Dave B pointed out that my answer to the wind speed/direction was the
opposite of what you want. I believe Dave answered this question
correctly.
--Mary
On Wed, 8 Jul 2009, Mary Haley wrote:
> Hi Chris,
>
> It's possible that the variable is not called exactly "UGRD" on the
> file.
>
> What does the following report:
>
> ncl_filedump 10m_Winds/2008-12_10m-wind.grb
>
> or
>
> ncl_filedump 10m_Winds/2008-12_10m-wind.grb | grep -i ugrd
>
> Do you see a variation of "UGRD"?
>
> As for your other questions:
>
>> 2) If anyone could offer some code examples that would fill an array of
>> values (over all [or some] times) from the horizontal grid that are
>> valid for a given lat/lon that would be really helpful.
>
> Can you elaborate here? I'm not sure what you mean by "from the horizontal
> grid that are valid"...
>
>> 3) Are there any built-in functions (or contributed ones) that will
>> convert my U and V components into Speed and Direction?
>
> This was asked once before on ncl-talk. See:
>
> http://www.ncl.ucar.edu/Support/talk_archives/2009/0381.html
>
>
> --Mary
>
> On Wed, 8 Jul 2009, Christopher G. Herbster wrote:
>
>> Hi all,
>>
>> I have downloaded 10m winds (U and V) in grib format and I am having
>> trouble reading the files.
>>
>> I have cat'ed both components into a single file. An ultimate goal is
>> to extract wind information for an arbitrary location and use that
>> information to build a wind rose.
>>
>> 1) When I try to read in the variables from the file I get an error that
>> says they don't exist or there is a problem with the file.
>>
>> ;***************************************
>> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
>> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/wind_rose.ncl"
>> ;
>> ; Need the next one for the read functions
>> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
>>
>> ;***************************************
>> begin
>> ;
>> fname = "10m_Winds/2008-12_10m-wind.grb"
>> ;
>> ;
>> ; Open file to read
>> infile = addfile(fname,"r") ; Open GRIB file to read
>> ;
>> ; Fill the U and V arrays
>> ugrd = infile->UGRD
>> vgrd = infile->VGRD
>>
>> usize = dimsizes(ugrd)
>> print ("usize is " + usize)
>>
>>
>> end
>>
>> -----------
>>
>> This yields:
>>
>> $ ncl read_reanalysis_windrose.ncl
>> Copyright (C) 1995-2007 - All Rights Reserved
>> University Corporation for Atmospheric Research
>> NCAR Command Language Version 4.3.0
>> The use of this software is governed by a License Agreement.
>> See http://www.ncl.ucar.edu/ for more details.
>> fatal:Either file (infile) isn't defined or variable (UGRD) is not a
>> variable in the file
>> fatal:Execute: Error occurred at or near line 26 in file
>> read_reanalysis_windrose.ncl
>>
>> ----------
>>
>> wgrib says this is what is in the file:
>>
>> $ wgrib 10m_Winds/2008-12_10m-wind.grb -v
>> 1:0:D=2008120100:UGRD:10 m above gnd:kpds=33,105,10:6hr fcst:"u wind [m/s]
>> 2:20388:D=2008120106:UGRD:10 m above gnd:kpds=33,105,10:6hr fcst:"u wind
>> [m/s]
>> 3:40776:D=2008120112:UGRD:10 m above gnd:kpds=33,105,10:6hr fcst:"u wind
>> [m/s]
>> 4:61164:D=2008120118:UGRD:10 m above gnd:kpds=33,105,10:6hr fcst:"u wind
>> [m/s]
>> 5:81552:D=2008120200:UGRD:10 m above gnd:kpds=33,105,10:6hr fcst:"u wind
>> [m/s]
>> 6:101940:D=2008120206:UGRD:10 m above gnd:kpds=33,105,10:6hr fcst:"u
