Antarctic late Cenozoic pectinid-bearing sedimentary strata are chiefly confined to localities in the northern part of the Antarctic Peninsula, in the McMurdo Sound area, and Marine Plain, East Antarctica. Ages of these deposits range from Oligocene to Holocene. Chlamys-like scallops, which are absent from today's Southern Ocean, thrived in Antarctic waters during both glacial and interglacial episodes, but disappeared during the Late Pliocene. Their extinction is believed to result from the combined effects of increased carbonate solubility, habitat loss and limitations in food availability, associated with major cooling.
Abstract. The stable isotopic composition of water vapor over the ocean is governed by the isotopic composition of surface water, ambient vapor isotopic composition, exchange and mixing processes at the water-air interface as well as the local meteorological conditions. In this study we present water vapor and surface water isotope ratios in samples collected across the latitudinal transect from Mauritius to Prydz Bay in the Antarctic coast. The samples were collected on-board the ocean research vessel SA Agulhas during the 9th (Jan-2017) and 10th (Dec-2017 to Jan-2018) Southern Ocean expeditions. The inter annual variability of the meteorological factors governing water vapor isotopic composition is explained. The parameters governing the isotopic composition of evaporation flux from the oceans can be considered separately or simultaneously in the Craig-Gordon (CG) models. The Traditional Craig-Gordon (TCG) (Craig and Gordon, 1965) and the Unified Craig-Gordon (UCG) (Gonfiantini et al., 2018) models were used to evaluate the isotopic composition of evaporation flux for the molecular diffusivity ratios suggested by Merlivat (1978) (MJ), Cappa et al. (2003) (CD) and Pfahl and Wernli (2009) (PW) and for different ocean surface conditions. We found that the UCG model with CD molecular diffusivity ratios where equal contribution from molecular and turbulent diffusion is the best match for our observations. By assigning the representative end member isotopic compositions and solving the two-component mixing model, a relative contribution from locally generated and advected moisture was calculated along the transect. Our results suggest varying contribution of advected westerly component with an increasing trend upto 65° S. Beyond 65° S, the proportion of Antarctic moisture was found to be increasing linearly towards the coast.
During the seasonal work of the Russian Antarctic expedition (RAE-65), the monitoring of the water-ice ecological system was conducted in the Nella fjord (Prude Bay, East Antarctica). This monitoring is conducted annually since the IPY in 2007 in frames of the project “Assessment of the ecology of the Antarctic sea ice zone” (“Krial”) (Melnikov, 2020). The purpose of the monitoring is the assessment of the role of water-ice biota in global biosphere processes in the Southern Ocean.
Total-dissolvable iron has been measured in sections of three ice cores from
Law Dome, East Antarctica, and the results used to calculate atmospheric iron
deposition over this region during the late Holocene and to provide a preliminary
estimate of aerosol iron deposition during the Last Glaciol Maximum I LGM).
Ice-core sections dating from 56-2730 BP (late Holocene) and ~18000 BP (LGM) were
decontaminated using trace-metal clean techniques, and total-dissolvable iron was
determined in the acidified meltwatcrs by flow-injection analysis. Our results
suggest that the atmospheric iron flux onto the Law Dome region has varied
significantly over time-scales ranging from seasonal to Glaciol-interglaciol. The
iron concentrations in ice-core sections from the past century suggest (1) a 2
4-fold variation in the atmospheric iron flux over a single annual cycle, with the
highest flux occurring during the spring and summer, and (2) a nearly 7-fold
variation in the annual maximum atmospheric iron flux over a 14 year period. The
average estimated atmospheric iron flux calculated from our late-Holocene samples
is 0.056-0.14 mg m a−1, which agrees well with Holocene flux
estimates derived from aluminium measurements in inland Antarctic ice cores and a
recent order-of-magnitude estimate of present-day atmospheric iron deposition over
the Southern Ocean. The iron concentration of an ice-corc section dating from the
LGM was more than 50 times higher than in the late-Holocene ice samples. Using a
snow-accumulation rate estimate of 130 kg m −2
a−1 for this period, we calculate 0.87 mgm
−2 a−1 as a preliminary estimate of
atmospheric iron deposition during the LGM, which is 6-16 times greater than our
average late-Holocene iron flux. Our data are consistent with the suggestion that
there was a significantly greater flux of atmospheric iron onto the Southern Ocean
during the LGM than during then Holocene.
Surface wind trends and variability over Antarctica and the Southern Ocean and their implications to wind energy in the region are analyzed using the gridded ERA-Interim reanalysis data between 1979 and 2017 and the Self-Organizing Map (SOM) technique. In general, surface winds are stronger over the coastal regions of East Antarctica and the Transantarctic Mountains and weaker over the Ross and Ronne ice shelves and the Antarctic Peninsula; and stronger in winter and weaker in summer. Winds in the southern Indian and Pacific Oceans and along coastal regions exhibit a strong interannual variability that appears to be correlated to the Antarctic Oscillation (AAO) index. A significantly positive trend in surface wind speeds is found across most regions and about 20% and 17% of the austral autumn and summer wind trends, respectively, and less than 1% of the winter and spring wind trends may be explained by the trends in the AAO index. Except for the Antarctic Peninsula, Ronne and Ross ice shelves, and small areas in the interior East Antarctica, most of the continent is found to be suitable for the development of wind power.
Linkages between East Antarctic Ice Sheet extent and Southern Ocean temperatures based on a Pliocene high‐resolution record of ice‐rafted debris off Prydz Bay, East Antarctica