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Get NASA POWER data from the POWER API

Source: R/get_power.R
get_power.Rd

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.

Usage

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")
)

Arguments

community

A case-insensitive character vector providing community name: “AG”, “RE” or “SB”. See argument details for more.

pars

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.

temporal_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.

lonlat

A numeric vector of geographic coordinates for a cell or region entered as x, y (longitude, latitude) coordinates. See argument details for more.

dates

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.

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. Only used with lonlat as a single point of x, y coordinates, not for use with “global” or with a regional request.

wind_elevation

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/.

wind_surface

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

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 degree swath that represents solar noon at the middle longitude of the swath. Defaults to LST.

Value

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.

Note

The associated metadata shown in the decorative header are not saved if the data are exported to a file format other than a native R data format, e.g., .Rdata, .rda or .rds.

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 lonlat

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).

For global coverage

To get global coverage for “climatology”, supply “global” while also specifying “climatology” for the temporal_api.

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.

wind_surface

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.

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

Rate limiting

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.

References

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

Author

Adam H. Sparks adamhsparks@gmail.com

Examples

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
}