Sea ice production variability in Antarctic coastal polynyas

Tamura, Takeshi; Ohshima, Κay I.; Fraser, Alexander; Williams, Guy D.

doi:10.1002/2015jc011537

Cited by 143 publications

(209 citation statements)

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“…≥ 30%) with thickness ≤ 20 cm, and sea-ice production was estimated within such areas. The ice production was estimated on a daily basis from heat flux calculation using the daily mean AMSR2 thin ice thickness by a method similar to that used by the previous studies [5], [18], [19]. The sea-ice production rate Vi is estimated by assuming that heat from the ocean below is negligible and that all of the heat loss to the atmosphere contributes to the freezing of seawater, given by…”

Section: Estimation Of Sea-ice Productionmentioning

confidence: 99%

“…We compared ice production from AMSR2, AMSR-E [19], and SSM/I-SSMIS [18] data in the four largest ice production polynya areas in the Antarctic Ocean: the Ross Ice Shelf Polynya (RISP), CDP, Mertz Polynya (MP), and Amundsen Polynya (AP). The polynya areas are indicated in Fig.…”

Section: Comparisons Among Amsr2 Amsr-e and Ssm/i-ssmis Datamentioning

confidence: 99%

“…Algorithms have been developed based on this relationship to detect Antarctic coastal polynyas and to estimate the thin ice thickness on a daily time scale from passive microwave satellite data, namely, TB data from the Special Sensor Microwave Imager (SSM/I) and the Special Sensor Microwave Imager/Sounder (SSMIS) on Defense Meteorological Satellite Program (DMSP) satellites [17], [18] and the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) on the National Aeronautics and Space Administration's (NASA) Aqua satellite [19]. In these studies, thin ice thickness for the comparisons was based on heat flux calculations using ice surface temperatures from clear-sky satellite thermal infrared images.…”

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confidence: 99%

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Sea-Ice Production in Antarctic Coastal Polynyas Estimated From AMSR2 Data and Its Validation Using AMSR-E and SSM/I-SSMIS Data

Nihashi

Ohshima

Tamura

2017

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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Abstract-Antarctic coastal polynyas are very high sea-ice production areas. The resultant large amount of brine rejection leads to the formation of dense water. The dense water forms Antarctic Bottom Water, which is the densest water in the global overturning circulation and a key player in climate change as a significant sink for heat and carbon dioxide. In this study, an algorithm was developed that uses AMSR2 data (2012-present) to detect polynya area and estimate thin ice thickness by a method similar to that used to develop the algorithm for AMSR-E data. Landfast sea-ice areas were also detected using AMSR2 data. Ice production in the polynyas was estimated by a heat flux calculation using AMSR2 sea-ice data. In four major polynyas, AMSR2 ice production was compared with AMSR-E (2003-2011) ice production through comparison of them with SSM/I-SSMIS ice production. The comparison confirmed that the ice production from AMSR-E/2 data, which have higher spatial resolution than SSM/I-SSMIS data, can be used to analyze time series covering more than 10 years. For example, maps of annual ice production based on AMSR-E/2 data revealed detailed changes of the Mertz Polynya, where the ice production decreased significantly after the Mertz Glacier Tongue calving in 2010. Continuous monitoring of the coastal polynyas by the AMSR series sensors is essential for climate-change-related analyses in the Antarctic Ocean.

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Section: Estimation Of Sea-ice Productionmentioning

confidence: 99%

Section: Comparisons Among Amsr2 Amsr-e and Ssm/i-ssmis Datamentioning

confidence: 99%

mentioning

confidence: 99%

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Sea-Ice Production in Antarctic Coastal Polynyas Estimated From AMSR2 Data and Its Validation Using AMSR-E and SSM/I-SSMIS Data

Nihashi

Ohshima

Tamura

2017

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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“…Since the calving of the MGT, the Mertz Polynya has decreased significantly in size (Tamura et al, 2016), changing ocean circulation Cougnon et al, 2017;Kusahara et al, 2017) and increasing sea-ice concentrations (Tamura et al, 2012). The iceberg B09B grounded on the SouthEastern flank of the Adélie Bank shortly after the collision, and a new polynya has formed on its leeward side .…”

