Antarctic Peninsula Regional Circulation and its Impact on the Surface Melt of Larsen C Ice Shelf

2021 ◽  
pp. 1-38
Author(s):  
Chongran Zhang ◽  
Jing Zhang ◽  
Qigang Wu
Keyword(s):  
Time Series ◽  
Surface Temperature ◽  
Sea Level ◽  
Antarctic Peninsula ◽  
Weddell Sea ◽  
Amundsen Sea ◽  
Budget Analysis ◽  
Regional Circulation ◽  
Mode 2 ◽  
Surface Melt

AbstractEnhanced surface melt over the ice shelves of the Antarctic Peninsula (AP) is one of the precursors to their collapse, which can be proceeded by accelerated ground glacier flow and increased contribution to sea level rise. With the collapse of Larsen A and B, and the major 2017 calving event from Larsen C, whether Larsen C is bound for a similar fate has received increasing attention. Here, the interannual variation of regional circulation over the AP region is studied using the Empirical Orthogonal Function (EOF) / Principal Component (PC) analysis on the sea level pressure of ERA5 reanalysis. The EOF modes capture the variations of depth, location and extent of Amundsen Sea Low and Weddell Sea Low in each season. Statistically significant positive correlations exist between Larsen C surface temperature and the PC time series of EOF mode 1 in winter and spring through northerly/northwesterly wind anomalies west of the AP. The PC time series of EOF mode 2 is negatively correlated with Larsen C surface temperature in autumn and summer and surface melt in summer, all due to southerly wind anomalies east of the AP. Surface energy budget analysis associated with EOF mode 2 shows that downwelling longwave radiation over Larsen C is negatively statistically significantly, correlated with EOF mode 2 and is the major atmospheric forcing regulating the variation of Larsen C surface melt. Positively enhanced EOF mode 2 since 2004 is responsible for the recent cooling and decline of surface melt over Larsen C.

scholarly journals Climate drives long-term change in Antarctic Silverfish along the western Antarctic Peninsula

2021 ◽  
Author(s):  
Andrew Corso ◽  
Deborah Steinberg ◽  
Sharon Stammerjohn ◽  
Eric Hilton
Keyword(s):  
Sea Ice ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Antarctic Peninsula ◽  
Environmental Variability ◽  
Sea Surface ◽  
Larval Abundance ◽  
Western Antarctic Peninsula ◽  
Amundsen Sea ◽  
Antarctic Silverfish

Abstract Over the last half of the 20th century, the western Antarctic Peninsula has been one of the most rapidly warming regions on Earth, leading to substantial reductions in regional sea ice coverage. These changes are modulated by atmospheric forcing, including the Amundsen Sea Low (ASL) pressure system. We utilized a novel 25-year (1993–2017) time series to model the effects of environmental variability on larvae of a keystone species, the Antarctic Silverfish (Pleuragramma antarctica). Antarctic Silverfish use sea ice as spawning habitat and are important prey for penguins and other predators. We show that warmer sea surface temperature and decreased sea ice negatively impact larval abundance. Modulating both sea surface temperature and sea ice is ASL variability, where a strong ASL is associated with reduced larvae. These findings support a narrow sea ice and temperature tolerance for adult and larval fish. Further regional warming predicted to occur during the 21st century could displace fish populations, altering this pelagic ecosystem.

Winter climate change on the northern and southern Antarctic Peninsula

2020 ◽  
Vol 32 (5) ◽  
pp. 408-424
Author(s):  
Oleksandr M. Evtushevsky ◽  
Volodymyr O. Kravchenko ◽  
Asen V. Grytsai ◽  
Gennadi P. Milinevsky
Keyword(s):  
Time Series ◽  
Surface Temperature ◽  
Antarctic Peninsula ◽  
Southern Annular Mode ◽  
Meridional Wind ◽  
Winter Climate ◽  
Annular Mode ◽  
Temperature Trends ◽  
Pressure Anomaly ◽  
Tropical Sea

