1 Variability and trends of global sea ice cover and sea level: effects on physicochemical parameters

2020 ◽  
pp. 1-34
Keyword(s):  
Sea Ice ◽  
Sea Level ◽  
Physicochemical Parameters ◽  
Ice Cover ◽  
And Sea Level

scholarly journals Sea ice drift in the Southern Ocean: Regional patterns, variability, and trends

Elem Sci Anth ◽  
2017 ◽  
Vol 5 ◽  
Author(s):  
Ron Kwok ◽  
Shirley S. Pang ◽  
Sahra Kacimi
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Sea Level ◽  
Ice Cover ◽  
The Arctic ◽  
Positive Trend ◽  
Amundsen Sea ◽  
Regional Patterns ◽  
Ice Drift ◽  
Sea Ice Drift

Understanding long-term changes in large-scale sea ice drift in the Southern Ocean is of considerable interest given its contribution to ice extent, to ice production in open waters, with associated dense water formation and heat flux to the atmosphere, and thus to the climate system. In this paper, we examine the trends and variability of this ice drift in a 34-year record (1982–2015) derived from satellite observations. Uncertainties in drift (~3 to 4 km day–1) were assessed with higher resolution observations. In a linear model, drift speeds were ~1.4% of the geostrophic wind from reanalyzed sea-level pressure, nearly 50% higher than that of the Arctic. This result suggests an ice cover in the Southern Ocean that is thinner, weaker, and less compact. Geostrophic winds explained all but ~40% of the variance in ice drift. Three spatially distinct drift patterns were shown to be controlled by the location and depth of atmospheric lows centered over the Amundsen, Riiser-Larsen, and Davis seas. Positively correlated changes in sea-level pressures at the three centers (up to 0.64) suggest correlated changes in the wind-driven drift patterns. Seasonal trends in ice edge are linked to trends in meridional winds and also to on-ice/off-ice trends in zonal winds, due to zonal asymmetry of the Antarctic ice cover. Sea ice area export at flux gates that parallel the 1000-m isobath were extended to cover the 34-year record. Interannual variability in ice export in the Ross and Weddell seas linked to the depth and location of the Amundsen Sea and Riiser-Larsen Sea lows to their east. Compared to shorter records, where there was a significant positive trend in Ross Sea ice area flux, the longer 34-year trends of outflow from both seas are now statistically insignificant.

scholarly journals Extending the Arctic sea ice freeboard and sea level record with the Sentinel-3 radar altimeters

2019 ◽  
Author(s):  
Isobel R. Lawrence ◽  
Thomas W.K. Armitage ◽  
Michel C. Tsamados ◽  
Julienne C. Stroeve ◽  
Salvatore Dinardo ◽  
...  
Keyword(s):  
Sea Ice ◽  
Sea Level ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Arctic Sea ◽  
And Sea Level

Provenance of sediments in the western Sea of Japan over the last 30 ka: Implications for paleoenvironmental changes

2020 ◽  
Author(s):  
Ruxi Dou ◽  
Jianjun Zou ◽  
Xuefa Shi ◽  
Aimei Zhu ◽  
Zhi Dong ◽  
...  
Keyword(s):  
Sea Ice ◽  
Sea Level ◽  
Sea Of Japan ◽  
East Asian ◽  
Ice Cover ◽  
Meridional Overturning Circulation ◽  
Northwest Pacific ◽  
The Sea Of Japan ◽  
Sediment Grain Size ◽  
Northwest Pacific Ocean

<p>The Sea of Japan is a unique marginal sea in the northwest Pacific Ocean, which is known as "miniature ocean". Constrained by four shallow straits communicating with surroundings seas, it is very sensitive to glacio-eustatic sea level changes. Also, it is located beneath the East Asia Monsoon, which affects the hydrography of surface waters, deep circulations and accumulation of terrigenous materials. The presence of seasonal ice also plays a role in controlling the local distributions of terrigenous materials and deep ventilation in the Sea of Japan. An increasing body of studies revealed pronounced changes in past ocean environment in the Sea of Japan since the late Quaternary. However, it remains elusive for past environment changes in the western Sea of Japan. In this study, we investigate the lithology, rare earth elements and radiogenic isotopes of sediment core LV53-18 retrieved from the western Sea of Japan since the last glaciation.</p><p>The contents of coarse fraction of sediment grain size suggest an advance in sea ice cover during the last deglaciation and the early Holocene (15-8 ka) and potential perennial sea ice cover during Heinrich Stadial (HS) 1 and HS2. The variation in sea ice cover is explained by changing strength of East Asian Winter Monsoon (EAWM). On millennial timescales (HS2, HS1 and Younger Dryas), our grainsize data shows a reverse correlation between the EAWM and the East Asian Summer Monsoon (EASM), indicating by Chinese stalagmite δ<sup>18</sup>O record, and it is ascribed to the slowdown of Atlantic Meridional Overturning Circulation (AMOC). The brine rejection related to sea-ice generation enhances local deep ventilation.</p><p>Both the concentration of ∑REEs and positive Eu anomaly (1.2~1.4) reveal a sustained contribution of calcium-rich volcanic materials after 8 ka, which coincides with the onset and intensity of Liman Cold Current during the sea-level highstand. Furthermore, the <sup>87</sup>Sr/<sup>86</sup>Sr values (0.706347 to 0.711713) decrease after 8 ka while εNd (-5.09 to -2.45) are more radiogenic, which further corroborate the presence of volcanic materials. On the basis of a binary mixture of volcanic material and upper crust, we estimated qualitatively the relative contributions of these two end-members. In summary, our study underlines the importance of EAWM in controlling the environment in the western Sea of Japan and reveals increasing volcanic contribution since 8 ka, which is related to the intensity of Liman Cold Current.</p><p>Note: This study was supported by the National Natural Science Foundation of China (Grant No. 41420104005, U1606401) and National Program on Global Change and Air-Sea Interaction (GASI-GEOGE-04).</p>

