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Author: Publisher: ISBN: Category : Arctic regions Languages : en Pages : 67
Book Description
This thesis provides a continuation of the analysis of the diminishing sea ice trend in the Arctic Ocean by examining results from the NPS 1/12 degree pan-Arctic coupled ice-ocean model. While many previous studies have analyzed changes in ice extent and concentration, this research focuses on ice thickness as it gives a better representation of ice volume variability. The skill of the model is examined by comparing its ice thickness output to actual sea ice thickness data gathered during the last three decades. The model comparison is made against the most recently released collection of Arctic ice draft measurements conducted by U.S. Navy submarines between 1979 and 2000. The NPS model indicates an accelerated thinning trend in Arctic sea ice during the last decade. The validation of model output with submarine upward-looking sonar data supports this result. This lends credence to the postulation that the Arctic is likely to be ice-free during the summer in the near future. The diminishing Arctic sea ice will have significant implications for both the physical and operational environment in which the U.S. Navy currently operates.
Author: Publisher: ISBN: Category : Arctic regions Languages : en Pages : 67
Book Description
This thesis provides a continuation of the analysis of the diminishing sea ice trend in the Arctic Ocean by examining results from the NPS 1/12 degree pan-Arctic coupled ice-ocean model. While many previous studies have analyzed changes in ice extent and concentration, this research focuses on ice thickness as it gives a better representation of ice volume variability. The skill of the model is examined by comparing its ice thickness output to actual sea ice thickness data gathered during the last three decades. The model comparison is made against the most recently released collection of Arctic ice draft measurements conducted by U.S. Navy submarines between 1979 and 2000. The NPS model indicates an accelerated thinning trend in Arctic sea ice during the last decade. The validation of model output with submarine upward-looking sonar data supports this result. This lends credence to the postulation that the Arctic is likely to be ice-free during the summer in the near future. The diminishing Arctic sea ice will have significant implications for both the physical and operational environment in which the U.S. Navy currently operates.
Author: Jacqueline M. Grebmeier Publisher: Springer ISBN: 9401788634 Category : Science Languages : en Pages : 461
Book Description
The Pacific Arctic region is experiencing rapid sea ice retreat, seawater warming, ocean acidification and biological response. Physical and biogeochemical modeling indicates the potential for step-function changes to the overall marine ecosystem. This synthesis book was coordinated within the Pacific Arctic Group, a network of international partners working in the Pacific Arctic. Chapter topics range from atmospheric and physical sciences to chemical processing and biological response to changing environmental conditions. Physical and biogeochemical modeling results highlight the need for data collection and interdisciplinary modeling activities to track and forecast the changing ecosystem of the Pacific Arctic with climate change.
Author: Eric T. DeWeaver Publisher: John Wiley & Sons ISBN: 1118671589 Category : Science Languages : en Pages : 431
Book Description
Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 180. This volume addresses the rapid decline of Arctic sea ice, placing recent sea ice decline in the context of past observations, climate model simulations and projections, and simple models of the climate sensitivity of sea ice. Highlights of the work presented here include An appraisal of the role played by wind forcing in driving the decline; A reconstruction of Arctic sea ice conditions prior to human observations, based on proxy data from sediments; A modeling approach for assessing the impact of sea ice decline on polar bears, used as input to the U.S. Fish and Wildlife Service's decision to list the polar bear as a threatened species under the Endangered Species Act; Contrasting studies on the existence of a "tipping point," beyond which Arctic sea ice decline will become (or has already become) irreversible, including an examination of the role of the small ice cap instability in global warming simulations; A significant summertime atmospheric response to sea ice reduction in an atmospheric general circulation model, suggesting a positive feedback and the potential for short-term climate prediction. The book will be of interest to researchers attempting to understand the recent behavior of Arctic sea ice, model projections of future sea ice loss, and the consequences of sea ice loss for the natural and human systems of the Arctic.
Author: Publisher: ISBN: Category : Microwave remote sensing Languages : en Pages : 224
Book Description
Data from the Electrically Scanning Microwave Radiometer (ESMR) on the Nimbus 5 satellite are used to determine the extent and distribution of Antarctic sea ice. The characteristics of the southern ocean, the mathematical formulas used to obtain quantitative sea ice concentrations, the general characteristics of the seasonal sea ice growth/decay cycle and regional differences, and the observed seasonal growth/decay cycle for individual years and interannual variations of the ice cover are discussed. The sea ice data from the ESMR are presented in the form of color-coded maps of the Antarctic and the southern oceans. The maps show brightness temperatures and concentrations of pack ice averaged for each month, 4-year monthly averages, and month-to-month changes. Graphs summarizing the results, such as areas of sea ice as a function of time in the various sectors of the southern ocean are included. The images demonstrate that satellite microwave data provide unique information on large-scale sea ice conditions for determining climatic conditions in polar regions and possible global climatic changes.
Author: Ola M. Johannessen Publisher: Springer Nature ISBN: 3030213013 Category : Technology & Engineering Languages : en Pages : 575
Book Description
This book provides in-depth information about the sea ice in the Arctic at scales from paleoenvironmental variability to more contemporary changes during the past and present centuries. The book is based on several decades of research related to sea ice in the Arctic and its variability, sea ice process studies as well as implications of the sea ice variability on human activities. The chapters provide an extensive overview of the research results related to sea ice in the Arctic at paleo-scales to more resent scales of variations as well as projections for changes during the 21st century. The authors have pioneered the satellite remote sensing monitoring of sea ice and used other monitoring data in order to study, monitor and model sea ice and its processes.
