Problem in sst plot
Fil
fil at METEOPT.COM
Fri May 15 18:34:18 EDT 2009
I finally got it working! I was using a variable (define sst TMPsfc-273.15),
then I just tried without the variable and now it draws the entire globe. :D
Thanks for the help!
2009/5/15 Fil <fil at meteopt.com>
> Hi,
>
> I get the same results with grib1 data. I also tried in a 64-bit box and I
> didn't get any error, but I get the same resulting map. Tried grads 1.9 and
> opengrads 2 and the result is the same.
>
> Filipe
>
> btw: grib1 is a LOT faster than grib2.
>
>
> 2009/5/15 Jennifer Adams <jma at cola.iges.org>
>
>> Wacky! My earlier sample was grib, but I get the same good results with
>> the grib2 version of this data.... on my mac. When I tried it on my 64-bit
>> linux box, I got an error I've never seen before:
>>
>> ga-> d sst
>> jpc_decode return = 0
>> Constant field. Value = 271.33
>> ga->
>>
>> That "jpc_decode" message is in the grib2 library in the dec_jpeg2000.c
>> souce file. I have no idea what it means. Or where it got the 271.33 number.
>> I will have to poke at it further. Could be a classic case of operator
>> error. In the meanwhile ... Can you try using the grib1 version of this data
>> instead? Go back to the original FTP site that you started with:
>> ftp://polar.ncep.noaa.gov/pub/sst/ophi/
>>
>> Jennifer
>> p.s. Why do these puzzles show up on Friday afternoons?
>>
>>
>>
>> On May 15, 2009, at 2:27 PM, Fil wrote:
>>
>> Hi Jennifer,
>>
>> With 0.083333 in the ctl it does shows "LON set to 0 360". Maybe it's
>> something I'm doing wrong but even then it won't draw lon < 0º. I'm sending
>> the files I'm using for testing. The grib can be downloaded from:
>>
>>
>> http://www.ftp.ncep.noaa.gov/data/nccf/com/gfs/prod/sst.20090514/rtgssthr_grb_0.083.grib2
>>
>> Thanks.
>>
>> 2009/5/15 Jennifer Adams <jma at cola.iges.org>
>>
>>> Fil, I have downloaded a data sample and done some testing. When you
>>> open your descriptor file with GrADS, look at the info written to the
>>> command window. Does it say "LON set to 0.042 359.944" or "LON set to 0
>>> 360"?
>>>
>>> The answer will depend on whether you have enough significant digits in
>>> the grid increment value in the XDEF and YDEF statements in your descriptor
>>> file. When I use "0.083333" instead of "0.083", then GrADS calculates that
>>> the file does indeed 'wrap' the globe and 'set lon -180 180' works as it
>>> should.
>>>
>>> Jennifer
>>>
>>>
>>> GrADS automatically issues a 'set lon 0 360' command when it opens a file
>>> that wraps the globe. It
>>>
>>>
>>> On May 15, 2009, at 1:31 PM, Fil wrote:
>>>
>>> You are right, I swapped the results. It seems that for some reason grads
>>> won't draw longitude < 0º with 'set lon' starting with a negative number.
>>> This won't be a problem (drawing first lon > 0º and then lon < 0º) except
>>> for the robinson projection which has to start with -180.
>>>
>>> Adding more digits unfortunately didn't work.
>>>
>>> Thank you very much for your help.
>>>
>>> 2009/5/14 Diane Stokes <Diane.Stokes at noaa.gov>
>>>
>>>> Sorry that didn't fix all cases for you. It worked for me running grads
>>>> v1.9b4 and v2.0.a3 on IBM AIX.
>>>>
>>>> I'm confused by your result with:
>>>> 'set lon -180 180'
>>>> you only see -180º to 0º. And with:
>>>> 'set lon 180 540'
>>>> you only see 0º to 180º. Do you have those results swapped in the text
>>>> of your msg?
>>>>
>>>> If you don't get advice from anyone else, I could only suggest you add a
>>>> couple more significant digits (3's in this case) to your increment
>>>> values.
>>>>
>>>> Good luck.
