[gradsusr] Precipitation Output Files Changed from NOAA AHPS: Can't read in GrADS anoymore
Jennifer M Adams
jadams21 at gmu.edu
Sun Jul 30 21:40:34 EDT 2017
Hi, James
The XDEF and YDEF entries in a descriptor file with PDEF 'nps’ describe the destination grid — the one you are interpolating *to*. There is no right/wrong way to do it, they can describe any grid you want. If you think the domain is too small for the data in the file, just expand it by tweaking the number, starting value, and increment until you are satisfied.
—Jennifer
> On Jul 30, 2017, at 12:08 AM, James Spinks <jspin881 at hotmail.com> wrote:
>
> Hi James,
>
> Thanks for the response. I was able to get the data to display, but had to add the xdef information because GrADS wouldn't open the file with out it. My only issue is that I do not believe the xdef and ydef information in the ctl file is accurate even though the file diplayed ok. Here is the modified ctl file:
>
> DSET ^nws_precip_1day_20170728_conus.nc
> dtype netcdf
> options yrev
> title amountofprecip
> undef -3.40282346638529e+38
> pdef 1051 813 nps 388 1591 -105.000000 4.7625
> ydef 881 linear 20 0.05
> xdef 1121 linear -125 0.05
> zdef 1 linear 1 1
> tdef 1 linear 00Z28Jul2017 1dy
> vars 4
> observation=>obs 1 y,x observation
> normal=>pcp 1 y,x normal
> departure_from_normal=>dpcp 1 y,x departure
> percent_of_normal=>ppcp 1 y,x percent
> endvars
>
> This ctl displays ok, but I'm not certain if the xdef and ydef info is accurate. Can you or anyone else please confirm? Thanks
>
>
>
> From: James T. Potemra <jimp at hawaii.edu>
> Sent: Friday, July 28, 2017 10:35 PM
> To: James Spinks
> Cc: GrADS Users Forum
> Subject: Re: [gradsusr] Precipitation Output Files Changed from NOAA AHPS: Can't read in GrADS anoymore
>
> Hi James,
>
> I was able to use ncdump on this file. There is no variable called "amountofprecip", but instead there is "normal", "departure_from_normal", and "percent_of_normal". The complete listing is below. The following ctl works with this file:
>
> DSET ^nws_precip_1day_20170728_conus.nc
> dtype netcdf
> options yrev
> title amountofprecip
> undef -3.40282346638529e+38
> pdef 1051 813 nps 388 1591 -105.000000 4.7625
> ydef 700 linear 20 0.05
> zdef 1 linear 1 1
> tdef 1 linear 00Z28Jul2017 1dy
> vars 4
> observation=>obs 1 y,x observation
> normal=>pcp 1 y,x normal
> departure_from_normal=>dpcp 1 y,x departure
> percent_of_normal=>ppcp 1 y,x percent
> endvars
>
>
> Jim
>> netcdf nws_precip_1day_20170728_conus {
>> dimensions:
>> y = 881 ;
>> x = 1121 ;
>> polar_stereographic = UNLIMITED ; // (0 currently)
>> variables:
>> int polar_stereographic(polar_stereographic) ;
>> polar_stereographic:latitude_of_projection_origin = 90. ;
>> polar_stereographic:straight_vertical_longitude_from_pole = -105. ;
>> polar_stereographic:standard_parallel = 60. ;
>> polar_stereographic:false_northing = 0. ;
>> polar_stereographic:grid_mapping_name = "polar_stereographic" ;
>> polar_stereographic:false_easting = 0. ;
>> float observation(y, x) ;
>> observation:_FillValue = -3.402823e+38f ;
>> observation:proj4 = "+proj=stere +lat_0=90 +lat_ts=60 +lon_0=-105 +k=90 +x_0=0 +y_0=0 +a=6371200 +b=6371200 +units=m +no_defs" ;
>> observation:grid_mapping = "polar_stereographic" ;
>> observation:name = "observation" ;
>> observation:coordinates = "x y" ;
>> observation:long_name = "Observation" ;
>> observation:units = "Inches" ;
>> observation:missing_value = -3.40282346638529e+38 ;
>> observation:esri_pe_string = "PROJCS[\"Polar_Stereographic\",GEOGCS[\"GCS_Coordinate_System_imported_from_GRIB_file\",DATUM[\"D_unknown\",SPHEROID[\"Sphere\",6371200.0,0.0]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]],PROJECTION[\"Stereographic_North_Pole\"],PARAMETER[\"false_easting\",0.0],PARAMETER[\"false_northing\",0.0],PARAMETER[\"central_meridian\",-105.0],PARAMETER[\"standard_parallel_1\",60.0],UNIT[\"Meter\",1.0]]" ;
>> float normal(y, x) ;
>> normal:_FillValue = -3.402823e+38f ;
>> normal:proj4 = "+proj=stere +lat_0=90 +lat_ts=60 +lon_0=-105 +k=90 +x_0=0 +y_0=0 +a=6371200 +b=6371200 +units=m +no_defs" ;
>> normal:grid_mapping = "polar_stereographic" ;
>> normal:name = "normal" ;
>> normal:coordinates = "x y" ;
>> normal:long_name = "PRISM normals" ;
>> normal:units = "Inches" ;
>> normal:missing_value = -3.40282346638529e+38 ;
