Data are downloaded from http://climate.weather.gc.ca and cached locally.
download.met(id, year, month, deltat, destdir = ".", destfile,
debug = getOption("oceDebug"))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".
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.
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.
String indicating the full pathname to the downloaded file.
The data are downloaded with download.file
pointed to the Environment Canada website [1]
using queries that had to be devised by reverse-engineering, since the agency
does not provide documentation about how to construct queries. Caution: the
query format changes from time to time, so download.met may work one
day, and fail the next.
The constructed query contains Station ID, as provided in the id argument.
Note that this seems to be a creation of Environment Canada, alone;
it is distinct from the more standard "Climate ID" and "WMO ID".
To make things more difficult, Environment Canada states that the
Station ID is subject to change over time. (Whether this applies to existing
data is unclear.)
Given these difficulties with Station ID, users are advised to consult
the Environment Canada website [1] before downloading any data,
and to check it from time to time
during the course of a research project, to see if the Station ID has changed.
Another approach would be to use Gavin Simpson's
canadaHCD package [2] to look up Station IDs. 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.
1. Environment Canada website for Historical Climate Data http://climate.weather.gc.ca/index_e.html
2. Gavin Simpon's canadaHCD package on GitHub
https://github.com/gavinsimpson/canadaHCD
The work is done with 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-class, met,
plot,met-method, read.met,
subset,met-method,
summary,met-method
# NOT RUN {
library(oce)
## Download data for Halifax International Airport, in September
## of 2003. (This dataset is used for data(met) provided with oce.)
metFile <- download.met(6358, 2003, 9, destdir=".")
met <- read.met(metFile)
# }
# NOT RUN {
# }
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