scholarly journals Search for the Little Ice Age in Southern Ocean Sea-Ice Records

1990 ◽  
Vol 14 ◽  
pp. 221-225 ◽  
Author(s):  
Claire L. Parkinson
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Little Ice Age ◽  
Weddell Sea ◽  
Ice Age ◽  
Amundsen Sea ◽  
Ice Edge ◽  
Time Of Year ◽  
Sea Ice Edge ◽  
Eastern Weddell Sea

Records from the expeditions of Cook, Bellingshausen, Wilkes, and Ross in the late 18th and early 19th centuries have been examined for the information they provide on locations of the Southern Ocean sea-ice edge during the period of the late Little Ice Age in much of the Northern Hemisphere. When these locations are compared with satellite-derived ice edge locations in the mid 1970s, there is a suggestion of particularly heavy ice covers in the eastern Weddell Sea in December 1772, in the Amundsen Sea in March 1839, and perhaps, on the basis of an isolated observation, in a portion of the western Weddell Sea in January 1820. However, overall no strong Little Ice Age signal is found for the sea ice of the Southern Ocean. Many of the observations from the four expeditions indicate sea-ice edge locations that lie within the range of ice edge locations at the same time of year in the mid 1970s, and a few of the observations suggest a less extensive ice cover than in the 1970s.

scholarly journals Search for the Little Ice Age in Southern Ocean Sea-Ice Records

1990 ◽  
Vol 14 ◽  
pp. 221-225 ◽  
Author(s):  
Claire L. Parkinson
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Little Ice Age ◽  
Weddell Sea ◽  
Ice Age ◽  
Amundsen Sea ◽  
Ice Edge ◽  
Time Of Year ◽  
Sea Ice Edge ◽  
Eastern Weddell Sea

Records from the expeditions of Cook, Bellingshausen, Wilkes, and Ross in the late 18th and early 19th centuries have been examined for the information they provide on locations of the Southern Ocean sea-ice edge during the period of the late Little Ice Age in much of the Northern Hemisphere. When these locations are compared with satellite-derived ice edge locations in the mid 1970s, there is a suggestion of particularly heavy ice covers in the eastern Weddell Sea in December 1772, in the Amundsen Sea in March 1839, and perhaps, on the basis of an isolated observation, in a portion of the western Weddell Sea in January 1820. However, overall no strong Little Ice Age signal is found for the sea ice of the Southern Ocean. Many of the observations from the four expeditions indicate sea-ice edge locations that lie within the range of ice edge locations at the same time of year in the mid 1970s, and a few of the observations suggest a less extensive ice cover than in the 1970s.

scholarly journals Evaluating seasonal sea-ice cover over the Southern Ocean from the Last Glacial Maximum

2020 ◽  
Author(s):  
Ryan A. Green ◽  
Laurie Menviel ◽  
Katrin J. Meissner ◽  
Xavier Crosta
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Last Glacial Maximum ◽  
Austral Summer ◽  
Ice Cover ◽  
Proxy Records ◽  
Ice Edge ◽  
Sea Ice Edge ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract. Sea-ice cover over the Southern Ocean responds to and impacts Southern Ocean dynamics and, thus, mid to high latitude climate in the Southern Hemisphere. In addition, sea-ice cover can significantly modulate the carbon exchange between the atmosphere and the ocean. As climate models are the only tool available to project future climate changes, it is important to assess their performance in simulating past changes. The Last Glacial Maximum (LGM, ∼21,000 years ago) represents an interesting target as it is a relatively well documented period with climatic conditions and a carbon cycle very different from pre-industrial conditions. Here, we study the changes in seasonal Antarctic sea-ice cover as simulated in numerical PMIP3 and LOVECLIM simulations of the LGM, and their relationship with windstress and ocean temperature. Simulations and paleo-proxy records suggest a fairly well constrained glacial winter sea-ice edge at 51.5° S (1 sigma range: 50°–55.5° S). Simulated glacial summer sea-ice cover however differs widely between models, ranging from almost no sea ice to a sea-ice edge reaching 55.5° S. The austral summer multi-model mean sea-ice edge lies at ∼60.5° S (1 sigma range: 57.5°–70.5° S). Given the lack of strong constraints on the summer sea-ice edge based on sea-ice proxy records, we extend our model-data comparison to summer sea-surface temperature. Our analysis suggests that the multi-model mean summer sea ice provides a reasonable, albeit upper end, estimate of the austral summer sea-ice edge allowing us to conclude that the multi-model mean of austral summer and winter sea-ice cover seem to provide good estimates of LGM conditions. Using these best estimates, we find that there was a larger sea-ice seasonality during the LGM compared to the present day.

scholarly journals Super-Critical Reflection of Ocean Waves; A New Factor in Ice-Edge Dynamics?

