scholarly journals Sea Ice Thickness in the Western Ross Sea

2020 ◽  
Author(s):  
Wolfgang Rack ◽  
Daniel Price ◽  
Christian Haas ◽  
Patricia J. Langhorne ◽  
Greg H. Leonard
Keyword(s):  
Sea Ice ◽  
Ross Sea ◽  
Ice Thickness ◽  
Sea Ice Thickness ◽  
Western Ross Sea

Sea ice deformation and thickness in the Western Ross Sea

2021 ◽  
Author(s):  
Wolfgang Rack ◽  
Daniel Price ◽  
Christian Haas ◽  
Patricia J. Langhorne ◽  
Greg H. Leonard
Keyword(s):  
Sea Ice ◽  
Satellite Images ◽  
Ross Sea ◽  
Thickness Distribution ◽  
Ice Thickness ◽  
Ice Dynamics ◽  
Sea Ice Thickness ◽  
Ice Volume ◽  
Terra Nova Bay ◽  
Western Ross Sea

<p>Sea ice cover is arguably the longest and best observed climate variable from space, with over four decades of highly reliable daily records of extent in both hemispheres. In Antarctica, a slight positive decadal trend in sea ice cover is driven by changes in the western Ross Sea, where a variation in weather patterns over the wider region forced a change in meridional winds. The distinguishing wind driven sea ice process in the western Ross Sea is the regular occurrence of the Ross Sea, McMurdo Sound, and Terra Nova Bay polynyas. Trends in sea ice volume and mass in this area unknown, because ice thickness and dynamics are particularly hard to measure.</p><p>Here we present the first comprehensive and direct assessment of large-scale sea-ice thickness distribution in the western Ross Sea. Using an airborne electromagnetic induction (AEM) ice thickness sensor towed by a fixed wing aircraft (Basler BT-67), we observed in November 2017 over a distance of 800 km significantly thicker ice than expected from thermodynamic growth alone. By means of time series of satellite images and wind data we relate the observed thickness distribution to satellite derived ice dynamics and wind data. Strong southerly winds with speeds of up to 25 ms<sup>-1</sup> in early October deformed the pack ice, which was surveyed more than a month later.</p><p>We found strongly deformed ice with a mean and maximum thickness of 2.0 and 15.6 m, respectively. Sea-ice thickness gradients are highest within 100-200 km of polynyas, where the mean thickness of the thickest 10% of ice is 7.6 m. From comparison with aerial photographs and satellite images we conclude that ice preferentially grows in deformational ridges; about 43% of the sea ice volume in the area between McMurdo Sound and Terra Nova Bay is concentrated in more than 3 m thick ridges which cover about 15% of the surveyed area. Overall, 80% of the ice was found to be heavily deformed and concentrated in ridges up to 11.8 m thick.</p><p>Our observations hold a link between wind driven ice dynamics and the ice mass exported from the western Ross Sea. The sea ice statistics highlighted in this contribution forms a basis for improved satellite derived mass balance assessments and the evaluation of sea ice simulations.</p>

scholarly journals A field and numerical study of the evolution of sea-ice thickness in the Ross Sea, Antarctica, 1998-99

2004 ◽  
Vol 50 (170) ◽  
pp. 436-446
Author(s):  
Tina Tin ◽  
Ralph Timmermann ◽  
Martin O. Jeffries
Keyword(s):  
Sea Ice ◽  
Field Data ◽  
Ross Sea ◽  
Numerical Study ◽  
Ice Formation ◽  
Ice Thickness ◽  
First Year ◽  
Sea Ice Thickness ◽  
Ice Field ◽  
Western Ross Sea

AbstractDuring two cruises in 1998 and 1999, we examined drift and ridging characteristics of sea ice in the Ross Sea, Antarctica. Mean ice thickness in the western Ross Sea in autumn was 0.5 m, while higher level-ice thicknesses, greater areal coverages of ridges and higher sails were found in the central and eastern Ross Sea in summer. Near the continent, ice drifted westward near the coast and turned eastward further north. We use a regional sea-ice−mixed-layer−pycnocline model to initiate backward trajectories at the time and location of field observations and examine the dynamic and thermodynamic processes that determine ice thickness along these trajectories. Model results agree with previously published field data to indicate that thermodynamic and dynamic thickening and snow-ice formation each contribute significantly to the ice mass of the summer ice field in the central and eastern Ross Sea. For first-year ice in the western Ross Sea, model results and field data both indicate that thermodynamic thickening is the dominant process that determines ice thickness, with dynamic thickening also contributing 20% to the net ice-thickening rate. However, model results fail to reproduce the prevalence of snow- ice formation that was seen in field data.

