Sea Ice Budget Studies of Baffin Bay Using A Numerical Ice Model

Annals of Glaciology ◽

10.1017/s0260305500003529 ◽

1984 ◽

Vol 5 ◽

pp. 75-80 ◽

Cited By ~ 1

Author(s):

T. E. Keliher ◽

J. S. Foley

Keyword(s):

Sea Ice ◽

Wind Fields ◽

Baffin Bay ◽

Model Average ◽

Short Period ◽

Order Of Magnitude ◽

Ice Conditions ◽

Ice Model

The dynamic-thermodynamic model of sea ice due to Hibler (1979) has been adapted for simulations of the Baffin Bay pack. The simulations were carried out for wind fields characteristic of the more common synoptic situations for July, the ice conditions of July 1969 being taken as typical of this month to initialize the model. Average long-term currents were also used. The modelled ice characteristics were consistent with expected results for the forcing fields and rheology of the ice. A comparison of advectional ice losses through Davis Strait with the melt in situ shows the melt to be an order of magnitude larger. However, the melt alone cannot clear the ice out of Baffin Bay. It seems that the mechanism for this process involves a slow consistent melt coupled with a short period of northwesterly winds.

Download Full-text

The implications of selected processing methods on satellite altimetry derived sea ice thickness state and trends in the seasonal ice zone

10.5194/egusphere-egu21-12240 ◽

2021 ◽

Author(s):

Isolde Glissenaar ◽

Jack Landy ◽

Alek Petty ◽

Nathan Kurtz ◽

Julienne Stroeve

Keyword(s):

Sea Ice ◽

Snow Depth ◽

Satellite Altimetry ◽

Region Of Interest ◽

The Arctic ◽

Ice Thickness ◽

Sea Ice Thickness ◽

Baffin Bay ◽

The Impact

The ice cover of the Arctic Ocean is increasingly becoming dominated by seasonal sea ice. It is important to focus on the processing of altimetry ice thickness data in thinner seasonal ice regions to understand seasonal sea ice behaviour better. This study focusses on Baffin Bay as a region of interest to study seasonal ice behaviour.We aim to reconcile the spring sea ice thickness derived from multiple satellite altimetry sensors and sea ice charts in Baffin Bay and produce a robust long-term record (2003-2020) for analysing trends in sea ice thickness. We investigate the impact of choosing different snow depth products (the Warren climatology, a passive microwave snow depth product and modelled snow depth from reanalysis data) and snow redistribution methods (a sigmoidal function and an empirical piecewise function) to retrieve sea ice thickness from satellite altimetry sea ice freeboard data.The choice of snow depth product and redistribution method results in an uncertainty envelope around the March mean sea ice thickness in Baffin Bay of 10%. Moreover, the sea ice thickness trend ranges from -15 cm/dec to 20 cm/dec depending on the applied snow depth product and redistribution method. Previous studies have shown a possible long-term asymmetrical trend in sea ice thinning in Baffin Bay. The present study shows that whether a significant long-term asymmetrical trend was found depends on the choice of snow depth product and redistribution method. The satellite altimetry sea ice thickness results with different snow depth products and snow redistribution methods show that different processing techniques can lead to different results and can influence conclusions on total and spatial sea ice thickness trends. Further processing work on the historic radar altimetry record is needed to create reliable sea ice thickness products in the marginal ice zone.

Download Full-text

Biomarker characterization of the North Water Polynya, Baffin Bay: Implications for local sea ice and temperature proxies

10.5194/bg-2021-177 ◽

2021 ◽

Author(s):

David J. Harning ◽

Brooke Holman ◽

Lineke Woelders ◽

Anne E. Jennings ◽

Julio Sepúlveda

Keyword(s):

