Download meteorological timeseries data

dod.met() attempts to download data from Environment Canada's historical-data website, and to cache the files locally. Lacking a published API, this function must rely on reverse-engineering of queries handled by that web server. For that reason, it is brittle.

Usage

dod.met(
  id,
  year,
  month,
  deltat,
  type = "xml",
  destdir = ".",
  age = 1,
  debug = 0
)

Arguments

id

a number giving the "Station ID" of the station of interest. If not provided, id defaults to 43405, for Halifax Dockyard. (Previously, the default was 6358, for Halifax International Airport, but in March 2024 it was noticed that 6358 held no data.) See “Details”.

year

a number giving the year of interest. Ignored unless deltat is "hour". If year is not given, it defaults to the present year.

month

a number giving the month of interest. Ignored unless deltat is "hour". If month is not given, it defaults to the present month. As a special case, if neither year nor month is given, and it is the first day of the month, dod.met() goes back one month, to avoid returning a file with no data.

deltat

an optional character string indicating the time step of the desired dataset. This may be "hour" or "month". If deltat is not given, it defaults to "hour".

type

a character value indicating which type of file to download, either "xml" (the default) for an XML file or "csv" for a CSV file.

destdir

a character value indicating the directory in which to store downloaded files.

age

a numerical value indicating a time interval, in days. If the file to be downloaded from the server already exists locally, and was created less than age days in the past, it will not be downloaded again. Setting age=0 forces a download, so that existing files will always be updated. By contrast, setting age to a negative number prevents the updating of files that already exist locally, regardless of their age.

debug

an integer value indicating the level of debugging. If this exceeds 0, then some debugging messages will be printed. This value is passed down to related functions, but with 1 subtracted for each pass.

Value

dod.met() returns a character value holding the full pathname of the downloaded file.

Details

If this function fails, users might try using Gavin Simpson's canadaHCD package (reference 2) or the weathercan package (reference 3).

References

1. Environment Canada website for Historical Climate Data https://climate.weather.gc.ca/index_e.html

2. Gavin Simpson's canadaHCD package on GitHub https://github.com/gavinsimpson/canadaHCD

3. Weathercan package https://github.com/ropensci/weathercan/tree/main

See also

Other functions that download files: dod.amsr(), dod.buoy(), dod.coastline(), dod.ctd(), dod.ctd.bats(), dod.ctd.bbmp(), dod.ctd.gtspp(), dod.ctd.itp(), dod.tideGauge(), dod.topo()

Author

Dan Kelley

Examples

# Meteorological data for Halifax, Nova Scotia.
if (interactive()) { # sidestep a pkgdown::build_site() error
    # NOTE: data file is removed at end, to pass CRAN checks
    library(dod)
    destdir <- tempdir()
    metFile <- dod.met(43405, destdir = destdir)
    if (requireNamespace("oce", quietly = TRUE) &&
        requireNamespace("XML", quietly = TRUE)) {
        library(oce)
        met <- read.met(metFile)
        t <- met[["time"]]
        p <- met[["pressure"]]
        oce.plot.ts(t, p, ylab = "Atm. Pressure [Pa]")
    }
    unlink(destdir, recursive = TRUE)
}