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• Analytic formulae derived for incident top-of-atmosphere solar irradiance normal to the Earth's surface (i.e., solar flux) as a function of Earth-axis tilt and latitude. • Net daily solar flux tabulated vs. latitude at top of atmosphere throughout year. • Utilizes latest values of solar irradiance and Earth-orbit. • Describes derivations and correction factors for computational transparency. The top-of-atmosphere solar irradiance normal to the Earth's surface varies as a function of latitude and longitude due to orbital effects throughout the year, with the most prominent being from variations in the Earth-axis tilt relative to the ecliptic and the Sun-Earth distance. Analytic formulae are derived to compute this net daily surface-normal solar flux as a function of Earth-axis tilt and latitude. Tabulated values are given for net daily flux at the top of the Earth's atmosphere as a function of latitude and date throughout the year 2023 including corrections for Sun-Earth distance. Updates over older such tabulations, which often used an erroneously high value of the incident total solar irradiance, include applying the latest IAU-accepted lower solar-irradiance value, causing a ∼ 1 % decrease in computed values from some prominent prior publications. [ABSTRACT FROM AUTHOR]

We review recent developments in combining solar irradiance datasets from different instruments to obtain one single composite, which is the key to understanding how irradiance varies on decadal timescales and beyond. [ABSTRACT FROM AUTHOR]