HYCOM download using OPenDAP

[Ganesh Gopalakrishnan]

Hi 

I am trying to download HYCOM ESPC 3 hourly fields of T, S, U, and V.

I used to download from 

https://tds.hycom.org/thredds/catalogs/ESPC-D-V02_s3z.html?dataset=ESPC-D-V02-s3z-2025

using URL

https://tds.hycom.org/thredds/dodsC/ESPC-D-V02/s3z/2025

but I am getting netcdf error when using OPenDap for some times like

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Error using matlab.internal.imagesci.netcdflib The NetCDF library encountered an error during execution of "open" function: "I/O failure (NC_EIO)". If the data source was an OPeNDAP URL, see the OPeNDAP Troubleshooting section in the Users Guide

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I am not sure why this error is occurring? Please let me know if you have any suggestions to overcome this problem. I tried different versions of Matlab, but no luck

So I looked into all unaggregated data ESPC nc files 

https://tds.hycom.org/thredds/catalog/datasets/ESPC-D-V02/data/catalog.html

in daily-netcdf files

https://tds.hycom.org/thredds/catalog/datasets/ESPC-D-V02/data/daily_netcdf/2025/catalog.html

Does these files are daily means for U,V, T, S? Please clarify

Also I found  3 hourly files in archive

https://tds.hycom.org/thredds/catalog/datasets/ESPC-D-V02/data/archive/2025/catalog.html

but the time stamp is same for all t0000,  t0003, ...t0021 files.

Please clarify whether this is the format files are processed.

I really appreciate any information about these files.

Many Thanks

GAnesh