Open AccessContinuous record of microparticle concentration and size distribution in the central Greenland NGRIP ice core during the last glacial period
Author(s) -
Ruth Urs,
Wagenbach Dietmar,
Steffensen Jørgen P.,
Bigler Matthias
Publication year - 2003
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2002jd002376
Subject(s) - ice core , groenlandia , atmospheric sciences , greenland ice sheet , glacial period , geology , last glacial maximum , climatology , particle size distribution , range (aeronautics) , environmental science , ice sheet , physical geography , particle size , oceanography , geography , geomorphology , paleontology , materials science , composite material
A novel laser microparticle detector used in conjunction with continuous sample melting has provided a more than 1500 m long record of particle concentration and size distribution of the NGRIP ice core, covering continuously the period approximately from 9.5–100 kyr before present; measurements were at 1.65 m depth resolution, corresponding to approximately 35–200 yr. Particle concentration increased by a factor of 100 in the Last Glacial Maximum (LGM) compared to the Preboreal, and sharp variations of concentration occurred synchronously with rapid changes in the δ 18 O temperature proxy. The lognormal mode μ of the volume distribution shows clear systematic variations with smaller modes during warmer climates and coarser modes during colder periods. We find μ ≈ 1.7 μm diameter during LGM and μ ≈ 1.3 μm during the Preboreal. On timescales below several 100 years μ and the particle concentration exhibit a certain degree of independence present especially during warm periods, when μ generally is more variable. Using highly simplifying considerations for atmospheric transport and deposition of particles we infer that (1) the observed changes of μ in the ice largely reflect changes in the size of airborne particles above the ice sheet and (2) changes of μ are indicative of changes in long range atmospheric transport time. From the observed size changes we estimate shorter transit times by roughly 25% during LGM compared to the Preboreal. The associated particle concentration increase from more efficient long range transport is estimated to less than one order of magnitude.