Seasonal variability of particle flux in the Weddell Sea and its relation to ice cover

Nature ◽  
1988 ◽  
Vol 335 (6189) ◽  
pp. 426-428 ◽  
Author(s):  
Gerhard Fischer ◽  
Dieter Fütterer ◽  
Rainer Gersonde ◽  
Susumu Honjo ◽  
Dorinda Ostermann ◽  
...  
Keyword(s):  
Seasonal Variability ◽  
Particle Flux ◽  
Ice Cover ◽  
Weddell Sea

Remote sensing of multiyear ice in the Antarctic

2021 ◽  
Author(s):  
Christian Melsheimer ◽  
Gunnar Spreen
Keyword(s):  
Time Series ◽  
Sea Ice ◽  
Global Climate ◽  
Ice Cover ◽  
Cold Season ◽  
Arctic Sea Ice ◽  
Weddell Sea ◽  
Detailed Knowledge ◽  
The Antarctic ◽  
Multiyear Ice

<p>The changing sea ice cover of polar seas is of key importance for the exchange of heat and moisture between atmosphere and ocean and hence for weather and climate, and in addition, the sea ice and its long-term changes are  an indicator for global change.  In order to properly understand and model the evolution of the sea ice cover and its interaction with the global climate system, we need detailed knowledge about sea ice, i.e., not only its extent, but also, e.g., its thickness and its type.</p> <p>We can broadly distinguish a few different sea ice types that have different dynamic and thermodynamic properties, namely: young ice (YI, thin/smooth new ice), first-year ice (FYI, formed during one cold season), and multiyear ice (MYI, which has survived at least one melt season). The  latter is of particular interest as it is usually thicker than other ice types (thus, takes more time to melt), much less saline, and may accommodate a unique ecosystem. Sea ice types in the Antarctic, until recently, have not been monitored much because of the lack of appropriate remote  sensing methods. While the Antarctic sea ice is greatly dominated by FYI, there are, nevertheless, considerable amounts of MYI, in particular in the Weddell Sea.</p> <p>We have recently adapted an algorithm for the detection of Arctic sea ice types for application in the Antarctic. The algorithm uses data from space-borne microwave radiometers and scatterometers as input. So far we have compiled a time series of daily Antarctic MYI data (and also an estimate of YI and FYI) data at a spatial resolution of 12.5 km, starting in 2013, but excluding the melt seasons when the algorithm does not work. Here give an overview of the data, showing, e.g., the quite large interannual variability of MYI and its evolution in the Weddell Sea, and discuss shortcomings of the algorithm and possible ways forward. The time series of daily Antarctic MYI data can in principle be extended backwards to the year 2000, when the used satellite data first became available, and with planned future satellite missions, it can be continued for years to come.</p>

scholarly journals Antarctic sea ice variability and trends, 1979–2010

2012 ◽  
Vol 6 (2) ◽  
pp. 931-956 ◽  
Author(s):  
C. L. Parkinson ◽  
D. J. Cavalieri
Keyword(s):  
Indian Ocean ◽  
Sea Ice ◽  
Ross Sea ◽  
Ice Cover ◽  
Weddell Sea ◽  
The Arctic ◽  
Future Research ◽  
Positive Trend ◽  
Antarctic Sea Ice ◽  
Ice Coverage

Abstract. In sharp contrast to the decreasing sea ice coverage of the Arctic, in the Antarctic the sea ice cover has, on average, expanded since the late 1970s. More specifically, satellite passive-microwave data for the period November 1978–December 2010 reveal an overall positive trend in ice extents of 17 100 ± 2300 km2 yr−1. Much of the increase, at 13 700 ± 1500 km2 yr−1, has occurred in the region of the Ross Sea, with lesser contributions from the Weddell Sea and Indian Ocean. One region, that of the Bellingshausen/Amundsen Seas, has, like the Arctic, instead experienced significant sea ice decreases, with an overall ice extent trend of −8200 ± 1200 km2 yr−1. When examined through the annual cycle over the 32-yr period 1979–2010, the Southern Hemisphere sea ice cover as a whole experienced positive ice extent trends in every month, ranging in magnitude from a low of 9100 ± 6300 km2 yr−1 in February to a high of 24 700 ± 10 000 km2 yr−1 in May. The Ross Sea and Indian Ocean also had positive trends in each month, while the Bellingshausen/Amundsen Seas had negative trends in each month, and the Weddell Sea and Western Pacific Ocean had a mixture of positive and negative trends. Comparing ice-area results to ice-extent results, in each case the ice-area trend has the same sign as the ice-extent trend, but differences in the magnitudes of the two trends identify regions with overall increasing ice concentrations and others with overall decreasing ice concentrations. The strong pattern of decreasing ice coverage in the Bellingshausen/Amundsen Seas region and increasing ice coverage in the Ross Sea region is suggestive of changes in atmospheric circulation. This is a key topic for future research.

