Recent Reoccurrence of Large Open‐Ocean Polynya on the Maud Rise Seamount

Jena, Babula; Ravichandran, M.; Turner, John

doi:10.1029/2018gl081482

Cited by 43 publications

(52 citation statements)

References 47 publications

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“…This feature was present in the winters of 1974–1976 and has been studied extensively via satellite data and modeling investigations (Carsey, 1980; Martinson et al, 1981). The 2016 polynya grew from an area of lower ice concentration close to the Maud Rise seamount (10°E, 68°S), with its initial appearance in the middle of July attributed to ocean preconditioning by salinity anomalies (Campbell et al, 2019; Jena et al, 2019). The polynya subsequently closed, but reopened and was clearly apparent in the SIC anomaly field on 1 November 2016 (Figure S2c).…”

Section: Establishment Of the 2016/2017 Record Negative Sea Ice Anomalymentioning

confidence: 99%

Recent Decrease of Summer Sea Ice in the Weddell Sea, Antarctica

Turner

Guarino

Arnatt

et al. 2020

Geophysical Research Letters

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In Austral summer 2016/2017, the sea ice extent (SIE) in the Weddell Sea dropped to a near‐record value in the satellite era (1.88 × 106 km2), a large negative seasonal anomaly that persisted in an unprecedented fashion for the following three summers. Various atmospheric and oceanic factors played a part in the change. Ice loss started in September 2016 when the northern Weddell Sea experienced westerly winds of record strength, advecting multiyear sea ice from the region. In late 2016, a polynya over Maud Rise contributed to low SIE over the eastern Weddell Sea. With extensive areas of open water early in the summer, upper ocean temperatures increased by ~0.5°C, with the anomalies persisting in subsequent years. The reappearance of the Maud Rise polynya in 2017, high ocean temperatures, and storms of record depth kept the summer SIE low.

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Section: Establishment Of the 2016/2017 Record Negative Sea Ice Anomalymentioning

confidence: 99%

Recent Decrease of Summer Sea Ice in the Weddell Sea, Antarctica

Turner

Guarino

Arnatt

et al. 2020

Geophysical Research Letters

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“…Some years showed reduced springtime sea ice concentration in the region (Lindsay et al 2004), particularly 1994 (Fetterrer et al 2017), but a definite polynya did not occur again until 2017. This polynya was much smaller than before (0.3-0.35 3 10 5 km 2 ) and was only present for several months (Fetterrer et al 2017;Jena et al 2019). At the time of writing, it has not reappeared.…”

Section: Introductionmentioning

confidence: 83%

Modeling the Influence of the Weddell Polynya on the Filchner–Ronne Ice Shelf Cavity

et al. 2019

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Open-ocean polynyas in the Weddell Sea of Antarctica are the product of deep convection, which transports Warm Deep Water (WDW) to the surface and melts sea ice or prevents its formation. These polynyas occur only rarely in the observational record but are a near-permanent feature of many climate and ocean simulations. A question not previously considered is the degree to which the Weddell polynya affects the nearby Filchner-Ronne Ice Shelf (FRIS) cavity. Here we assess these effects using regional ocean model simulations of the Weddell Sea and FRIS, where deep convection is imposed with varying area, location, and duration. In these simulations, the idealized Weddell polynyas consistently cause an increase in WDW transport onto the continental shelf as a result of density changes above the shelf break. This leads to saltier, denser source waters for the FRIS cavity, which then experiences stronger circulation and increased ice shelf basal melting. It takes approximately 14 years for melt rates to return to normal after the deep convection ceases. Weddell polynyas similar to those seen in observations have a modest impact on FRIS melt rates, which is within the range of simulated interannual variability. However, polynyas that are larger or closer to the shelf break, such as those seen in many ocean models, trigger a stronger response. These results suggest that ocean models with excessive Weddell Sea convection may not be suitable boundary conditions for regional models of the Antarctic continental shelf and ice shelf cavities.

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“…The polynya was assumed when the pixel values were found to be less than or equal to 15 % of SIC ( Fig. 4a-c) (Jena et al, 2019). In order to examine the role of oceanic processes in the formation of the phytoplankton bloom in the polynya, we used relevant physical oceanographic data.…”

Section: Methodsmentioning

confidence: 99%

“…However, anomalously record low sea ice extent and area were observed for three successive years from 2016 to 2018 with the maximum melting occurring in 2017 (Parkinson, 2019). Amid the pronounced melting, the largest and most prolonged Maud Rise (MR) open ocean polynya since the 1970s reappeared on 14 September 2017 (∼ 9.3 × 10 3 km 2 ) and expanded to a maximum on 1 December 2017 (∼ 298.1× 10 3 km 2 ) and existed for 79 d (Jena et al, 2019). Appearance of the polynyas plays an important role in the oceanic phytoplankton and primary production that control the biological pump of the ocean (Arrigo and Dijken, 2003;Shadwick et al, 2017), as well as being important for marine mammals and birds (Labrousse et al, 2018;Stirling, 1997), global heat and salt fluxes (Tamura et al, 2008), Antarctic bottom water properties (Zanowski et al, 2015), and atmospheric circulation (Weijer et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Satellite observations of unprecedented phytoplankton blooms in the Maud Rise polynya, Southern Ocean

Jena

Pillai

2020

The Cryosphere

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Abstract. The appearance of phytoplankton blooms within sea ice cover is of high importance considering the upper ocean primary production that controls the biological pump, with implications for atmospheric CO2 and global climate. Satellite-derived chlorophyll a concentration showed unprecedented phytoplankton blooms in the Maud Rise polynya, Southern Ocean, with chlorophyll a reaching up to 4.67 mg m−3 during 2017. Multi-satellite data indicated that the bloom appeared for the first time since the entire mission records started in 1978. An Argo float located in the polynya edge provided evidence of bloom conditions in austral spring 2017 (chlorophyll a up to 5.47 mg m−3) compared to the preceding years with prevailing low chlorophyll a. The occurrence of bloom was associated with the supply of nutrients into the upper ocean through Ekman upwelling (driven by wind stress curl and cyclonic ocean eddies) and improved light conditions of up to 61.9 einstein m−2 d−1. The net primary production from the Aqua Moderate Resolution Imaging Spectroradiometer chlorophyll-based algorithm showed that the Maud Rise polynya was as productive as the Antarctic coastal polynyas, with carbon fixation rates reaching up to 415.08 mg C m−2 d−1. The study demonstrates how the phytoplankton in the Southern Ocean (specifically over the shallow bathymetric region) would likely respond in the future under warming climate conditions and continued melting of Antarctic sea ice.

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Recent Reoccurrence of Large Open‐Ocean Polynya on the Maud Rise Seamount

Cited by 43 publications

References 47 publications

Recent Decrease of Summer Sea Ice in the Weddell Sea, Antarctica

Recent Decrease of Summer Sea Ice in the Weddell Sea, Antarctica

Modeling the Influence of the Weddell Polynya on the Filchner–Ronne Ice Shelf Cavity

Satellite observations of unprecedented phytoplankton blooms in the Maud Rise polynya, Southern Ocean

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