calculate_modis_daily: A single-date MODIS worker

In amadeus: Accessing and Analyzing Large-Scale Environmental Data

A single-date MODIS worker

Description

The function operates at MODIS/VIIRS products on a daily basis. Given that the raw hdf files are downloaded from NASA, standard file names include a data retrieval date flag starting with letter "A". Leveraging that piece of information, the function will select files of scope on the date of interest. Please note that this function does not provide a function to filter swaths or tiles, so it is strongly recommended to check and pre-filter the file names at users' discretion.

Usage

calculate_modis_daily(
  from = NULL,
  locs = NULL,
  locs_id = "site_id",
  radius = 0L,
  date = NULL,
  name_extracted = NULL,
  fun_summary = "mean",
  max_cells = 3e+07,
  geom = FALSE,
  ...
)

Arguments

from	SpatRaster. Preprocessed objects.
locs	SpatVector/sf/sftime object. Locations where MODIS values are summarized.
locs_id	character(1). Field name where unique site identifiers are stored. Default is "site_id"
radius	numeric. Radius to generate circular buffers.
date	Date(1). date to query.
name_extracted	character. Names of calculated covariates.
fun_summary	function. Summary function for multilayer rasters. Passed to foo. See exactextractr::exact_extract for details.
max_cells	integer(1). Maximum number of cells to be read at once. Higher values will expedite processing, but will increase memory usage. Maximum possible value is 2^31 - 1.
geom	FALSE/"sf"/"terra".. Should the function return with geometry? Default is FALSE, options with geometry are "sf" or "terra". The coordinate reference system of the sf or SpatVector is that of from. See exactextractr::exact_extract for details.
...	Placeholders.

Value

a data.frame or SpatVector object.

Author(s)

Insang Song

See Also

• Preprocessing: process_modis_merge(), process_modis_swath(), process_blackmarble()

Examples

## NOTE: Example is wrapped in `\dontrun{}` as function requires a large
##       amount of data which is not included in the package.
## Not run: 
locs <- data.frame(lon = -78.8277, lat = 35.95013, id = "001")
calculate_modis_daily(
  from = mod06l2_warp, # dervied from process_modis() example
  locs = locs,
  locs_id = "id",
  radius = 0,
  date = "2024-01-01",
  name_extracted = "cloud_fraction_0",
  fun_summary = "mean",
  max_cells = 3e7
)

## End(Not run)

amadeus documentation built on April 4, 2025, 12:21 a.m.