Problem in sst plot

Fri May 15 17:52:25 EDT 2009

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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