NOAA Center for Satellite Applications and Research banner
 
Intranet • Contact • Skip navigation
National Oceanographic & Atmospheric Administration website NOAA Center for Satellite Applications and Research website

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