Solar Activity, Solar Irradiance and Earth’s TemperatureProfessor Valentina Zharkova
https://arxiv.org/ftp/arxiv/papers/2008/2008.00439.pdf Summary
The Sun is the source of energy for the Earth and planets. The Sun has a magnetic field with
north and south poles switching every 11 years and so does solar activity and radiation, which in
the past modulated the terrestrial temperature. Solar activity is usually classified by numbers of
sunspots, or magnetic loops, appearing on the solar surface generated by solar dynamo
mechanism acting in the solar interior. The periodic occurrence of sunspots on the surface is
found to be modulated by the solar background magnetic field and can be used as a new proxy
of solar activity. Principal components analysis of solar magnetic field in cycles 21-23 detected
pairs of magnetic waves generated by double dynamo in two layers of the solar interior with
slightly different frequencies and a phase difference. These magnetic waves are reproduced with
mathematical formulae enabling to discover of a grand solar cycle of 350–400 years, caused by
the interference of these waves. When the waves are in anti-phase, the solar magnetic field and
solar activity are significantly reduced indicating grand solar minima (GSMs). The previous GSM
known as the Maunder minimum was recorded from 1645 to 1715 lasting for six cycles of eleven
years. The modern GSM starts in 2020 and will last for three solar cycles until 2053.
The solar radiation and terrestrial temperatures during this GSM are expected to be reduced but
not as low as during Maunder minimum. This is because the modern GSM is much shorter; and
because the terrestrial temperature has been increasing by the similar amount since
Maunder minimum.
The current study also uses the ephemeris of the Sun-Earth distances and associated variations
of solar irradiance during the Earth revolution about the Sun. The ephemeris of the S-E
distances show significant decreases of these distances by 0.005 au in 600-1600 by more than
0.01 au in 1600-2600 imposed by the solar inertial motion, or the deviation of the Sun–Earth
distances from Kepler’s third law. These Sun-Earth distance variations are reflected in
oscillations of the baseline magnetic field reported by Zharkova et al, 2019. The S-E distance
variations are followed by increases of solar irradiance in the first six months of each year in the
two millennia 600-2600, which are not fully offset by the solar radiation decreases in the last six
months. This study also reveals a continuous increase by more than 2.8% of solar irradiance
input to the Earth atmosphere in the second millennium (1600-2600) compared to the first (600-
2600). This solar radiation misbalance creates an annual surplus of the solar radiation in
millennium 1600-2600 to be processed by the terrestrial atmosphere and ocean environments.
Therefore, during the modern GSM (2020-2053) the two processes: decrease of solar activity and
increase in total solar irradiance because of SIM, will result in a reduction of the current
terrestrial temperature to levels reached in 1700, just after Maunder minimum.