AbstractDifferences in the decadal trend in the winter surface temperature in the northern and southern Antarctic Peninsula have been analysed. Time series from the two stations Esperanza and Faraday/Vernadsky since the early 1950s are used. The two time series are strongly correlated only during the 1980s and 1990s when their variability and trends are associated with both the Niño-4 region and Southern Annular Mode impacts. The winter cooling at the Faraday/Vernadsky station contrasts with the winter warming at the Esperanza station during the period of 2006–17. The different temperature trends are accompanied by weak correlations between the temperatures at these two stations. Linearly congruent components of the station temperature trends in 2006–17 indicate a dominant contribution of Southern Annular Mode (tropical sea surface temperature anomalies) to warming (cooling) in the northern (southern) Peninsula. Distinctive impacts of climate modes are observed in combination with the recent deepening of the negative sea-level pressure anomaly to the west of the peninsula and the related change in the zonal and meridional wind components. These factors apparently contribute to the occurrence of the boundary that crosses the peninsula and divides it into sub-regions with warming and cooling.

Major increases projected in extreme surface melt events in Antarctica, even under a moderate emission scenario

2020 ◽  
Author(s):  
Sarah Feron ◽  
Raul Cordero
Keyword(s):  
Sea Level ◽  
Antarctic Peninsula ◽  
Climate Models ◽  
Emission Scenario ◽  
Global Climate ◽  
Global Climate Models ◽  
Reference Period ◽  
West Antarctica ◽  
Surface Melt ◽  
The Antarctic

<p>Surface Melt (SM) is one of the factors that contribute to sea level rise; surface meltwater draining through the ice and beneath Antarctic glaciers may cause acceleration in their flow towards the sea. Changes in the frequency of relatively warm days (including heatwaves) can substantially alter the SM variability, thus leading to extreme melting events. By using simulations from 13 Global Climate Models (GCMs) and according to a moderate representative concentration pathways (RCP4.5), here we show that the frequency of extreme SM events (SM90; according to the 90th percentile over the reference period 1961-1990) may significantly increase in coastal areas of West Antarctica; in particular in the Antarctic Peninsula. By the end of the century SM90 estimates are expected to increase from currently 0.10 kg/m2/day to about 0.45 kg/m2/day in the Antarctic Peninsula. Increments in SM90 estimates are not just driven by changes in the average SM, but also by the variability in SM. The latter is expected to increase by around 50% in the Antarctic Peninsula.</p>

scholarly journals The 16-Year Periodicity In The Winter Surface Temperature Variations In The Antarctic Peninsula Region

2021 ◽  
Author(s):  
Oleksandr Evtushevsky ◽  
Asen Grytsai ◽  
Oleksiy Agapitov ◽  
Volodymyr Kravchenko ◽  
Gennadi Milinevsky
Keyword(s):  
Surface Temperature ◽  
Sea Level ◽  
Antarctic Peninsula ◽  
Southern Annular Mode ◽  
Meridional Wind ◽  
Environmental Research ◽  
Southwestern Atlantic ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
The Antarctic

Abstract The aim of this work is a comprehensive study of the 16-year periodicity of winter surface temperature in the Antarctic Peninsula (AP) region, described earlier, and its possible source based on weather station records over the 1952–2019 period making use of the Scientific Committee on Antarctic Research (SCAR) Reference Antarctic Data for Environmental Research (READER) database, as well as Fourier and wavelet analysis methods. It is shown that interdecadal oscillation with a period of about 16 years dominates in the northern AP (Esperanza and Orcadas), which is consistent with previous results. The 16-year periodicity is found to closely correlate with the sea level pressure anomaly in the southwestern Atlantic associated with the zonal wave-3 and the Southern Annular Mode patterns. The correlation maximum in the southwestern Atlantic, having the characteristic features of the anticyclonic circulation, affects the surface temperature in the northern AP through the related structure of the zonal and meridional wind anomalies. This effect is weaker to the south, where the Vernadsky station data do not show a regular interdecadal periodicity. Due to the correlated variability in the wave-3 ridges, the pronounced 16-year periods exist also in the surface temperature of southern Australia–New Zealand region, as well as in the zonal mean sea level pressure at 30–50°S. The sea surface temperatures are much less involved in the 16-year oscillation suggesting that atmospheric rather than oceanic processes appear to be more important for its occurrence.

scholarly journals Physical Mechanisms of the Wintertime Surface Air Temperature Variability in South Korea and the near-7-Day Oscillations

