cliBrtSunDurFrcGrid: Estimator for Fraction of Bright Sunshine Duration

cliBrtSunDurFrcGridR Documentation

Estimator for Fraction of Bright Sunshine Duration


Estimates monthly averages for daily fraction of bright sunshine duration, for a given region and year, by using the monthly time series of temperature and precipitation, and the elevation data.


  sc.year = 2000,
  aprchSIM = c("Solar123", "SPLASH"),
  filename = "",



multi-layer Raster*/SpatRaster object with one-year time series of monthly mean air temperature (in °C)


multi-layer Raster*/SpatRaster object with one-year time series of monthly precipitation sum (in mm)


single-layer Raster*/SpatRaster object with the elevation values (in meters above sea level)


'numeric' scalar with the value of the year (using astronomical year numbering)


'character' vector of length 1 that indicates the formula used to estimate the value of solar irradiance/irradiation for a specific day. Valid values are as follows:
(a) 'Solar123' - in this approach, first, the mean hourly solar irradiance under cloudless-sky conditions is calculated as proposed by Yin (1997b), with a minor modification, using the daytime means of optical air mass and cosine zenith; the former is computed as recommended by Yin (1997b), while the latter is estimated by using Eq 5 of Yin (1997a); however, in contrast to the original approach, where the solar constant was fixed at 4.9212 MJ m^{-2} hr^{-1}, according to Yin (1999), its value is corrected by calendar day for the variable ellipticity of the Earth's orbit, by using the scheme of Brock (1981); in the calculations, the values of solar declination and daylength are derived by using the approach of Brock (1981);
(b) 'SPLASH' - in this approach, first, under varying orbital parameters, the daily solar radiation at the top of the atmosphere is calculated (H_{0}, Eq 7 in Davis et al. (2017)), and then this value is multiplied by the atmospheric transmittivity to obtain the value of daily surface radiation; in this case as well, cloudless conditions are assumed, i.e., the transmission coefficient is taken into account with an universal value of 0.75, however, its value is modified as a function of elevation, by using the scheme of Allen (1996); the daylength is calculated via Eq 1.6.11 in Duffie and Beckman (1991), using the sunset hour angle (h_{s}, Eq 8. in Davis et al. (2017)); finally, the mean hourly surface radiation is derived as the quotient of the daily surface radiation and the daylength.


output filename


additional arguments passed on to writeRaster


See cliBrtSunDurFrcPoints.


A 12-layer SpatRaster object with one-year time series of monthly mean relative sunshine duration.


The objects 'rs.temp' and 'rs.prec' must be 12-layer Raster*/SpatRaster objects, while the object 'rl.elv' has to be a single-layer Raster*/SpatRaster object. These Raster*/SpatRaster objects must have the same bounding box, projection, and resolution. The object 'sc.year' has to be a single integer number.


Allen RG (1996) Assessing integrity of weather data for reference evapotranspiration estimation. J Irrig Drain Eng 122(2):97–106. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1061/(ASCE)0733-9437(1996)122:2(97)")}

Berger A, Loutre MF (1991) Insolation values for the climate of the last 10 million years. Quat Sci Rev 10(4):297-317. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1016/0277-3791(91)90033-Q")}

Brock TD (1981) Calculating solar radiation for ecological studies. Ecol Model 14(1–2):1-19. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1016/0304-3800(81)90011-9")}

Davis TW, Prentice IC, Stocker BD, Thomas RT, Whitley RJ, Wang H, Evans BJ, Gallego-Sala AV, Sykes MT, Cramer W (2017) Simple process-led algorithms for simulating habitats (SPLASH v.1.0): robust indices of radiation, evapotranspiration and plant-available moisture. Geosci Model Dev 10(2):689–708. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.5194/gmd-10-689-2017")}

Duffie JA, Beckman WA (1991) Solar Engineering of Thermal Processes. Second Edition. Wiley-Interscience, New York, NY

Yin X (1997a) Calculating daytime mean relative air mass. Agric For Meteorol 87(2-3):85-90. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1016/S0168-1923(97)00029-4")}

Yin X (1997b) Optical Air Mass: Daily Integration and its Applications. Meteorol Atmos Phys 63(3-4):227-233. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1007/BF01027387")}

Yin X (1999) Bright Sunshine Duration in Relation to Precipitation, Air Temperature and Geographic Location. Theor Appl Climatol 64(1–2):61–68. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1007/s007040050111")}



# Loading mandatory data for the Example 'Single-Year Grid'
inp_exSglyGrid <- lapply(inp_exSglyGrid, crop, extent(20.15, 20.25, 46.25, 46.35))

# Estimate values of the monthly mean relative sunshine duration
# at a grid cell near Szeged, Hungary (46.3N, 20.2E), in the year 2010
with(inp_exSglyGrid, {
rs.bsdf <- cliBrtSunDurFrcGrid(temp, prec, elv, sc.year = 2010)

macroBiome documentation built on May 29, 2024, 5:07 a.m.