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Search NASA CMR for GEDI or ICESat-2 granules

Source: R/search.R
sl_search.Rd

Searches NASA's Common Metadata Repository (CMR) for satellite lidar granules that overlap a bounding box and optional date range. The sensor (GEDI or ICESat-2) is determined automatically from product, since the valid product strings do not overlap.

Usage

sl_search(
  bbox,
  product = c("L2A", "L2B", "L4A", "L4C", "L1B", "ATL03", "ATL06", "ATL07", "ATL08",
    "ATL10", "ATL13", "ATL24"),
  date_start = NULL,
  date_end = NULL
)

Arguments

bbox

An sl_bbox object created by sl_bbox(), or a numeric vector c(xmin, ymin, xmax, ymax).

product

Character. One of:

  • GEDI: "L1B", "L2A", "L2B", "L4A", "L4C"

  • ICESat-2: "ATL03", "ATL06", "ATL07", "ATL08", "ATL10", "ATL13", "ATL24"

date_start, date_end

Either a Date object or a character string in strict "YYYY-MM-DD" format (e.g. "2020-06-01"). Other character forms (e.g. "01/06/2020", "June 1 2020", "2020-06") are rejected with an informative error to avoid ambiguity. POSIXct inputs are not accepted — format them explicitly with format(x, "%Y-%m-%d").

Bounds are treated as UTC and inclusive of the end date: a range of "2020-06-01" to "2020-06-30" covers every granule whose start time falls on any of those 30 days.

date_start defaults to the mission start (2019-03-25 for GEDI, 2018-10-14 for ICESat-2). date_end defaults to today.

Value

A classed data frame (sl_gedi_search or sl_icesat2_search) with columns:

id

CMR granule identifier.

time_start

POSIXct start time of the granule.

time_end

POSIXct end time of the granule.

url

HTTPS data URL.

geometry

wk_wkt polygon of the granule swath footprint.

The returned object carries bbox and product as attributes so sl_read() can dispatch without re-specifying them.

Details

No authentication is needed for the search itself; Earthdata credentials are only required when reading data via sl_read().

The CMR search filters by bounding box on the server side. For finer spatial filtering (e.g. against an irregular polygon), filter the returned geometry column with your favourite spatial package.

See also

sl_read() to read data from the returned granules.

Examples

if (FALSE) { # interactive()
# GEDI L2A over a small Pacific Northwest forest bbox, summer 2020.
granules <- sl_search(
  sl_bbox(-124.04, 41.39, -124.01, 41.42),
  product    = "L2A",
  date_start = "2020-06-01",
  date_end   = "2020-09-01"
)
granules

# ICESat-2 ATL08 (land + canopy segments) over the same bbox, 2020.
sl_search(
  sl_bbox(-124.10, 41.36, -124.00, 41.45),
  product    = "ATL08",
  date_start = "2020-01-01",
  date_end   = "2021-01-01"
)
}