Get Daily Climate Data from USDA-NRCS SCAN (Soil Climate Analysis Network) Stations

Query soil/climate data from USDA-NRCS SCAN Stations.

Usage

fetchSCAN(
  site.code = NULL,
  year = NULL,
  report = "SCAN",
  timeseries = c("Daily", "Hourly"),
  tz = "US/Central",
  ...
)

SCAN_sensor_metadata(site.code)

SCAN_site_metadata(site.code = NULL)

Arguments

site.code: a vector of site codes. If NULL SCAN_site_metadata() returns metadata for all SCAN sites and no sensor data.
year: a vector of years
report: report name, single value only; default 'SCAN', other example options include individual sensor codes, e.g. 'SMS' for Soil Moisture Storage, 'TEMP' for temperature
timeseries: either 'Daily' or 'Hourly'
tz: Target timezone to convert datetime columns of results. Default: "US/Central".
...: additional arguments. May include intervalType, format, sitenum, interval, year, month. Presence of additional arguments bypasses default batching functionality provided in the function and submits a 'raw' request to the API form.

Value

a list of data.frame objects, where each element name is a sensor type, plus a metadata table; different report types change the types of sensor data returned. SCAN_sensor_metadata() and SCAN_site_metadata() return a data.frame. NULL on bad request.

Details

Possible above and below ground sensor types include: 'SMS' (soil moisture), 'STO' (soil temperature), 'SAL' (salinity), 'TAVG' (daily average air temperature), 'TMIN' (daily minimum air temperature), 'TMAX' (daily maximum air temperature), 'PRCP' (daily precipitation), 'PREC' (daily precipitation), 'SNWD' (snow depth), 'WTEQ' (snow water equivalent),'WDIRV' (wind direction), 'WSPDV' (wind speed), 'LRADT' (solar radiation/langley total).

This function converts below-ground sensor depth from inches to cm. All temperature values are reported as degrees C. Precipitation, snow depth, and snow water content are reported as inches.

The datetime column in sensor data results is converted to the target time zone specified in tz argument, the default is "US/Central". Use tz = "UTC" (or other OlsonNames() that do not use daylight savings, e.g. "US/Arizona") to avoid having a mix of time offsets due to daylight savings time.

SCAN Sensors

All Soil Climate Analysis Network (SCAN) sensor measurements are reported hourly.

Element Measured	Sensor Type	Precision
Air Temperature	Shielded thermistor	0.1 degrees C
Barometric Pressure	Silicon capacitive pressure sensor	1%
Precipitation	Storage-type gage or tipping bucket	Storage: 0.1 inches;
Relative Humidity	Thin film capacitance-type sensor	1%
Snow Depth	Sonic sensor (not on all stations)	0.5 inches
Snow Water Content	Snow pillow device and a pressure transducer (not on all stations)	0.1 inches
Soil Moisture	Dielectric constant measuring device. Typical measurements are at 2", 4", 8", 20", and 40" where possible.	0.50%
Soil Temperature	Encapsulated thermistor. Typical measurements are at 2", 4", 8", 20", and 40" where possible.	0.1 degrees C
Solar Radiation	Pyranometer	0.01 watts per meter
Wind Speed and Direction	Propellor-type anemometer	Speed: 0.1 miles per hour; Direction: 1 degree

SNOTEL Sensors

All Snow Telemetry (SNOTEL) sensor measurements are reported daily.

Element Measured	Sensor Type	Precision
Air Temperature	Shielded thermistor	0.1 degrees C
Barometric Pressure	Silicon capacitive pressure sensor	1%
Precipitation	Storage-type gage or tipping bucket	Storage: 0.1 inches; Tipping bucket: 0.01 inches
Relative Humidity	Thin film capacitance-type sensor	1%
Snow Depth	Sonic sensor	0.5 inches
Snow Water Content	Snow pillow device and a pressure transducer	0.1 inches
Soil Moisture	Dielectric constant measuring device. Typical measurements are at 2", 4", 8", 20", and 40" where possible.	0.50%
Soil Temperature	Encapsulated thermistor. Typical measurements are at 2", 4", 8", 20", and 40" where possible.	0.1 degrees C
Solar Radiation	Pyranometer	0.01 watts per meter
Wind Speed and Direction	Propellor-type anemometer	Speed: 0.1 miles per hour; Direction: 1 degree

See the fetchSCAN tutorial for additional usage and visualization examples.

References

See the Soil Climate Analysis Network home page for more information on the SCAN program, and links to other associated programs such as SNOTEL, at the National Weather and Climate Center. You can get information on available web services, as well as interactive maps of snow water equivalent, precipitation and streamflow.

Author

D.E. Beaudette, A.G. Brown, J.M. Skovlin

Examples

if (FALSE) { # \dontrun{
    # get data
    x <- try(fetchSCAN(site.code = c(356, 2072), year = c(2015, 2016)))
    str(x, 1)

    # get sensor metadata
    m <- SCAN_sensor_metadata(site.code = c(356, 2072))
    m
    
    # get site metadata
    m <- SCAN_site_metadata(site.code = c(356, 2072))
    m
    
    # # get hourly data (warning, result is large ~11MB) 
    # x <- try(fetchSCAN(site.code = c(356, 2072), 
    #                    year = 2015, 
    #                    timeseries = "Hourly"))
    #
    # # data are in US/Central time, standard or daylight savings time based on day of year
    # unique(format(x$SMS$datetime, '%Z'))
    #
    # # the site metadata indicate timeseries data time zone (dataTimeZone)
    # # for site 356 the timezone is offset of 8 hours behind UTC
    #
    # # to obtain all datetime data with a consistent offset use ETC GMT offset
    # # e.g. "Etc/GMT+8". note the sign is inverted ("GMT+8" vs. `dataTimeZone=-8`)
    # x <- try(fetchSCAN(site.code = c(356, 2072), 
    #          year = 2015, 
    #          timeseries = "Hourly", 
    #          tz = "Etc/GMT+8"))
    
} # }