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.

Distribution of gymnosomatous pteropods in western Antarctic Peninsula shelf waters: influences of Southern Ocean water masses

Polar Record ◽  
2013 ◽  
Vol 51 (1) ◽  
pp. 58-71 ◽  
Author(s):  
P.M. Suprenand ◽  
D.L. Jones ◽  
J.J. Torres
Keyword(s):  
Southern Ocean ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Antarctic Peninsula ◽  
Sampling Site ◽  
Water Masses ◽  
Sea Surface ◽  
Western Antarctic Peninsula ◽  
Hydrographic Data ◽  
Explanatory Variables

ABSTRACTDistributions of gymnosomatous pteropods,Spongiobranchaea australisandClione antarctica, were determined at six sites along a latitudinal gradient in western Antarctica Peninsula shelf waters using vertically stratified trawls. Hydrographic data were collected at the same sites with conductivity-temperature-depth casts, and correlations of explanatory variables to gymnosome distributions were determined using statistical analyses performed in Matlab, a high level programming software to conduct numerical computation and visualisation. Explanatory variables included sampling site, latitude, longitude and depth, seawater temperature, salinity and density, Southern Ocean Antarctic Surface Water, Winter Water, Upper Circumpolar Deep Water and warm transitional waters, as well as oceanographic remote sensing data for coloured dissolved organic matter, chlorophyllaconcentration, normalised fluorescence line height, nighttime sea surface temperature, photosynthetically active radiation, particulate inorganic carbon, particulate organic carbon, daytime sea surface temperature and daily sea ice concentration. Hydrographic data revealed that warmer water masses were prevalent along the western Antarctic Peninsula, and the distributions of both gymnosome species were primarily influenced by water masses, temperature, sampling site and latitude. As a consequence, distributional shifts of gymnosomes are predicted in response to the current warming trends.

scholarly journals Assessing bias corrections of oceanic surface conditions for atmospheric models

2019 ◽  
Vol 12 (1) ◽  
pp. 321-342 ◽  
Author(s):  
Julien Beaumet ◽  
Gerhard Krinner ◽  
Michel Déqué ◽  
Rein Haarsma ◽  
Laurent Li
Keyword(s):  
Sea Ice ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
General Circulation ◽  
General Circulation Models ◽  
Substantial Improvement ◽  
Sea Surface ◽  
Sea Ice Concentration ◽  
Ice Concentration ◽  
Analogue Method

Abstract. Future sea surface temperature and sea-ice concentration from coupled ocean–atmosphere general circulation models such as those from the CMIP5 experiment are often used as boundary forcings for the downscaling of future climate experiments. Yet, these models show some considerable biases when compared to the observations over present climate. In this paper, existing methods such as an absolute anomaly method and a quantile–quantile method for sea surface temperature (SST) as well as a look-up table and a relative anomaly method for sea-ice concentration (SIC) are presented. For SIC, we also propose a new analogue method. Each method is objectively evaluated with a perfect model test using CMIP5 model experiments and some real-case applications using observations. We find that with respect to other previously existing methods, the analogue method is a substantial improvement for the bias correction of future SIC. Consistency between the constructed SST and SIC fields is an important constraint to consider, as is consistency between the prescribed sea-ice concentration and thickness; we show that the latter can be ensured by using a simple parameterisation of sea-ice thickness as a function of instantaneous and annual minimum SIC.

Holocene variability in sea surface temperature and sea ice extent in the northern Bering Sea: A multiple biomarker study

2017 ◽  
Vol 113 ◽  
pp. 1-9 ◽  
Author(s):  
Jiaping Ruan ◽  
Yuanhui Huang ◽  
Xuefa Shi ◽  
Yanguang Liu ◽  
Wenjie Xiao ◽  
...  
Keyword(s):  
Sea Ice ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Bering Sea ◽  
Sea Surface ◽  
Sea Ice Extent ◽  
Northern Bering Sea

scholarly journals Driving Forces of Circum-Antarctic Glacier and Ice Shelf Front Retreat over the Last Two Decades

2020 ◽  
Author(s):  
Celia A. Baumhoer ◽  
Andreas J. Dietz ◽  
Christof Kneisel ◽  
Heiko Paeth ◽  
Claudia Kuenzer
Keyword(s):  
Sea Ice ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Air Temperature ◽  
Environmental Variables ◽  
Sea Surface ◽  
Ice Shelf ◽  
Antarctic Ice Sheet ◽  
Ice Shelves ◽  
The Antarctic

