Predictions of strengths of long-term variations in sunspot activity

Abstract

Recently, using Greenwich data (1879-1976) and SOON/NOAA data (1977-2002) on sunspot groups we found a big or a moderate drop in the solar equatorial rotation rate, A, occurred after every four solar cycles suggesting theexistence of double cycle (DHC) and Gleissberg cycle (GC) in A. We also found the existence of Hale cycle (HC) and GC in the latitude gradient of the rotation, B (Javaraiah 2003). Using these results here we made forecasts for the following: (i) epochs of the forthcoming big and moderate drops in A; (ii) the epoch of maximum ‖B‖ during the current GC of B; (iii) the strengths of DHCs and HCs of sunspot activity which follow the big and the moderate drops in A; (iv) violation of the Gnevyshev & Ohl rule during the current HC 11 which consists of cycles 22 and 23; and (v) deduced the near complete absence of sunspot activity during the deep Maunder minimum.