[gradsusr] Stage IV HRAP Radar data

[Huddleston, John]

Wayne

The nctoasc program was used to get the corners.  It looks like it should be something like:

dset ^nws_precip_conus_20081101.nc
dtype netcdf
title amountofprecip
undef -1
xdef 1051 linear -131.432251   0.0637026784
ydef 813 linear  20.749580    0.04262164576
zdef 1 linear 1 1
tdef 1 linear 00:00Z01nov2008 1dy
vars 1
amountofprecip=>pcp  1 y,x amountofprecip
endvars

John Huddleston

________________________________________
From: gradsusr-bounces at gradsusr.org [gradsusr-bounces at gradsusr.org] On Behalf Of Wayne Gibson [gibson at nacse.org]
Sent: Friday, April 09, 2010 3:52 PM
To: gradsusr at gradsusr.org
Subject: [gradsusr] Stage IV HRAP Radar data

Hello,

I've been trying unsuccessfully to read a netcdf Stage IV Radar file as
found in the tar file


http://water.weather.gov/p_download_new/2008/200811/nws_precip_20081101_nc.tar.gz

The actual file is nws_precip_conus_20081101.nc It's apparent that the
file cannot be read directly with GRADS using sdfopen due to the error
message:

      gadsdf: SDF file has no discernable X coordinate.

So I've tried creating a GRADS ctl file so that the data can be read
with the "open" function.  I'm fairly sure that I'm not correctly
creating the GRADS control file as I either get error messages about the
lat/lon bounds or when I try to plot, the message is "Cannot contour
grid - all undefined values".

There is a C program available at the same web site to convert the data
to a lat/lon grid and I'm also working on compiling that code, but it
seems that it should be easy to read the netcdf file with GRADS.  I've
also searched on the web for an existing control file that could be used
as a template, assuming that other folks would be displaying RADAR data
using GRADS, but I've come up empty handed.

Does anyone have a control file they could share or offer suggestions on
what should be in the control file?  (If I dump all the data with ncdump
it's apparent that there is data in the file in the correct units, and
the data also contains the values "-1" and "-2" to delineate ocean and
missing data value.)

Wayne Gibson
Oregon State University

------------------------------------------------------------------------------------------------
GRADS version: 2.0.a8
Operating System: Linux 2.6.18-164
Version ncdump: 2.6.2 SUN

ncdump -c nws_precip_conus_20081101.nc
netcdf nws_precip_conus_20081101 {
dimensions:
        hrapy = 813 ;
        hrapx = 1051 ;
        latlong = 4 ;
        dates = 11 ;
variables:
        short amountofprecip(hrapy, hrapx) ;
                amountofprecip:long_name = "24-Hour Rainfall" ;
                amountofprecip:units = "1/100 mm" ;
                amountofprecip:grid = "hrap_grid=polar stereograph
projection" ;
                amountofprecip:resolution = "4km*4km" ;
                amountofprecip:dateofdata = "2008110112Z" ;
                amountofprecip:dateofcreation = "2008110221Z" ;
                amountofprecip:location = "continental united states" ;
                amountofprecip:author = "national weather service rfcs
genereated by program ROUT" ;
                amountofprecip:comments = "preliminary data...subject to
change" ;
        float lat(latlong) ;
                lat:order = "bottom_left,bottom_right,top_right,top_left" ;
        float lon(latlong) ;
                lon:order = "bottom_left,bottom_right,top_right,top_left" ;
        float true_lat ;
        float true_lon ;
        char timeofdata(dates) ;
        char timeofcreation(dates) ;
        float hrap_xor ;
                hrap_xor:comments = "offset in x direction of hrap grid" ;
        float hrap_yor ;
                hrap_yor:comments = "offset in x direction of hrap grid" ;
data:
}




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