Possible solar influences on the dust profile of the GISP2 Ice Core from central Greenland

Abstract

The Greenland Ice Sheet Project 2 (GISP2) ice core dust profile in glacial (Wisconsinan) ice from Central Greenland has been measured using Laser‐Light Scattering (LLS) from ice. This data exhibits considerable high frequency variability. By applying appropriate running averages to the data, certain regularities emerge. Thus, for example, when the data was smoothed with rectangular 4 and 5 year running averages, ∼11 year dust modulations of considerable amplitude were revealed. In this paper, we show how further smoothing of the data causes very large, longer period dust modulations centered at ∼91 years in a Gaussian distribution to emerge. We believe that this corresponds to the 80–90 year modulation of the 11 year sunspot cycle first suggested by Gleissberg. We also show how adjacent 11 year dust periods can combine in a unique way to generate a 22 year (Hale) period of dust modulation. The way this occurs is similar to that by which a 22 year modulation of the measured terrestrial neutron flux is generated from two 11 year periods. Taken together with our observation of a ∼200 year (Suess) dust modulation period, these observations strengthen our claim that the dust modulations we measured in GISP2 ice are solar induced and suggest a mechanism for their production.