Getting M2T1NXAER (MERRA-2 PM_{2.5}) via OPeNDAP

[kodiologist]

Consider this Python script:

Code: Select all

from datetime import datetime
from pydap.client import get_cmr_urls
print(get_cmr_urls(
    doi = '10.5067/KLICLTZ8EM9D',
    time_range = [datetime(2013, 7, 15), datetime(2013, 7, 15)],
    limit = 1000)[0])

It produces the URL:

https://opendap.earthdata.nasa.gov/collections/C1276812830-GES_DISC/granules/M2T1NXAER.5.12.4%3AMERRA2_400.tavg1_2d_aer_Nx.20130715.nc4

But when I visit the URL, I get

Hyrax - Resource Not Found (404)… The specified path 'collections/C1276812830-GES_DISC/granules/M2T1NXAER.5.12.4:MERRA2_400.tavg1_2d_aer_Nx.20130715' does not identify a granule in CMR.

Please let me know if there's some other way to get this dataset (M2T1NXAER) via OPeNDAP, since the service I've been using for the past few years (at https://goldsmr4.gesdisc.eosdis.nasa.gov/opendap/MERRA2/M2T1NXAER.5.12.4 ) has been retired.

[kodiologist]

Turns out it's just a file-extension thing. If I add another ".nc4", yielding

https://opendap.earthdata.nasa.gov/collections/C1276812830-GES_DISC/granules/M2T1NXAER.5.12.4%3AMERRA2_400.tavg1_2d_aer_Nx.20130715.nc4.nc4

, it works fine.

[GES DISC - alouise517]

Dear User,

Thank you for contacting us with your data access issue. It is necessary to add either ".nc4.nc4" (DAP2, older protocol that was used on goldsmr4) or ".dap.nc4" (DAP4, newer and recommended protocol) when accessing the file via wget/curl or a browser.

However, if you want to do any further server-side subsetting of the original granules spatially, temporally, or otherwise, you will need to append ".dap.nc4" and use the "dap4.ce" constraint expression at the end of the file extension (i.e., ".dap.nc4?dap4.ce=/lon[0:1:575]"). You can find further instructions in the following tutorial, in Step 3, showing the "Cloud OPeNDAP-enabled Granule Subset URL" URL syntax: https://disc.gsfc.nasa.gov/information/tools?title=OPeNDAP%20In%20The%20Cloud.

We are pleased to hear that your issue was resolved ahead of us getting back to you. Please do not hesitate to reach out if you have any further issues or need additional information or clarification. Thank you.

Regards,
GES DISC User Services