1. Modeling incoming solar radiation Ehrhard Raschke (Hamburg) Stefan Kinne (Hamburg) Yoko Tsuschima (Yokohama) Stephan Bakan (Hamburg) With data contributions from GISS and LaRC

2. Is it so easy? In principle the incoming solar irradiance reaching the Top of the atmosphere (ToA) can be computed easily using the principles of spherical geometry and the astro- mechanical parameters (distance Sun-Earth, obliquity of the orbit, perhelion and inclination of the rotational axis), which are determining the Earth‘s orbit around the Sun.

3. Summary of possible error sources in computations of the insolation at ToA:  Total solar irradiance (TSI = ~ 1361 Wm -2 ), solar cycles  Orbital parameters : eccentricity, obliquity, perihelion  Inclusion of a leapday (strictly the tropical year?)  Spatial resolution, time resolution  Definition of sunset and sunrise  Definition of TOA and  Occasional bugs in the code !

4. J F M A M J J A SO N D Monthly zonal anomalies in IPPC models related to ISCCP

5. 1985 - 1988

6. 6 weeks with patiently repeated questions to modelers for information

7. Masterpiece by Y.-C. Zhang

8. Modelers (e.g. for the IPCC AR4) and also climatologists (ISCCP and SRB) obtain often different results ! Should we tolerate ? Tild of axis ±0.5 degrees

9. CONTROL RUNFor Enhanced InsolationFor Reduced Insolation Total cloud cover

10. ISCCP minus SRB: Monthly global averages of the insolation at TOA Why do the seasonal differences increase with time ? Data from ISCCP and SRB projects

11. IPCC 2007

12. How are the other radiation climatologies computing the insolation at TOA? -.-.-.- Please don’t forget: There is only one Sun – Earth - System ! Therefore modelers and climatologists should compute the same solar input into the climate system.

14. From G. Schmidt, GISS, 2006 0.5 hours 2.5 hours

15. S S S