scholarly journals Snow-ice growth: a fresh-water flux inhibiting deep convection in the Weddell Sea, Antarctica

2001 ◽  
Vol 33 ◽  
pp. 45-50 ◽  
Author(s):  
V.I. Lytle ◽  
S.F. Ackley
Keyword(s):  
Sea Ice ◽  
Thermohaline Circulation ◽  
Deep Convection ◽  
Ice Cover ◽  
Snow Accumulation ◽  
Heat Fluxes ◽  
Weddell Sea ◽  
Salt Flux ◽  
Ice Formation ◽  
Atmospheric Conditions

AbstractDuring a field experiment in July 1994, while the R.V. Nathaniel B. Palmer was moored to a drifting ice floe in the Weddell Sea, Antarctica, data were collected on sea-ice and snow characteristics. We report on the evolution of ice which grew in a newly opened lead. As expected with cold atmospheric conditions, congelation ice initially formed in the lead. Subsequent snow accumulation and large ocean heat fluxes resulted in melt at the base of the ice, and enhanced flooding of the snow on the ice surface. This flooded snow subsequently froze, and, 5 days after the lead opened, all the congelation ice had melted and 26 cm of snow ice had formed. We use measured sea-ice and snow salinities, thickness and oxygen isotope values of the newly formed lead ice to calculate the salt flux to the ocean. Although there was a salt flux to the ocean as the ice initially grew, we calculate a small net fresh-wlter input to the upper ocean by the end of the 5 day period. Similar processes of basal melt and surface snow-ice formation also occurred on the surrounding, thicker sea ice. Oceanographic studies in this region of the Weddell Sea have shown that salt rejection by sea-ice formation may enhance the ocean vertical thermohaline circulation and release heat from the deeper ocean to melt the ice cover. This type of deep convection is thought to initiate the Weddell polynya, which was observed only during the 1970s. Our results, which show that an ice cover can form with no salt input to the ocean, provide a mechanism which may help explain the more recent absence of the Weddell polynya.

Biogeochemistry of platelet ice: its influence on particle flux under fast ice in the Weddell Sea, Antarctica

2002 ◽  
pp. 169-179
Author(s):  
David N. Thomas ◽  
Hilary Kennedy ◽  
Gerhard Kattner ◽  
Dieter Gerdes ◽  
G. S. Dieckmann ◽  
...  
Keyword(s):  
Particle Flux ◽  
Weddell Sea ◽  
Fast Ice ◽  
Platelet Ice

Radiothermal radiation of the ice cover of the Arakhley lake as a geo-indicator of changes in a water body

2020 ◽  
Vol 26 (7) ◽  
pp. 6-16
Author(s):  
V. Venslavsky ◽  
◽  
А. Orlov ◽  
Yu. Kharin ◽  
◽  
...  
Keyword(s):  
Thermal Radiation ◽  
Water Body ◽  
Seasonal Variability ◽  
Crack Formation ◽  
Time Lag ◽  
Ice Cover ◽  
Anthropogenic Factors ◽  
Microwave Range ◽  
Ecological State ◽  
The Impact

