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Published byRamiro Luty Modified over 2 years ago

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

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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.

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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 !

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

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1985 - 1988

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6 weeks with patiently repeated questions to modelers for information

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Masterpiece by Y.-C. Zhang

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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

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CONTROL RUNFor Enhanced InsolationFor Reduced Insolation Total cloud cover

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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

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IPCC 2007

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

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