Daymet OPENDAP

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andrewcarsten
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Daymet OPENDAP

by andrewcarsten » Sun May 26, 2024 11:57 am America/New_York

I am accessing Daymet through the OPENDAP endpoint https://thredds.daac.ornl.gov/thredds/dodsC/daymet-v4-agg/na.ncml https://download-lagu.blog

I'm experiencing very slow download speeds. On the USGS VPN I'm getting ~2Kb/s and from home without VPN I'm getting ~5Mb/s. In my experience this is quite slow.

I am interpolating daymet variables to Alaska's HUC12, and generally I have I request the data by year and by quarter to stay within the allowable size of the request. This has been fine in the past but now in addition to the slow download speeds and maybe because of it I'm also getting curl timeout errors.

I changed the download request to monthly chunks and that is better but eventually I run into the same timeout errors. Just checking and asking to see if there is something on the server side that might be slowing the downloads down? For more context I'm using python and xarray to open and process the data via xarray using the OPENDAP endpoint linked above. Any help would be appreciated.

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ORNL - mthornton
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Re: Daymet OPENDAP

by ORNL - mthornton » Mon May 27, 2024 9:42 am America/New_York

Thank you for your message. Our lead on OPeNDAP has been notified and will respond as soon as possible.

ORNL - yaxingwei
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Re: Daymet OPENDAP

by ORNL - yaxingwei » Wed May 29, 2024 7:12 pm America/New_York

Hi @andrewcarsten,

Thanks for contacting us and apologize that you still have issue with downloading data via the USGS VPN.

May I first confirm with you about the units of the download speeds mentioned in your message? Was is "Kb/s" or "KB/s"? And, did you have this issue recently, or the download speed had always been this slow from the USGS VPN?

I did multiple tests from within both the ORNL network as well as my home network. When downloading Daymet OPeNDAP data from within the ORNL network, I could get a speed of more than 60MB/s. When downloading from my home network, I got a speed of about ~3MB/s, similar to what you got from your home network. The speed difference was significant, but I think the network itself was the main reason for this difference. Regarding the extremely slow download speed from the USGS VPN, it's really hard for us to diagnose the issue. Have you contacted USGS IT support about that?

Thanks again for the message.

Best,
Yaxing
Dr. Yaxing Wei (weiy@ornl.gov)
Lead Scientist, ORNL DAAC
Environmental Sciences Division
Oak Ridge National Laboratory
https://daac.ornl.gov

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