Describe any FVCOM archive, so it can be read like a built-in one

fvcom_archives() ships the NECOFS Gulf of Maine hindcast because that is what one server publishes. FVCOM itself is run for coastlines everywhere, by groups who publish on their own THREDDS servers, and this is how to reach any of them: point it at an OPeNDAP endpoint and it works out the rest.

Usage

fvcom_archive(
  url,
  label = NULL,
  reference = NA_character_,
  frequency = "monthly"
)

Arguments

url

the OPeNDAP endpoint, as a THREDDS dodsC URL

label

a human-readable name; defaults to the URL

reference

the citation for this model run, if there is one. FVCOM output is somebody's work, and this is where to record whose.

frequency

what one time step represents, for documentation

Value

a list in the shape fvcom_archives() entries take, ready to pass to accessFVCOM() as archive

Details

The reader depends on FVCOM's structure rather than on the region, so anything written by FVCOM should work — values on nodes and element centroids, sigma layers, lon/lat and lonc/latc, and an Itime day count. What differs between deployments is the mesh, the period, and which variables were saved, all of which are read from the file.

What it checks

The endpoint is opened and inspected once, so a URL that is wrong, blocked, or not FVCOM fails here — with the reason — rather than part-way through a fetch. The mesh size, time span, and variable list come back in the returned spec, so str() on it says what the archive actually holds.

A caution about aggregations

Point this at an aggregation of hourly output and it may not open at all. nc_open() reads the whole time coordinate first, and a decade of hourly fields is enough time steps to exceed a server's DAP timeout — which is exactly why the built-in GOM3 entry is the monthly mean. Prefer a monthly aggregation, or a single file, over a long hourly one.

See also

accessFVCOM(), fvcom_archives()

Examples

if (FALSE) { # \dontrun{
# Any FVCOM endpoint, not just the built-in ones
mine <- fvcom_archive(
  "http://www.smast.umassd.edu:8080/thredds/dodsC/fvcom/hindcasts/30yr_gom3/mean",
  label = "GOM3 monthly means")

str(mine)   # mesh size, period, and variables actually present

env <- accessFVCOM(vars = "SST", years = 2010, months = 1:12,
                   bounding_box = bb, archive = mine)
} # }