Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Interactions of Ice Sheets and Glaciers with the Ocean
Author: Air-Ice-Ocean Interaction
Author: Miles McPheePublisher: Springer Science & Business Media
ISBN: 0387783350
Category : Science
Languages : en
Pages : 218
Book Description
At a time when the polar regions are undergoing rapid and unprecedented change, understanding exchanges of momentum, heat and salt at the ice-ocean interface is critical for realistically predicting the future state of sea ice. By offering a measurement platform largely unaffected by surface waves, drifting sea ice provides a unique laboratory for studying aspects of geophysical boundary layer flows that are extremely difficult to measure elsewhere. This book draws on both extensive observations and theoretical principles to develop a concise description of the impact of stress, rotation, and buoyancy on the turbulence scales that control exchanges between the atmosphere and underlying ocean when sea ice is present. Several interesting and unique observational data sets are used to illustrate different aspects of ice-ocean interaction ranging from the impact of salt on melting in the Greenland Sea marginal ice zone, to how nonlinearities in the equation of state for seawater affect mixing in the Weddell Sea. The book’s content, developed from a series of lectures, may be appropriate additional material for upper-level undergraduates and first-year graduate students studying the geophysics of sea ice and planetary boundary layers.
Interactions Calotte Polaire/océan
Author: Nacho MerinoPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
The next generation of climate models will include an ice-sheet model in order to improve the ice sheet mass balance projections by accounting for the ice dynamics and ice-oceans interactions. On the one hand, the Southern Ocean (SO) is indeed driving the acceleration of the Antarctic outlet glaciers via an increase in the basal melting of the ice shelves. On the other hand, the increasing ice discharge from Antarctic Ice Sheet (AIS) contributes to the current sea level rise and is likely to become the largest cryospheric contributor to sea level rise by the end of the current century. In addition, the related freshening may have significant implications on future sea-ice cover and on bottom water formation. However, it is not clear yet how the ocean and ice-sheet components of future coupled systems will account for the ice-ocean interactions, which are both causes and consequences of the AIS mass imbalance. Here in this work, different aspects of the standalone ocean and ice-sheet components have been investigated. A first step of this thesis has been focused in the representation of the glacial freshwater fluxes in current ocean models. Based on recent glaciological estimates, the ice shelf basal melting fluxes have been spatially distributed in an ORCA025 grid, and the calving rates have been applied into an improved version of the NEMO-ICB iceberg model. This preliminary study has been used to produce a monthly iceberg meltwater climatology, to be used to force current ocean models. This work shows the importance of representing the iceberg meltwater fluxes when modeling sea ice, which can be inexpensively achieve by using our climatology. The improvements in the representation of the glacial freshwater fluxes have been considered in the study of the ocean model response to the Antarctic mass imbalance. This study considers a realistic perturbation in the glacial freshwater forcing as close as possible as it will be represented in future ice-sheet/ocean models. According to our results, up to 50% of the recent Antarctic sea ice volume changes might be caused by the observed decadal AIS mass imbalance rate. Glacial freshwater forcing appears to be crucial to correctly represent the ice-ocean interactions and projecting sea ice cover of future coupled systems. However, the estimation of the glacial freshwater input in future climate models will be strongly dependent upon the capacity of ice-sheet models to reproduce the grounding line migrations of marine ice sheet glaciers. Current ice-sheet models present large uncertainties related to different parametrizations. In the context of the future climate models, we have studied the sensitivity of ocean-driven grounding line retreats to the application of two different friction laws and two different englacial stress approximations. The model responses almost indistinctively to either the SSA or the SSA* englacial stress approximations. However, differences in the contribution of the glacier to the sea level rise can be up to 50% depending on the friction law considered. The more physically constrained Schoof friction law is significantly more reactive to the ocean perturbations than Weertman law and should be considered in future coupled systems. This work underlines that uncertainties related to the ice sheet model estimates of grounding line migrations may not only contribute to uncertainties in sea level projections, but also the sea ice cover through the ice-ocean interaction in future ocean models.This conclusion suggests the need for improving the representation of both the ice shelf basal melting and the glacier interaction with the bedrock, in order to improve the climate projections of future climate models, in which the spatial and seasonal distribution of the glacial freshwater fluxes may play an important role in setting the sea ice cover.