Sea Ice ◽

The Arctic ◽

Sea Ice Extent ◽

Baffin Bay ◽

The North ◽

North Water Polynya ◽

Lipid Biomarker ◽

North Water ◽

Order Of Magnitude ◽

Insight Into

Abstract. The North Water Polynya (NOW, Greenlandic Inuit: Pikialasorsuaq), Baffin Bay, is the largest polynya and one of the most productive regions in the Arctic. This area of thin to absent sea ice is a critical moisture source for local ice sheet sustenance and coupled with the inflow of nutrient-rich Arctic Surface Water, supports a diverse community of Arctic fauna and indigenous people. Although paleoceanographic records can provide critical insight into the NOW’s past behavior, it is critical that we fully understand the modern functionality of the paleoceanographic proxies beforehand. In this study, we analyzed lipid biomarkers, including algal highly-branched isoprenoids and sterols for sea ice extent and pelagic productivity, and algal alkenones and archaeal GDGTs for ocean temperature, in a suite of modern surface sediment samples from within and around the NOW. Our data show that all highly-branched isoprenoids exhibit strong correlations with each other and show highest concentrations within the NOW, which suggests a spring/autumn sea ice diatom source rather than a combination of sea ice and open water diatoms as seen elsewhere in the Arctic. Sterols are also highly concentrated in the NOW and exhibit an order of magnitude higher concentration here compared to sites south of the NOW, consistent with the order of magnitude higher primary productivity observed within the NOW relative to surrounding waters in spring/summer months. Finally, our temperature calibrations for alkenones, GDGTs and OH-GDGTs reduce the uncertainty present in global temperature calibrations, but also identify some additional variables that may be important in controlling their local distribution, such as salinity, nutrients, and dissolved oxygen. Collectively, our datasets provide new insight into the utility of these lipid biomarker proxies in high-latitude settings and will help provide a refined perspective on the Holocene development of the NOW with their application in downcore reconstructions.

Download Full-text

In Situ Creep Model Testing for the Tunnel Anchor Foundation of Xingkang Suspension Bridge in Luding of China

Advances in Civil Engineering ◽

10.1155/2020/8898777 ◽

2020 ◽

Vol 2020 ◽

pp. 1-19

Author(s):

Lina Wen ◽

Qiangong Cheng ◽

Qiang Cheng ◽

Xifeng Guo ◽

Bin Zhang

Keyword(s):

Suspension Bridge ◽

Surrounding Rock ◽

Creep Model ◽

Left Bank ◽

Creep Tests ◽

The Real ◽

Order Of Magnitude ◽

Bridge Foundation

Due to the limitations of geography and geology, cast concrete tunnel anchors were used to provide counterforces for Xingkang Suspension Bridge foundation at the left bank of Daduhe River. In this study, the in situ creep tests were conducted on two model tunnel anchors at a scale of 1:10 near the real working anchor site. Thus, the long-term deformation of the real working tunnel anchors installed at the bridge foundation could be determined from the creep test of model tunnel anchors. The creep tests were conducted under three different loads and lasted for 102.2 h, 167.5 h, and 189.4 h, respectively. The model anchor, the surrounding rock, and their interface were all monitored and measured during the creep testing. In addition, the numerical calculation, in which the Burger creep constitution was used for describing the surrounding rock and the Mohr–Coulomb criterion for describing the concrete anchor, was performed to further evaluate the long-term stability of the real working tunnel anchors. The numerical calculations are in good agreement with the laboratory testing results, and the creep deformations of the anchor and the surrounding rock have the same order of magnitude. The results show that the tunnel anchor and surrounding rock of Xingkang Bridge are in a stable creep state under the three different loads.

Download Full-text

The impact of denying sea ice information on the predictability of atmospheric processes over the Arctic and at mid-latitude regions

10.5194/egusphere-egu2020-11692 ◽

2020 ◽

Author(s):

Leandro Ponsoni ◽

Daniela Flocco ◽

François Massonnet ◽

Steve Delhaye ◽

Ed Hawkins ◽

...

Keyword(s):

Sea Ice ◽

General Circulation ◽

Model Comparison ◽

General Circulation Models ◽

Arctic Sea Ice ◽

The Arctic ◽

Atmospheric Processes ◽

Ice Conditions ◽

The Impact

In this work, we make use of an inter-model comparison and of a perfect model approach, in which model outputs are used as true reference states, to assess the impact that denying sea ice information has on the prediction of atmospheric processes, both over the Arctic and at mid-latitude regions. To do so, two long-term control runs (longer than 250 years) were generated with two state-of-the-art General Circulation Models (GCM), namely EC-Earth and HadGEM. From these two reference states, we have identified three different years in which the Arctic sea ice volume (SIV) was (i) maximum, (ii) minimum and (iii) a representative case for the mean state. By departing from each of these three dates (not necessarily the same for the two models), we generated a set of experiments in which the control runs are restarted both from original and climatological sea ice conditions. Here, climatological sea ice conditions are estimated as the time-average of sea ice parameters from the respective long-term control runs. The experiments are 1-year long and all of them start in January when ice is still thin, snow depth is small, air-ocean temperatures contrast the most and, therefore, the heat conductive flux in sea ice (at the surface) is nearly maximum. To robustly separate the response to degrading the initial sea ice state from background internal variability, each of the two counterfactual experiments (reference and climatological) consists of 50 ensembles members. Threstatedese ensembles are generated by adding small random perturbations to the sea surface temperature (EC-Earth) or to the air temperature (HadGEM) fields. Preliminary results reinforce the importance of having the right sea ice state for improving the (sub-)seasonal prediction of atmospheric parameters (e.g., 2m-temperature and geopotential) and circulation (e.g., Westerlies and Jet Stream) not only over the Arctic, but also at mid-latitude regions.

