Tuesday, July 14, 2020

New Hope for Cycle 25?

The bright spot at about 10 o'clock
is from a sunspot about to rotate
into view. (NASA/SDO photo)
A group of scientists is challenging the current consensus among solar researchers that Sunspot Cycle 25 will similar to the now-ending Cycle 24, and predicting a cycle "of major proportions." 

According to the ARRL Letter, the scientists, associated with a variety of institutions in the U.S. and the U.K., including NASA's Goddard Space Flight Center, the National Center for Atmospheric Research, and the University of Maryland, say their calculations, using a mathematical technique known as a Hilbert transform to analyze 270 years of monthly sunspot numbers, suggest "that Sunspot Cycle 25 will have a magnitude that rivals the top few since records began." 
The group's paper, posted online on Cornell University's arxiv.org website, says their best estimate for Cycle 25 is a maximum level of 233 sunspots, predicting "with 95% confidence that the Cycle 25 amplitude will fall between 153 and 305 spots." The consensus prediction of a NOAA/NASA-led panel of experts is for a relatively weak cycle, with a peak between 95 and 130 sunspots. 

This group is basing its far sunnier prediction on the expectation that 2020 will see an end to both sunspot and magnetic cycles on the sun, as well as evidence from the latitude of early Cycle 25 spots (higher than usual) that suggests a very active solar cycle. However, they conclude, "only time will tell."

The full paper is online at <https://arxiv.org/pdf/2006.15263.pdf>.