Abstract
RECORDS of 14C in tree rings provide a proxy for changes in solar activity on timescales of decades to centuries1,2. Here I report an association between Maunder-type solar cycles recorded in tree rings and fluctuations in surface wind intensity on a roughly 200-year timescale over a period of about 2,000 years in the mid-Holocene. The wind record is preserved as changes in the thickness of varved sediments in Elk Lake, Minnesota, which contain a large aeolian component. Changes in cyclonic activity and tropospheric winds have been reported1–5 to occur in this region a few days after strong coronal mass ejections (CMEs); increases of up to 7% in zonal flow have been reported5 at an altitude of ~ 300 m after strong CMEs in winter. The implication of this association is that century-scale changes in surface winds over Minnesota were the long-term (Maunder-scale) counterpart of short-term (daily) changes in winds after CMEs. The weak magnetic field strength of the Earth at this time6,7 might be relevant to a possible mechanism for the association.
Published Version
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