Global Radiation Calculation as applied in WOFOST/CGMS¹ When the sunshine duration is known, the global radiation is calculated using the Ångström-Prescott formula. Constants depend on the geographic location.

where	Rg	:	Incoming daily global solar radiation	[MJ m-2 d-1]
	Ra	:	Daily extra-terrestrial radiation	[MJ m-2 d-1]
	Aa	:	Empirical constant	[-]
	Ba	:	Empirical constant	[-]
	n	:	Bright sunshine hours per day	[hr]
	<Ld	:	Astronomical day length	[hr]

Constants: Select a CountryAlbaniaAustriaBelgiumCroatiaCyprusCzech RepublicDenmarkEgyptEstoniaFinlandFranceGermanyIcelandIrelandItalyLuxembourgMaltaNetherlandsNorwayPolandPortugalRomaniaSlovakiaSloveniaSpainSwedenSwitzerlandSyriaTunisiaTurkeyUK

Spatial variation: Select a MapUk and IrelandWestern EuropeSwitzerlandEastern EuropeScandinaviaWestern AziaNorthern Africa

<When sunshine duration is not available but minimum and maximum temperature and cloud cover are known, the Extended Hargreaves (a.k.a. Supit ) formula is applied. Constants depend on geographic location:

where	<Rg	:	Incoming daily global solar radiation	[MJ m-2 d-1]
	Ra		Daily extra-terrestrial radiation	[MJ m-2 d-1]
	CC		Mean total cloud cover during daytime	[octa]
	Tmax		Maximum temperature	[°C]
	Tmin	:	Minimum temperature	[°C]
	As	:	Empirical constants	[°C-0.5]
	Bs	:	Empirical constants	[-]
	Cs	:	Empirical constants	[MJ m-2 d-1]

Constants: Select a CountryAustriaCroatiaCyprusCzech RepublicEstoniaFinlandFranceGermanyIcelandIrelandItalyLuxembourgNetherlandsPolandPortugalRomaniaSlovakiaSloveniaSpainSwedenSwitzerlandSyriaTunisiaTurkeyUK

Spatial variation:Select a MapUk and IrelandWestern Europe

When only minimum and maximum temperatures are known, the Hargreaves equation is applied. Again, the constants depend on geographic location:

where	Rg	:	Incoming daily global solar radiation	[MJ m-2 d-1]
	Ra		Daily extra-terrestrial radiation	[MJ m-2 d-1]
	Tmax		Maximum temperature	[°C]
	Tmin	:	Minimum temperature	[°C]
	Ah	:	Empirical constants	[°C-0.5]
	Bh	:	Empirical constants	[MJ m-2 d-1]

Constants: Select a CountryAlbaniaAustriaBelgiumDenmarkEgyptFinlandFranceGermanyIcelandIrelandItalyLuxembourgMaltaNetherlandsPolandPortugalRomaniaSlovakiaSloveniaSpainSwedenSwitzerlandUK

Spatial variation:Select a Map Uk and Ireland Western Europe

For more information contact Privateers N.V. / ParBleu Technologies

¹CGMS is the Crop Growth Monitoring System as applied by the European Commission