Ice cover and sea level of the Aral Sea from satellite altimetry and radiometry (1992–2006)

2009 ◽  
Vol 76 (3) ◽  
pp. 272-286 ◽  
Author(s):  
Alexei V. Kouraev ◽  
Andrey G. Kostianoy ◽  
Sergey A. Lebedev
Keyword(s):  
Sea Level ◽  
Satellite Altimetry ◽  
Ice Cover ◽  
Aral Sea ◽  
And Sea Level

scholarly journals Evaporative fractionation of H<sub>2</sub><sup>18</sup>O in the polar ocean and the invisibility of large changes of ice volume and sea level in the Saalian δ<sup>18</sup>O proxy records

2017 ◽  
Author(s):  
Robert G. Johnson
Keyword(s):  
Sea Ice ◽  
Sea Level ◽  
Thermohaline Circulation ◽  
World Ocean ◽  
Oceanic Circulation ◽  
Glacial Ice ◽  
Ice Volume ◽  
Circulation Mode ◽  
Polar Ocean ◽  
And Sea Level

Abstract. The oxygen isotope ratio, δ18O, as measured in skeletons of oceanic foraminifera, is a proxy for changes in world glacial ice volume and sea level and is of fundamental importance in the study of past climate change. However, in the Late Saalian glaciation the δ18O proxy reflects neither a large increase in glacial ice volume from 155 ka–142 ka nor the subsequent major deglaciation from 142 ka–136.5 ka in which sea level rose from about −140 m to +4 m at the end of the Drenthe sub stage. This deglaciation was caused by a large reduction in the ice sheet moisture supply due to storm path diversion associated with the loss of thermohaline circulation and the capping of the high latitude North Atlantic with melt water that passed through the Mediterranean Sea from the overflow of a giant ice-blocked Siberian lake. The δ18O proxy also fails to record the subsequent ice volume buildup of the Warthe substage in which sea level fell about 80 m. The explanation for the invisibility involves the fractionation and sequestration of large mounts of H218O in the effectively isolated and sea-ice-free polar ocean. The sequestration and subsequent release of polar water, enriched in H218O, distorted the fractionation record in the world ocean and destroyed the accuracy of the δ18O proxy. The proposed physical consequences of the ice-free polar ocean also include a sea-ice-free Labrador Sea and Baffin Bay and an oceanic circulation mode that drove the Drenthe substage glaciation to its maximum extent in Eurasia. The initial cause for the anomalous effects in the δ18O record was the known ice-flow blockage of all the Siberian rivers that discharge into the polar ocean west of the Lena River. Without adequate stratification by inflowing fresh river water, sea ice was unable to freeze on the deep polar ocean and the fractionation and the physical changes in the polar ocean that are proposed here followed.

Wind- and Sea Level-Induced Shore Evolution in Poland

1997 ◽  
Author(s):  
Ryszard B. Zeidler ◽  
Marek Skaja ◽  
Grzegorz Różyński ◽  
Jarka Kaczmarek
Keyword(s):  
Sea Level ◽  
And Sea Level

Seasonal variations in the properties and structural composition of sea ice and snow cover in the Bellingshausen and Amundsen Seas, Antarctica

1997 ◽  
Vol 43 (143) ◽  
pp. 138-151 ◽  
Author(s):  
M. O. Jeffries ◽  
K. Morris ◽  
W.F. Weeks ◽  
A. P. Worby
Keyword(s):  
Sea Ice ◽  
Isotopic Composition ◽  
Snow Cover ◽  
Sea Water ◽  
Ice Cores ◽  
Ice Cover ◽  
Snow Accumulation ◽  
Ice Formation ◽  
Frazil Ice ◽  
Core Sets

AbstractSixty-three ice cores were collected in the Bellingshausen and Amundsen Seas in August and September 1993 during a cruise of the R.V. Nathaniel B. Palmer. The structure and stable-isotopic composition (18O/16O) of the cores were investigated in order to understand the growth conditions and to identify the key growth processes, particularly the contribution of snow to sea-ice formation. The structure and isotopic composition of a set of 12 cores that was collected for the same purpose in the Bellingshausen Sea in March 1992 are reassessed. Frazil ice and congelation ice contribute 44% and 26%, respectively, to the composition of both the winter and summer ice-core sets, evidence that the relatively calm conditions that favour congelation-ice formation are neither as common nor as prolonged as the more turbulent conditions that favour frazil-ice growth and pancake-ice formation. Both frazil- and congelation-ice layers have an av erage thickness of 0.12 m in winter, evidence that congelation ice and pancake ice thicken primarily by dynamic processes. The thermodynamic development of the ice cover relies heavily on the formation of snow ice at the surface of floes after sea water has flooded the snow cover. Snow-ice layers have a mean thickness of 0.20 and 0.28 m in the winter and summer cores, respectively, and the contribution of snow ice to the winter (24%) and summer (16%) core sets exceeds most quantities that have been reported previously in other Antarctic pack-ice zones. The thickness and quantity of snow ice may be due to a combination of high snow-accumulation rates and snow loads, environmental conditions that favour a warm ice cover in which brine convection between the bottom and top of the ice introduces sea water to the snow/ice interface, and bottom melting losses being compensated by snow-ice formation. Layers of superimposed ice at the top of each of the summer cores make up 4.6% of the ice that was examined and they increase by a factor of 3 the quantity of snow entrained in the ice. The accumulation of superimposed ice is evidence that melting in the snow cover on Antarctic sea-ice floes ran reach an advanced stage and contribute a significant amount of snow to the total ice mass.

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