A solar cycle 25 prediction based on 4D-var data assimilation approach

Abstract

Based on our modern 4D-var data assimilation pipeline Solar Predict we present in this short proceeding paper our prediction for the next solar cycle 25. As requested by the Solar Cycle 25 panel call issued on January 2019 by NOAA/SWPC and NASA, we predict the timing of next minimum and maximum as well as their amplitude. Our results are the following: the minimum should have occured within the first semester of year 2019. The maximum should occur in year 2024.4 ± 6 months, with a value of the sunspot number equal to 92±10. This is in agreement with the NOAA/NASA consensus published in April 2019. Note that our prediction errors are based on 1-σ measure and do not consider all the systematics, so they are likely underestimated. We will update our prediction and error analysis regularly as more data becomes available and we improve our prediction pipeline.

Simulations of Solar and Stellar Dynamos and Their Theoretical Interpretation

“…3 , which shows the longitudinally-averaged line of sight component of the magnetic field for every Carrington rotation since 1975 (based on Wilcox, GONG and Solis synoptic map data; Brun et al. 2020 ). Strong fields emerge at mid-latitudes and then, over the course of roughly 11 years, appear progressively nearer the equator; the polarity of these emergent fields is the same for most of the low-latitude events in the Northern hemisphere, and opposite to that in the Southern; the overall polarity of the field flips at the end of each 11-year period.…”

“…3 Solar butterfly diagram of the line of sight surface magnetic field up to Carrington rotation 2265 (Brun et al. 2020 ) …”

“…4 over the past few cycles (Brun et al. 2020 ). These relations constitute another powerful constraint on dynamo models.…”