Energy Balance in the Corona over the 22-Year Solar Cycle

Abstract

Wheatland and Litvinenko (2001) presented a model for dynamical energy balance in the flaring solar corona which predicts a time lag between flare occurrence and the supply of energy to the corona (`driving'). They also suggested that an observed net lag between flare numbers and sunspot numbers over cycles 21 and 22 might provide support for the model. Temmer, Veronig, and Hanslmeier (2003) examined data for five individual solar cycles (19–23) and confirmed a lag between flare and sunspot numbers for odd solar cycles, but found no lag for even cycles. Following the suggestion of Temmer, Veronig, and Hanslmeier, the energy balance model is here extended to incorporate 22-year driving consistent with the phenomenological Gnevyshev—Ohl rule. The model is found to exhibit a greater lag for the smaller (even) cycles, in contradiction with the findings of Temmer, Veronig, and Hanslmeier. A modification to the model is investigated in which the flaring rate is proportional to the free energy and to the driving rate for small driving rates, but is proportional only to the free energy for large driving rates. The modified model can in principle account for the observations.