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Solar Radiation at Top of Atmosphere

There are four tasks to be accomplished to calculate solar radiation at the top of the atmosphere for a given year:
1. determine Earth's orbital parameters which are the eccentricity of the orbit, the obliquity, and the longitude of perihelion;
2. determine time of vernal equinox;
3. determine time integrated insolation at any latitude and longitude on Earth;
4. determine sun's strength or radiation output.

Read questions, answers and comments about insolation.

The file SRTERMS.TXT contains the definition of terms used in calculating insolation. The file SRERROR4X3.TXT lists the approximations that are used by the 4x3 Atmosphere-Ocean Model. This Model assumes the constant orbital parameters of 2000 AD, and that the solar constant is fixed at 1367 W/mē.


The following links allow the user to produce tables and graphs of insolation and solar behavior:
Produce a table of sunrise, sunset, and daily insolation as a function of latitude, longitude, year, and month.
Produce a table of monthly latitude insolation for a whole year.


The following programs were used to calculate insolation for the 4x3 Atmosphere-Ocean Model.
ORBPAR.SUB Calculates the three orbital parameters as a function of year. The values are based on Andre Berger's 1978 solution.
ORBIT.SUB Calculates the distance to the sun and the Earth's declination angle as a function of time of year and the orbital parameters.
COSZ0.SUB Calculates the Model's time integrated zentih angle at each grid cell on the Earth as a function of the declination angle and the time interval of the day. This subroutine can return two output arrays, the zenith angle weighted by time and the zenith angle weighted by sunlight.

Page Links to 4x3 Atmophere-Ocean Model
COLOR PLOTS STATISTICS MODEL DOC MODEL DATA SUNLIGHT PUBLICA
LINE PLOTS GEN INFO MODEL CODE OBSERVE DATA TIDES and MOON PEOPLE
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Curator: Gary L. Russell . . . . . 2005/02/09/11:53:00