Estimating the thickness of ridged sea ice from ship observations in the Ross Sea

2003 ◽  
Vol 15 (1) ◽  
pp. 47-54 ◽  
Author(s):  
TINA TIN ◽  
MARTIN O. JEFFRIES ◽  
MIKKO LENSU ◽  
JUKKA TUHKURI
Keyword(s):  
Sea Ice ◽  
Ross Sea ◽  
Low Cost ◽  
Thickness Distribution ◽  
Ice Thickness ◽  
Equivalent Thickness ◽  
Sea Ice Thickness ◽  
Antarctic Sea Ice ◽  
Using Data ◽  
Original Formula

Ship-based observations of sea ice thickness using the Antarctic Sea Ice Processes and Climate (ASPeCt) protocol provide information on ice thickness distribution at relatively low cost. This protocol uses a simple formula to calculate the mass of ice in ridges based on surface observations. We present two new formulae and compare these with results from the “Original” formula using data obtained in the Ross Sea in autumn and winter. The new “r-star” formula uses a more realistic ratio of sail and keel areas to transform dimensions of sails to estimates of mean keel areas. As a result, estimates of “equivalent thickness” (i.e. mean thickness of ice in ridged areas) increased by over 200%. The new “Probability” formula goes one step further, by incorporating the probability that a sail is associated with a keel underwater, and the probability that keels may be found under level surfaces. This resulted in estimates of equivalent thickness comparable with the Original formula. Estimates of equivalent thickness at one or two degree latitude resolution are sufficiently accurate for validating sea ice models. Although ridges are small features in the Ross Sea, we have shown that they constitute a significant fraction of the total ice mass.

Structural characteristics and development of sea ice in the western Ross Sea

1993 ◽  
Vol 5 (1) ◽  
pp. 63-75 ◽  
Author(s):  
M. O. Jeffries ◽  
W. F. Weeks
Keyword(s):  
Sea Ice ◽  
Internal Structure ◽  
Ross Sea ◽  
Ice Cores ◽  
Arctic Sea Ice ◽  
Weddell Sea ◽  
The Arctic ◽  
Ice Thickness ◽  
Pack Ice ◽  
Western Ross Sea

The internal structure of ice cores from western Ross Sea pack ice floes showed considerable diversity. Snow-ice formation made a small, but significant contribution to ice growth. Frazil ice was common and its growth clearly occurred during both the pancake cycle and deformation events. Congelation ice was also common, in both its crystallographically aligned and non-aligned varieties. Platelet ice was found in only one core next to the Drygalski Ice Tongue, an observation adding to the increasing evidence that this unusual ice type occurs primarily in coastal pack ice near ice tongues and ice shelves. The diverse internal structure of the floes indicates that sea ice development in the Ross Sea is as complex as that in the Weddell Sea and more complex than in the Arctic. The mean ice thickness at the ice core sites varied between 0.71 m and 1.52 m. The thinnest ice generally occurred in the outer pack ice zone. Regardless of latitude, the ice thickness data are further evidence that Antarctic sea ice is thinner than Arctic sea ice.

scholarly journals Sea-ice thickness and roughness in the Ross Sea, Antarctica

2001 ◽  
Vol 33 ◽  
pp. 187-193 ◽  
Author(s):  
Tina Tin ◽  
Martin O. Jeffries
Keyword(s):  
Surface Roughness ◽  
Sea Ice ◽  
Ross Sea ◽  
Geographical Location ◽  
Ice Thickness ◽  
Snow Surface ◽  
Sea Ice Thickness ◽  
Antarctic Sea Ice ◽  
Ice Roughness ◽  
Ice Floes

AbstractSea-ice thickness and roughness data collected on three cruises in the Ross Sea, Antarctica, showed interseasonal, regional and interannual variability. Variability was reduced to season, or age of ice floe, when sea-ice roughness values from around Antarctica were compared. There were statistically significant correlations between mean snow elevation and mean ice thickness; snow surface roughness and mean ice thickness; and snow surface roughness and ice bottom roughness, which appeared to be independent of season, geographical location and deformation history of ice floes. Our field data indicate that ice thickness can be predicted from snow elevation measurements with higher accuracy in summer. The feasibility of using snow surface roughness to infer ice thickness and ice bottom roughness is promising, and can provide us with a means to study the thickness and underside of Antarctic sea ice at good spatial and temporal resolution.

