[ncl-talk] reading Radar grib2 data

Tue Sep 20 13:08:36 MDT 2016

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.gov_data_2D_ReflectivityAtLowestAltitude_-3FC-3DM-3BO-3DD&d=CwIFaQ&c=qHNyRuJKHYeI-vwTnTfWXq4fkZpyjWUA1LcPL7eQSSQ&r=6RmpIe4P-G8omsHqYS85uBS-3JaNVk3lvOG-hmdOrr8&m=-wmbteWjzMGfyNTMNd5uAvkhRqQJ8DXFgxj8Lx7y-hg&s=t4UunwJaFKhQMwPUUVM4nAKyf8zdpzJUB0qP36mHwus&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,
>> Givat Ram, Jerusalem 91904, Israel
>>
>> Tel: 972 547 231 170
>> Fax: (972)-25662581
>>
>>
>>
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>>