Continuous record of microparticle concentration and size distribution in the central Greenland NGRIP ice core during the last glacial period
A novel laser microparticle detector used in conjunction with continuous samplemelting has provided a more than 1500 m long record of particle concentrationand size distribution of the NGRIP ice core, covering continuously the periodapproximately from 9.5 kyr to 100 kyr before present. Measurements were at 1.65 mdepth resolution, corresponding to approximately 35 yr to 200 yr. Particleconcentration increased by a factor of 100 in the Last Glacial Maximum (LGM)compared to the Preboreal, and sharp variations of concentration occurredsynchronously with rapid changes in the d18O temperature proxy. The lognormalmode mu of the volume distribution shows clear systematic variations withsmaller modes during warmer climates and coarser modes during colder periods.Using some simple models for the atmospheric transport anddeposition of particles we infer that (1) the observed changes of mu in theice largely reflect changes in the size of airborne particles above the ice sheetand (2) changes of mu are indicative of changes in long range atmospherictransport time.