Laura Herraiz-Borreguero
Cooperative Research Centre
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Publication
Featured researches published by Laura Herraiz-Borreguero.
Nature Communications | 2016
Gd Williams; Laura Herraiz-Borreguero; Fabien Roquet; Takeshi Tamura; Kay I. Ohshima; Yasushi Fukamachi; Alexander D. Fraser; Libao Gao; H. Chen; Clive R. McMahon; Robert G. Harcourt; Mark A. Hindell
A fourth production region for the globally important Antarctic bottom water has been attributed to dense shelf water formation in the Cape Darnley Polynya, adjoining Prydz Bay in East Antarctica. Here we show new observations from CTD-instrumented elephant seals in 2011–2013 that provide the first complete assessment of dense shelf water formation in Prydz Bay. After a complex evolution involving opposing contributions from three polynyas (positive) and two ice shelves (negative), dense shelf water (salinity 34.65–34.7) is exported through Prydz Channel. This provides a distinct, relatively fresh contribution to Cape Darnley bottom water. Elsewhere, dense water formation is hindered by the freshwater input from the Amery and West Ice Shelves into the Prydz Bay Gyre. This study highlights the susceptibility of Antarctic bottom water to increased freshwater input from the enhanced melting of ice shelves, and ultimately the potential collapse of Antarctic bottom water formation in a warming climate.
Journal of Geophysical Research | 2010
Laura Herraiz-Borreguero; Stephen R. Rintoul
[1] Subantarctic Mode Water (SAMW) is formed by deep mixing on the equatorward side of the Antarctic Circumpolar Current. The subduction and export of SAMW from the Southern Ocean play an important role in global heat, freshwater, carbon, and nutrient budgets. However, the formation process and variability of SAMW remain poorly understood, largely because of a lack of observations. To determine the temporal variability of SAMW in the Australian sector of the Southern Ocean, we used a 15 year time series of repeat expendable bathythermograph sections from 1993 to 2007, seven repeat conductivity-temperature-depth sections from 1991 to 2001, and sea surface height maps. The mean temperature of the SAMW lies between 8.5°C and 9.5°C (mean of 8.8°C, standard deviation of 0.3°C), and there is no evidence of a trend over the 18 year record. However, the temperature, salinity, and pycnostad strength of the SAMW can change abruptly from section to section. In addition, the SAMW pool on a single section often consists of two or more modes with distinct temperature, salinity, and vertical homogeneity characteristics but similar density. We show that the multiple types of mode water can be explained by the advection of anomalous water from eddies and meanders of the fronts bounding the Subantarctic Zone and by recirculation of SAMW of different ages. Our results suggest that infrequently repeated sections can potentially produce misleading results because of aliasing of high interannual variability.
Journal of Geophysical Research | 2015
Laura Herraiz-Borreguero; R Coleman; Ian Allison; Stephen R. Rintoul; Mike Craven; Gd Williams
Antarctic ice sheet mass loss has been linked to an increase in oceanic heat supply, which enhances basal melt and thinning of ice shelves. Here we detail the interaction of modified Circumpolar Deep Water (mCDW) with the Amery Ice Shelf, the largest ice shelf in East Antarctica, and provide the first estimates of basal melting due to mCDW. We use subice shelf ocean observations from a borehole site (AM02) situated ?70 km inshore of the ice shelf front, together with open ocean observations in Prydz Bay. We find that mCDW transport into the cavity is about 0.22?±?0.06 Sv (1 Sv?=?106 m3 s?1). The inflow of mCDW drives a net basal melt rate of up to 2?±?0.5 m yr?1 during 2001 (23.9?±?6.52 Gt yr?1 from under about 12,800 km2 of the north-eastern flank of the ice shelf). The heat content flux by mCDW at AM02 shows high intra-annual variability (up to 40%). Our results suggest two main modes of subice shelf circulation and basal melt regimes: (1) the “ice pump”/high salinity shelf water circulation, on the western flank and (2) the mCDW meltwater-driven circulation in conjunction with the “ice pump,” on the eastern flank. These results highlight the sensitivity of the Amerys basal melting to changes in mCDW inflow. Improved understanding of such ice shelf-ocean interaction is crucial to refining projections of mass loss and associated sea level rise.
Journal of Geophysical Research | 2016
Laura Herraiz-Borreguero; John A. Church; Ian Allison; B. Peña-Molino; R Coleman; Matthias Tomczak; Mike Craven
Despite the Amery Ice Shelf (AIS) being the third largest ice shelf in Antarctica, the seasonal variability of the physical processes involved in the AIS-ocean interaction remains undocumented and a robust observational, oceanographic-based basal melt rate estimate has been lacking. Here we use year-long time series of water column temperature, salinity, and horizontal velocities measured along the ice shelf front from 2001 to 2002. Our results show strong zonal variations in the distribution of water masses along the ice shelf front: modified Circumpolar Deep Water (mCDW) arrives in the east, while in the west, Ice Shelf Water (ISW) and Dense Shelf Water (DSW) formed in the Mackenzie polynya dominate the water column. Baroclinic eddies, formed during winter deep convection (down to 1100 m), drive the inflow of DSW into the ice shelf cavity. Our net basal melt rate estimate is 57.4 ± 25.3 Gt yr−1 (1 ± 0.4 m yr−1), larger than previous modeling-based and glaciological-based estimates, and results from the inflow of DSW (0.52 ± 0.38 Sv; 1 Sv = 106 m3 s−1) and mCDW (0.22 ± 0.06 Sv) into the cavity. Our results highlight the role of the Mackenzie polynya in the seasonal exchange of water masses across the ice shelf front, and the role of the ISW in controlling the formation rate and thermohaline properties of DSW. These two processes directly impact on the ice shelf mass balance, and on the contribution of DSW/ISW to the formation of Antarctic Bottom Water.
Nature Geoscience | 2013
Kay I. Ohshima; Yasushi Fukamachi; Gd Williams; Sohey Nihashi; Fabien Roquet; Yujiro Kitade; Takeshi Tamura; Daisuke Hirano; Laura Herraiz-Borreguero; Iain C. Field; Mark A. Hindell; Shigeru Aoki; Masaaki Wakatsuchi
Ecosphere | 2016
Mark A. Hindell; Clive R. McMahon; Marthan Nieuwoudt Bester; Lars Boehme; Daniel P. Costa; Michael A. Fedak; Christophe Guinet; Laura Herraiz-Borreguero; Robert G. Harcourt; Luis A. Hückstädt; Kit M. Kovacs; Christian Lydersen; Trevor McIntyre; Toby A. Patterson; Fabien Roquet; Gd Williams; Jean-Benoit Charrassin
Ocean Dynamics | 2011
Laura Herraiz-Borreguero; Stephen R. Rintoul
Geophysical Research Letters | 2013
Matthew P. Couldrey; L. Jullion; Alberto C. Naveira Garabato; Craig Rye; Laura Herraiz-Borreguero; P. Brown; Michael P. Meredith; Kevin L. Speer
Deep-sea Research Part Ii-topical Studies in Oceanography | 2011
Laura Herraiz-Borreguero; Stephen R. Rintoul
Journal of Geophysical Research | 2013
Laura Herraiz-Borreguero; Ian Allison; Mike Craven; Keith W. Nicholls; Ma Rosenberg