Satellite‐based estimates of Antarctic surface meltwater fluxes

Abstract

[1] This study generates novel satellite-derived estimates of Antarctic-wide annual (1999Antarctic-wide annual ( -2009 surface meltwater production using an empirical relationship between radar backscatter from the QuikSCAT (QSCAT) satellite and melt calculated from in situ energy balance observations. The resulting QSCAT-derived melt fluxes significantly agree with output from the regional climate model RACMO2.1 and with independent ground-based observations. The highresolution (4.45 km) QSCAT-based melt fluxes uniquely detect interannually persistent and intense melt (>400 mm water equivalent (w.e.) year À1) on interior Larsen C Ice Shelf that is not simulated by RACMO2.1. This supports a growing understanding of the importance of a föhn effect in this region and quantifies the resulting locally enhanced melting that is spatially consistent with recently observed Larsen C thinning. These new results highlight important cryosphere-climate interactions and processes that are presently not fully captured by the coarser-resolution (27 km) regional climate model. Citation: Trusel, L. D., K. E. Frey, S. B. Das, P. Kuipers Munneke, and M. R. van den Broeke (2013), Satellite-based estimates of Antarctic surface meltwater fluxes, Geophys. Res. Lett., 40,[6148][6149][6150][6151][6152][6153]

Oceanic and atmospheric forcing of Larsen C Ice-Shelf thinning

“…A spatial correspondence between ice-shelf collapses and mean atmospheric temperature suggests that atmospheric warming may have pushed some ice shelves beyond a thermal limit of viability (Morris and Vaughan, 2003); the northern edge of LCIS is at this limit. Observations of LCIS firn-air thickness confirm that there is sufficient firn air available for compaction, that lower firn air spatially corresponds with higher melting, and that the northward-intensified surface lowering spatially corresponds to areas of high melting and firn compaction (Holland et al, 2011;Trusel et al, 2013;Luckman et al, 2014). Modelled firn compaction entirely offset the lowering in one study of -2008, albeit with a high uncertainty.…”

“…In particular, our surveys do not capture the rapid lowering in northern LCIS. Ice divergence may play a part in this, since the known acceleration of LCIS is northward-intensified (Haug et al, 2010;Khazendar et al, 2011), but there are also good reasons to expect changes in surface melting to be largest in the north (Holland et al, 2011;Trusel et al, 2013;Luckman et al, 2014). The pattern of changes in basal melting is unknown.…”

Meltwater produced by wind–albedo interaction stored in an East Antarctic ice shelf

“…2a) near the grounding zone than towards the calving front, approximately 50 km downstream, where the surface-based temperature inversion prevails. This regional warming doubles the surface meltwater production when compared with the region farther downstream, as derived by microwave radar backscatter 19 . Secondly, the strong near-surface winds have the potential to erode the snow surface 20 .…”

“…8), which is about 26% and 73% of the area of high MSWD and blue-ice area below 500 m, respectively. Melt rates are underestimated in these areas, because the surface melt volume is derived from the backscatter signal over a snow surface 19 . Supplementary Fig.…”

Identification of Air Masses Responsible for Warm Events on the East Antarctic Coast

“…Present available observation dataset, however, is of insufficient length to address that these warming trends are anthropogenically forced, because natural interannual to multi-decadal variability may obscure these warming trends (Jones et al 2016). While no significant warming trends have been recorded in East Antarctica (EA) in recent decades (Altnau et al 2014), surface snowmelt is observed every summer over ice shelves, even in the East Antarctic coast (Toriensi et al 2003;Picard and Fily 2006;Trusel et al 2013). Even a slight increase in the summer air temperature on the East Antarctic coast therefore is expected to enhance surface melt and its role in ice loss.…”