Synoptic controls on precipitation pathways and snow delivery to high‐accumulation ice core sites in the Ross Sea region, Antarctica

Abstract

[1] Dominant storm tracks to two ice core sites on the western margin of the Ross Sea, Antarctica (Skinner Saddle (SKS) and Evans Piedmont Glacier), are investigated to establish key synoptic controls on snow accumulation. This is critical in terms of understanding the seasonality, source regions, and transport pathways of precipitation delivered to these sites. In situ snow depth and meteorological observations are used to identify major accumulation events in [2007][2008], which differ considerably between sites in terms of their magnitude and seasonal distribution. While snowfall at Evans Piedmont Glacier occurs almost exclusively during summer and spring, Skinner Saddle receives precipitation year round with a lull during the months of April and May. Cluster analysis of daily back trajectories reveals that the highest-accumulation days at both sites result from fast-moving air masses, associated with synoptic-scale low-pressure systems. There is evidence that short-duration pulses of snowfall at SKS also originate from mesocyclone development over the Ross Ice Shelf and local moisture sources. Changes in the frequency and seasonal distribution of these mechanisms of precipitation delivery will have a marked impact on annual accumulation over time and will therefore need careful consideration during the interpretation of stable isotope and geochemical records from these ice cores.

The Ross Sea Dipole – temperature, snow accumulation and sea ice variability in the Ross Sea region, Antarctica, over the past 2700 years

“…In recent decades, a Roosevelt Island polynya has been observed and merges at times with the much larger Ross Sea polynya (Morales Maqueda et al, 2004). In contrast to the Ross Sea Polynya (Sinclair et al, 2010), a local polynya could provide a potent source of isotopically enriched vapour for precipitation at RICE, perhaps exaggerating the actual warming of the area as interpreted from water stable-isotope data. We expect the influence of a Roosevelt Island polynya to have a reduced effect on the more distant Siple Dome, which is consistent with our observations.…”

“…a −1 . It has been shown that Antarctic ERAi data capture precipitation variability but generally underestimate the precipitation total (Wang et al, 2016;Sinclair et al, 2010;Bromwich et al, 2011). Further, the ERAi data are not directly comparable to local measurements because they do not capture periods of snow scouring by wind.…”

Regional Antarctic snow accumulation over the past 1000 years

“…However, the Transantarctic Mountains block flow to southern Victoria Land so that this region is influenced by storms that cross the Ross Sea (Sodeman and Stohl, 2009). As a consequence, the snow accumulation rates are higher in northern and southern Victoria Land, while the middle region (including the McMurdo Dry Valleys) lies in the precipitation shadows of cyclones from the north and the south, experiencing overall lower snow accumulation rates (Sinclair et al, 2010).…”

Twentieth-Century Surface Temperature Trends in the Western Ross Sea, Antarctica: Evidence from a High-Resolution Ice Core

“…In general, Antarctic precipitation is weighted toward periods with above-average atmospheric temperatures (Helsen et al 2006;Marshall 2009), but the frequency of synoptic-scale storms plays a significant role in coastal areas because low pressure centers advect warm, moist air across the continent in all seasons (Sinclair et al 2010;Nicolas and Bromwich 2011). As shown in Fig.…”