ModelE AR5 Simulations: Past Climate Change and Future Climate Predictions
Solar Radiation at Top of Atmosphere
There are four tasks to be accomplished to calculate solar radiation at top-of-atmosphere for a given year:
- determine Earth's orbital parameters which are eccentricity of the orbit, obliquity (Tropic of Cancer), and longitude of perihelion (angle between perihelion and vernal equinox);
- determine time of vernal equinox;
- determine time integrated insolation at any latitude and longitude on Earth;
- 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 SRERROR.TXT lists the approximations that are used by Model E. Tables produced by subsequent web pages assume that the solar constant is fixed at 1367 W/m2.
The following 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 Model E.
| ORBPAR.SUB | Calculates the three orbital parameters as a function of year. Values are based on Andre Berger's 1978 solution. |
|---|---|
| ORBIT.SUB | Calculates distance to the sun and Earth's declination angle as functions 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. |
Contact
Please address questions about these AR5 webpages to Dr. Gary Russell.