Download Full-text

Using CloudSat snowfall rate observations to constrain and characterize the uncertainties of Arctic snow-on-sea-ice

10.5194/egusphere-egu2020-11436 ◽

2020 ◽

Author(s):

Alex Cabaj ◽

Paul Kushner ◽

Alek Petty ◽

Stephen Howell ◽

Christopher Fletcher

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Snow Depth ◽

Arctic Sea Ice ◽

The Arctic ◽

Ice Thickness ◽

Sea Ice Thickness ◽

The Arctic Ocean ◽

Ice Model

Snow on Arctic sea ice plays multiple&#8212;and sometimes contrasting&#8212;roles in several feedbacks between sea ice and the global climate system. For example, the presence of snow on sea ice may mitigate sea ice melt by increasing the sea ice albedo and enhancing the ice-albedo feedback. Conversely, snow can inhibit sea ice growth by insulating the ice from the atmosphere during the sea ice growth season. In addition to its contribution to sea ice feedbacks, snow on sea ice also poses a challenge for sea ice observations. In particular, snow contributes to uncertainties in retrievals of sea ice thickness from satellite altimetry measurements, such as those from ICESat-2. Snow-on-sea-ice models can produce basin-wide snow depth estimates, but these models require snowfall input from reanalysis products. In-situ snowfall measurements are absent over most of the Arctic Ocean, so it can be difficult to determine which reanalysis snowfall product is best suited to be used as input for a snow-on-sea-ice model.In the absence of in-situ snowfall rate measurements, measurements from satellite instruments can be used to quantify snowfall over the Arctic Ocean. The CloudSat satellite, which is equipped with a 94 GHz Cloud Profiling Radar instrument, measures vertical radar reflectivity profiles from which snowfall rates can be retrieved. This instrument provides the most extensive high-latitude snowfall rate observation dataset currently available. CloudSat&#8217;s near-polar orbit enables it to make measurements at latitudes up to 82&#176;N, with a 16-day repeat cycle, over the time period from 2006-2016.We present a calibration of reanalysis snowfall to CloudSat observations over the Arctic Ocean, which we then apply to reanalysis snowfall input for the NASA Eulerian Snow On Sea Ice Model (NESOSIM). This calibration reduces the spread in snow depths produced by NESOSIM when different reanalysis inputs are used. In light of this calibration, we revise the NESOSIM parametrizations of wind-driven snow processes, and we characterize the uncertainties in NESOSIM-generated snow depths resulting from uncertainties in snowfall input. We then extend this analysis further to estimate the resulting uncertainties in sea ice thickness retrieved from ICESat-2 when snow depth estimates from NESOSIM are used as input for the retrieval.

Download Full-text

Can we extend local sea-ice measurements to satellite scale? An example from the N-ICE2015 expedition

Annals of Glaciology ◽

10.1017/aog.2017.37 ◽

2017 ◽

Vol 59 (76pt2) ◽

pp. 163-172 ◽

Cited By ~ 1

Author(s):

Anja Rösel ◽

Jennifer King ◽

Anthony P. Doulgeris ◽

Penelope M. Wagner ◽

A. Malin Johansson ◽

...

Keyword(s):

Sea Ice ◽

Satellite Data ◽

Arctic Sea Ice ◽

Ice Thickness ◽

Remotely Sensed Data ◽

Sea Ice Thickness ◽

In Situ Data ◽

Ice Conditions ◽

Area North

ABSTRACTKnowledge of Arctic sea-ice conditions is of great interest for Arctic residents, as well as for commercial usage, and to study the effects of climate change. Information gained from analysis of satellite data contributes to this understanding. In the course of using in situ data in combination with remotely sensed data, the question of how representative local scale measurements are of a wider region may arise. We compare in situ total sea-ice thickness measurements from the Norwegian young sea ICE expedition in the area north of Svalbard with airborne-derived total sea-ice thickness from electromagnetic soundings. A segmented and classified synthetic aperture radar (SAR) quad-pol ALOS-2 Palsar-2 satellite scene was grouped into three simplified ice classes. The area fractions of the three classes are: 11.2% ‘thin’, 74.4% ‘level’, and 14.4% ‘deformed’. The area fractions of the simplified classes from ground- and helicopter-based measurements are comparable with those achieved from the SAR data. Thus, this study shows that there is potential for a stepwise upscaling from in situ, to airborne, to satellite data, which allow us to assess whether in situ data collected are representative of a wider region as observed by satellites.