The object of this study was the ecosystem of a water body; the subject was the radio-thermal radiation of the ice cover as a geo-indicator of changes in the ecological state of the Lake Arakhley. On the basis of a systematic approach, the work assessed the contribution of the seasonal variability of the properties of the ice cover to the intensity of radio-thermal radiation as a geo-indicator of the ecological system. At present, the influence of the ice cover deformation during the crack formation period on the intensity of radio-thermal radiation has not been sufficiently studied, which determined the relevance of an experimental study for use in problems of assessing anthropogenic factors of influence. The aim of the study was to measure the seasonal variability of the intensity of radio-thermal radiation as a background geo-indicator of the temperature regime and deformation of the ice cover during the crack formation period in the absence of direct anthropogenic factors. In January-March 2020, remote radio-physical methods were used to study the intensity of radio-thermal radiation of the microwave range for the test area of the ice cover of the Lake Arakhley during synchronous contact measurements of deformation and temperature in a niche at a depth of 40 cm from the surface. According to the data obtained, the reaction of the deformation sensor signal to daily temperature variations with a time lag of 1…3 hours was recorded. According to the results of the study, the correlation coefficient of the data of the ice deformation channel and the intensity of radio-thermal radiation in the range of 8…14 mm exceeded ± 0.7 (with a window of 1000 s), with the data of the temperature sensor in most areas exceeded ± 0.9. This proves the relationship between the temperature and deformation of the ice surface with the intensity of radio-thermal radiation, as a seasonal geo-indicator in determining the ecological state of the lake. The increments in the brightness temperature during the period of increased crack formation in the 14 mm channel, with a significant correlation with the deformation data, were about 3…6 K, which can also serve as a geo-indicator of seasonal changes in the properties of the ice cover. The results of the study were obtained in the absence of direct anthropogenic factors and are background geoindicators of the seasonal state of the ice cover during the period of temperature and dynamic loads during deformation and cracking, and in the future will be used in practice for correction in assessing the impact of anthropogenic factors

scholarly journals Pack-Ice Motion in the Weddell Sea in Relation to Weather Systems and Determination of a Weddell Sea Sea-Ice Budget

1989 ◽  
Vol 12 ◽  
pp. 104-112 ◽  
Author(s):  
D.W.S. Limbert ◽  
S.J. Morrison ◽  
C.B. Sear ◽  
P. Wadhams ◽  
M.A. Rowe
Keyword(s):  
Sea Ice ◽  
Surface Pressure ◽  
Ice Cover ◽  
Weddell Sea ◽  
Air Pressure ◽  
Ice Formation ◽  
Pack Ice ◽  
The Impact

As part of the Winter Weddell Sea Project 1986 (WWSP 86), a buoy, transmitting via TIROS-N satellites to Service Argos, was inserted into an ice floe in the southern Weddell Sea. Operational U.K. Meteorological Office numerical surface-pressure analyses, which utilized the buoy’s measured values of air pressure and temperature, are used to assess the impact of weather systems on pack-ice movement. The motion of the buoy is shown to be related closely to the position of the circumpolar trough and to the tracks of depressions crossing the area. The tracks of this and other buoys deployed during WWSP 86 are analysed, together with the known drifts of some ice-bound vessels, to establish the overall movement of sea ice in the central and western Weddell Sea. Using these data, the area of ice transported northward out of the Weddell Sea is determined. Roughly 60% of the winter sea-ice cover is discharged out of the area, and is replaced by new ice formation in coastal polynyas and by influx of new ice from the east. In summer, a further 30% is discharged northward out of the region, leaving 40% cover and by implication a 30% loss by melting.

scholarly journals Antarctic sea ice variability and trends, 1979–2010

2012 ◽  
Vol 6 (4) ◽  
pp. 871-880 ◽  
Author(s):  
C. L. Parkinson ◽  
D. J. Cavalieri
Keyword(s):  
Indian Ocean ◽  
Sea Ice ◽  
Ross Sea ◽  
Ice Cover ◽  
Weddell Sea ◽  
The Arctic ◽  
Future Research ◽  
Positive Trend ◽  
Antarctic Sea Ice ◽  
Ice Coverage

Abstract. In sharp contrast to the decreasing sea ice coverage of the Arctic, in the Antarctic the sea ice cover has, on average, expanded since the late 1970s. More specifically, satellite passive-microwave data for the period November 1978–December 2010 reveal an overall positive trend in ice extents of 17 100 ± 2300 km2 yr−1. Much of the increase, at 13 700 ± 1500 km2 yr−1, has occurred in the region of the Ross Sea, with lesser contributions from the Weddell Sea and Indian Ocean. One region, that of the Bellingshausen/Amundsen Seas, has (like the Arctic) instead experienced significant sea ice decreases, with an overall ice extent trend of −8200 ± 1200 km2 yr−1. When examined through the annual cycle over the 32-yr period 1979–2010, the Southern Hemisphere sea ice cover as a whole experienced positive ice extent trends in every month, ranging in magnitude from a low of 9100 ± 6300 km2 yr−1 in February to a high of 24 700 ± 10 000 km2 yr−1 in May. The Ross Sea and Indian Ocean also had positive trends in each month, while the Bellingshausen/Amundsen Seas had negative trends in each month, and the Weddell Sea and western Pacific Ocean had a mixture of positive and negative trends. Comparing ice-area results to ice-extent results, in each case the ice-area trend has the same sign as the ice-extent trend, but the magnitudes of the two trends differ, and in some cases these differences allow inferences about the corresponding changes in sea ice concentrations. The strong pattern of decreasing ice coverage in the Bellingshausen/Amundsen Seas region and increasing ice coverage in the Ross Sea region is suggestive of changes in atmospheric circulation. This is a key topic for future research.