Air-Ice-Ocean Interaction
Author: Miles McPheePublisher: Springer
ISBN: 9780387783345
Category : Science
Languages : en
Pages : 0
Book Description
At a time when the polar regions are undergoing rapid and unprecedented change, understanding exchanges of momentum, heat and salt at the ice-ocean interface is critical for realistically predicting the future state of sea ice. By offering a measurement platform largely unaffected by surface waves, drifting sea ice provides a unique laboratory for studying aspects of geophysical boundary layer flows that are extremely difficult to measure elsewhere. This book draws on both extensive observations and theoretical principles to develop a concise description of the impact of stress, rotation, and buoyancy on the turbulence scales that control exchanges between the atmosphere and underlying ocean when sea ice is present. Several interesting and unique observational data sets are used to illustrate different aspects of ice-ocean interaction ranging from the impact of salt on melting in the Greenland Sea marginal ice zone, to how nonlinearities in the equation of state for seawater affect mixing in the Weddell Sea. The book’s content, developed from a series of lectures, may be appropriate additional material for upper-level undergraduates and first-year graduate students studying the geophysics of sea ice and planetary boundary layers.
The Law of the Sea and the Polar Regions
Author: Erik Jaap MolenaarPublisher: Brill Nijhoff
ISBN: 9789004255203
Category : Conservation of natural resources
Languages : en
Pages : 0
Book Description
The Law of the Sea and the Polar Regions: Interactions between Global and Regional Regimes examines regional regimes for the Arctic and Antarctic on among others science, maritime security, marine-protected areas, fisheries and shipping, by means of common research questions; thus enabling overall synthesis and identification of differences, similarities, and trends.
Atmospheric-ocean-sea Ice Interactions in Polar Regions
Author: E. AugsteinInteraction of Sea Ice, Snow, and Glaciers with the Atmosphere and Ocean
Author: V. M. KotlyakovA model study of upper ocean-sea ice interactions
Author: T. FICHEFETExperiments on the Interaction of Ice Sheets with the Polar Oceans
Author: Craig McConnochiePublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Antarctica and Greenland have been losing mass at an increasing rate over recent decades. The reducing volume of ice in Antarctica and Greenland has been a significant contribution to global sea level rise and will continue to be so in the future. Much of the mass loss occurs at the edge of the ice sheets where glaciers flow into the ocean. Interactions between the ice and the ocean are important in controlling the ablation rate of the glaciers. As such, there has been much recent work examining the response of ice shelves to changing ocean conditions. The majority of this work has used numerical models that allow a range of ocean conditions to be simulated. Here, we investigate the major ice-ocean interactions through idealized laboratory experiments. Initially, the effect of fluid temperature on the ablation of a vertical ice wall is investigated. At the low temperatures and oceanic salinities that our experiments were conducted at, the temperature at the ice-fluid interface will be below 0 degrees Celsius and the interface salinity will be non-zero. Because of this, it is useful to consider a driving temperature defined as the difference between the fluid temperature and the freezing point at the fluid salinity. It is shown that the ablation rate increases like the driving temperature to the 4/3 power, while the interface temperature increases almost linearly with the driving temperature. Ablation of an ice wall releases cold fresh water that rises up the ice face as a turbulent plume. This turbulent plume enhances the transport of heat and salt to the ice-fluid interface and helps to maintain ablation of the ice. The properties of the plume are investigated in detail and a model is developed that describes them. The ocean around Antarctica and Greenland is generally stably stratified in salinity. The effect of stratification is investigated to examine the potential sensitivity of the ice sheets to changes in ambient fluid stratification. Regimes are found where small changes in the strength of stratification can lead to large changes in the ablation rate and the plume properties. This result highlights the possibility that weakening stratification, not just warming oceans, could lead to increased mass loss from the ice sheets. In many locations around Greenland, plumes of freshwater are released at the base of the glacier. These subglacial plumes are modelled in the laboratory by releasing a two-dimensional freshwater plume at the base of the ice face. The additional source of buoyancy typically leads to significantly higher ablation rates and plume velocities, consistent with past numerical and observational studies. These laboratory experiments represent an increasingly realistic model of the ice shelves around Antarctica and Greenland. Despite important physical processes still being excluded, the experiments present a useful and previously unavailable dataset with which numerical models can be tested and oceanographic field observations can be compared.
Arctic and Antarctic Sea Ice and Its Interactions with Ocean and the Atmosphere
Author: O. M. JohannessenPublisher:
ISBN:
Category : International cooperation
Languages : en
Pages :
Book Description