Errors when using wget to download MERR2 data

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makorb
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Errors when using wget to download MERR2 data

by makorb » Fri May 05, 2023 4:39 pm America/New_York

Hi y'all,
I've been trying to download subsets of the MERRA2 data (selecting the U2M and V2M variables) through OPeNDAP (following along with this resource: https://daac.gsfc.nasa.gov/information/howtotitle=How%20to%20Obtain%20Data%20in%20NetCDF%20Format%20via%20OPeNDAP). I have made sure to generate the prerequisite Earthdata files (according to this source: https://disc.gsfc.nasa.gov/information/howto?title=How%20to%20Generate%20Earthdata%20Prerequisite%20Files) and double checked for errors (using this source: https://daac.gsfc.nasa.gov/information/howto?title=How%20To%20resolve%20data%20download%20problems).

I am working on a MacOSX BigSur computer and I have been successfully able to download the example data, SeaWiFS Deep Blue Aerosol Level3 gridded daily at 1x1 degree resolution that was included in the tutorial (https://daac.gsfc.nasa.gov/information/howtotitle=How%20to%20Obtain%20Data%20in%20NetCDF%20Format%20via%20OPeNDAP). However, when I try to input my own opendap url (https://goldsmr4.gesdisc.eosdis.nasa.gov/opendap/hyrax/MERRA2/M2T1NXSLV.5.12.4/2010/01/MERRA2_300.tavg1_2d_slv_Nx.20100101.nc4?U2M[0:1:23][0:1:360][0:1:575]), my download fails.

I run the following line:
wget --load-cookies ~/.urs_cookies --save-cookies ~/.urs_cookies --keep-session-cookies https://goldsmr4.gesdisc.eosdis.nasa.gov/opendap/hyrax/MERRA2/M2T1NXSLV.5.12.4/2010/01/MERRA2_300.tavg1_2d_slv_Nx.20100101.nc4?U2M[0:1:23][0:1:360][0:1:575]

And get the following:
--2023-05-05 13:38:37-- https://goldsmr4.gesdisc.eosdis.nasa.gov/opendap/hyrax/MERRA2/M2T1NXSLV.5.12.4/2010/01/MERRA2_300.tavg1_2d_slv_Nx.20100101.nc4?U2M[0:1:23][0:1:360][0:1:575]
Resolving goldsmr4.gesdisc.eosdis.nasa.gov (goldsmr4.gesdisc.eosdis.nasa.gov)... 2001:4d0:241a:4041::95, 198.118.197.95
Connecting to goldsmr4.gesdisc.eosdis.nasa.gov (goldsmr4.gesdisc.eosdis.nasa.gov)|2001:4d0:241a:4041::95|:443... failed: Network is unreachable.
Connecting to goldsmr4.gesdisc.eosdis.nasa.gov (goldsmr4.gesdisc.eosdis.nasa.gov)|198.118.197.95|:443... connected.
HTTP request sent, awaiting response... 403 403
2023-05-05 13:38:44 ERROR 403: 403

Could someone help me figure out where I am going wrong?
Thanks so much!

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GES DISC - mgreene
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Re: Errors when using wget to download MERR2 data

by GES DISC - mgreene » Fri May 05, 2023 4:56 pm America/New_York

Hello,
A subject matter expert has been contacted and we will get back to you as soon as possible.
In the meantime, please take a look at the following Data Access instructions.

https://disc.gsfc.nasa.gov/information/documents?title=Data%20Access

Regards,

GES DISC - mgreene
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Re: Errors when using wget to download MERR2 data

by GES DISC - mgreene » Mon May 08, 2023 11:04 am America/New_York

Dear makorb,

Thanks for your interest in MERRA-2 data.

The OPenDAP operator was missing in your data URL which caused the failure. Please try:

https://goldsmr4.gesdisc.eosdis.nasa.gov/opendap/hyrax/MERRA2/M2T1NXSLV.5.12.4/2010/01/MERRA2_300.tavg1_2d_slv_Nx.20100101.nc4.nc4?U2M[0:1:23][0:1:360][0:1:575]

Note that the first nc4 is the MERRA-2 data format, and the second nc4 is the OPeNDAP operator.


Instead of manually constructing the data URL for OPeNDAP, We recommend using the subset interface to avoid URL constructing errors and handling the filename changes for the reprocessed data. Here is how to do it:

* start from https://disc.gsfc.nasa.gov/

* Search the product name, in your case, M2T1NXSLV_5.12.4

* Click on 'Subset/Getdata'

* Select the download Method as 'Get File Subsets using OPeNDAP' or 'Get File Subsets using the GES DISC Subsetter' for subsetting the vertical dimension of 3-dimensional data

* select temporal range, spatial range
* select variables
* click 'Get Data'
* click and get 'Download Links List', and follow downloading instructions


The MERRA-2 data reprocessing information page:

Records of MERRA-2 Data Reprocessing and Service Changes
(https://disc.gsfc.nasa.gov/information/documents?title=Records%20of%20MERRA-2%20Data%20Reprocessing%20and%20Service%20Changes)

Hope this help,

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