Get POWER global meteorology and surface solar energy
climatology data and return a tidy data frame tibble::tibble()
object. All options offered by the official POWER API
are supported. Requests are formed to submit one request per point.
There is no need to make synchronous requests for multiple parameters for
a single point or regional request. See section on “Rate Limiting”
for more.
get_power(
community = c("ag", "re", "sb"),
pars,
temporal_api = c("daily", "monthly", "hourly", "climatology"),
lonlat,
dates = NULL,
site_elevation = NULL,
wind_elevation = NULL,
wind_surface = NULL,
time_standard = c("LST", "UTC")
)A data frame as a POWER.Info class, an extension of the
tibble::tibble, object of POWER data including location, dates
(not including “climatology”) and requested parameters; a decorative
header of metadata is included in this object.
A case-insensitive character vector providing community name: “AG”, “RE” or “SB”. See argument details for more.
case-insensitive 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. These values are checked internally for validity before sending the
query to the POWER API.
A case-insensitive character vector providing the temporal API end-point for data being queried, supported values are “hourly”, “daily”, “monthly” or “climatology”. Defaults to “daily”. See argument details for more.
A numeric vector of geographic coordinates for a cell or region entered as x, y (longitude, latitude) coordinates. See argument details for more.
A character vector of start and end dates in that order,
e.g., dates = c("1983-01-01", "2017-12-31").
Not used when
temporal_api is set to “climatology”.
See argument details for more.
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. Only used with lonlat as a
single point of x, y coordinates, not for use with “global” or with
a regional request.
A user-supplied value for elevation at a single point
in metres. Wind elevation values are required to be between 10 and 300
metres. Only used with lonlat as a single point of x, y coordinates,
not for use with “global” or with a regional request. If this
parameter is provided, the wind_surface parameter is required with the
request, see
https://power.larc.nasa.gov/docs/methodology/meteorology/wind/.
A user-supplied wind surface for which the corrected
wind-speed is to be supplied. See wind-surface section for more detail.
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 degree swath that represents
solar noon at the middle longitude of the swath.
Defaults to LST.
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.
Provides access to the Agroclimatology Archive, which contains industry-friendly parameters formatted for input to crop models.
Provides access to the Sustainable Buildings Archive, which contains industry-friendly parameters for the buildings community to include parameters in multi-year monthly averages.
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.
There are four valid values.
The hourly average of pars by hour, day, month and year,
the time zone is LST by default.
The daily average of pars by day, month and year.
The monthly average of pars by month and year.
Provide parameters as 22-year climatologies (solar) and 30-year climatologies (meteorology); the period climatology and monthly average, maximum, and/or minimum values.
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).
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).
To get global coverage for “climatology”,
supply “global” while also specifying “climatology” for the
temporal_api.
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.
There are 17 surfaces that may be used for corrected wind-speed values using the following equation: $$ WSC_hgt = WS_10 m\times(\frac{hgt}{WS_50m})^\alpha$$ Valid surface types are described here.
35-m broadleaf-evergreen trees (70% coverage)
20-m broadleaf-deciduous trees (75% coverage)
20-m broadleaf and needleleaf trees (75% coverage)
17-m needleleaf-evergreen trees (75% coverage)
14-m needleleaf-deciduous trees (50% coverage)
Savanna:18-m broadleaf trees (30%) & groundcover
0.6-m perennial groundcover (100%)
0.5-m broadleaf shrubs (variable %) & groundcover
0.5-m broadleaf shrubs (10%) with bare soil
Tundra: 0.6-m trees/shrubs (variable %) & groundcover
Rough bare soil
Crop: 20-m broadleaf-deciduous trees (10%) & wheat
Rough glacial snow/ice
Smooth sea ice
Open water
Airport: flat ice/snow
Airport: flat rough grass
The POWER API endpoints limit
queries to prevent server overloads due to repetitive and rapid requests.
If you find that the API is throttling your queries, I suggest
that you investigate the use of limit_rate() from ratelimitr to
create self-limiting functions that will respect the rate limits that the
API has in place. It is considered best practice to check the
POWER website for the
latest rate limits as they differ between temporal APIs and may
change over time as the project matures.
Adam H. Sparks adamhsparks@gmail.com
https://power.larc.nasa.gov/docs/methodology/ https://power.larc.nasa.gov
if (FALSE) { # interactive()
# Fetch daily "AG" community temperature, relative humidity and
# precipitation for January 1 1985 at Kingsthorpe, Queensland, Australia
ag_d <- get_power(
community = "AG",
lonlat = c(151.81, -27.48),
pars = c("RH2M", "T2M", "PRECTOTCORR"),
dates = "1985-01-01",
temporal_api = "daily"
)
ag_d
# Fetch single point climatology for air temperature
ag_c_point <- get_power(
community = "AG",
pars = "T2M",
c(151.81, -27.48),
temporal_api = "climatology"
)
ag_c_point
# Fetch interannual solar cooking parameters for a given region
sse_i <- get_power(
community = "RE",
lonlat = c(112.5, -55.5, 115.5, -50.5),
dates = c("1984", "1985"),
temporal_api = "monthly",
pars = c("CLRSKY_SFC_SW_DWN", "ALLSKY_SFC_SW_DWN")
)
sse_i
}
Run the code above in your browser using DataLab