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Respected Dr. Seman,<br>
<br>
I had read this two links (you sent) earlier. But, I guess I donot need
a data descriptor file for the '.nc' files I have, as these are SDF
(which you can see in the ncdump headers I sent yesterday. It seems
length of 'vaiable name' should be maximum 15 charcaters, not 16.
Follwoing line I found in the link:
<a class="moz-txt-link-freetext" href="http://www.iges.org/grads/gadoc/descriptorfile.html#VARS">http://www.iges.org/grads/gadoc/descriptorfile.html#VARS</a>.
<blockquote type="cite"><em>varname</em> This is a 1-15 character
"name" or abbreviation for the data variable. <i>varname</i> may
contain alphabetic and numeric characters but it must start with an
alphabetic character (a-z).</blockquote>
What is why it truncates the 16th alphabet. How can I handle these two
problems (display packed byte and varname > 15 chars)? I am pasting
the attributes informations of a file below.<br>
<br>
--------------------------<br>
ga-> sdfopen 20060101-UKMO-L4UHfnd-GLOB-v01.nc<br>
Scanning self-describing file: 20060101-UKMO-L4UHfnd-GLOB-v01.nc<br>
SDF file 20060101-UKMO-L4UHfnd-GLOB-v01.nc is open as file 1<br>
LON set to -179.975 179.975<br>
LAT set to -89.975 89.986<br>
LEV set to 0 0<br>
Time values set: 2006:1:1:12 2006:1:1:12<br>
ga-> q attr<br>
Native Attributes for File 1 : OSTIA Sea Surface Temperature Analysis<br>
global String Conventions CF-1.0<br>
global String title OSTIA Sea Surface Temperature Analysis<br>
global String DSD_entry_id UKMO-TSANAL-v01-GLOB<br>
global String references None<br>
global String institution UK Met Office<br>
global String contact <a class="moz-txt-link-abbreviated" href="mailto:john.stark@metoffice.gov.uk">john.stark@metoffice.gov.uk</a><br>
global String GDS_version_id v1.0-rev1.5<br>
global String netcdf_version_id 3.6.0-p1 of Jul 4 2005 16:41:16 $<br>
global String creation_date 2006-01-02 14:00 UTC<br>
global String product_version 0.1<br>
global String history Created from sst:temperature from
/data/local/frhn/OSTIA/analysis/20060102_UKMO_L4UHfnd_GLOB_v01.nc;
error:; bias:; sea ice:<br>
global String grid_resolution 0.05000 degree<br>
global String comment WARNING Some applications are unable to properly
handle signed byte values. If values are encountered > 127, please
substract 256 from this reported value<br>
global String start_date 2006-01-01 UTC<br>
global String start_time 00:00:00 UTC<br>
global String stop_date 2006-01-02 UTC<br>
global String stop_time 00:00:00 UTC<br>
global Float32 southernmost_latitude -90<br>
global Float32 northernmost_latitude 90<br>
global Float32 westernmost_longitude -180<br>
global Float32 easternmost_longitude 180<br>
global String file_quality_index 0<br>
lon String long_name longitude<br>
lon String units degrees_east<br>
lat String long_name latitude<br>
lat String units degrees_north<br>
time String long_name reference time of sst field<br>
time String units seconds since 1981-01-01 00:00:00<br>
sst_foundation String long_name foundation sea surface temperature<br>
sst_foundation String units kelvin<br>
sst_foundation Int16 _FillValue -32768<br>
sst_foundation Float32 add_offset 273.15<br>
sst_foundation Float32 scale_factor 0.01<br>
sst_foundation Int16 valid_min -32767<br>
sst_foundation Int16 valid_max 32767<br>
sst_foundation String standard_name sea_surface_temperature<br>
analysis_error String long_name error estimate from the analysis<br>
analysis_error String units kelvin<br>
analysis_error Byte _FillValue -128<br>
analysis_error Float32 add_offset 0<br>
analysis_error Float32 scale_factor 0.05<br>
analysis_error Byte valid_min -127<br>
analysis_error Byte valid_max 127<br>
bias String long_name analysis error bias<br>
bias String units kelvin<br>
bias Byte _FillValue -128<br>
bias Float32 add_offset 0<br>
bias Float32 scale_factor 0.01<br>
bias Byte valid_min -127<br>
bias Byte valid_max 127<br>
sea_ice_fractio String long_name sea ice fraction<br>
sea_ice_fractio String units 1<br>
sea_ice_fractio Byte _FillValue -128<br>
sea_ice_fractio Float32 add_offset 0<br>
sea_ice_fractio Float32 scale_factor 0.01<br>
sea_ice_fractio Byte valid_min -127<br>
sea_ice_fractio Byte valid_max 127<br>
sea_ice_fractio String standard_name sea_ice_area_fraction<br>
sea_ice_fractio String comment Data derived from OSI-SAF sea ice product<br>
mask String long_name mask<br>
mask String comment b0: 1=sea ; b1: 1=land ; b2: 1=lakes ; b3: 1=ice<br>
ga-><br>
<br>
----------------------------------------<br>
<br>
Regards,<br>
<br>
M. Mahakur<br>
<br>
Charles Seman wrote:
<blockquote cite="mid454CFFAE.4030908@noaa.gov" type="cite">M. Mahakur,
<br>
<br>
Have you checked out this web site?