>> wind [m/s]
>> 7:122328:D=2008120212:UGRD:10 m above gnd:kpds=33,105,10:6hr fcst:"u
>> wind [m/s]
>> 8:142716:D=2008120218:UGRD:10 m above gnd:kpds=33,105,10:6hr fcst:"u
>> wind [m/s]
>> 9:163104:D=2008120300:UGRD:10 m above gnd:kpds=33,105,10:6hr fcst:"u
>> wind [m/s]
>> 10:183492:D=2008120306:UGRD:10 m above gnd:kpds=33,105,10:6hr fcst:"u
>> wind [m/s]
>> <... snip ...>
>> 120:2428428:D=2008123018:UGRD:10 m above gnd:kpds=33,105,10:6hr fcst:"u
>> wind [m/s]
>> 121:2448816:D=2008123100:UGRD:10 m above gnd:kpds=33,105,10:6hr fcst:"u
>> wind [m/s]
>> 122:2469204:D=2008123106:UGRD:10 m above gnd:kpds=33,105,10:6hr fcst:"u
>> wind [m/s]
>> 123:2489592:D=2008123112:UGRD:10 m above gnd:kpds=33,105,10:6hr fcst:"u
>> wind [m/s]
>> 124:2509980:D=2008123118:UGRD:10 m above gnd:kpds=33,105,10:6hr fcst:"u
>> wind [m/s]
>> 125:2530368:D=2008120100:VGRD:10 m above gnd:kpds=34,105,10:6hr fcst:"v
>> wind [m/s]
>> 126:2550756:D=2008120106:VGRD:10 m above gnd:kpds=34,105,10:6hr fcst:"v
>> wind [m/s]
>> 127:2571144:D=2008120112:VGRD:10 m above gnd:kpds=34,105,10:6hr fcst:"v
>> wind [m/s]
>> 128:2591532:D=2008120118:VGRD:10 m above gnd:kpds=34,105,10:6hr fcst:"v
>> wind [m/s]
>> 129:2611920:D=2008120200:VGRD:10 m above gnd:kpds=34,105,10:6hr fcst:"v
>> wind [m/s]
>> 130:2632308:D=2008120206:VGRD:10 m above gnd:kpds=34,105,10:6hr fcst:"v
>> wind [m/s]
>> 131:2652696:D=2008120212:VGRD:10 m above gnd:kpds=34,105,10:6hr fcst:"v
>> wind [m/s]
>> 132:2673084:D=2008120218:VGRD:10 m above gnd:kpds=34,105,10:6hr fcst:"v
>> wind [m/s]
>> 133:2693472:D=2008120300:VGRD:10 m above gnd:kpds=34,105,10:6hr fcst:"v
>> wind [m/s]
>> 134:2713860:D=2008120306:VGRD:10 m above gnd:kpds=34,105,10:6hr fcst:"v
>> wind [m/s]
>> <... snip ...>
>> 244:4958796:D=2008123018:VGRD:10 m above gnd:kpds=34,105,10:6hr fcst:"v
>> wind [m/s]
>> 245:4979184:D=2008123100:VGRD:10 m above gnd:kpds=34,105,10:6hr fcst:"v
>> wind [m/s]
>> 246:4999572:D=2008123106:VGRD:10 m above gnd:kpds=34,105,10:6hr fcst:"v
>> wind [m/s]
>> 247:5019960:D=2008123112:VGRD:10 m above gnd:kpds=34,105,10:6hr fcst:"v
>> wind [m/s]
>> 248:5040348:D=2008123118:VGRD:10 m above gnd:kpds=34,105,10:6hr fcst:"v
>> wind [m/s]
>>
>>
>> ------------
>>
>> Any help in getting past this fundamental point is greatly appreciated.
>>
>>
>> 2) If anyone could offer some code examples that would fill an array of
>> values (over all [or some] times) from the horizontal grid that are
>> valid for a given lat/lon that would be really helpful.
>>
>>
>> 3) Are there any built-in functions (or contributed ones) that will
>> convert my U and V components into Speed and Direction?
>>
>>
>> Thanks in advance for any help!
>>
>> Cheers,
>> Chris Herbster
>>
>> --
>>
>> Dr. Christopher G. Herbster
>> Associate Professor
>> Director of Science and Technology
>> for the ERAU Weather Center
>> Applied Aviation Sciences
>> Embry-Riddle Aeronautical Univ.
>> 600 S. Clyde Morris Blvd.
>> Daytona Beach, FL 32114-3900
>>
>> 386.226.6444 Office
>> 386.226.6446 Weather Center
>> http://wx.erau.edu/
>>
>> Schedule at: http://wx.erau.edu/faculty/herbster/Schedules/
>>
>>
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Received on Wed Jul 08 2009 - 14:46:29 MDT
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