Climate Dynamics Starts with the Sun

NASA ImageFrom Wallace and Hobbs

r = 6.96x108 m

T=5780K

Photosphere Sunspots

Faculae

Figure 1.1

Integration of Intensity over a Hemisphere to Get Net Downward Energy Flux Density in W/m2.

1 m2 area

We want Watts per m2.

Figure 1.2

Sun and Earth Blackbody Spectra, Trace Gas Absorption Lines

From Wallace and Hobbs

From Wallace and Hobbs Figure 1.3

Climate Dynamics Starts with the Sun

NASA ImageFrom Wallace and Hobbs

r = 6.96x108 m

T=5780K

Photosphere Sunspots

Faculae

Figure 1.4

The Earth’s Orbit is Elliptical

Figure 1.5

Measurement of the Solar Constant from Satellite is Difficult

Figure 1.6

Improved Instrument More Scattering,Higher IrradianceMeasured

Kopp and Lean (2010)

Recent Solar Constant Measurements from the SORCE Experiment

Figure 1.7 Courtesy of Greg Kopp (LASP)

Climate Dynamics Starts with the Sun

NASA ImageFrom Wallace and Hobbs

r = 6.96x108 m

T=5780K

Photosphere Sunspots

Faculae

Figure 1.8

11-Year Sunspot Cycle Indicates Variations in Solar Luminosity

Percent Area of Photosphere Covered by Sunspots

Fraction Area of Entire Photosphere Covered by Sunspots

Yellow>1%

Figure 1.9

Direct Measurements of Solar “Constant”

IPCC 2013

SatelliteRetrievals

Figure 1.10

Solar “Constant” Reconstructions Suggest Stronger Longer-Term Variations

IPCC 2007Figure 1.11

IPCC 2013 Figure 1.12

Solar Forcing Since 1750 is Relatively Small Compared to Other External

Perturbations to the Climate System. *Volcanic Ignored.