The definitions come from datamatch::bathymetry_variables(), which owns them
so every consumer describes a covariate identically.
Details
These are static — they do not vary by month or year — so they are fetched
once for the study area and attached to every time step, unlike the Copernicus
covariates. They replace the SRTM30 depth, slope, and distance-to-shore layers
the original model used (original/load_covars.R lines 98-104), which came
from a server that no longer exists.
Fetching and attaching are datamatch::fetch_bathymetry() and
datamatch::attach_bathymetry() directly; this package only supplies the
study area and cache location from a config.
References
NOAA National Centers for Environmental Information (2022). ETOPO 2022
15 Arc-Second Global Relief Model. doi:10.25921/fd45-gt74
— the terrain
itself; datamatch::fetch_bathymetry() requests its 60 arc-second bedrock
grid
Pante E, Simon-Bouhet B (2013). marmap: a package for importing, plotting and analyzing bathymetric and topographic data in R. PLoS ONE 8(9), e73051. doi:10.1371/journal.pone.0073051 — how it is downloaded
Examples
names(bathymetry_covariates())
#> [1] "DEPTH" "SLOPE" "ASPECT" "TPI"