Minimum Far-Infrared Solar Brightness Temperature and Sunspot Activity

摘要

Since 1971 we measured the absolute solar far-infrared brightness temperature with balloon-borne lamellar-grating interferometers in a series of flights [1-6] at the CNES balloon launching station in Aire/Adour, France. In Figure 1 we show the result of the last flight no. 10 of September 14, 1978 as an example. Our successful flights are listed in Table 1 including measured or extrapolated minimum solar brightness temperatures as well as daily and monthly sunspot numbers [7-9] as a measure of solar activity. Contrary to ref. [6] the minimum brightness temperatures listed are not corrected for the center-to-limb variation.