[ncl-talk] reading Radar grib2 data

Tue Sep 20 15:38:39 MDT 2016

Hi Wei,
Great! I'm glad you were able to figure out the problem.
 -dave

On Tue, Sep 20, 2016 at 2:30 PM, Wei Huang <whuang at univ-wea.com> wrote:
> Hi Dave,
>
> It looks like that the problem comes from libpng in-consistency.
>
> My NCL is built with 1.2.50,  but my system running with 1.5.13.
>
> If I build NCL with 1.2.50 using static lib, the problem goes away.
>
> Thanks for helping figure out the problem.
>
> Wei Huang
>
>
> -----Original Message-----
> From: David Brown [mailto:dbrown at ucar.edu]
> Sent: Tuesday, September 20, 2016 2:09 PM
> To: Wei Huang
> Cc: Barry Lynn; ncl-talk at ucar.edu
> Subject: Re: [ncl-talk] reading Radar grib2 data
>
> Hi Wei,
> That is quite strange. I don't think the tables should play a significant role here. The data should be the same no matter what NCL (or wgrib2) thinks the names and units of data are.
> Have you tried wgrib2 yourself on this dataset? If it disagrees with NCL then I would worry that something is wrong with your NCL version.
> I don't think there have been any recent changes that would affect this dataset.
>  -dave
>
> On Tue, Sep 20, 2016 at 12:43 PM, Wei Huang <whuang at univ-wea.com> wrote:
>> Dave,
>>
>> Here is what I run the script, and the result:
>>
>> [whuang at htdgfxl07 mrms]$ cat d.ncl
>>  f =
>> addfile("MRMS_ReflectivityAtLowestAltitude_00.50_20160920-173034.grib2
>> ","r")  v = f->ReflectivityAtLowestAltitude_P0_L102_GLL0
>>  printMinMax(v,0)
>>  print(avg(v))
>> [whuang at htdgfxl07 mrms]$ ncl -Q d.ncl
>> (0)     ReflectivityAtLowestAltitude: min=-999   max=-999
>> (0)     -999
>>
>> Certainly something wrong at my end.
>>
>> Do you have any idea what could be wrong? Like the tables:
>> ncep/0/0.0.table, ncep/4/4.2.table, and ncep/4/4.2.209.*.table?
>>
>> Thanks,
>>
>> Wei
>>
>> ________________________________________
>> From: David Brown [dbrown at ucar.edu]
>> Sent: Tuesday, September 20, 2016 1:30 PM
>> To: Wei Huang
>> Cc: Barry Lynn; ncl-talk at ucar.edu
>> Subject: Re: [ncl-talk] reading Radar grib2 data
>>
>> Hi Wei,
>> The values in this data are not all -999 and wgrib2 and ncl agree on
>> the statistics for the single record in this file:
>>
>> wgrib2 -V
>> MRMS_ReflectivityAtLowestAltitude_00.50_20160920-173034.grib2
>> 1:0:vt=2016092017:500 m above mean sea
>> level:anl:ReflectivityAtLowestAltitude ReflectivityAtLowestAltitude
>> [dBZ]:
>>     ndata=24500000:undef=0:mean=-460.646:min=-999:max=61
>> <<<<<<<<<<<<<<<<<<<<
>>     grid_template=0:winds(N/S):
>> lat-lon grid:(7000 x 3500) units 1e-06 input WE:NS output WE:SN res 48
>> lat 54.995000 to 20.005001 by 0.010000 lon 230.004999 to 299.994997 by
>> 0.010000 #points=24500000
>>
>>
>> ncl 0> f =
>> addfile("MRMS_ReflectivityAtLowestAltitude_00.50_20160920-173034.grib2
>> ","r") ncl 2> v = f->ReflectivityAtLowestAltitude_P0_L102_GLL0
>> ncl 3> printMinMax(v,0)
>> (0)     ReflectivityAtLowestAltitude (dBZ) : min=-999   max=61
>> ncl 4> print(avg(v))
>> (0)     -460.6458
>>
>>  -dave
>>
>>
>> On Tue, Sep 20, 2016 at 11:56 AM, Wei Huang <whuang at univ-wea.com> wrote:
>>> Yes, I “gunzip” the file first.
>>>
>>>
>>>
>>> Thanks,
>>>
>>>
>>>
>>> Wei Huang
>>>
>>>
>>>
>>> From: Barry Lynn [mailto:barry.h.lynn at gmail.com]
>>> Sent: Tuesday, September 20, 2016 12:52 PM
>>> To: Wei Huang
>>> Cc: ncl-talk at ucar.edu
>>> Subject: Re: [ncl-talk] reading Radar grib2 data
>>>
>>>
>>>
>>> Hi:
>>>
>>>
>>>
>>> Is there any chance you need to gunzip the file first?
>>>
>>>
>>>
>>> On Tue, Sep 20, 2016 at 8:45 PM, Wei Huang <whuang at univ-wea.com> wrote:
>>>
>>> Dear NCL users,
>>>
>>> I am trying to process a radar grib2 dataset downloaded from:
>>>
>>> https://urldefense.proofpoint.com/v2/url?u=http-3A__mrms.ncep.noaa.go
>>> v_data_2D_ReflectivityAtLowestAltitude_-3FC-3DM-3BO-3DD&d=CwIFaQ&c=qH
>>> NyRuJKHYeI-vwTnTfWXq4fkZpyjWUA1LcPL7eQSSQ&r=6RmpIe4P-G8omsHqYS85uBS-3
>>> JaNVk3lvOG-hmdOrr8&m=-wmbteWjzMGfyNTMNd5uAvkhRqQJ8DXFgxj8Lx7y-hg&s=t4
>>> UunwJaFKhQMwPUUVM4nAKyf8zdpzJUB0qP36mHwus&e=
>>>
>>> For example, I tried dataset:
>>> MRMS_ReflectivityAtLowestAltitude_00.50_20160920-173034.grib2.gz
>>>
>>> I tried to read the data, but all its value is: -999.
>>>
>>> The file seems a pretty good size.
>>>
>>> Has anyone tried such data before and want to share experience?
>>>
>>> Thanks,
>>>
>>> Wei Huang
>>> whuang at univ-wea.com
>>>
>>>
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>>>
>>> --
>>>
>>> Barry H. Lynn, Ph.D
>>>
>>> Senior Lecturer,
>>>
>>> The Institute of the Earth Science,
>>> The Hebrew University of Jerusalem,
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