<br>
<a class="moz-txt-link-freetext" href="http://www.iges.org/grads/gadoc/descriptorfile.html#unpack">http://www.iges.org/grads/gadoc/descriptorfile.html#unpack</a>
<br>
<br>
Not sure why 'sea_ice_fraction' is not displayed... 16 characters is
<br>
GrADS limit...
<br>
<a class="moz-txt-link-freetext" href="http://www.iges.org/grads/gadoc/descriptorfile.html#VARS">http://www.iges.org/grads/gadoc/descriptorfile.html#VARS</a>
<br>
<br>
I hope this helps,
<br>
Chuck
<br>
<br>
M.Mahakur wrote:
<br>
<blockquote type="cite">Respected GrADS users:
<br>
<br>
How can I open the packed netcdf byte data (ncdumped headers of a
single
<br>
file I am pasting here)? I could display the variable 'sst_foundation'
<br>
using sdfopen. I guess GrADS is taking care of off_set and
scale_factor.
<br>
But I could not do for the other variables (i.e.. analysis_error, bias,
<br>
sea_ice_fraction and mask), which are packed bytes.
<br>
<br>
Secondly, variable 'sea_ice_fraction' is getting truncated to
<br>
'sea_ice_fractio'!!
<br>
<br>
Thanks in advance.
<br>
<br>
With Regards,
<br>
<br>
M. Mahakur
<br>
<br>
---------------------------------------------------
<br>
ga-> q file
<br>
File 1 : OSTIA Sea Surface Temperature Analysis
<br>
Descriptor: 20060101-UKMO-L4UHfnd-GLOB-v01.nc
<br>
Binary: 20060101-UKMO-L4UHfnd-GLOB-v01.nc
<br>
Type = Gridded
<br>
Xsize = 7200 Ysize = 3600 Zsize = 1 Tsize = 1
<br>
Number of Variables = 5
<br>
sst_foundation 0 -999 foundation sea surface temperature
<br>
analysis_error 0 -999 error estimate from the analysis
<br>
bias 0 -999 analysis error bias
<br>
sea_ice_fractio 0 -999 sea ice fraction
<br>
mask 0 -999 mask
<br>
<br>
<br>
---------Headers from ncdump------------------------------------
<br>
netcdf 20060101-UKMO-L4UHfnd-GLOB-v01 {
<br>
dimensions:
<br>
lon = 7200 ;
<br>
lat = 3600 ;
<br>
time = 1 ;
<br>
variables:
<br>
int time(time) ;
<br>
time:long_name = "reference time of sst field" ;
<br>
time:units = "seconds since 1981-01-01 00:00:00" ;
<br>
float lat(lat) ;
<br>
lat:long_name = "latitude" ;
<br>
lat:units = "degrees_north" ;
<br>
float lon(lon) ;
<br>
lon:long_name = "longitude" ;
<br>
lon:units = "degrees_east" ;
<br>
short sst_foundation(time, lat, lon) ;
<br>
sst_foundation:long_name = "foundation sea surface
<br>
temperature" ;
<br>
sst_foundation:units = "kelvin" ;
<br>
sst_foundation:_FillValue = -32768s ;
<br>
sst_foundation:add_offset = 273.15f ;
<br>
sst_foundation:scale_factor = 0.01f ;
<br>
sst_foundation:valid_min = -32767s ;
<br>
sst_foundation:valid_max = 32767s ;
<br>
sst_foundation:standard_name = "sea_surface_temperature"
;
<br>
byte analysis_error(time, lat, lon) ;
<br>
analysis_error:long_name = "error estimate from the
<br>
analysis" ;
<br>
analysis_error:units = "kelvin" ;
<br>
analysis_error:_FillValue = -128b ;
<br>
analysis_error:add_offset = 0.f ;
<br>
analysis_error:scale_factor = 0.05f ;
<br>
analysis_error:valid_min = -127b ;
<br>
analysis_error:valid_max = 127b ;
<br>
byte bias(time, lat, lon) ;
<br>
bias:long_name = "analysis error bias" ;
<br>
bias:units = "kelvin" ;
<br>
bias:_FillValue = -128b ;
<br>
bias:add_offset = 0.f ;
<br>
bias:scale_factor = 0.01f ;
<br>
bias:valid_min = -127b ;
