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STAR / SMCD / EMB Radiation Budget

Parameter Definition

Parameters available in the NESDIS Solar Resource Data Base are listed in the table below. (Note: In the Units column of this table "period" refers to hour, day, or month.)

Solar Resource Parameters
Parameter and definition	Units
*Insolation* Amount of the total solar radiation incident on a horizontal surface at the surface of the earth. This is the same as Global Horizontal Irradiance (GHI).	Wh/m²/period
*Midday Insolation (Three-hour)* Sum of three hourly averages of the total solar radiation incident on a horizontal surface at the surface of the earth within 1.5 hours of local solar noon, divided by three.	Wh/m²/period
*Midday Insolation (One-hour)* Hourly average of the total solar radiation incident on a horizontal surface at the surface of the earth within 0.5 hours of local solar noon.	Wh/m²/period
*Clear-Sky Days* Number of days having an average cloud cover less than 10% during a given month. Given in terms of percent of total days in Period.	%
*Clear-Sky Insolation* Amount of the total solar radiation incident on a horizontal surface at the surface of the earth when the cloud cover is less than 10%.	Wh/m²/period
*Diffuse Radiation* Amount of solar radiation incident on a horizontal surface at the surface of the earth under all-sky conditions excluding the direct radiation from the sun's beam.	Wh/m²/period
*Direct Normal Radiation* Amount of solar radiation at the surface of the earth incident on a flat surface perpendicular to the Sun's beam excluding the surrounding sky (diffuse) radiation.	Wh/m²/period
*Insolation Clearness Index* Amount of the total solar radiation incident on a horizontal surface at the surface of the earth given as a fraction of insolation available at the top of the atmosphere.	Dimensionless range: 0-1
*Normalized Insolation Clearness Index* Zenith angle-independent expression of Isolation Clearness Index. Calculated as (Insolation Clearness Index) / (1.031 * exp(-1.4 / (0.9 + 9.4 * cos(solar zenith angle) )) + 0.1)	Dimensionless range: 0-1
*Clear-Sky Insolation Clearness Index* Amount of the total solar radiation incident on a horizontal surface at the surface of the earth with cloud cover is less than 10%; given as a fraction of insolation available at the top of the atmosphere.	Dimensionless range: 0-1
*Daylight Cloud Amount* Cloud amount (ratio of number of cloudy pixels to total number of pixels in a grid cell) averaged for daytime.	% range: 0-100