Weddell Sea Polynya analysis using SMOS-SMAP Sea Ice Thickness Retrieval

Mchedlishvili, Alexander; Spreen, Gunnar; Melsheimer, Christian; Huntemann, Marcus

doi:10.5194/tc-2021-138

Cited by 2 publications

(6 citation statements)

References 10 publications

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“…In summary, previous studies have shown that the signature of the Maud Rise polynya can be observationally detected 2 weeks (Heuzé et al, 2021) to 1 month (Mchedlishvili et al, 2021) before it opens, depending on the satellites used. We here show that for all polynya events since 1979, and in particular all those of the 21st century, the upcoming opening can be detected three to four months ahead via their anomalous sea ice thickness and drift, controlled by anomalous dynamic and thermodynamic forcings from the atmosphere and ocean.…”

Section: Discussion and Summarymentioning

confidence: 88%

“…Nevertheless, the two altimeters and SMOS all agree that 3-4 months ahead, in May/June, sea ice is preconditioned for the polynya via an overall thinning (thickness more than one standard deviation away from the average values of the Envisat/ CryoSat-2 and SMOS 10-year datasets). This preconditioning makes the Maud Rise polynya predictable in the early winter, months earlier than the one-month-ahead thinning found by Mchedlishvili et al (2021) for the 2017 polynya only. Given that the polynya is more likely to develop within thin flat sea ice, next, we focus on the potential causes for this sea ice reduction in the early winter.…”

Section: Sea Ice Condition Throughout Wintermentioning

confidence: 84%

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Early Winter Triggering of the Maud Rise Polynya

Zhou

Heuzé

Mohrmann

2022

Geophysical Research Letters

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What triggers Maud Rise polynya, a large opening in the winter Antarctic sea ice, is still debated. We show that the upcoming opening of all Maud Rise polynyas can be detected in early winter up to four months ahead, especially since the 2002 expansion in satellite observations. In all polynya years, continuous anomalous sea ice thinning begins in May, caused by atmospheric and oceanic forcings. Dynamically, an anomalous cyclonic circulation in the atmosphere and the ocean strengthens the Weddell Gyre and exerts anomalously intense stresses on the ice. Thermodynamically, the warm water advected by the intensified circulation, and most importantly entrained into the mixed layer, thins the ice from below at the beginning of the freezing season, preconditioning the region for a polynya event months later. This four‐month‐ahead pattern enables early predictions of the polynya, and improved expedition planning and sensor deployment.

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Section: Discussion and Summarymentioning

confidence: 88%

Section: Sea Ice Condition Throughout Wintermentioning

confidence: 84%

Early Winter Triggering of the Maud Rise Polynya

Zhou

Heuzé

Mohrmann

2022

Geophysical Research Letters

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“…Tietsche et al, 2018), but papers about its quality and applicability for the Southern Ocean are in preparation (e.g. Mchedlishvili et al, 2021). Even though the 10-year time period is too short for deriving climatological mean values, we decided to include it as an observational baseline, where relevant, to compare the CMIP6 data to.…”

Section: Sea Ice Thicknessmentioning

confidence: 99%

“…Spurious OWP appearance or deep convection in the Weddell Sea remains a challenge in modern climate models (e.g. Sellar et al, 2019;Mauritsen et al, 2019; and references marked with an asterisk (*) in Table A1). Ocean convection due to static instabilities is an important process in the formation of OWPs, which is not modelled directly due to the relatively coarse resolution of many CMIP6 models (Table 1) but parameterised instead (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Southern Ocean polynyas in CMIP6 models

Mohrmann

Heuzé²,

Swart

2021

The Cryosphere

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Abstract. Polynyas facilitate air–sea fluxes, impacting climate-relevant properties such as sea ice formation and deep water production. Despite their importance, polynyas have been poorly represented in past generations of climate models. Here we present a method to track the presence, frequency and spatial distribution of polynyas in the Southern Ocean in 27 models participating in the Climate Model Intercomparison Project Phase 6 (CMIP6) and two satellite-based sea ice products. Only half of the 27 models form open-water polynyas (OWPs), and most underestimate their area. As in satellite observations, three models show episodes of high OWP activity separated by decades of no OWP, while other models unrealistically create OWPs nearly every year. In contrast, the coastal polynya area is overestimated in most models, with the least accurate representations occurring in the models with the coarsest horizontal resolution. We show that the presence or absence of OWPs is linked to changes in the regional hydrography, specifically the linkages between polynya activity with deep water convection and/or the shoaling of the upper water column thermocline. Models with an accurate Antarctic Circumpolar Current transport and wind stress curl have too frequent OWPs. Biases in polynya representation continue to exist in climate models, which has an impact on the regional ocean circulation and ventilation that should be addressed. However, emerging iceberg discharge schemes, more adequate vertical grid type or overflow parameterisation are anticipated to improve polynya representations and associated climate prediction in the future.

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Weddell Sea Polynya analysis using SMOS-SMAP Sea Ice Thickness Retrieval

Cited by 2 publications

References 10 publications

Early Winter Triggering of the Maud Rise Polynya

Early Winter Triggering of the Maud Rise Polynya

Southern Ocean polynyas in CMIP6 models

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