The effect of spatial and temporal accumulation rate variability in West Antarctica on soluble ion deposition

Annually-dated snowpit and ice core records from two areas of West Antarctica are used to investigate spatial accumulation patterns and to evaluate temporal accumulation rate/glaciochemical concentration and flux relationships. Mean accumulation rate gradients in Marie Byrd Land (11-23 gcm(-2)yr(-1) over 150 km, decreasing to the south) and Siple Dome (10-18 gcm(-2)yr(-1) over 60 km, decreasing to the south) are consistent for at least the last several decades, and demonstrate the influence of the offshore quasi-permanent Amundsen Sea low pressure system on moisture flux into the region. Local and regional-scale topography in both regions appears to affect orographic lifting, air mass trajectories, and accumulation distribution. Linear regression of mean annual soluble ion concentration and flux data vs, accumulation rates in both regions indicates that 1) concentrations are independent of and thus not a rescaling of accumulation rate time-series, and 2) chemical flux to the ice sheet surface is mainly via wet deposition, and changes in atmospheric concentration play a significant role. We therefore suggest that, in the absence of detailed air/snow transfer models, ice core chemical concentration and not flux time-series provide a better estimate of past aerosol loading in West Antarctica.