Effects of an Explosive Polar Cyclone Crossing the Antarctic Marginal Ice Zone

Vichi, Marcello; Eayrs, Clare; Alberello, Alberto; Bekker, Anriëtte; Bennetts, Luke G.; Holland, David M.; Jong, Ehlke de; Joubert, Warren; MacHutchon, Keith; Messori, Gabriele; Mojica, Jhon F.; Onorato, Miguel; Saunders, Clinton; Skatulla, Sebastian; Toffoli, Alessandro

doi:10.1029/2019gl082457

Cited by 87 publications

(150 citation statements)

References 68 publications

Supporting

Mentioning

146

Contrasting

Order By: Relevance

“…Thus, it is both the character of ice and snow overhead, and the physiological response to severe light limitation that may address the question raised at the start of this section. A crucial point here is that 100% sea ice cover (in the winter Antarctic sea ice) as seen from satellite does not necessarily imply a completely consolidated ice surface (Vichi et al, 2019). While the ocean may indeed be completely covered, the ice itself may be unconsolidated, being primarily composed of pancakes loosely connected by frazil or brash ice.…”

Section: Growth Under Extreme Light Limitationmentioning

confidence: 96%

“…Waves are known to propagate several hundred kilometres into the ice, effectively preventing the formation of pack ice-like conditions (Kohout et al, 2014;Meylan et al, 2014). Wind forcing is also known to be highly effective in causing ice break-up and motion, with intense synoptic events in the Weddell and Eastern Indian oceans occurring frequently (Vichi et al, 2019;Uotila et al, 2000). Such events, along with interactions with the westerly wind belt, drive the formation of gaps within the MIZ, as well as within pack ice.…”

Section: Growth Under Extreme Light Limitationmentioning

confidence: 99%

See 1 more Smart Citation

Southern Ocean BGC-Argo Detect Under Ice Phytoplankton Growth Before Sea Ice Retreat

Hague

Vichi

2020

Preprint

Self Cite

View full text Add to dashboard Cite

Abstract. The seasonality of sea ice in the Southern Ocean has profound effects on the life cycle (phenology) of phytoplankton residing under the ice. The current literature investigating this relationship is primarily based on remote sensing, which often lacks data for half the year or more. One prominent hypothesis holds that following ice retreat in spring, buoyant melt waters enhance irradiance levels, triggering a bloom which follows the ice edge. However, an analysis of BGC-Argo data sampling under Antarctic sea ice suggests that this is not necessarily the case. Rather than precipitating rapid accumulation, we show that melt waters enhance growth in an already highly active phytoplankton population. Blooms observed in the wake of the receding ice edge can then be understood as the emergence of a growth process that started earlier under sea ice. Indeed, we estimate that growth initiation occurs, on average, 4–5 weeks before ice retreat, typically starting in August and September. Novel techniques using on-board data to detect the timing of ice melt were used. Furthermore, such growth is shown to occur under conditions of substantial ice cover (> 90 % satellite ice concentration) and deep mixed layers (> 100 m), conditions previously thought to be inimical to growth. This led to the development of several 0D model experiments in which we sought to investigate the mechanisms responsible for such early growth. The results of theses experiments suggest that a combination of higher light transfer (penetration) through sea ice and extreme low light adaptation by phytoplankton can account for the observed phenology.

show abstract

Section: Growth Under Extreme Light Limitationmentioning

confidence: 96%

Section: Growth Under Extreme Light Limitationmentioning

confidence: 99%

Southern Ocean BGC-Argo Detect Under Ice Phytoplankton Growth Before Sea Ice Retreat

Hague

Vichi

2020

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…Francis et al, 2019) by virtue of their anomalous moisture and heat transport to high latitudes (Woods & Caballero, 2016;Grieger et al, 2018) and the strong surface winds they carry (Schemm, 2018). Severe storms can generate energetic waves (up to 8 m) in the Southern Ocean capable of penetrating hundreds of kilometers into the sea ice covered ocean (Kohout et al, 2014;Vichi et al, 2019). Concomitantly, the sea ice cover acts as a buffer and attenuates the wave energy over https://doi.org/10.5194/tc-2020-219 Preprint.…”

