download.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.
download.met(
id,
year,
month,
deltat,
type = "xml",
destdir = ".",
destfile,
force = FALSE,
quiet = FALSE,
debug = getOption("oceDebug")
)String indicating the full pathname to the downloaded file.
A number giving the "Station ID" of the station of interest. If not
provided, id defaults to 6358, for Halifax International Airport. See
“Details”.
A number giving the year of interest. Ignored unless deltat
is "hour". If year is not given, it defaults to the present year.
A number giving the month of interest. Ignored unless deltat
is "hour". If month is not given, it defaults to the present
month.
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".
String indicating which type of file to download, either
"xml" (the default) for an XML file or "csv" for a CSV file.
Optional string indicating the directory in which to store
downloaded files. If not supplied, "." is used, i.e. the data file
is stored in the present working directory.
Optional string indicating the name of the file. If not supplied, the file name is constructed from the other parameters of the function call, so subsequent calls with the same parameters will yield the same result, thus providing the key to the caching scheme.
Logical value indicating whether to force a download, even if the file already exists locally.
Logical value passed to download.file(); a TRUE value
silences output.
an integer specifying whether debugging information is
to be printed during the processing. This is a general parameter that
is used by many oce functions. Generally, setting debug=0
turns off the printing, while higher values suggest that more information
be printed. If one function calls another, it usually reduces the value of
debug first, so that a user can often obtain deeper debugging
by specifying higher debug values.
library(oce)
# Download data for Halifax International Airport, in September
# of 2003. This dataset is used for data(met) provided with oce.
# Note that requests for data after 2012 month 10 yield all
# missing values, for reasons unknown to the author.
metFile <- download.met(6358, 2003, 9, destdir=".")
met <- read.met(metFile)
Dan Kelley
If this function fails, users might try using Gavin Simpson's canadaHCD
package (reference 2). This package maintains a copy of the Environment
Canada listing of stations, and its find_station() function provides an easy
way to determine Station IDs. After that, its hcd_hourly function (and
related functions) make it easy to read data. These data can then be
converted to the met class with as.met(), although doing so leaves many
important metadata blank.
Environment Canada website for Historical Climate Data
https://climate.weather.gc.ca/index_e.html
Gavin Simpson's canadaHCD package on GitHub
https://github.com/gavinsimpson/canadaHCD
The work is done with utils::download.file().
Other functions that download files:
download.amsr(),
download.coastline(),
download.topo()
Other things related to met data:
[[,met-method,
[[<-,met-method,
as.met(),
met,
met-class,
plot,met-method,
read.met(),
subset,met-method,
summary,met-method