Turbulent Pumping of Magnetic Flux Reduces the Memory of the Solar Cycle

Nandy Dibyendu, dnandi@iiserkol.ac.in, Indian Institute of Science Education and Research, Kolkata, India
Karak Bidya Binay, bidya_karak@physics.iisc.ernet.in, Indian Institute of Science, Bangalore, India

Abstract
Predicting solar activity is important for assessing its forcing on space environment and planetary atmospheres. However, recent efforts to predict the amplitude of the solar cycle have not converged. We have earlier demonstrated that the dynamical memory of the solar dynamo mechanism impacts predictability and that this memory is different for advection and diffusion dominated solar convection zones. Here we present recent results which demonstrate that downward turbulent pumping of magnetic flux reduces the memory of both advection and diffusion dominated solar dynamos to less than a cycle and that stronger pumping induces a severe degradation of this short memory. Based on this we argue that reliable forecasts of the solar cycle can be made only half-a-cycle in advance and sequential data assimilation is necessary in forecasting models to account for the Sun's short memory.