Section: Introductionmentioning

confidence: 99%

Atmospheric extremes triggered the biggest calving event in more than 50 years at the Amery Ice shelf in September 2019

Francis

Mattingly

Lhermitte

et al. 2020

Preprint

View full text Add to dashboard Cite

Abstract. Ice shelf instability is one of the main sources of uncertainty in Antarctica's contribution to future sea level rise. Calving events play crucial role in ice shelf weakening but remain unpredictable and their governing processes are still poorly understood. In this study, we analyze the unexpected September 2019 calving event from the Amery Ice Shelf, the largest since 1963 and which occurred almost a decade earlier than expected, to better understand the role of the atmosphere in calving. We find that atmospheric extremes provided a deterministic role in this event. The calving was triggered by the occurrence of a series of anomalously-deep and stationary explosive twin polar cyclones over the Cooperation and Davis Seas which generated strong offshore winds leading to increased sea ice removal, fracture amplification along the pre-existing rift, and ultimately calving of the massive iceberg. The observed record-anomalous atmospheric conditions were promoted by blocking ridges and Antarctic-wide anomalous poleward transport of heat and moisture. Blocking highs helped in (i) directing moist and warm air masses towards the ice shelf and in (ii) maintaining stationary the observed extreme cyclones at the front of the ice shelf for several days. Accumulation of cold air over the ice sheet, due to the blocking highs, led to the formation of an intense cold-high pressure over the ice sheet, which helped fuel sustained anomalously-deep cyclones via increased baroclinicity. Our results stress the importance of atmospheric extremes in ice shelf instability and the need to be accounted for when considering Antarctic ice shelf variability and contribution to sea level, especially given that more of these extremes are predicted under a warmer climate.

show abstract

“…Despite U10 being reasonably fitted by a Weibull distribution (with shape parameter close to 2) (Figures S2–S7), U10 is likely not perfectly homogeneous over the studied areas, in particular in larger or orography‐complex areas. In addition, the increased heat flux from the ocean to the atmosphere and associated turbulence over open water areas can induce changes in winds (Vihma et al, 2014; Vichi et al, 2019), meaning that the probability of large winds to achieve its maximum over a water cell or an ice‐covered cell could be different. Therefore,

F_{N_{2}}

might not be the only factor that explains the intensified changes in

{false{{U10}^{w} false}}_{\max}^{MON}

, as compared to

{false{U10 false}}_{\max}^{MON}

, which ultimately affects

{false{H_{s} false}}_{\max}^{MON}

.…”

Section: Resultsmentioning

confidence: 99%

Sea Ice Retreat Contributes to Projected Increases in Extreme Arctic Ocean Surface Waves

Casas-Prat

2020

Geophysical Research Letters

View full text Add to dashboard Cite

The projected changes and trends in the regional annual and monthly maxima of the significant wave height (Hs) in the Arctic Ocean are studied using wave simulations derived from the CMIP5 (Coupled Model Intercomparison Project Phase 5) climate simulations for 1979–2005 and 2081–2100 periods. Under the RCP8.5 scenario, the regional annual maximal Hs increases on average up to ∼3 cm/year, or >0.5%/year, relative to the 1986–2005 climatological value, in many Arctic areas (and up to 0.8%/year in the east side of the Arctic Ocean). While strong winds need to occur for large waves to develop, the changes in wind speed alone cannot explain the increases in the regional maximal Hs. Sea ice retreat also plays an important role by increasing fetch to promote wave growth, thereby contributing notably to the projected increase in wave height. It also contributes to increasing the probability of strong winds over the widening ice‐free waters.

show abstract

Effects of an Explosive Polar Cyclone Crossing the Antarctic Marginal Ice Zone

Cited by 87 publications

References 68 publications

Southern Ocean BGC-Argo Detect Under Ice Phytoplankton Growth Before Sea Ice Retreat

Southern Ocean BGC-Argo Detect Under Ice Phytoplankton Growth Before Sea Ice Retreat

Atmospheric extremes triggered the biggest calving event in more than 50 years at the Amery Ice shelf in September 2019

Sea Ice Retreat Contributes to Projected Increases in Extreme Arctic Ocean Surface Waves

Contact Info

Product

Resources

About