Section: Study Areamentioning

confidence: 99%

Mapping Antarctic Suspension Feeder Abundances and Seafloor Food-Availability, and Modeling Their Change After a Major Glacier Calving

et al. 2018

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Seafloor communities are a critical part of the unique and diverse Antarctic marine life. Processes at the ocean-surface can strongly influence the diversity and abundance of these communities, even when they live at hundreds of meters water depth. However, even though we understand the importance of this link, there are so far no quantitative spatial predictions on how seafloor communities will respond to changing conditions at the ocean surface. Here, we map patterns in abundance of important habitat-forming suspension feeders on the seafloor in East Antarctica, and predict how these patterns change after a major disturbance in the icescape, caused by the calving of the Mertz Glacier Tongue. We use a purpose-built ocean model for the time-period before and after the calving of the Mertz-Glacier Tongue in 2010, data from satellites and a validated food-availability model to estimate changes in horizontal flux of food since the glacier calving. We then predict the post-calving distribution of suspension feeder abundances using the established relationships with the environmental variables, and changes in horizontal flux of food. Our resulting maps indicate strong increases in suspension feeder abundances close to the glacier calving site, fueled by increased food supply, while the remainder of the region maintains similar suspension feeder abundances despite a slight decrease in total food supply. The oceanographic setting of the entire region changes, with a shorter ice-free season, altered seafloor currents and changes in food-availability. Our study provides important insight into the flow-on effects of a changing icescape on seafloor habitat and fauna in polar environments. Understanding these connections is important in the context of current and future effects of climate change, and the mapped predictions of the seafloor fauna as presented for the study region can be used as a decision-tool for planning potential marine protected areas, and for focusing future sampling and monitoring initiatives.

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“…This dense water sinks to fill the abyssal depths of the ocean with Antarctic Bottom Water. The surface buoyancy fluxes that drive the abyssal overturning are largest in regions of sea ice production or open water (polynyas) close to the Antarctic coast where the insulation provided by sea ice is minimal (Tamura et al 2016) and may therefore also depend on local wind stress variations that act to keep polynyas free of ice. However, most climate models form bottom water through open-ocean polynyas that connect directly to the deep ocean (Heuzé et al 2015).…”

Section: Introductionmentioning

confidence: 99%

The Energetics of Southern Ocean Upwelling

Hogg

Spence

Saenko

et al. 2017

Journal of Physical Oceanography

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The ocean's meridional overturning circulation is closed by the upwelling of dense, carbon-rich waters to the surface of the Southern Ocean. It has been proposed that upwelling in this region is driven by strong westerly winds, implying that the intensification of Southern Ocean winds in recent decades may have enhanced the rate of upwelling, potentially affecting the global overturning circulation. However, there is no consensus on the sensitivity of upwelling to winds or on the nature of the connection between Southern Ocean processes and the global overturning circulation. In this study, the sensitivity of the overturning circulation to changes in Southern Ocean westerly wind stress is investigated using an eddy-permitting ocean-sea ice model. In addition to a suite of standard circulation metrics, an energy analysis is used to aid dynamical interpretation of the model response. Increased Southern Ocean wind stress enhances the upper cell of the overturning circulation through creation of available potential energy in the Southern Hemisphere, associated with stronger upwelling of deep water. Poleward shifts in the Southern Ocean westerlies lead to a complicated transient response, with the formation of bottom water induced by increased polynya activity in the Weddell Sea and a weakening of the upper overturning cell in the Northern Hemisphere. The energetic consequences of the upper overturning cell response indicate an interhemispheric connection to the input of available potential energy in the Northern Hemisphere.

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Sea ice production variability in Antarctic coastal polynyas

Cited by 143 publications

References 56 publications

Sea-Ice Production in Antarctic Coastal Polynyas Estimated From AMSR2 Data and Its Validation Using AMSR-E and SSM/I-SSMIS Data

Sea-Ice Production in Antarctic Coastal Polynyas Estimated From AMSR2 Data and Its Validation Using AMSR-E and SSM/I-SSMIS Data

Mapping Antarctic Suspension Feeder Abundances and Seafloor Food-Availability, and Modeling Their Change After a Major Glacier Calving

The Energetics of Southern Ocean Upwelling

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