Import "Lite" Meteorological data from the NOAA Integrated Surface Database (ISD)

This function is an alternative to importNOAA(), and provides access to the "Lite" format of the data. This a subset of the larger importNOAA() dataset featuring eight common climatological variables. As it assigns the nearest measurement to the "top of the hour" to the data, specific values are likely similar but different to those returned by importNOAA(). Read the technical document for more information.

Usage

importNOAAlite(code = "037720-99999", year = 2025, quiet = FALSE, path = NA)

Arguments

code: The identifying code as a character string. The code is a combination of the USAF and the WBAN unique identifiers. The codes are separated by a “-” e.g. code = "037720-99999".
year: The year to import. This can be a vector of years e.g. year = 2000:2005.
quiet: If FALSE, print missing sites / years to the screen, and show a progress bar if multiple sites are imported.
path: If a file path is provided, the data are saved as an rds file at the chosen location e.g. path = "C:/Users/David". Files are saved by year and site.

Value

Returns a data frame of surface observations. The data frame is consistent for use with the openair package. Note that the data are returned in GMT (UTC) time zone format. Users may wish to express the data in other time zones, e.g., to merge with air pollution data. The lubridate package is useful in this respect.

Details

Note the following units for the main variables:

date: Date/time in POSIXct format. **Note the time zone is UTC and may need to be adjusted to merge with other local data.
latitude: Latitude in decimal degrees (-90 to 90).
longitude: Longitude in decimal degrees (-180 to 180). Negative numbers are west of the Greenwich Meridian.
elev: Elevation of site in metres.
ws: Wind speed in m/s.
wd: Wind direction in degrees. 90 is from the east.
air_temp: Air temperature in degrees Celcius.
atmos_pres: The sea level pressure in millibars.
dew_point: The dew point temperature in degrees Celcius.
precip_6: 6-hour precipitation in mm.
precip_1: 1-hour precipitation in mm.
sky: Sky Condition Total Coverage Code.

The data are returned in GMT (UTC). It may be necessary to adjust the time zone when combining with other data. For example, if air quality data were available for Beijing with time zone set to "Etc/GMT-8" (note the negative offset even though Beijing is ahead of GMT. See the openair package and manual for more details), then the time zone of the met data can be changed to be the same. One way of doing this would be attr(met$date, "tzone") <- "Etc/GMT-8" for a meteorological data frame called met. The two data sets could then be merged based on date.

Parallel Processing

If you are importing a lot of meteorological data, this can take a long while. This is because each combination of year and station requires downloading a separate data file from NOAA's online data directory, and the time each download takes can quickly add up. importNOAA() and importNOAAlite() can use parallel processing to speed downloading up, powered by the capable {mirai} package. If users have any {mirai} "daemons" set, these functions will download files in parallel. The greatest benefits will be seen if you spawn as many daemons as you have cores on your machine, although one fewer than the available cores is often a good rule of thumb. Your mileage may vary, however, and naturally spawning more daemons than station-year combinations will lead to diminishing returns.

# set workers - once per session
mirai::daemons(4)

# import lots of data - NB: no change in importNOAA()!
big_met <- importNOAA(code = "037720-99999", year = 2010:2020)

Author

Jack Davison

Examples


if (FALSE) { # \dontrun{
heathrow_lite <- importNOAAlite(code = "037720-99999", year = 2025)
} # }