Snow accumulation variability in Wilkes Land, East Antarctica, and the relationship to atmospheric ridging in the 130°-170°E region since 1930 -: art. no. 4673

Wilkes Land annual snow accumulation variability is explored together with ice core chemistry data as proxies for circumpolar atmospheric circulation in the 110degreesE-135degreesE sector of the circumpolar trough. Four accumulation time series spanning 1930-1985 show a pattern of accumulation related to maritime air mass incursions over the East Antarctic ice sheet slope, which is regionally consistent on interannual and interdecadal timescales. The temporal accumulation pattern in Wilkes Land shows decadal fluctuations of +/-10%. Both these fluctuations and the overall trend of increasing accumulation since the middle 1960s are consistent with a poleward shift and intensification of the circumpolar trough. This is consistent with a shift toward the high index state of the southern annular mode. Interannual variability of snow accumulation rate throughout Wilkes Land was found to be dependent upon shifts in the preferred tracks of cyclones along or across the coast and in the location of cyclolysis regions. Significant differences in this temporal accumulation pattern over Wilkes Land can occur as a result of the time-varying location of atmospheric ridging and the circumpolar long-wave structure south of New Zealand and Australia. Snow accumulation at an additional site (GD09) displays a well-defined interdecadal pattern, and the mean annual nitrate (NO3-) concentration of snow is correlated to the winter sea level pressure gradient between East Antarctica and the sub-Antarctic and the upper geopotential height and zonal wind data over East Antarctica. Strong, surface wind drainage during tropospheric ridging in Wilkes Land produces anomalous snow accumulation and annual mean NO3- concentration in firn at GD09.