[ncl-talk] 回复：Re: I might find some bugs about calculation of wet-bulb temperature

[Mr.J]

Hi Mary,
Thank you for you reply. That is useful.I have checked the description page of wrf_user_getvar, it has been updated. However, there is still a mistake about the unit of wet-bulb temp. On the page, it shows the unit is C, but I think it should be K. I have tried to get the wet-bulb temp by using "twb=wrf_user_getvar(a,"twb",0)" and print the summary of variable "twb". The result is:please refer to it. Thank you very much!
Hopefully, my second question in my previous email could be answer. Someone may check and correct it, because it may mislead some new men in NCL.
Whatever, I love NCL, the wonderful software! : )
Merry Christmas!Shengxuan
--------------------------------


----- 原始邮件 -----
发件人：Mary Haley <haley at ucar.edu>
收件人：shengxuan_ji at sina.com
抄送人：ncl-talk <ncl-talk at ucar.edu>, wrfhelp NCAR-MMM <wrfhelp at ucar.edu>
主题：Re: [ncl-talk] I might find some bugs about calculation of wet-bulb temperature
日期：2014年12月24日 23点49分

Hi,
I do not know the answer to your second question about the correct units of "p" for wrf_wetbulb, but wrfhelp should be able to answer that.
The documentation for "wrf_user_getvar" says to use "tw", but it should be "twb".  I don't know if this is an error in the documentation or the WRFUserARW.ncl script, but I've updated the documentation to reflect this.
--Mary

On Tue, Dec 23, 2014 at 12:26 AM, Mr.J <shengxuan_ji at sina.com> wrote:
Dear Sir / Madam	Thank you for your hard working on the development of NCL software. I can easily manipulate the met data and professional plots now.
During my usage of wrf related functions, I found a bug, which is about calculation of wet-bulb temperature. I noticed that after the version6.2.0, the Wet bulb temperature is available to be calculated in one step by wrf_user_getvar(file,"tw",time). However, when I used the wayto get it, I got a error massage: 
		fatal:["Execute.c":6321]:variable (tw) is not in file (nc_file)
I think it means the function "wrf_user_getvar" is trying to get the "tw" variable from the wrfout file instead of calculating the diagnostics "we-t bulb temperature".
Secondly, I tried to use the other way to calculate the "Tw" by using the function " wrf_wetbulb ",  I also found some incorrect stuffs.On the description page of the "wrf_wetbulb", it shows that we need to put argument "p" in mb (hPa). However in the given example 1, the scriptuses "p   = wrf_user_getvar(a,"p",0)" to get the pressure. It may be wrong, because the unit is Pa calculating in this way. All in all, what unitshould I use for the pressure. (Please refer to test_scrpit1.ncl)
Thirdly, in the description page of function "wrf_wetbulb", the unit of return value is [C]. When I get the results, these values are larger than250. So, I am confused about the return value unit. Is it [C] or [K]? (Please refer to test_script2.ncl)
The attachments are my test scripts, please check them. The wrfout file is too large to put it on a website, you may findanother one to try the scripts.
My system details:ncl version: 6.2.0( I also tried the vesion 6.2.1, the results are the same.)
uname -a Linux nowcast 2.6.32-358.el6.x86_64 #1 SMP Tue Jan 29 11:47:41 EST 2013 x86_64 x86_64 x86_64 GNU/Linux
gcc --versiongcc (GCC) 4.4.7 20120313 (Red Hat 4.4.7-3)Copyright (C) 2010 Free Software Foundation, Inc.
cat /etc/redhat-releaseRed Hat Enterprise Linux Server release 6.4 (Santiago)

To be honest, I am not sure whether these are bugs or not. Please help me to deal with these questions. Hope your reply ASAP. Thank you very very much!
Yours sincerely,Shengxuan JI--------------------------------


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