>>>> Diane
>>>>
>>>>
>>>> Fil wrote:
>>>>
>>>>> Hi, Diane
>>>>>
>>>>> Thanks a lot for your help, your solution works perfectly for polar
>>>>> stereographic projections. But on other projections it still doesn't
>>>>> show anything from -180º to 0º longitude. If I try to plot just for
>>>>> North America, I get an "Entire Grid Undefined" message.
>>>>>
>>>>> With 'set lon -180 180' it only draws from -180º to 0º. With lon 180
>>>>> 540
>>>>> only draws from 0º to 180º. With lon -360 0 it won't draw anything. And
>>>>> with 0 360 it will draw the entire globe, but with the problem (for me)
>>>>> of getting centered in lon 180º which cuts Europe in half.
>>>>>
>>>>> Thanks.
>>>>>
>>>>> 2009/5/13 Diane Stokes <Diane.Stokes at noaa.gov
>>>>> <mailto:Diane.Stokes at noaa.gov>>
>>>>>
>>>>>
>>>>> Hi, Filipe.
>>>>>
>>>>> I recently ran into the same problem with a different dataset on the
>>>>> same grid.
>>>>>
>>>>> The spatial resolution the data you are viewing is 1/12 of a degree.
>>>>> The increment in the xdef and ydef statements of your control file
>>>>> is
>>>>> 0.083. (That's how the increment is stored in the grib file, so
>>>>> it's
>>>>> not a result of anything you did wrong).
>>>>>
>>>>> That increment value is not sufficient to wrap the data completely
>>>>> around the globe. You have 4320 points in your xdef:
>>>>> 4321 x 0.083 = 358.643
>>>>>
>>>>> If you zoom in on the north pole, you'll see the data displayed does
>>>>> not
>>>>> extend far enough north either.
>>>>>
>>>>> If you add a few significant digits to the increment values in your
>>>>> xdef
>>>>> and ydef statements, eg:
>>>>>
>>>>> xdef 4320 linear 0.042000 0.083333
>>>>> ydef 2160 linear -89.958000 0.083333
>>>>>
>>>>> you'll get a more accurate mapping of the data. The values above
>>>>> will
>>>>> also bring the left and right edge of the grid sufficiently close
>>>>> that
>>>>> GrADS will know that the data does wrap the globe. You'd then be
>>>>> able
>>>>> to display the field when setting longitude values less than 0 or
>>>>> greater than 360.
>>>>>
>>>>> Diane
>>>>>
>>>>>
>>>>>
>>>>> Filipe wrote:
>>>>>
>>>>> Hello all,
>>>>>
>>>>> I'm trying to plot sst data from
>>>>> ftp://polar.ncep.noaa.gov/pub/sst/ophi/ ,
>>>>> but for some reason I get a white strip at longitude 0º when
>>>>> using nps
>>>>> projection, as you can see from this pic:
>>>>>
>>>>> http://img8.imageshack.us/img8/2815/userlist2.png
>>>>>
>>>>> When using any other projection, grads only draws from lon > 0º,
>>>>> as you can
>>>>> see from these pics:
>>>>>
>>>>> http://img8.imageshack.us/img8/5487/userlist1.png
>>>>> http://img8.imageshack.us/img8/7201/userlist3.png
>>>>>
>>>>> I don't know what I'm doing wrong, hope someone can help me. I'm
>>>>> using
>>>>> latest grib2ctl.pl, wgrib v1.8.0.12x and grads 2.05a (I also
>>>>> tested v1.9 and
>>>>> opengrads 2.05). I used the script
>>>>> http://pastebin.com/f3dc65253
>>>>>
>>>>> Best regards.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Fil - MeteoPT.com
>>>>>
>>>>
>>>
>>> --
>>> Jennifer M. Adams
>>> IGES/COLA
>>> 4041 Powder Mill Road, Suite 302
>>> Calverton, MD 20705
>>> jma at cola.iges.org
>>>
>>>
>>>
>>>
>> <grads.gs><sst.ctl><sst.png>
>>
>>
>> --
>> Jennifer M. Adams
>> IGES/COLA
>> 4041 Powder Mill Road, Suite 302
>> Calverton, MD 20705
>> jma at cola.iges.org
>>
>>
>>
>>
>
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