Abstract. The safety band of Antarctica consisting of floating glacier tongues and ice shelves buttresses ice discharge of the Antarctic Ice Sheet. Recent disintegration events of ice shelves and glacier retreat indicate a weakening of this important safety band. Predicting calving front retreat is a real challenge due to complex ice dynamics in a data-scarce environment being unique for each ice shelf and glacier. We explore to what extent easy to access remote sensing and modelling data can help to define environmental conditions leading to calving front retreat. For the first time, we present a circum-Antarctic record of glacier and ice shelf front retreat over the last two decades in combination with environmental variables such as air temperature, sea ice days, snowmelt, sea surface temperature and wind direction. We find that the Antarctic ice sheet area shrank 29,618 ± 29 km2 in extent between 1997–2008 and gained an area of 7,108 ± 144.4 km2 between 2009 and 2018. Retreat concentrated along the Antarctic Peninsula and West Antarctica including the biggest ice shelves Ross and Ronne. Glacier and ice shelf retreat comes along with one or several changes in environmental variables. Decreasing sea ice days, intense snow melt, weakening easterlies and relative changes in sea surface temperature were identified as enabling factors for retreat. In contrast, relative increases in air temperature did not correlate with calving front retreat. To better understand drivers of glacier and ice shelf retreat it is of high importance to analyse the magnitude of basal melt through the intrusion of warm Circumpolar Deep Water (CDW) driven by strengthening westerlies and to further assess surface hydrology processes such as meltwater ponding, runoff and lake drainage.

scholarly journals Evaluation of global monitoring and forecasting systems at Mercator Océan

Ocean Science ◽  
2013 ◽  
Vol 9 (1) ◽  
pp. 57-81 ◽  
Author(s):  
J.-M. Lellouche ◽  
O. Le Galloudec ◽  
M. Drévillon ◽  
C. Régnier ◽  
E. Greiner ◽  
...  
Keyword(s):  
Quality Control ◽  
Sea Ice ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Sea Surface ◽  
Altimeter Data ◽  
Open Boundary ◽  
Vertical Profiles ◽  
Validation Procedure

Abstract. Since December 2010, the MyOcean global analysis and forecasting system has consisted of the Mercator Océan NEMO global 1/4° configuration with a 1/12° nested model over the Atlantic and the Mediterranean. The open boundary data for the nested configuration come from the global 1/4° configuration at 20° S and 80° N. The data are assimilated by means of a reduced-order Kalman filter with a 3-D multivariate modal decomposition of the forecast error. It includes an adaptive-error estimate and a localization algorithm. A 3-D-Var scheme provides a correction for the slowly evolving large-scale biases in temperature and salinity. Altimeter data, satellite sea surface temperature and in situ temperature and salinity vertical profiles are jointly assimilated to estimate the initial conditions for numerical ocean forecasting. In addition to the quality control performed by data producers, the system carries out a proper quality control on temperature and salinity vertical profiles in order to minimise the risk of erroneous observed profiles being assimilated in the model. This paper describes the recent systems used by Mercator Océan and the validation procedure applied to current MyOcean systems as well as systems under development. The paper shows how refinements or adjustments to the system during the validation procedure affect its quality. Additionally, we show that quality checks (in situ, drifters) and data sources (satellite sea surface temperature) have as great an impact as the system design (model physics and assimilation parameters). The results of the scientific assessment are illustrated with diagnostics over the year 2010 mainly, assorted with time series over the 2007–2011 period. The validation procedure demonstrates the accuracy of MyOcean global products, whose quality is stable over time. All monitoring systems are close to altimetric observations with a forecast RMS difference of 7 cm. The update of the mean dynamic topography corrects local biases in the Indonesian Throughflow and in the western tropical Pacific. This improves also the subsurface currents at the Equator. The global systems give an accurate description of water masses almost everywhere. Between 0 and 500 m, departures from in situ observations rarely exceed 1 °C and 0.2 psu. The assimilation of an improved sea surface temperature product aims to better represent the sea ice concentration and the sea ice edge. The systems under development are still suffering from a drift which can only be detected by means of a 5-yr hindcast, preventing us from upgrading them in real time. This emphasizes the need to pursue research while building future systems for MyOcean2 forecasting.

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