Queries NASA's Common Metadata Repository (CMR) to search Earth science datasets related to a specified keyword. Optionally filters results by a temporal range.
Arguments
- keyword
Character. A search term or phrase used to find relevant datasets in titles, descriptions, keywords, and provider names.
- n_results
Integer. The number of dataset entries to retrieve. If more than 2000, multiple pages will be requested automatically.
- start_date
Character or NULL. Optional start date filter in "YYYY-MM-DD" format. If provided, must be used with
end_date.- end_date
Character or NULL. Optional end date filter in "YYYY-MM-DD" format. If provided, must be used with
start_date.
Value
A data frame containing metadata about the matching datasets, with only cleaned column names (columns with '.' or '$' removed).
Details
CMR is the Earthdata search engine, the backend database that stores metadata about:
- Satellite datasets - Earth science data (climate, ocean, atmosphere, land) - Observational granules (single files like images, temperature readings, etc.) - Services (subsetting, reformatting, and other data services)
The search finds matches based on the keyword provided. The keyword can appear in:
- Dataset titles - Dataset descriptions - Dataset keywords (tags) - Some provider names
The function accesses the CMR API endpoint:
https://cmr.earthdata.nasa.gov/
search/collections.json
(Note: This is an API endpoint and may return an error when opened in a browser.)
It harmonizes columns across API pages and returns up to the number of requested results.
If no results are found, an empty data frame is returned.
Examples
if (FALSE) { # \dontrun{
# Search for 1 dataset related to sea surface temperature
results <- get_earthdata(keyword = "sea surface temperature", n_results = 1)
# Search with a temporal constraint
results_time <- get_earthdata(
keyword = "sea surface temperature",
n_results = 1,
start_date = "2020-01-01",
end_date = "2020-01-02"
)
} # }