[ncl-talk] Reading ECMWF THREDDS data using OPENDAP

Fri Sep 11 15:40:54 MDT 2015

Hi Mary,

No my issue was never resolved.  I contacted Dave Stepaniak about this and he speculates that it is possible, however, trying to add my RDA username/passwd to the NCL Opendap call is another issue.  I can set my cookies using wget to remotely access an RDA dataset but doing this in NCL is proving problematic.  I have decided to run a NCL script on geyser to access the data on glade ans sftp it back to me.  However, I am running into another issue.  If I transfer the data using NETCDF3 it works OK.  However when I use the setfileoption to netcdf4 the file fills with missing values on my local system(although it is Ok on glade).  I am assuming that it is some issue with sftp.

;  setfileoption("nc","Format","NetCDF3")
;  setfileoption("nc","Format","NetCDF4")

I have remotely access the RDA datsets
From: Mary Haley <haley at ucar.edu>
Sent: Friday, September 11, 2015 5:14 PM
To: Vollaro, David
Cc: ncl-talk at ucar.edu
Subject: Re: [ncl-talk] Reading ECMWF THREDDS data using OPENDAP

Dave,

I didn't see any response to this. Was it ever resolved?

The issue is that these files are not being served by an OPeNDAP server, and hence you can't open them with an OPeNDAP-enabled client.

--Mary

On Fri, Sep 4, 2015 at 3:29 PM, Vollaro, David <dvollaro at albany.edu<mailto:dvollaro at albany.edu>> wrote:

Hi,

I am trying to read an ECMWF dataset from the NCAR RDA THREDDS servver using NCL.

I am using the example OPENDAP script from NCL but am having trouble accessing the data.

The snippet of the NCL script I am using is below, as is the link to the datasset I am trying to access.

I have sucessfully accessed data using OPENDAP before, so I am hoping that it is just an incorrecct

link-id.  I am running 6.1.2...Thanks...

Dave Vollaro

--------------- code snippet --------------

  url = "http://rda.ucar.edu/thredds/fileServer/aggregations/e/ds627.0/15/"
filename = url + "ERA_Interim_atmospheric_model_forecast_for_surface-198808/files/ei.oper.fc.sfc.regn128sc.1988080100"
print(filename)
;***********************************************
;  DATA SOURCE
;***********************************************

  exists = isfilepresent(filename)
  if(.not.exists) then
    print("OPeNDAP isfilepresent test unsuccessful.")
    print("File doesn't exist or NCL doesn't have OPeNDAP ability on this system")
  else
    print("OPeNDAP isfilepresent test successful.")
    file_nc = addfile(filename,"r")
  end if
  names = getfilevarnames(file_nc)          ;Get the variable names in the
  print(names)                               ;GRIB file and print them out.
end

--------- end snippet-------

  link:
http://rda.ucar.edu/thredds/catalog/aggregations/e/ds627.0/15/ERA_Interim_atmospheric_model_forecast_for_surface-198808/catalog.html?dataset=aggregations/e/ds627.0/15/ERA_Interim_atmospheric_model_forecast_for_surface-198808/files/ei.oper.fc.sfc.regn128sc.1988080100

error:

(0)     http://rda.ucar.edu/thredds/fileServer/aggregations/e/ds627.0/15/ERA_Interim_atmospheric_model_forecast_for_surface-198808/files/ei.oper.fc.sfc.regn128sc.1988080100
syntax error, unexpected WORD_WORD, expecting SCAN_ATTR or SCAN_DATASET or SCAN_ERROR
context: <html^><head><title>Apache Tomcat/7.0.63 - Error report</title><style></style> </head><body><h1>HTTP Status 401 - </h1><HR size="1" noshade="noshade"><p><b>type</b> Status report</p><p><b>message</b> <u></u></p><p><b>description</b> <u>This request requires HTTP authentication.</u></p><HR size="1" noshade="noshade"><h3>Apache Tomcat/7.0.63</h3></body></html>
ncopen: filename "http://rda.ucar.edu/thredds/fileServer/aggregations/e/ds627.0/15/ERA_Interim_atmospheric_model_forecast_for_surface-198808/files/ei.oper.fc.sfc.regn128sc.1988080100": NetCDF: Malformed or inaccessible DAP DDS
(0)     OPeNDAP isfilepresent test unsuccessful.
(0)     File doesn't exist or NCL doesn't have OPeNDAP ability on this system

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