Extract Weather Data From the NASA POWER API Using Australian GPS Coordinates

Extracts satellite and modelled weather data from the NASA POWER API at the GPS points provided. This is a wrapper for nasapower::get_power() that will only work with Australian locations.

Usage

extract_power(
  x,
  start_date,
  end_date,
  pars,
  community,
  temporal_api = NULL,
  site_elevation = NULL,
  wind_elevation = NULL,
  wind_surface = NULL,
  temporal_average = NULL,
  time_standard = "LST"
)

Source

https://power.larc.nasa.gov/

Arguments

x

List. An object with names containing vector pairings of longitude and latitude values expressed as decimal degree values in that order, each individual vectors' items should be named "x" (longitude) and "y" (latitude), respectively. The list item names should be descriptive of the individual vectors and will be included in a "location" column of the output.

start_date

Integer. A string representing the start date of the query in the format 'yyyymmdd' (ISO-8601). Not used when temporal_api is set to “climatology”. See argument details for more.

end_date

Integer. A string representing the end date of the query in the format 'yyyymmdd' (ISO-8601). Not used when temporal_api is set to “climatology”. See argument details for more.

pars

A character vector of solar, meteorological or climatology parameters to download. When requesting a single point of x, y coordinates, a maximum of twenty (20) pars can be specified at one time, for “daily”, “monthly” and “climatology” temporal_apis. If the temporal_api is specified as “hourly” only 15 pars can be specified in a single query. See temporal_api for more.

community

A character vector providing community name: “ag”, “re” or “sb”. See argument details for more.

temporal_api

Temporal API end-point for data being queried, supported values are “hourly”, “daily”, “monthly” or “climatology”. See argument details for more.

site_elevation

A user-supplied value for elevation at a single point in metres. If provided this will return a corrected atmospheric pressure value adjusted to the elevation provided.

wind_elevation

A user-supplied value for elevation at a single point in metres. Wind Elevation values in Meters are required to be between 10m and 300m. If this parameter is provided, the wind-surface parameter is required with the request, see https://power.larc.nasa.gov/docs/methodology/meteorology/wind/.

wind_surface

A user-supplied wind surface for which the corrected wind-speed is to be supplied. See wind-surface section for more detail.

temporal_average

Deprecated. This argument has been superseded by temporal_api to align with the new POWER API terminology.

time_standard

POWER provides two different time standards:

Universal Time Coordinated (UTC): is the standard time measure that used by the world.
Local Solar Time (LST): a 15 Degrees swath that represents solar noon at the middle longitude of the swath. Defaults to LST.

Value

A data.table::data.table with data from the POWER API.

Argument details for “community”

there are three valid values, one must be supplied. This will affect the units of the parameter and the temporal display of time series data.

ag: Provides access to the Agroclimatology Archive, which contains industry-friendly parameters formatted for input to crop models.
sb: Provides access to the Sustainable Buildings Archive, which contains industry-friendly parameters for the buildings community to include parameters in multi-year monthly averages.
re: Provides access to the Renewable Energy Archive, which contains parameters specifically tailored to assist in the design of solar and wind powered renewable energy systems.

Argument details for `temporal_api`

There are four valid values.

hourly: The hourly average of pars by hour, day, month and year, the time zone is LST by default.
daily: The daily average of pars by day, month and year.
monthly: The monthly average of pars by month and year.
climatology: Provide parameters as 22-year climatologies (solar) and 30-year climatologies (meteorology); the period climatology and monthly average, maximum, and/or minimum values.

Argument details for `x`

For a single point: To get a specific cell, 1/2 x 1/2 degree, supply a length-two numeric vector giving the decimal degree longitude and latitude in that order for data to download,
e.g., lonlat = c(-179.5, -89.5).
For regional coverage: To get a region, supply a length-four numeric vector as lower left (lon, lat) and upper right (lon, lat) coordinates, e.g., lonlat = c(xmin, ymin, xmax, ymax) in that order for a given region, e.g., a bounding box for the south western corner of Australia: lonlat = c(112.5, -55.5, 115.5, -50.5). *Maximum area processed is 4.5 x 4.5 degrees (100 points).

Argument details for `dates`

if one date only is provided, it will be treated as both the start date and the end date and only a single day's values will be returned, e.g., dates = "1983-01-01". When temporal_api is set to “monthly”, use only two year values (YYYY), e.g. dates = c(1983, 2010). This argument should not be used when temporal_api is set to “climatology” and will be ignored if set.

Argument details for `wind_surface`

There are 17 surfaces that may be used for corrected wind-speed values using the following equation: $$WSC_hgt = WS_10m\times(\frac{hgt}{WS_50m})^\alpha$$ Valid surface types are described here.

vegtype_1: 35-m broadleaf-evergreen trees (70% coverage)
vegtype_2: 20-m broadleaf-deciduous trees (75% coverage)
vegtype_3: 20-m broadleaf and needleleaf trees (75% coverage)
vegtype_4: 17-m needleleaf-evergreen trees (75% coverage)
vegtype_5: 14-m needleleaf-deciduous trees (50% coverage)
vegtype_6: Savanna:18-m broadleaf trees (30%) & groundcover
vegtype_7: 0.6-m perennial groundcover (100%)
vegtype_8: 0.5-m broadleaf shrubs (variable %) & groundcover
vegtype_9: 0.5-m broadleaf shrubs (10%) with bare soil
vegtype_10: Tundra: 0.6-m trees/shrubs (variable %) & groundcover
vegtype_11: Rough bare soil
vegtype_12: Crop: 20-m broadleaf-deciduous trees (10%) & wheat
vegtype_20: Rough glacial snow/ice
seaice: Smooth sea ice
openwater: Open water
airportice: Airport: flat ice/snow
airportgrass: Airport: flat rough grass

Author

Adam H. Sparks, adamhsparks@gmail.com

Examples

if (FALSE) { # interactive()
locs <- list(
  "Merredin" = c(x = 118.28, y = -31.48),
  "Corrigin" = c(x = 117.87, y = -32.33),
  "Tamworth" = c(x = 150.84, y = -31.07)
  )

extract_power(
  x = locs,
  start_date = "19850101",
  end_date = "19850101",
  community = "ag",
  pars = c("RH2M", "T2M", "PRECTOTCORR"),
  temporal_api = "daily"
)
}