Figure 4
From: Shape and size constraints on dust optical properties from the Dome C ice core, Antarctica
Effects of the particle size distributions and shapes on dust AOD evaluated as described in the text.
(a) Size-resolved (on the CESM size bins, identified by the grey solid lines on the x-axis) sets of MEE (um2) from the SPES analyses (solid lines) and as used in the CESM [Albani et al.41] (dotted line). (b) Normalized particle size distributions (on the CESM size bins) from the EPICA Dome C (EDC) core for the LGM and Holocene periods (average distributions) [Delmonte et al.30]. (c) Atmospheric column extinction (AOD) due to dust, assuming (1) the dust mixing ratio and size distributions from a CESM simulation of the LGM climate (C4fn-lgm) [Albani et al.41], tuned to match dust deposition and size distributions at EDC and (2) the MEE determined from SPES analyses of sample DC-617-3&4, assuming spherical particles. (d) LGM/current climate ratio of dust AOD, calculated assuming the dust mixing ratio and size distributions from the CESM simulations (C4fn & C4fn-lgm) [Albani et al.41], tuned to match dust deposition and size distributions at EDC and the MEE determined from SPES analyses of sample DC-617-3&4, assuming spherical particles. (e) Dust AOD anomaly for changes in dust size distributions alone (comparing the LGM vs current size distributions), assuming the dust load of the tuned current climate simulation of d) and MEE of spheres (DC-617-3&4). (f) Anomaly (expressed as fraction) between the dust AOD based on MEE assuming prolate prisms (DC-280-3) with respect to that of spheres, assuming the same dust size distributions for current climate as in (d). (g) Same as (f), comparing the cases with prolate (DC-280-3) and oblate (DC-617-3) prisms. (h) Same as (f), comparing the cases with prolate (DC-280-3) prisms and a mixture (1:0.6) of prolate prisms and isometric particles (DC-280-1). Numbers in the bottom left corner of panels c-f represent the average value of the respective fields for latitudes <60 S. This figure was plotted by S. Albani specifically for this paper by means of an own-made script with IDL. IDL Version 8.2.1 (linux x86_64 m64). (c) 2012, Exelis Visual Information Solutions, Inc.
