Impact of known local and tropical volcanic eruptions of the past millennium on the WAIS Divide microparticle record

We present a new method for inferring the relative location (low- versus high-southern latitude), and therefore the potential climatic impact, of past eruptions based on the particle size distribution (PSD) of micrometer-sized ash measured continuously in the West Antarctic Ice Sheet (WAIS) Divide ice core. We find that particles from a high-southern latitude eruption (Buckle Island, Antarctica (1839 Common Era, C.E.)) have a PSD with mode diameter 5 mu m coarser than the background dust (mode 5.1 mu m), while ash particles originating from stratospheric tropical eruptions, including Tambora (1815 C.E.), Kuwae (1458 C.E.), and Unknown (1258 C.E.), have PSDs with mode diameters similar to 0.6-1.5 mu m finer than the background. In addition, volcanic ash particles from global-scale eruptions are deposited similar to 3-6 months earlier and over a shorter time interval than sulfate aerosols. We hypothesize that this phasing is driven by differences in atmospheric processing and aerosol/particle transport and deposition.