Terminators Predicting the end of sunspot cycle 24

Terminators: Predicting the end of sunspot cycle 24 and its impacts on space weather, weather and climate AAS 234 – i. Poster 305. 03 Robert J. Leamon University of Maryland/ NASA GSFC leamonrj@umd. edu ; 202 -848 -3616 Scott W. Mc. Intosh NCAR High Altitude Observatory mscott@ucar. edu

Key Points • People have tried to tie El Niño to the solar cycle for years; we finally have because it's not solar max or min that's critical (don't smooth the data!). • Cycle 24 will Terminate and Cycle 25 will turn on mid-2020, and with it a change in cosmic ray flux and a swing from El Niño to La Niña. • Ergo we can predict it — the big “so what” is that governments can prepare for and mitigate “unpredictable natural disasters. ”

Terminators • Top: “F 10. 7” radio flux (activity proxy) • Middle: sunspot number (SSN) by hemisphere. • Bottom: coronal brightpoints (small scale magnetic features) • Sharp increase (<27 days) in SSN and F 10. 7 at Terminator; change in magnetic field configuration (complexity), change (sharp decrease) in galactic cosmic ray flux.

Technique • Key breakthrough: modified Superposed Epoch Analysis – Garmin/ Ironman training! • Solar cycles have different lengths (11 -ish) • Instead of superposition of time series data at 11 years, consider the “phase” or fraction of the cycle from terminator to terminator. • A coherent pattern emerges – note Oceanic Niño Index. ENSO F 10. 7 GCR h. SSN

Implications • Hurricanes: Atlantic sea surface temp and hurricane “power” peak first year in La Niña after El Niño (warm waters/ upper level wind shear). • Commodity Crops: Shocks in US Wheat, Corn and Oats prices show strong correlation with El Niño to La Niña swings at Terminators. • 2019 will be warmest year on record (cf. 1997 -98 El Niño — and Terminator); 2020 less hot. ENSO F 10. 7 GCR h. SSN

When will the Cycle Terminate? • Already have April 2020 from BP band tracking. • Hilbert Transform – signal processing technique (“phase of clock”) • “Wraps” of Hilbert phase also show that El Niño flips are not random but related…

Unit Cycle • Black line: average last 5 solar cycles from terminator to terminator (through June 2017). • Red hatch: error (standard deviation) • Black dot: “you are here” — May 2019 observation

Future Prediction • We already know when Cycle 24 will end (April 2020) • Enough of Cycle 25 visible to make (Oct 2031 ± 9 mo) • Take unit cycle prediction and stretch it between April 2020 and Oct 2031…

Climate and Climate Change… • Why does this relationship hold for the past six solar cycles? • A: Needs climate change. – Warming troposphere gives rise to a cooling stratosphere… – Couples with a thickened ionosphere during El Niño conditions (feedback loop from warm waters) – Making the atmosphere more susceptible to the rapid drop in incoming (charged) GCRs when the sun's magnetic field reconfigures at the Terminator… – Changing the atmospheric conductivity, reducing thunderstorm activity and shifting cloud patterns across the Pacific.

Jupiter… • “A Model of a Tidally Synchronized Solar Dynamo”, Stefani et al. • But need to rely on more than just planetary motions — they mention the Mc. Intosh & Leamon 55º and Rossby wave explanation: “It is here where also the specific role of the ± 55º latitude region for starting the dynamo cycle (Mc. Intosh, 2015) might find an explanation, which could not be provided by our simple 1 D model. ” • If only it was the 11 -ish year cycle we had to be concerned about, but it isn’t.

Summary • Band model/ Terminators can simultaneously explain: – solar cycle timing (minimum and maximum) – sudden onset in activity at Terminator – Rossby wave surges (don’t smooth the data) – hemispheric differences – why last solar cycle was unusually long – implications for El Niño and terrestrial weather/ climate.