2010 ◽  
Vol 23 (8) ◽  
pp. 2197-2212 ◽  
Author(s):  
Kwang-Yul Kim ◽  
Joon-Woo Roh
Keyword(s):  
Time Series ◽  
South Korea ◽  
Surface Temperature ◽  
Sea Level ◽  
Seasonal Cycle ◽  
Rossby Waves ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
The Third ◽  
Second Mode

Abstract The first three principal modes of wintertime surface temperature variability in Seoul, South Korea (37.33°N, 126.59°E), are extracted from the 1979–2008 observed records via cyclostationary EOF (CSEOF) analysis. The first mode represents the seasonal cycle, the principle physical mechanism of which is associated with the continent–ocean sea level pressure contrast. The second mode mainly describes the overall wintertime warming or cooling. The third mode depicts subseasonal fluctuations of surface temperature. Sea level pressure anomalies to the west of South Korea (eastern China) and those with an opposite sign to the east of South Korea (Japan) are a major physical factor both for the second mode and the third mode. These sea level pressure anomalies with opposite signs alter the amount of warm air to the south of South Korea, which changes the surface temperature in South Korea. The PC time series of the seasonal cycle is significantly correlated with the East Asian winter monsoon index and exhibits a conspicuous downward trend. The PC time series of the second mode exhibits a positive trend. These trends imply that the wintertime surface temperature in South Korea has increased and the seasonal cycle has weakened gradually over the past 30 yr; the sign of greenhouse warming is clear in both PC time series. The ∼7-day oscillations are a major component of high-frequency variability in much of the analysis domain and are a manifestation of Rossby waves. Rossby waves aloft result in the concerted variation of physical variables in the atmospheric column. Due to the stronger mean zonal wind, the disturbances by Rossby waves propagate eastward at ∼8–12 m s−1; the passing of Rossby waves with alternating signs produces the ∼7-day temperature oscillations in South Korea.

scholarly journals Comparing ice discharge through West Antarctic Gateways: Weddell vs. Amundsen Sea warming

2015 ◽  
Vol 9 (2) ◽  
pp. 1705-1733 ◽  
Author(s):  
M. A. Martin ◽  
A. Levermann ◽  
R. Winkelmann
Keyword(s):  
Sea Level ◽  
Ice Sheet ◽  
Back Stress ◽  
Step Function ◽  
Ocean Warming ◽  
Weddell Sea ◽  
Amundsen Sea ◽  
Function Type ◽  
West Antarctic ◽  
Grounding Line

Abstract. Future changes in Antarctic ice discharge will be largely controlled by the fate of the floating ice shelves, which exert a back-stress onto Antarctica's marine outlet glaciers. Ice loss in response to warming of the Amundsen Sea has been observed and investigated as a potential trigger for the marine ice-sheet instability. Recent observations and simulations suggest that the Amundsen Sea Sector might already be unstable which would have strong implications for global sea-level rise. At the same time, regional ocean projections show much stronger warm-water intrusion into ice-shelf cavities in the Weddell Sea compared to the observed Amundsen warming. Here we present results of numerical ice sheet modelling with the Parallel Ice Sheet Model (PISM) which show that idealized, step-function type ocean warming in the Weddell Sea leads to more immediate ice discharge with a higher sensitivity to small warming levels than the same warming in the Amundsen Sea. This is consistent with the specific combination of bedrock and ice topography in the Weddell Sea Sector which results in an ice sheet close to floatation. In response to even slight ocean warming, ice loss increases rapidly, peaks and declines within one century. While the cumulative ice loss in the Amundsen Sea Sector is of similar magnitude after five centuries of continued warming, ice loss increases at a slower pace and only for significantly higher warming levels. Although there is more marine ice stored above sea level in close vicinity of the grounding line compared to the Weddell Sea Sector, the ice sheet is farther from floatation and the grounding line initially retreats more slowly.

scholarly journals Abundance and Biodiversity of Top Predators - Seabirds and Marine Mammals - in Antarctic Seas

2020 ◽  
Vol 3 (3) ◽  
Keyword(s):  
Sea Level ◽  
Marine Mammals ◽  
Weddell Sea ◽  
Amundsen Sea ◽  
Top Predators ◽  
Very High

