Solar minimum and ENSO prediction
Two solar physicists, Robert Leamon from NASA
Goddard Space Flight Center, and Scott McIntosh from the High Altitude
Observatory at Boulder, CO, have made an interesting observation that links
changes in solar activity with changes in the El Niño Southern Oscillation
As they reported at the AGU 2017 Fall Meeting,
the termination of the solar magnetic activity bands at the solar equator that
mark the end of the Hale cycle coincides since the 1960’s with a shift from El
Niño to La Niña conditions in the Pacific.
“We look at the
particulate and radiative implications of these termination points, their temporal
recurrence and signature, from the Sun to the Earth, and show the correlated
signature of solar cycle termination events and major oceanic oscillations that
extend back many decades. A combined one-two punch of reduced particulate
forcing and increased radiative forcing that result from the termination of one
solar cycle and rapid blossoming of another correlates strongly with a shift
from El Niño to La Niña conditions in the Pacific Ocean.”
More information is available at the talk they
gave at the last SORCE Meeting:
As they say in the talk, the probability that the
pattern is due to chance is very low. Particularly since the termination of the
magnetic activity bands at the equator coincides quite precisely with the El
Niño-La Niña shift.
Figure: Top: Six-month
smoothed monthly sunspot number from SIDC. Bottom: Oceanic El Niño Index from
NOAA. Red and blue boxes mark the El Niño and La Niña periods in the repeating
Since the 1960’s the early solar minimum is
associated with La Niña conditions, the late solar minimum is associated with
El Niño conditions, and the rapid increase from minimum to maximum is
associated to La Niña conditions again. As the authors note, this pattern did
not take place in the 1954 minimum, although the rise in activity was also
associated with La Niña conditions then. It is unclear why the ENSO system
responded differently at that time, but it is clear that solar activity was not
the only factor affecting ENSO.
The pattern appears to be repeating again this
minimum. The early minimum has been associated to La Niña conditions and, as we
move towards the late minimum, an El Niño is being forecasted for late 2018.
The authors made their claim for a 2020 La Niña before the 2018 El Niño was
forecasted. Now a repetition of the pattern looks even more probable and we
should expect a La Niña when solar activity increases in late 2020 to 2021.
via Watts Up With That? https://ift.tt/1Viafi3