Estimating the annual cycle of sea-ice thickness and volume in the Ross Sea

2011 ◽  
Vol 58 (9-10) ◽  
pp. 1250-1260 ◽  
Author(s):  
Tracy L. DeLiberty ◽  
Cathleen A. Geiger ◽  
Stephen F. Ackley ◽  
Anthony P. Worby ◽  
Michael L. Van Woert
Keyword(s):  
Sea Ice ◽  
Annual Cycle ◽  
Ross Sea ◽  
Ice Thickness ◽  
Sea Ice Thickness

scholarly journals Sea-ice production and air/ice/ocean/biogeochemistry interactions in the Ross Sea during the PIPERS 2017 autumn field campaign

2020 ◽  
Vol 61 (82) ◽  
pp. 181-195 ◽  
Author(s):  
S. F. Ackley ◽  
S. Stammerjohn ◽  
T. Maksym ◽  
M. Smith ◽  
J. Cassano ◽  
...  
Keyword(s):  
Heat Flux ◽  
Sea Ice ◽  
Multidisciplinary Approach ◽  
Ross Sea ◽  
Ice Thickness ◽  
Biogeochemical Processes ◽  
Sea Ice Thickness ◽  
Ocean Biogeochemistry ◽  
Ice Edge ◽  
Ice Production

AbstractThe Ross Sea is known for showing the greatest sea-ice increase, as observed globally, particularly from 1979 to 2015. However, corresponding changes in sea-ice thickness and production in the Ross Sea are not known, nor how these changes have impacted water masses, carbon fluxes, biogeochemical processes and availability of micronutrients. The PIPERS project sought to address these questions during an autumn ship campaign in 2017 and two spring airborne campaigns in 2016 and 2017. PIPERS used a multidisciplinary approach of manned and autonomous platforms to study the coupled air/ice/ocean/biogeochemical interactions during autumn and related those to spring conditions. Unexpectedly, the Ross Sea experienced record low sea ice in spring 2016 and autumn 2017. The delayed ice advance in 2017 contributed to (1) increased ice production and export in coastal polynyas, (2) thinner snow and ice cover in the central pack, (3) lower sea-ice Chl-a burdens and differences in sympagic communities, (4) sustained ocean heat flux delaying ice thickening and (5) a melting, anomalously southward ice edge persisting into winter. Despite these impacts, airborne observations in spring 2017 suggest that winter ice production over the continental shelf was likely not anomalous.

scholarly journals Autumn sea ice thickness, ridging and heat flux variability in and adjacent to Terra Nova Bay, Ross Sea, Antarctica

2001 ◽  
Vol 106 (C3) ◽  
pp. 4437-4448 ◽  
Author(s):  
Martin O. Jeffries ◽  
Kim Morris ◽  
Ted Maksym ◽  
Nickolai Kozlenko ◽  
Tina Tin
Keyword(s):  
Heat Flux ◽  
Sea Ice ◽  
Ross Sea ◽  
Ice Thickness ◽  
Sea Ice Thickness ◽  
Terra Nova Bay ◽  
Flux Variability ◽  
Terra Nova

scholarly journals Sea-ice freeboard and thickness in the Ross Sea from airborne (IceBridge 2013) and satellite (ICESat 2003–2008) observations

2020 ◽  
Vol 61 (82) ◽  
pp. 24-39 ◽  
Author(s):  
Liuxi Tian ◽  
Hongjie Xie ◽  
Stephen F. Ackley ◽  
Jiakui Tang ◽  
Alberto M. Mestas-Nuñez ◽  
...  
Keyword(s):  
Sea Ice ◽  
Ross Sea ◽  
Deep Ocean ◽  
Ice Thickness ◽  
Ice Shelf ◽  
Sea Ice Thickness ◽  
Mean Values ◽  
Digital Mapping ◽  
Mapping System ◽  
Two Peaks

AbstractNASA's Operation IceBridge mission flew over the Ross Sea, Antarctica (20 and 27 November 2013) and collected data with Airborne Topographic Mapper (ATM) and Digital Mapping System (DMS). Using the DMS and reflectivity of ATM L1B, leads are detected to define local sea level height. The total freeboard is then obtained and converted to ice thickness. The estimated mean sea-ice thickness values are found to be in the 0.48–0.99 m range. Along the N-S track, sea ice was thinner southward rather than northward of the fluxgate, resulting in two peaks of modal thickness: 0.35 m (south) and 0.7 m (north). This supports that new ice produced in coastal polynyas is transported northward by katabatic winds off the ice-shelf. The lowest (2%) elevation method used for freeboard retrieval for ICESat is also tested for ATM data. It is found that the lowest elevation method tends to overestimate freeboard, but mean values are less affected than mode values. Using mean thickness values of ICESat and ATM along the ‘fluxgate’, separating the shelf from the deep ocean, the exported ice volume at this ‘fluxgate’ is found to be higher during the ICESat years (2003–2008) than during the IceBridge year (2013).

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