This article concerns the comparison of data collected in different Antarctic seas by the same team, same platform (mainly from the bridge of icebreaking RV Polarstern, 18 m above sea level), and thus the same methodology. Drastic differences were noted, from very high numbers in the Weddell Sea to very low ones in the Amundsen Sea. Biodiversity was low, as reflected by low numbers of species, a few of them representing the vast majority in numbers of individuals: between 85% and 95% of the total.

scholarly journals Particle flux on the continental shelf in the Amundsen Sea Polynya and Western Antarctic Peninsula

Elem Sci Anth ◽  
2015 ◽  
Vol 3 ◽  
Author(s):  
Hugh W. Ducklow ◽  
Stephanie E. Wilson ◽  
Anton F. Post ◽  
Sharon E. Stammerjohn ◽  
Matthew Erickson ◽  
...  
Keyword(s):  
Time Series ◽  
Antarctic Peninsula ◽  
Particle Flux ◽  
Phytoplankton Bloom ◽  
Bacterial Respiration ◽  
Polar Regions ◽  
Western Antarctic Peninsula ◽  
Amundsen Sea ◽  
Incubation Experiments ◽  
Phaeocystis Antarctica

Abstract We report results from a yearlong, moored sediment trap in the Amundsen Sea Polynya (ASP), the first such time series in this remote and productive ecosystem. Results are compared to a long-term (1992–2013) time series from the western Antarctic Peninsula (WAP). The ASP trap was deployed from December 2010 to December 2011 at 350 m depth. We observed two brief, but high flux events, peaking at 8 and 5 mmol C m−2 d−1 in January and December 2011, respectively, with a total annual capture of 315 mmol C m−2. Both peak fluxes and annual capture exceeded the comparable WAP observations. Like the overlying phytoplankton bloom observed during the cruise in the ASP (December 2010 to January 2011), particle flux was dominated by Phaeocystis antarctica, which produced phytodetrital aggregates. Particles at the start of the bloom were highly depleted in 13C, indicating their origin in the cold, CO2-rich winter waters exposed by retreating sea ice. As the bloom progressed, microscope visualization and stable isotopic composition provided evidence for an increasing contribution by zooplankton fecal material. Incubation experiments and zooplankton observations suggested that fecal pellet production likely contributed 10–40% of the total flux during the first flux event, and could be very high during episodic krill swarms. Independent estimates of export from the surface (100 m) were about 5–10 times that captured in the trap at 350 m. Estimated bacterial respiration was sufficient to account for much of the decline in the flux between 50 and 350 m, whereas zooplankton respiration was much lower. The ASP system appears to export only a small fraction of its production deeper than 350 m within the polynya region. The export efficiency was comparable to other polar regions where phytoplankton blooms were not dominated by diatoms.

Temporal and Spatial SST (Sea Surface Temperature) Distribution and its Impact on Chlorophyll - A Concentration in Southern Ocean during 2002-2012

2014 ◽  
Vol 675-677 ◽  
pp. 1197-1200
Author(s):  
Chen Zeng ◽  
Hui Ping Xu
Keyword(s):  
Spatial Distribution ◽  
Southern Ocean ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Ross Sea ◽  
Weddell Sea ◽  
Sea Surface ◽  
Prydz Bay ◽  
Amundsen Sea ◽  
Temporal And Spatial

Sea Surface Temperature (SST) has great impact on algae growth in ocean. And the variation of SST closely relate with global climate. As 1/5 of the greatest ocean, southern ocean SST temporal and spatial distribution needs wide attention. We uses MODIS SST inversed algorithm to find its regulation in this decade (October 2002 to March 2012, October to December and January to March a year). Significant annual cycles appears that SST rises from October and falls in February, while area >70° has peak in January. SST decreases with latitude ascending from spatial distribution. Through in high latitude, Ross Sea, Prydz Bay and Weddell Sea enjoy quite high temperature comparing to its adjacent area in same period. Almost whole blooms occur in these three seas in December, January and February, among which Prydz Bay has the highest suitable SST with 0.3-1.7°C, Amundsen Sea has the second with-0.2-0.3°C, Ross Sea has the lowest with-0.9- -0.8°C. Amundsen Sea owns the vigorous bloom and the narrowest suitable temperature period.

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