Potential Incoming Solar Radiation

Author: O.Conrad (c) 2010
Menu: Terrain Analysis | Lighting and Visibility

Description

Calculation of potential incoming solar radiation (insolation). Times of sunrise/sunset will only be calculated if time span is set to single day. Most options should do well, but TAPES-G based diffuse irradiance calculation ('Atmospheric Effects' methods 2 and 3) needs further revision!

References

Böhner, J., Antonić, O. (2009): Land Surface Parameters Specific to Topo-Climatology. In: Hengl, T. & Reuter, H.I. [Eds.]: Geomorphometry - Concepts, Software, Applications.
Hofierka, J., Šúri, M. (2002): The solar radiation model for Open source GIS: implementation and applications. International GRASS users conference in Trento, Italy, September 2002. ResearchGate
Oke, T.R. (1988): Boundary Layer Climates. London, Taylor & Francis.
Wilson, J.P., Gallant, J.C. (2000): Secondary topographic attributes. In: Wilson, J.P., Gallant, J.C. [Eds.]: Terrain analysis: Principles and applications. New York, John Wiley & Sons, Inc., 87-131. ResearchGate

Parameters

	Name	Type	Identifier	Description	Constraints
Input	Elevation	grid, input	`GRD_DEM`	-	-
	Sky View Factor	grid, input, optional	`GRD_SVF`	-	-
	Water Vapour Pressure [mbar]	grid, input, optional	`GRD_VAPOUR`	-	-
	Linke Turbidity Coefficient	grid, input, optional	`GRD_LINKE`	-	-
Output	Direct Insolation	grid, output	`GRD_DIRECT`	-	-
	Diffuse Insolation	grid, output	`GRD_DIFFUS`	-	-
	Total Insolation	grid, output, optional	`GRD_TOTAL`	-	-
	Direct to Diffuse Ratio	grid, output, optional	`GRD_RATIO`	-	-
	Compare to Flat Terrain	grid, output, optional	`GRD_FLAT`	-	-
	Duration of Insolation	grid, output, optional	`GRD_DURATION`	-	-
	Sunrise	grid, output, optional	`GRD_SUNRISE`	-	-
	Sunset	grid, output, optional	`GRD_SUNSET`	-	-
Options	Grid System	grid system	`PARAMETERS_GRID_SYSTEM`	-	-
	Default	floating point number	`GRD_VAPOUR_DEFAULT`	default value if no grid has been selected	Minimum: 0.000000 Default: 10.000000
	Default	floating point number	`GRD_LINKE_DEFAULT`	default value if no grid has been selected	Minimum: 0.000000 Default: 3.000000
	Solar Constant [W/m²]	floating point number	`SOLARCONST`	-	Minimum: 0.000000 Default: 1361.000000
	Local Sky View Factor	boolean	`LOCALSVF`	Use sky view factor based on local slope (after Oke 1988), if no sky viev factor grid is given.	Default: 1
	Units	choice	`UNITS`	Units for output radiation values.	Available Choices: [0] kWh/m² [1] kJ/m² [2] J/cm² Default: 0
	Shadow	choice	`SHADOW`	Choose 'slim' to trace grid node's shadow, 'fat' to trace the whole cell's shadow, or ignore shadowing effects. The first is slightly faster but might show some artifacts.	Available Choices: [0] slim [1] fat [2] none Default: 1
	Location	choice	`LOCATION`	-	Available Choices: [0] constant latitude [1] calculate from grid system Default: 0
	Latitude	degree	`LATITUDE`	-	Minimum: -90.000000 Maximum: 90.000000 Default: 53.000000
	Time Period	choice	`PERIOD`	Momentum output will be in units of power [W/m²], time span will be in units of energy, either [kWh/m²], [kJ/m²], or [J/cm²].	Available Choices: [0] moment [1] day [2] range of days Default: 1
	Day	date	`DAY`	-	Default: 2026-04-15
	Last Day	date	`DAY_STOP`	-	Default: 2026-04-15
	Resolution [d]	integer number	`DAYS_STEP`	Time step size for a range of days calculation given in days.	Minimum: 1 Default: 5
	Moment [h]	floating point number	`MOMENT`	-	Minimum: 0.000000 Maximum: 24.000000 Default: 12.000000
	Time Span [h]	value range	`HOUR_RANGE`	Time span used for the calculation of daily radiation sums.	-
	Resolution [h]	floating point number	`HOUR_STEP`	Time step size for a day's calculation given in hours.	Minimum: 0.000000 Maximum: 24.000000 Default: 0.500000
	Atmospheric Effects	choice	`METHOD`	-	Available Choices: [0] Height of Atmosphere and Vapour Pressure [1] Air Pressure, Water and Dust Content [2] Lumped Atmospheric Transmittance [3] Hofierka and Šúri Default: 2
	Height of Atmosphere [m]	floating point number	`ATMOSPHERE`	-	Minimum: 0.000000 Default: 12000.000000
	Barometric Pressure [mbar]	floating point number	`PRESSURE`	-	Minimum: 0.000000 Default: 1013.000000
	Water Content [cm]	floating point number	`WATER`	Water content of a vertical slice of atmosphere in cm: 1.5 to 1.7, average=1.68	Minimum: 0.000000 Default: 1.680000
	Dust [ppm]	floating point number	`DUST`	Dust factor: 100 ppm (standard)	Minimum: 0.000000 Default: 100.000000
	Lumped Atmospheric Transmittance [Percent]	floating point number	`LUMPED`	The transmittance of the atmosphere, usually between 60 and 80 percent.	Minimum: 0.000000 Maximum: 100.000000 Default: 70.000000
	Update	choice [GUI]	`UPDATE`	show direct insolation for each time step.	Available Choices: [0] do not update [1] fit histogram stretch for each time step [2] constant histogram stretch for all time steps Default: 0
	Constant Histogram Stretch	floating point number [GUI]	`UPDATE_STRETCH`	-	Minimum: 0.000000 Default: 1.000000

