[gradsusr] xdfopen via opendap (developed from re Re: sdfopen with opendap file)

Wed Jun 22 02:00:48 EDT 2011

Dear Jennifer
Thank you very much for your advice.I made it following your suggestion.
Best Regards,Takaya Namba

From: jma at cola.iges.org
To: gradsusr at gradsusr.org
Date: Tue, 21 Jun 2011 08:43:24 -0400
Subject: Re: [gradsusr] xdfopen via opendap (developed from re Re: sdfopen	with opendap file)

On Jun 20, 2011, at 3:57 PM, James T. Potemra wrote:Takaya:

I don't think that the template option works with data via OPeNDAP, only on
local files. That is incorrect. Templating works on OPeNDAP URLs the same way it works on local file names, you need to add 'options template' to the descriptor file. 
As for the descriptor file, this is what works for me:
dset http://data.nodc.noaa.gov/opendap/pathfinder/Version5.0/Monthly/%y4/%y4%m2.s04m1pfv50-bsst-16b.hdfdtype netcdfoptions yrev templatetitle Please Put An Accurate Title in Every Descriptor Fileundef 0unpack scale_factor add_offxdef 8192 linear -180 0.043945ydef 4096 linear -90 0.043945zdef 1 linear 0 1tdef 12 linear 00z01JAN1985 1movars 1bsst 0 y,x temperatureendvars
The xdfopen interface wouldn't find the unpacking attribute names because they are non-standard ("add_off"), so a full descriptor is necessary. You can expand the tdef statement to include all the years in the data set, I just used 12 to make sure the templating was working. 
--Jennifer

The data provider needs to aggregate the data on the server
side
of things. Otherwise, you will have to write your script to loop through
all the
files.

You are also welcome to get the Pathfinder SST from our site,
http://apdrc.soest.hawaii.edu.
The exact URL is:

http://apdrc.soest.hawaii.edu:80/dods/public_data/satellite_product/AVHRR/avhrr_mon

for the monthly values (and these are aggregated).

Jim

Namba Takaya wrote:
Dear Sir

I tried to read the HDF file of pathfinder monthly sst via opendap

Fortunately I could read the sst data by xdfopen and data descriptor
file(bsst.ctl) as bellow,
Then I tried to develop using % of DSET in the data descriptor file.
Then I have a problem explained below and could you tell me how to
solve the problem?

Best Regards, Takaya Namba

bsst.ctl (data descriptor file)

DSET
http://data.nodc.noaa.gov/opendap/pathfinder/Version5.0/Monthly/1985/198501.s04m1pfv50-bsst-16b.hdf
options yrev
***DSET
http://data.nodc.noaa.gov/opendap/pathfinder/Version5.0/Monthly/%y4/%y4%m2.s04m1pfv50-bsst-16b.hdf
TITLE This is a sample
UNDEF 99999.0
YDEF lat 4096 LINEAR -90 0.043945
XDEF lon 8192 LINEAR -180 0.043945
***TDEF time 1 linear 00:00z1! 5JAN1985 1mo
VARS 1:
bsst=>bsst 1 99 surface temperature
ENDVARS

However, I would like to use
DSET
http://data.nodc.noaa.gov/opendap/pathfinder/Version5.0/Monthly/%y4/%y4%m2.s04m1pfv50-bsst-16b.hdf
instead of
DSET
http://data.nodc.noaa.gov/opendap/pathfinder/Version5.0/Monthly/1985/198501.s04m1pfv50-bsst-16b.hdf.
Because I would like to do all the thirty years from jan 1988 to 2009.

I added the line in the bsst.ctl
TDEF time 1 linear 00:00z15JAN1985 1mo
and then
grads -cl batch-opendap.gs.

However, the error comes like below,

Error: nc_open failed to open file
http://data.nodc.noaa.gov/opendap/pathfinder/Version5.0/Monthly/%y4/%y4%m2.s04m1pfv50-bsst-16b.hdf
NetCDF: DAP server error
gadsdf: Couldn't i! ngest SDF metadata.
SDF Descriptor file bsst.ctl was not suc cessfully opened & parsed.

I understand that I could not replace /%y4/%y4%m2 with /1985/198501 by
the data descriptor file.
Could you tell me how can I replace by the proper descriptor file as I
expected?

(batch-opendap.gs grads script file)
'set gxout shaded'
'xdfopen bsst.ctl'
'q file'
say result
'set lat 10 50'
'set lon 120 170'
'set T 1'
'set Z 1'
'd bsst'
'cbar'
'quit'

dncdump -h
"http://data.nodc.noaa.gov/opendap/pathfinder/Version5.0/Monthly/1985/198501.s04m1pfv50-bsst-16b.hdf"

is as below,

netcdf 198501.s04m1pfv50-bsst-16b { // format variant: 64bit
dimensions:
lat = 4096 ;
&n! bsp; lon = 8192 ;
variables:
short bsst(lat, lon) ;
bsst:dsp_PixelType = 1b ;
bsst:dsp_PixelSize = 2b ;
bsst:dsp_Flag = 0s ;
bsst:dsp_nBits = 16s ;
bsst:dsp_LineSize = 0 ;
bsst:dsp_cal_name = "Temperature" ;
bsst:units = "Temp" ;
bsst:dsp_cal_eqnNumber = 2s ;
bsst:dsp_cal_CoeffsLeng! th = 8s ;
&n bsp; bsst:dsp_cal_coeffs = 0.075f, -3.f ;
bsst:scale_factor = 0.075f ;
bsst:add_off = -3.f ;

------------------------------------------------------------------------

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 --Jennifer M. AdamsIGES/COLA4041 Powder Mill Road, Suite 302Calverton, MD 20705jma at cola.iges.org 

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