Automates downloading, cleaning, reformatting of data from the Global Surface Summary of the Day (GSOD) data provided by the [US National Centers for Environmental Information (NCEI)(https://www.ncei.noaa.gov/access/metadata/landing-page/bin/iso?id=gov.noaa.ncdc:C00516), Three additional useful elements: saturation vapour pressure (es), actual vapour pressure (ea) and relative humidity (RH) are calculated and returned in the final data frame using the improved August-Roche-Magnus approximation (Alduchov and Eskridge 1996).
Usage
get_GSOD(
years,
station = NULL,
country = NULL,
max_missing = NULL,
agroclimatology = FALSE
)Arguments
- years
Year(s) of weather data to download.
- station
Optional. Specify a station or multiple stations for which to retrieve, check and clean weather data using STATION. The NCEI reports years for which the data are available. This function checks against these years. However, not all cases are properly documented and in some cases files may not exist for download even though it is indicated that data was recorded for the station for a particular year. If a station is specified that does not have an existing file on the server, this function will silently fail and move on to existing files for download and cleaning.
- country
Optional. Specify a country for which to retrieve weather data; full name, 2 or 3 letter ISO or 2 letter FIPS codes can be used. All stations within the specified country will be returned.
- max_missing
Optional. The maximum number of days allowed to be missing from a station's data before it is excluded from final file output.
- agroclimatology
Optional. Logical. Only clean data for stations between latitudes 60 and -60 for agroclimatology work, defaults to
FALSE. Set toTRUEto include only stations within the confines of these latitudes.
Value
A data.table::data.table() object of GSOD weather data.
Details
All units are converted to International System of Units (SI), e.g, Fahrenheit to Celsius and inches to millimetres.
Data summarise each year by station, which include vapour pressure and relative humidity elements calculated from existing data in GSOD.
All missing values in resulting files are represented as NA regardless of
which field they occur in.
For a complete list of the fields and description of the contents and units,
please refer to Appendix 1 in the GSODR vignette,
vignette("GSODR", package = "GSODR").
For more information see the description of the data provided by NCEI, https://www.ncei.noaa.gov/data/global-summary-of-the-day/doc/readme.txt.
Note
GSODR attempts to validate year and station combination
requests, however, in certain cases the start and end date may encompass
years where no data is available. In these cases no data will be returned.
It is suggested that the user check the latest data availability for the
station(s) desired using get_inventory() as this list is frequently
updated by the NCEI and is not shipped with GSODR.
While GSODR does not distribute GSOD weather data, users of the data should note the conditions that the U.S. NCEI places upon the GSOD data. “The following data and products may have conditions placed on their international commercial use. They can be used within the U.S. or for non- commercial international activities without restriction. The non-U.S. data cannot be redistributed for commercial purposes. Re-distribution of these data by others must provide this same notification. A log of IP addresses accessing these data and products will be maintained and may be made available to data providers.”
References
Alduchov, O.A. and Eskridge, R.E., 1996. Improved Magnus form approximation of saturation vapor pressure. Journal of Applied Meteorology and Climatology, 35(4), pp.601-609. DOI: <10.1175%2F1520-0450%281996%29035%3C0601%3AIMFAOS%3E2.0.CO%3B2>.
Author
Adam H. Sparks, adamhsparks@gmail.com
Examples
if (FALSE) { # interactive()
# Download weather station data for Toowoomba, Queensland for 2010
tbar <- get_GSOD(years = 2010, station = "955510-99999")
# Download weather data for the year 1929
w_1929 <- get_GSOD(years = 1929)
# Download weather data for the year 1929 for Ireland
ie_1929 <- get_GSOD(years = 1929, country = "Ireland")
}