ghcnd: Get all GHCND data from a single weather site

Description Usage Arguments Details Value Base URL Note Author(s) See Also Examples

View source: R/ghcnd.R

Description

This function uses ftp to access the Global Historical Climatology Network daily weather data from NOAA's FTP server for a single weather site. It requires the site identification number for that site and will pull the entire weather dataset for the site.

Usage

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ghcnd(stationid, refresh = FALSE, ...)

ghcnd_read(path, ...)

Arguments

stationid

(character) A character vector giving the identification of the weather stations for which the user would like to pull data. To get a full and current list of stations, the user can use the ghcnd_stations() function. To identify stations within a certain radius of a location, the user can use the meteo_nearby_stations() function.

refresh

(logical) If TRUE force re-download of data. Default: FALSE

...

In the case of ghcnd() additional curl options to pass through to crul::HttpClient. In the case of ghcnd_read further options passed on to read.csv

path

(character) a path to a file with a .dly extension - already downloaded on your computer

Details

This function saves the full set of weather data for the queried site locally in the directory specified by the path argument.

You can access the path for the cached file via attr(x, "source")

You can access the last modified time for the cached file via attr(x, "file_modified")

Messages are printed to the console about file path and file last modified time which you can suppress with suppressMessages()

For those station ids that are not found, we will delete the file locally so that a bad station id file is not cached. The returned data for a bad station id will be an empty data.frame and the attributes are empty strings.

Value

A tibble (data.frame) which contains data pulled from NOAA's FTP server for the queried weather site. A README file with more information about the format of this file is available from NOAA (http://www1.ncdc.noaa.gov/pub/data/ghcn/daily/readme.txt). This file is formatted so each line of the file gives the daily weather observations for a single weather variable for all days of one month of one year. In addition to measurements, columns are included for certain flags, which add information on observation sources and quality and are further explained in NOAA's README file for the data.

Base URL

The base url for data requests can be changed. The allowed urls are: https://www1.ncdc.noaa.gov/pub/data/ghcn/daily/all (default), ftp://ftp.ncei.noaa.gov/pub/data/ghcn/daily/all, ftp://ftp.ncdc.noaa.gov/pub/data/ghcn/daily/all

You can set the base url using the RNOAA_GHCND_BASE_URL environment variable; see example below.

The reason for this is that sometimes one base url source is temporarily down, but another base url may work. It doesn't make sense to allow an arbitrary base URL; open an issue if there is another valid base URL for GHNCD data that we should add to the allowed set of base urls.

Note

See ghcnd_cache for managing cached files

Author(s)

Scott Chamberlain myrmecocystus@gmail.com, Adam Erickson adam.erickson@ubc.ca

See Also

To generate a weather dataset for a single weather site that has been cleaned to a tidier weather format, the user should use the ghcnd_search() function, which calls ghcnd() and then processes the output, or meteo_tidy_ghcnd(), which wraps the ghcnd_search() function to output a tidy dataframe. To pull GHCND data from multiple monitors, see meteo_pull_monitors()

Examples

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## Not run: 
# Get data
ghcnd(stationid = "AGE00147704")

stations <- ghcnd_stations()
ghcnd(stations$id[40])

library("dplyr")
ghcnd(stations$id[80300]) %>% select(id, element) %>% slice(1:3)

# manipulate data
## using built in fxns
dat <- ghcnd(stationid = "AGE00147704")
(alldat <- ghcnd_splitvars(dat))

## using dplyr
library("dplyr")
dat <- ghcnd(stationid = "AGE00147704")
filter(dat, element == "PRCP", year == 1909)

# refresh the cached file
ghcnd(stationid = "AGE00147704", refresh = TRUE)

# Read in a .dly file you've already downloaded
path <- system.file("examples/AGE00147704.dly", package = "rnoaa")
ghcnd_read(path)

# change the base url for data requests
Sys.setenv(RNOAA_GHCND_BASE_URL =
  "ftp://ftp.ncdc.noaa.gov/pub/data/ghcn/daily/all")
ghcnd(stations$id[45], verbose = TRUE)
## must be in the allowed set of urls
# Sys.setenv(RNOAA_GHCND_BASE_URL = "https://google.com")
# ghcnd(stations$id[58], verbose = TRUE)

## End(Not run)

rnoaa documentation built on May 19, 2021, 9:13 a.m.