- Original Message -----
From: "张洁（~袅人~）" <jessezhang1010 at gmail.com>
To: "wrf-users" <wrf-users at ucar.edu>
Sent: Friday, June 11, 2010 9:40:25 PM
Subject: [Wrf-users] how to set sigma values

Dear all,
Sorry, i forgot the attachment in previous mail.
I 'm using WRF3.1.1. I focus on some meteorology variables on the
following 7 heights which are terrain-following.
less than 7m,
7m - 15m,
15m - 50m,
50m - 75m,
75m - 100m,
100m - 200m,
greater than 200m.
How to set these sigma values according to this requirement ?
Before, i set eta_levels in namelist.input to 1.000, 0.9992, 0.9983,
0.9945, 0.9917, 0.9889, 0.9778, 0.950, 0.80, 0.50, 0.0.
However, it showed much errors like
WOULD GO OFF TOP: KF_ETA_PARA I,J,DPTHMX,DPMIN 31 42 NaN 5000.000
WOULD GO OFF TOP: KF_ETA_PARA I,J,DPTHMX,DPMIN 32 42 NaN 5000.000
....... .......
The rsl.error files have been uploaded as attachment.
Any help will be appreciated.
Thanks in advance.



------------------ Jesse Zhang
College of Information Technical Science,Nankai University
94#, Weijin Road, Tianjin 300071
jessezhang1010 at gmail.com



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