Q. From D.Park
It is said that Sunspots lower Total Solar irradiance reaching Earth, so an active Sun at Solar max should drop not increase TSI?
A..TSM Solar Observations.
If that were all there was to the Earth’s radiative balance, scientists studying the Sun would have probably long since moved on to another climate-related problem. Analyzing the Sun and its affects on climate, however, is further complicated by the fact that the amount of radiation arriving from the Sun is NOT constant.
Variations in TSI are due to a balance between decreases caused by sunspots and increases caused by bright areas called faculae which surround sunspots. Sunspots are dark blotches on the Sun in which magnetic forces are very strong, and these forces block the hot solar plasma, and as a result sunspots are cooler and darker than their surroundings.
Faculae, which appear as bright blotches on the surface of the Sun, put out more radiation than normal and increase the solar irradiance. They too are the result of magnetic storms, and their numbers increase and decrease in concert with sunspots.
Although solar energy reaching the Earth decreases when the portion of the Sun’s surface that faces the Earth happens to be rife with spots and faculae, the total energy averaged over a full 30-day solar rotation actually increases. Therefore the TSI is larger during the portion of the 11 year cycle when there are more sunspots, even though the individual spots themselves cause a decrease in TSI when facing Earth.
I hope this clears up the Q.
David.