Download Full-text

Coupled Sea Ice–Ocean-State Estimation in the Labrador Sea and Baffin Bay

Journal of Physical Oceanography ◽

10.1175/jpo-d-12-065.1 ◽

2013 ◽

Vol 43 (5) ◽

pp. 884-904 ◽

Cited By ~ 34

Author(s):

Ian Fenty ◽

Patrick Heimbach

Keyword(s):

Sea Ice ◽

North Atlantic ◽

Numerical Models ◽

Labrador Sea ◽

In Situ Observation ◽

Quasi Equilibrium ◽

Ocean Variability ◽

The Relationship ◽

Ice Model

Abstract Sea ice variability in the Labrador Sea is of climatic interest because of its relationship to deep convection, mode-water formation, and the North Atlantic atmospheric circulation. Historically, quantifying the relationship between sea ice and ocean variability has been difficult because of in situ observation paucity and technical challenges associated with synthesizing observations with numerical models. Here the relationship between ice and ocean variability is explored by analyzing new estimates of the ocean–ice state in the northwest North Atlantic. The estimates are syntheses of in situ and satellite hydrographic and ice data with a regional ⅓° coupled ocean–sea ice model. The synthesis of sea ice data is achieved with an improved adjoint of a thermodynamic ice model. Model and data are made consistent, in a least squares sense, by iteratively adjusting control variables, including ocean initial and lateral boundary conditions and the atmospheric state, to minimize an uncertainty-weighted model–data misfit cost function. The utility of the state estimate is demonstrated in an analysis of energy and buoyancy budgets in the marginal ice zone (MIZ). In mid-March the system achieves a state of quasi-equilibrium during which net ice growth and melt approaches zero; newly formed ice diverges from coastal areas and converges via wind and ocean forcing in the MIZ. The convergence of ice mass in the MIZ is ablated primarily by turbulent ocean–ice enthalpy fluxes. The primary source of the enthalpy required for sustained MIZ ice ablation is the sensible heat reservoir of the subtropical-origin subsurface waters.

Download Full-text

Dynamic–Thermodynamic Sea Ice Model: Ridging and Its Application to Climate Study and Navigation

Journal of Climate ◽

10.1175/jcli3484.1 ◽

2005 ◽

Vol 18 (18) ◽

pp. 3840-3855 ◽

Cited By ~ 4

Author(s):

Sergey V. Shoutilin ◽

Alexander P. Makshtas ◽

Motoyoshi Ikeda ◽

Alexey V. Marchenko ◽

Roman V. Bekryaev

Keyword(s):

Sea Ice ◽

Arctic Basin ◽

Circulation Pattern ◽

Ice Cover ◽

The Arctic ◽

Partial Recovery ◽

Pacific Side ◽

Pattern Production ◽

Ice Model

Abstract A dynamic–thermodynamic sea ice model with the ocean mixed layer forced by atmospheric data is used to investigate spatial and long-term variability of the sea ice cover in the Arctic basin. The model satisfactorily reproduces the averaged main characteristics of the sea ice and its extent in the Arctic Basin, as well as its decrease in the early 1990s. Employment of the average ridge shape for describing the ridging allows the authors to suggest that it occurs in winter and varies from year to year by a factor of 2, depending on an atmospheric circulation pattern. Production and horizontal movement of ridges are the focus in this paper, as they show the importance of interannual variability of the Arctic ice cover. The observed thinning in the 1990s is a result of reduction in ridge formation on the Pacific side during the cyclonic phase of the Arctic Oscillation. The model yields a partial recovery of sea ice cover in the last few years of the twentieth century. In addition to the sea ice cover and average thickness compared with satellite data, the ridge amount is verified with observations taken in the vicinity of the Russian coast. The model results are useful to estimate long-term variability of the probability of ridge-free navigation in different parts of the Arctic Ocean, including the Northern Sea Route area.

Download Full-text

An Improved Chamber for in situ Measurement of Primary Productivity by Sea Ice Algae

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f82-073 ◽

1982 ◽

Vol 39 (3) ◽

pp. 522-524 ◽

Cited By ~ 9

Author(s):

G. C. Schrader ◽

R. Horner ◽

G. F. Smith

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Primary Productivity ◽

In Situ Measurement ◽

Carbon Uptake ◽

Ice Algae ◽

Sea Ice Algae ◽

Scuba Divers ◽

Ice Conditions

A modified chamber was designed for in situ measurement of carbon uptake of micro-algae growing on the underside of sea ice. The chamber, operated by SCUBA divers, accommodates a wider range of ice conditions, has better holding capability, and reduces sample loss during retrieval.Key words: Arctic Ocean, sea ice algae, primary productivity

Download Full-text