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

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Presentation on theme: "Modeling incoming solar radiation Ehrhard Raschke (Hamburg) Stefan Kinne (Hamburg) Yoko Tsuschima (Yokohama) Stephan Bakan (Hamburg) With data contributions."— Presentation transcript:

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

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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.

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14 From G. Schmidt, GISS, hours 2.5 hours

15 S S S

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