scholarly journals Sea-ice motion in the Weddell Sea from drifting-buoy and AVHRR data

1996 ◽  
Vol 42 (141) ◽  
pp. 249-254 ◽  
Author(s):  
David Crane ◽  
Peter Wadhams
Keyword(s):  
Sea Ice ◽  
Time Lag ◽  
Ice Cover ◽  
Weddell Sea ◽  
Coherent Motion ◽  
Meteorological Forcing ◽  
Differential Motion ◽  
Ice Field ◽  
High Concentrations ◽  
Ice Floes

AbstractA study of sea ice in the northern Weddell Sea was done, relating the ice motion, determined using an array of satellite-tracked drifters, deployed into ice floes, to parameters describing the nature of the ice cover, obtained from an analysis of Advanced Very High Resolution Radiometer (AVHRR) imagery. It was found that the ice motion was predominantly wind-driven, responding to the passage of low-pressure systems across the area. The correlation length of the strain field over the entire measurement period was around 200 km. At high concentrations the ice responded as a rigid body with coherent motion, but below a concentration of around 93%, differential motion occurred. The nature of the ice motion was found to depend upon the lead parameters, with low values of pure convergence and divergence and larger values of vorticity and deformation of the ice field. The vorticity was found to be well correlated with the atmospheric pressure, with a time lag of less than 3 h, implying an almost instantaneous response of the ice cover to meteorological forcing.

scholarly journals On the Seasonal Signal of the Filchner Overflow, Weddell Sea, Antarctica

2014 ◽  
Vol 44 (4) ◽  
pp. 1230-1243 ◽  
Author(s):  
E. Darelius ◽  
K. O. Strand ◽  
S. Østerhus ◽  
T. Gammeslrød ◽  
M. Årthun ◽  
...  
Keyword(s):  
Seasonal Variability ◽  
Weddell Sea ◽  
Shelf Water ◽  
Ice Shelf ◽  
Sea Bottom ◽  
Plume Region ◽  
Long Time ◽  
Seasonal Signals ◽  
Bottom Waters ◽  
Seasonal Signal

Abstract The cold ice shelf water (ISW) that formed below the Filchner–Ronne Ice Shelf in the southwestern Weddell Sea, Antarctica, escapes the ice shelf cavity through the Filchner Depression and spills over its sill at a rate of 1.6 Sverdrups (Sv; 1 Sv ≡ 106 m3 s−1), thus contributing significantly to the production of Weddell Sea Bottom Water. Here, the authors examine all available observational data from the region—including five year-long time series of mooring data from the Filchner sill—to examine the seasonal variability of the outflow. The temperature of the ISW outflow is found to vary seasonally by 0.07°C with a maximum in April. The accompanying signal in salinity causes a seasonal signal in density of 0.03–0.04 kg m−3, potentially changing the penetration depth of the ISW plume by more than 500 m. Contrary to recent modeling, the observations show no seasonal variability in outflow velocity. The seasonality observed at the sill is, at least partly, due to the admixture of high-salinity shelf water from the Berkner Bank. Observations and numerical modeling suggest, however, seasonal signals in the circulation upstream (i.e., in the ice shelf cavity and in the Filchner Depression) that—although processes and linkages are unclear—are likely to contribute to the seasonal signal observed at the sill. In the plume region downstream of the sill, the source variability is apparent only within the very densest portions of the ISW plume. In the more diluted part of the plume, the source variability is overcome by the seasonality in the properties of the water entrained at the shelf break. This will have implications for the properties of the generated bottom waters.

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