Command Line


Usage: saga_cmd ta_lighting 2 [-GRD_DEM ] [-GRD_SVF ] [-GRD_VAPOUR ] [-GRD_VAPOUR_DEFAULT ] [-GRD_LINKE ] [-GRD_LINKE_DEFAULT ] [-GRD_DIRECT ] [-GRD_DIFFUS ] [-GRD_TOTAL ] [-GRD_RATIO ] [-GRD_FLAT ] [-GRD_DURATION ] [-GRD_SUNRISE ] [-GRD_SUNSET ] [-SOLARCONST ] [-LOCALSVF ] [-UNITS ] [-SHADOW ] [-LOCATION ] [-LATITUDE ] [-PERIOD ] [-DAY ] [-DAY_STOP ] [-DAYS_STEP ] [-MOMENT ] [-HOUR_RANGE_MIN ] [-HOUR_RANGE_MAX ] [-HOUR_STEP ] [-METHOD ] [-ATMOSPHERE ] [-PRESSURE ] [-WATER ] [-DUST ] [-LUMPED ]
  -GRD_DEM:                 Elevation
	grid, input
  -GRD_SVF:                 Sky View Factor
	grid, input, optional
  -GRD_VAPOUR:              Water Vapour Pressure [mbar]
	grid, input, optional
  -GRD_VAPOUR_DEFAULT:   Default
	floating point number
	Minimum: 0.000000
	Default: 10.000000
  -GRD_LINKE:               Linke Turbidity Coefficient
	grid, input, optional
  -GRD_LINKE_DEFAULT:    Default
	floating point number
	Minimum: 0.000000
	Default: 3.000000
  -GRD_DIRECT:              Direct Insolation
	grid, output
  -GRD_DIFFUS:              Diffuse Insolation
	grid, output
  -GRD_TOTAL:               Total Insolation
	grid, output, optional
  -GRD_RATIO:               Direct to Diffuse Ratio
	grid, output, optional
  -GRD_FLAT:                Compare to Flat Terrain
	grid, output, optional
  -GRD_DURATION:            Duration of Insolation
	grid, output, optional
  -GRD_SUNRISE:             Sunrise
	grid, output, optional
  -GRD_SUNSET:              Sunset
	grid, output, optional
  -SOLARCONST:           Solar Constant [W/m²]
	floating point number
	Minimum: 0.000000
	Default: 1361.000000
  -LOCALSVF:                Local Sky View Factor
	boolean
	Default: 1
  -UNITS:                   Units
	choice
	Available Choices:
	[0] kWh/m²
	[1] kJ/m²
	[2] J/cm²
	Default: 0
  -SHADOW:                  Shadow
	choice
	Available Choices:
	[0] slim
	[1] fat
	[2] none
	Default: 1
  -LOCATION:
                                 Location
                                 	choice
                                 	Available Choices:
                                 	[0] constant latitude
                                 	[1] calculate from grid system
                                 	Default: 0
  -LATITUDE:             Latitude
	degree
	Minimum: -90.000000
	Maximum: 90.000000
	Default: 53.000000
  -PERIOD:
                                 Time Period
                                 	choice
                                 	Available Choices:
                                 	[0] moment
                                 	[1] day
                                 	[2] range of days
                                 	Default: 1
  -DAY:                    Day
	date
	Default: 2026-04-15
  -DAY_STOP:               Last Day
	date
	Default: 2026-04-15
  -DAYS_STEP:               Resolution [d]
	integer number
	Minimum: 1
	Default: 5
  -MOMENT:
                                 Moment [h]
                                 	floating point number
                                 	Minimum: 0.000000
                                 	Maximum: 24.000000
                                 	Default: 12.000000
  -HOUR_RANGE_MIN:       Time Span [h]
	value range
  -HOUR_RANGE_MAX:       Time Span [h]
	value range
  -HOUR_STEP:
                                 Resolution [h]
                                 	floating point number
                                 	Minimum: 0.000000
                                 	Maximum: 24.000000
                                 	Default: 0.500000
  -METHOD:
                                 Atmospheric Effects
                                 	choice
                                 	Available Choices:
                                 	[0] Height of Atmosphere and Vapour Pressure
                                 	[1] Air Pressure, Water and Dust Content
                                 	[2] Lumped Atmospheric Transmittance
                                 	[3] Hofierka and Šúri
                                 	Default: 2
  -ATMOSPHERE:
                                 Height of Atmosphere [m]
                                 	floating point number
                                 	Minimum: 0.000000
                                 	Default: 12000.000000
  -PRESSURE:
                                 Barometric Pressure [mbar]
                                 	floating point number
                                 	Minimum: 0.000000
                                 	Default: 1013.000000
  -WATER:                Water Content [cm]
	floating point number
	Minimum: 0.000000
	Default: 1.680000
  -DUST:                 Dust [ppm]
	floating point number
	Minimum: 0.000000
	Default: 100.000000
  -LUMPED:
                                 Lumped Atmospheric Transmittance [Percent]
                                 	floating point number
                                 	Minimum: 0.000000
                                 	Maximum: 100.000000
                                 	Default: 70.000000