1989 ◽  
Vol 12 ◽  
pp. 157-161 ◽  
Author(s):  
Vernon A. Squire
Keyword(s):  
Sea Ice ◽  
Ocean Waves ◽  
Internal Gravity Waves ◽  
Momentum Equation ◽  
Weddell Sea ◽  
Force Balance ◽  
Radiation Stress ◽  
Ice Edge ◽  
Balance Of Forces ◽  
Sea Ice Edge

Movement of the sea-ice edge on short time-scales (<1 d) is due to a balance of forces between several mechanisms (wind stress, sea-surface tilt, internal ice stress, and Coriolis force) which are often comparable in magnitude. Other factors such as the force induced by partial reflection of short seas, internal gravity waves in the pycnocline, etc., may also contribute. Through the momentum equation, these mechanisms affect the dynamics of the ice edge. In this paper we suggest another mechanism which may have importance, namely, a radiation-stress contribution which derives from obliquely incident waves which are totally reflected from the ice edge by a process analogous to total internal reflection in optics. Such reflection generates both normal and shear forces at the ice edge, the former tending to compact the pack ice and the latter to shear the absolute edge. The effect is studied using some recent data collected during the Winter Weddell Sea Project 1986 in Antarctica, where it is found that the contribution to the force balance is significant. For thicker sea ice and icebergs acted upon by oblique seas, the radiation stress-induced force may outweigh more conventional terms in the momentum equation.

scholarly journals Development of Sea Ice in the Weddell Sea

1989 ◽  
Vol 12 ◽  
pp. 92-96 ◽  
Author(s):  
M.A. Lange ◽  
S.F. Ackley ◽  
P. Wadhams ◽  
G.S. Dieckmann ◽  
H. Eicken
Keyword(s):  
Sea Ice ◽  
Coastal Region ◽  
Ice Cores ◽  
Arctic Basin ◽  
Major Elements ◽  
Weddell Sea ◽  
The Arctic ◽  
Frazil Ice ◽  
Sea Ice Edge ◽  
Eastern Weddell Sea

We report on the development and physical properties of sea ice in the central and eastern Weddell Sea. The investigations were part of the Winter Weddell Sea Project 1986, which extended over the months of July through December. Major elements of the glaciological part of this study included continuous shipborne observations of sea-ice conditions and occasional helicopter reconnaissance flights, extensive measurements of snow and ice thicknesses at daily ice stations, and detailed analyses of sampled ice cores from each ice station. Textural investigations of the sampled ice revealed the dominance of frazil ice in the central Weddell Sea and the occurrence of an additional ice class, called platelet ice, together with the commonly known frazil and congelation ice in the coastal region of the eastern Weddell Sea. These results, in combination with the visual ice observations, reveal two major mechanisms for sea-ice generation in the Antarctic, which were not sufficiently well accounted for in previous investigations. In the central Weddell Sea, a cycle of pancake-ice formation and its growth into consolidated floes seems to be the dominant process of the advancing sea-ice edge. In the coastal waters, the growing sea-ice cover consists, to a considerable degree, of ice platelets which are formed in the underlying water column in front of the ice-shelf edges. Thus, congelation-ice growth, which is mainly controlled by atmospheric, thermodynamic forcing, seems to be of less importance in the central and south-eastern Weddell Sea than, for example, in the Arctic Basin.

scholarly journals Super-Critical Reflection of Ocean Waves; A New Factor in Ice-Edge Dynamics?

1989 ◽  
Vol 12 ◽  
pp. 157-161 ◽  
Author(s):  
Vernon A. Squire
Keyword(s):  
Sea Ice ◽  
Ocean Waves ◽  
Internal Gravity Waves ◽  
Momentum Equation ◽  
Weddell Sea ◽  
Force Balance ◽  
Radiation Stress ◽  
Ice Edge ◽  
Balance Of Forces ◽  
Sea Ice Edge

Movement of the sea-ice edge on short time-scales (&lt;1 d) is due to a balance of forces between several mechanisms (wind stress, sea-surface tilt, internal ice stress, and Coriolis force) which are often comparable in magnitude. Other factors such as the force induced by partial reflection of short seas, internal gravity waves in the pycnocline, etc., may also contribute. Through the momentum equation, these mechanisms affect the dynamics of the ice edge. In this paper we suggest another mechanism which may have importance, namely, a radiation-stress contribution which derives from obliquely incident waves which are totally reflected from the ice edge by a process analogous to total internal reflection in optics. Such reflection generates both normal and shear forces at the ice edge, the former tending to compact the pack ice and the latter to shear the absolute edge. The effect is studied using some recent data collected during the Winter Weddell Sea Project 1986 in Antarctica, where it is found that the contribution to the force balance is significant. For thicker sea ice and icebergs acted upon by oblique seas, the radiation stress-induced force may outweigh more conventional terms in the momentum equation.

scholarly journals Estimating the extent of Antarctic summer sea ice during the Heroic Age of Antarctic Exploration

2016 ◽  
Vol 10 (6) ◽  
pp. 2721-2730 ◽  
Author(s):  
Tom Edinburgh ◽  
Jonathan J. Day
Keyword(s):  
Sea Ice ◽  
Climate Models ◽  
Arctic Sea Ice ◽  
Weddell Sea ◽  
Steady Increase ◽  
Ice Coverage ◽  
Lack Of Information ◽  
Ice Conditions ◽  
Ice Edge ◽  
Sea Ice Edge

Abstract. In stark contrast to the sharp decline in Arctic sea ice, there has been a steady increase in ice extent around Antarctica during the last three decades, especially in the Weddell and Ross seas. In general, climate models do not to capture this trend and a lack of information about sea ice coverage in the pre-satellite period limits our ability to quantify the sensitivity of sea ice to climate change and robustly validate climate models. However, evidence of the presence and nature of sea ice was often recorded during early Antarctic exploration, though these sources have not previously been explored or exploited until now. We have analysed observations of the summer sea ice edge from the ship logbooks of explorers such as Robert Falcon Scott, Ernest Shackleton and their contemporaries during the Heroic Age of Antarctic Exploration (1897–1917), and in this study we compare these to satellite observations from the period 1989–2014, offering insight into the ice conditions of this period, from direct observations, for the first time. This comparison shows that the summer sea ice edge was between 1.0 and 1.7° further north in the Weddell Sea during this period but that ice conditions were surprisingly comparable to the present day in other sectors.

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