GSODR (version 1.0.3)

get_GSOD: Download, clean, reformat generate new elements and return a tidy data.frame of GSOD weather data

Description

This function 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://data.noaa.gov/dataset/global-surface-summary-of-the-day-gsod, and elements three new variables; saturation vapour pressure (es) <U+2013> Actual vapour pressure (ea) and relative humidity (RH). Stations reporting a latitude of < -90 or > 90 or longitude of < -180 or > 180 are removed. Stations may be individually checked for number of missing days to assure data quality and omitting stations with too many missing observations. All units are converted to International System of Units (SI), e.g., Fahrenheit to Celsius and inches to millimetres. Alternative elevation measurements are supplied for missing values or values found to be questionable based on the Consultative Group for International Agricultural Research's Consortium for Spatial Information group's (CGIAR-CSI) Shuttle Radar Topography Mission 90 metre (SRTM 90m) digital elevation data based on NASA's original SRTM 90m data. Further information on these data and methods can be found on GSODR's GitHub repository here: https://github.com/ropensci/GSODR/blob/master/data-raw/fetch_isd-history.md.

Usage

get_GSOD(years = NULL, station = NULL, country = NULL, dsn = NULL,
  filename = NULL, max_missing = NULL, agroclimatology = FALSE,
  CSV = FALSE, GPKG = 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 STNID. 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 on the ftp server 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 from the FTP server.

country

Optional. Specify a country for which to retrieve weather data; full name or ISO codes can be used. See country_list for a full list of country names and ISO codes available.

dsn

Optional. Local file path to write file out to. Must be specified if CSV or GPKG parameters are selected. If unspecified and CSV or GPKG are set to TRUE, dsn will default to the current working directory.

filename

Optional. The filename for resulting file(s) to be written with no file extension. File extension will be automatically appended to file outputs. If unspecified by the user it will default to "GSOD" followed by the file extension(s) set using CSV or GPKG.

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 to TRUE to include only stations within the confines of these latitudes.

CSV

Optional. Logical. If set to TRUE, create a comma separated value (CSV) file and save it locally in a user specified location, if dsn is not specified by the user, defaults to the current working directory.

GPKG

Optional. Logical. If set to TRUE, create a GeoPackage file and save it locally in a user specified location, if dsn is not specified by the user, defaults to the current working directory.

Value

A data.frame object of weather data or a comma-separated value (CSV) or GeoPackage (GPKG) file saved to local disk.

Details

Data summarise each year by station, which include vapour pressure and relative humidity elements calculated from existing data in GSOD.

If the option to save locally is selected. Output may be saved as comma- separated value (CSV) or GeoPackage (GPKG) files in a directory specified by the user, defaulting to the current working directory.

When querying selected stations and electing to write files to disk, all years queried and stations queried will be merged into one final output file.

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 desciption of the contents and units, please refer to the vignette("GSODR_output_fields", package = "GSODR").

For more information see the description of the data provided by NCEI, http://www7.ncdc.noaa.gov/CDO/GSOD_DESC.txt.

References

Jarvis, A., Reuter, H. I, Nelson, A., Guevara, E. (2008) Hole-filled SRTM for the globe Version 4, available from the CGIAR-CSI SRTM 90m Database http://srtm.csi.cgiar.org

See Also

reformat_GSOD

Examples

# NOT RUN {
# Download weather station for Toowoomba, Queensland for 2010
t <- get_GSOD(years = 2010, station = "955510-99999")

# Download data for Philippines for year 2010 and generate a yearly
# summary GeoPackage file, Philippines_GSOD-2010.gpkg, file in the user's
# home directory with a maximum of five missing days per station allowed.

get_GSOD(years = 2010, country = "Philippines", dsn = "~/",
filename = "Philippines_GSOD", GPKG = TRUE, max_missing = 5)

# Download global GSOD data for agroclimatology work for years 2009 and 2010
# and generate yearly summary files, GSOD-agroclimatology-2010.csv and
# GSOD-agroclimatology-2011.csv in the user's home directory.

get_GSOD(years = 2010:2011, dsn = "~/",
filename = "GSOD_agroclimatology_2010-2011", agroclimatology = TRUE,
CSV = TRUE)

# }
# NOT RUN {
# }