>> normal:esri_pe_string = "PROJCS[\"Polar_Stereographic\",GEOGCS[\"GCS_Coordinate_System_imported_from_GRIB_file\",DATUM[\"D_unknown\",SPHEROID[\"Sphere\",6371200.0,0.0]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]],PROJECTION[\"Stereographic_North_Pole\"],PARAMETER[\"false_easting\",0.0],PARAMETER[\"false_northing\",0.0],PARAMETER[\"central_meridian\",-105.0],PARAMETER[\"standard_parallel_1\",60.0],UNIT[\"Meter\",1.0]]" ;
>> float departure_from_normal(y, x) ;
>> departure_from_normal:_FillValue = -3.402823e+38f ;
>> departure_from_normal:proj4 = "+proj=stere +lat_0=90 +lat_ts=60 +lon_0=-105 +k=90 +x_0=0 +y_0=0 +a=6371200 +b=6371200 +units=m +no_defs" ;
>> departure_from_normal:grid_mapping = "polar_stereographic" ;
>> departure_from_normal:name = "departure_from_normal" ;
>> departure_from_normal:coordinates = "x y" ;
>> departure_from_normal:long_name = "Departure from normal" ;
>> departure_from_normal:units = "Inches" ;
>> departure_from_normal:missing_value = -3.40282346638529e+38 ;
>> departure_from_normal:esri_pe_string = "PROJCS[\"Polar_Stereographic\",GEOGCS[\"GCS_Coordinate_System_imported_from_GRIB_file\",DATUM[\"D_unknown\",SPHEROID[\"Sphere\",6371200.0,0.0]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]],PROJECTION[\"Stereographic_North_Pole\"],PARAMETER[\"false_easting\",0.0],PARAMETER[\"false_northing\",0.0],PARAMETER[\"central_meridian\",-105.0],PARAMETER[\"standard_parallel_1\",60.0],UNIT[\"Meter\",1.0]]" ;
>> float percent_of_normal(y, x) ;
>> percent_of_normal:_FillValue = -3.402823e+38f ;
>> percent_of_normal:proj4 = "+proj=stere +lat_0=90 +lat_ts=60 +lon_0=-105 +k=90 +x_0=0 +y_0=0 +a=6371200 +b=6371200 +units=m +no_defs" ;
>> percent_of_normal:grid_mapping = "polar_stereographic" ;
>> percent_of_normal:name = "percent_of_normal" ;
>> percent_of_normal:coordinates = "x y" ;
>> percent_of_normal:long_name = "Percent of normal" ;
>> percent_of_normal:units = "Percent" ;
>> percent_of_normal:missing_value = -3.40282346638529e+38 ;
>> percent_of_normal:esri_pe_string = "PROJCS[\"Polar_Stereographic\",GEOGCS[\"GCS_Coordinate_System_imported_from_GRIB_file\",DATUM[\"D_unknown\",SPHEROID[\"Sphere\",6371200.0,0.0]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]],PROJECTION[\"Stereographic_North_Pole\"],PARAMETER[\"false_easting\",0.0],PARAMETER[\"false_northing\",0.0],PARAMETER[\"central_meridian\",-105.0],PARAMETER[\"standard_parallel_1\",60.0],UNIT[\"Meter\",1.0]]" ;
>> double x(x) ;
>> x:units = "Meter" ;
>> x:long_name = "x coordinate of projection" ;
>> x:standard_name = "projection_x_coordinate" ;
>> double y(y) ;
>> y:units = "Meter" ;
>> y:long_name = "y coordinate of projection" ;
>> y:standard_name = "projection_y_coordinate" ;
>>
>> // global attributes:
>> :creation_time = "20170729T001638" ;
>> :Conventions = "CF-1.6" ;
>> }
>
>
>
> On 7/28/17 1:52 PM, James Spinks wrote:
>> Hi all,
>>
>> NOAA AHPS changed their netcdf for format for the precipitation data as stated here:http://www.nws.noaa.gov/om/notification/scn17-32ahps_pcpnaaa.htm
>>
>> will be available in the following formats:
>> - Climate and Forecast (CF)-Network Common Data Form (netCDF)
>>
>> Precipitation products will no longer be available in the following
>> formats:
>> - netCDF not adhering to the netCDF CF metadata convention
>>
>> I'm not exactly sure the difference of the two and how it effects grads. I previously had a .ctl file the would read the original netcdf file just fine:
>>
>> DSET ^nws_precip_1day_20170728_conus.nc
>>
>> dtype netcdf
>> title amountofprecip
>> undef -1
>> pdef 1051 813 nps 388 1591 -105.000000 4.7625
>> xdef 1500 linear -135 0.05
>> ydef 700 linear 20 0.05
>> zdef 1 linear 1 1
>> tdef 1 linear 00Z28Jul2017 1dy
>> vars 1
>> amountofprecip=>pcp 1 y,x amountofprecip
>> endvars
>>
>>
>> Now this ctl does not work nor does ncdump read the new file from http://water.weather.gov/precip/downloads/
>>
>> Has anyone had any success opening the new updated precip data in GrADS from AHPS? If so, do you have a ctl file you could share?
>>
>> Thanks,
>>
>> James Spinks
>>
>>
>>
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>>
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>
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--
Jennifer Miletta Adams
Center for Ocean-Land-Atmosphere Studies (COLA)
George Mason University
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