Guest Post by David Archibald
The two major items of interest are the likely month of minimum in the Solar Cycle 24 ? 25 transition and the likely amplitude of Solar Cycle 25. The latter can be derived from the solar polar magnetic field strength. Figure 1 following indicates that 25 is likely to be slightly larger than 24 in amplitude:
Figure 1: Solar Polar Field Strength from Wilcox Solar Observatory
The strength of the solar polar magnetic fields is a bit higher than what it was at the 23/24 minimum, shown by the red bar in Figure 1.
Figure 2: aa Index 1868 ? 2019
The aa Index is the longest magnetic instrument record, measuring the average of stations in London and Melbourne. What it shows is that we have left the Modern Warm Period behind and have entered a new cold period with magnetic activity similar to that…
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