Re: [las_users] Error on large/high volume data sets - "remote server was unable to deliver data"

[Ansley Manke <ansley.b.manke@xxxxxxxx>]

Hi Kacie,
As a test, try making a short time selection and smaller range in longitude to see if you can get a result.

In LAS we handle large grids like this by asking for a decimated version when the request is really large. A several-hundred by several-hundred pixel image can't show that fine a grid anyway so we make a smaller request, striding the data request so it's a more reasonable size to be shipping around.

I have put the MUR dataset into a test server running LAS v8 and I can get an XT plot for a year's worth of it. See the attached screenshot. However for the entire time range the data that is returned from the NetCDF library reading the datset is all zero's.

Likewise I can make time series plots that are 6 or 8 months long, but requests for more data results in error messages from the NetCDF library reading the data.

Going back to the html view of the dataset, I can get coordinates successfully. Ask for lat 8000:1:8000, lon 32000:1:32000, time 0:10:2791 and the coordinates are returned correctly.  Try:
http://thredds.jpl.nasa.gov/thredds/dodsC/GHRSST_JPL-L4UHfnd-GLOB-MUR_TIMEAGG/aggregate__ghrsst_JPL-L4UHfnd-GLOB-MUR.ncml.ascii?lat[8000:1:8000],lon[32000:1:32000],time[0:10:3791],analysed_sst[0:10:3791]

But, try to get analysed_sst at those same index ranges, and we get an error.  That's this constrained url:
http://thredds.jpl.nasa.gov/thredds/dodsC/GHRSST_JPL-L4UHfnd-GLOB-MUR_TIMEAGG/aggregate__ghrsst_JPL-L4UHfnd-GLOB-MUR.ncml.ascii?analysed_sst[0:10:3791][8000:1:8000][32000:1:32000]

The software behind the url access to the datset is not the same netCDF library that Ferret, running within LAS is using to read this opendap data but it seems to me this is an indication that both pieces of software are having trouble accessing the dataset along the time dimension.

Ansley

On 4/19/2013 1:55 PM, Shelton, Kacie E (398C) wrote:

Hi.

We are getting a near instant error when requesting Hovmoller plots of MUR and AVHRR_OI data sets.  (See included images.)

"A remote server was unable to deliver the data LAS needs to make your product."

The links are good; MUR links to here: http://thredds.jpl.nasa.gov/thredds/dodsC/GHRSST_JPL-L4UHfnd-GLOB-MUR_TIMEAGG/aggregate__ghrsst_JPL-L4UHfnd-GLOB-MUR.ncml.html

Likewise the link for AVHRR_OI is good. 

We suspect this error has something to do with the volume of requested data; MUR is high resolution (~1km global), and AVHRR_OI has 30 yrs of global data. 

We do not get an error on loading any one particular granule, nor on a time series plot -- the Hovmoller plot is where we see this error. 

Any ideas on what is going on, or how we can fix this?

Thank you,
Kacie

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