MODIS DATA

[Michael Angelo Valete]

Dear OPENDAP Support Team,

Good day.

I am Michael Angelo P. Valete from the Philippine Space Agency. We have ongoing research on satellite-based agricultural drought monitoring. We previously accessed MODIS NDVI and LST through this website: https://opendap.cr.usgs.gov/opendap/hyrax/DP137/MOLT/MOD13C2.061/contents.html and https://opendap.cr.usgs.gov/opendap/hyrax/DP137/MOLT/MOD11C3.061/contents.html. As of today, the links are not accessible. May we know the reason why?

Thank you so much.

Sincerely,

Michael Angelo P. Valete Science Research Specialist Earth Sciences Space Mission Studies Division Philippine Space Agency 29th Floor, Cyber One Building, 11 Eastwood Ave., Bagumbayan, Quezon City

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[Miguel Jimenez]

Hi Michael, 

NASA is in the process of migrating all of NASA Earth science data to the cloud, which will continue through 2026, and this will result in many of the on premises site to slowly disappear, and older versions of the data become deprecated. Relevant for your particular workflow is that, the OPenDAP end point for MODIS data is being migrated to the cloud. This change will result in the same data available through a different URL, but exactly the same OPeNDAP protocol. 

However, as a consequence of the OPeNDAP server being migrated to the cloud, it will change how users find the urls as the server will no longer represent the data as a local file system.

Two ways to find the data are 

1) Earthdata Searth

https://search.earthdata.nasa.gov/search

It operates similar to a search engine like google. You can type the concept collection ID, and additional filters (such as time range, bounding boxes, etc). You can find a tutorial on how to use Earthdata Search to find OPeNDAP URLS in the following resource:

https://www.earthdata.nasa.gov/learn/tutorials/get-started-opendap-subset-download-nasa-earth-data

NOTE: This is very useful to find a handful of OPeNDAP urls, but perhaps not for finding all (say 100s or 1000s) or OPeNDAP urls. See option 2 below.

2) Python to query the CMR

NASA’s 

Common Metadata Repository  holds the information about all publicly Earthdata collections from NASA ( EarthdataSearch above queries the CMR and consolidates the data for the browsing experience). Any application / program can be written in any programing language to query the CMR to find all, potentially 1000s of OPeNDAP urls, based on acceptable parameters to the CMR API. We describe one below:

Pydap, a python application we help develop to query and access opendap data, can be used to query all available OPeNDAP urls from the CMR (cloud or non cloud urls). 

You can see some interactive examples in the following resources:

a) Query, and access multiple NASA granules of Ocean data:  https://github.com/OPENDAP/NASA-tutorials/blob/main/binder/ECCO.ipynb

b) Query and access multiple NASA granules of Atmos data:  https://github.com/OPENDAP/NASA-tutorials/blob/main/binder/MERRA-2_Access.ipynb

c) Simple demo on searching and Cloud OPeNDAP urls for ECOSTRESS data via CMR.  https://github.com/OPENDAP/NASA-tutorials/blob/main/binder/CMR_queries.ipynb 

To search the right data via python, you at a minimum need the Concept Collection ID, or the DOI of the dataset you are interested. You can find this information for the relevant data products you are interested, in the following links:

www.earthdata.nasa.gov/data/catalog/lpcloud-mod11c3-061

www.earthdata.nasa.gov/data/catalog/lpcloud-mod13c2-061

Finally. The URLs may change as the service migrates to the cloud. But the protocols (DAP4 for example) remains the same.

Thanks again for reaching out!

Miguel Jimenez-Urias, PhD
Computational Oceanographer | Sc. Community Director
OPeNDAP, Inc

https://www.linkedin.com/in/MiguelJimenezUrias/