<br>
bias:valid_max = 127b ;
<br>
byte sea_ice_fraction(time, lat, lon) ;
<br>
sea_ice_fraction:long_name = "sea ice fraction" ;
<br>
sea_ice_fraction:units = "1" ;
<br>
sea_ice_fraction:_FillValue = -128b ;
<br>
sea_ice_fraction:add_offset = 0.f ;
<br>
sea_ice_fraction:scale_factor = 0.01f ;
<br>
sea_ice_fraction:valid_min = -127b ;
<br>
sea_ice_fraction:valid_max = 127b ;
<br>
sea_ice_fraction:standard_name = "sea_ice_area_fraction"
;
<br>
sea_ice_fraction:comment = "Data derived from OSI-SAF
<br>
sea ice product" ;
<br>
byte mask(time, lat, lon) ;
<br>
mask:long_name = "mask" ;
<br>
mask:comment = "b0: 1=sea ; b1: 1=land ; b2: 1=lakes ;
<br>
b3: 1=ice" ;
<br>
<br>
// global attributes:
<br>
:Conventions = "CF-1.0" ;
<br>
:title = "OSTIA Sea Surface Temperature Analysis" ;
<br>
:DSD_entry_id = "UKMO-TSANAL-v01-GLOB" ;
<br>
:references = "None" ;
<br>
:institution = "UK Met Office" ;
<br>
:contact = <a class="moz-txt-link-rfc2396E" href="mailto:john.stark@metoffice.gov.uk">"john.stark@metoffice.gov.uk"</a> ;
<br>
:GDS_version_id = "v1.0-rev1.5" ;
<br>
:netcdf_version_id = "3.6.0-p1 of Jul 4 2005 16:41:16
<br>
$" ;
<br>
:creation_date = "2006-01-02 14:00 UTC" ;
<br>
:product_version = "0.1" ;
<br>
:history = "Created from sst:temperature from
<br>
/data/local/frhn/OSTIA/analysis/20060102_UKMO_L4UHfnd_GLOB_v01.nc;
<br>
error:; bias:; sea ice:" ;
<br>
:grid_resolution = " 0.05000 degree" ;
<br>
:comment = "WARNING Some applications are unable to
<br>
properly handle signed byte values. If values are encountered > 127,
<br>
please substract 256 from this reported value" ;
<br>
:start_date = "2006-01-01 UTC" ;
<br>
:start_time = "00:00:00 UTC" ;
<br>
:stop_date = "2006-01-02 UTC" ;
<br>
:stop_time = "00:00:00 UTC" ;
<br>
:southernmost_latitude = -90.f ;
<br>
:northernmost_latitude = 90.f ;
<br>
:westernmost_longitude = -180.f ;
<br>
:easternmost_longitude = 180.f ;
<br>
:file_quality_index = "0" ;
<br>
data:
<br>
<br>
time = 788961600 ;
<br>
<br>
lat = -89.975, -89.925, -89.875, -89.825, -89.775, -89.725, -89.675,
<br>
-89.625, -89.575, -89.525, -89.475, -89.425, -89.375, -89.325,
<br>
-89.275,
<br>
</blockquote>
<br>
--
<br>
<br>
Please note that <a class="moz-txt-link-abbreviated" href="mailto:Charles.Seman@noaa.gov">Charles.Seman@noaa.gov</a> should be considered my NOAA
<br>
email address, not <a class="moz-txt-link-abbreviated" href="mailto:cjs@gfdl.noaa.gov">cjs@gfdl.noaa.gov</a>.
<br>
<br>
********************************************************************
<br>
Charles Seman <a class="moz-txt-link-abbreviated" href="mailto:Charles.Seman@noaa.gov">Charles.Seman@noaa.gov</a>
<br>
U.S. Department of Commerce / NOAA / OAR
<br>
Geophysical Fluid Dynamics Laboratory voice: (609) 452-6547
<br>
201 Forrestal Road fax: (609) 987-5063
<br>
Princeton, NJ 08540-6649 <a class="moz-txt-link-freetext" href="http://www.gfdl.noaa.gov/~cjs/">http://www.gfdl.noaa.gov/~cjs/</a>
<br>
********************************************************************
<br>
<br>
"The contents of this message are mine personally and do not reflect
<br>
any position of the Government or NOAA."
<br>
<br>
</blockquote>
<br>
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