Author: National Research Council Publisher: National Academies Press ISBN: 0309265266 Category : Science Languages : en Pages : 93
Book Description
Recent well documented reductions in the thickness and extent of Arctic sea ice cover, which can be linked to the warming climate, are affecting the global climate system and are also affecting the global economic system as marine access to the Arctic region and natural resource development increase. Satellite data show that during each of the past six summers, sea ice cover has shrunk to its smallest in three decades. The composition of the ice is also changing, now containing a higher fraction of thin first-year ice instead of thicker multi-year ice. Understanding and projecting future sea ice conditions is important to a growing number of stakeholders, including local populations, natural resource industries, fishing communities, commercial shippers, marine tourism operators, national security organizations, regulatory agencies, and the scientific research community. However, gaps in understanding the interactions between Arctic sea ice, oceans, and the atmosphere, along with an increasing rate of change in the nature and quantity of sea ice, is hampering accurate predictions. Although modeling has steadily improved, projections by every major modeling group failed to predict the record breaking drop in summer sea ice extent in September 2012. Establishing sustained communication between the user, modeling, and observation communities could help reveal gaps in understanding, help balance the needs and expectations of different stakeholders, and ensure that resources are allocated to address the most pressing sea ice data needs. Seasonal-to-Decadal Predictions of Arctic Sea Ice: Challenges and Strategies explores these topics.
Author: Burton G. Hurdle Publisher: Springer Science & Business Media ISBN: 1461580358 Category : Science Languages : en Pages : 788
Book Description
" ... as soon as one has traversed the greater part of the wild sea, one comes upon such a huge quantity of ice that nowhere in the whole world has the like been known." "This ice is of a wonderful nature. It lies at times quite still, as one would expect, with openings or large fjords in it; but sometimes its movement is so strong and rapid as to equal that of a ship running before the wind, and it drifts against the wind as often as with it." Kongespeilet - 1250 A.D. ("The Mirror of Kings") Modern societies require increasing amounts influence on the water mass and on the resulting of scientific information about the environment total environment of the region; therefore, cer tain of its characteristics will necessarily be in whieh they live and work. For the seas this information must describe the air above the sea, included.
Author: Mary Kathleen Brennan Publisher: ISBN: Category : Languages : en Pages : 57
Book Description
Arctic sea ice concentrations have undergone rapid declines in recent decades. Many factors have been shown to contribute to this decline, and much of it has been attributed to greenhouse gas forcing and natural variability. In order to understand the relative roles of these factors on Arctic sea ice decline, a longer record of spatially complete data is needed. This project employs data assimilation to combine climate model output and proxy records to reconstruct past climate fields using the Last Millennium Reanalysis (LMR) framework, resulting in spatially complete gridded fields with annual resolution over the last two millennia. First the use of the LMR framework to reconstruct Arctic sea ice concentrations is tested through two methods: pseudo proxy experiments and comparing real proxy reconstructions to other records. Pseudo proxy results indicate strong performance in reconstructing Arctic sea ice. Correlation coefficients between the true and reconstructed values range between 0.63 and 0.77 depending on the climate model output used in the assimilation. The total Arctic sea ice extent reconstructed with the LMR using real proxy data compare well with satellite observations with correlation coefficients ranging between 0.54 and 0.84 depending on the climate model data used in the assimilation. These reconstructions were also compared to other records that precede satellite data and the LMR reconstructions show larger and longer lasting sea ice decline in response to early 20th century warming. The total sea ice extent minimum observed in these reconstructions between 1920-1960 is similar to the values observed in the 1990s. Next, two major questions are investigated using the 2000-year Arctic sea ice reconstruction: (1) Are the current sea ice changes unprecedented? and (2) Does sea ice respond to volcanic eruptions? The first is investigated through examining the distribution of total Arctic sea ice extent. The results indicate that both the trends and values of sea ice extent observed in the satellite era are unprecedented with respect to the LMR reconstruction of the last 1000 years. The second question is investigated through a composite average of sea ice extent before and after the 23 largest volcanic eruptions. These results show a statistically significant increase in total Arctic sea ice extent one year after an eruption. Finally, the sensitivity of these reconstructions to proxy location, model prior and the number of prior ensemble members used in the data assimilation scheme is examined. These experiments indicate that the proxies in the Arctic region (above 60N) explain most of the variance in the LMR sea ice reconstructions as expected. The role of the model prior is investigated by comparing the covariance between surface air temperature and Arctic sea ice across four different models. Overall the covariance is very similar except in some isolated regions in central Russia and China, in the North Atlantic and the central Pacific. In these regions the correlation coefficient is positive, but the coefficient of efficiency is negative indicating that there is a difference in the mean or variance in the covariance across models. 200 ensemble members are found to be sufficient in representing the variance in the full 1000 year last millennium model runs.
Author: National Research Council Publisher: National Academies Press ISBN: 0309054494 Category : Science Languages : en Pages : 645
Book Description
This volume reflects the current state of scientific knowledge about natural climate variability on decade-to-century time scales. It covers a wide range of relevant subjects, including the characteristics of the atmosphere and ocean environments as well as the methods used to describe and analyze them, such as proxy data and numerical models. They clearly demonstrate the range, persistence, and magnitude of climate variability as represented by many different indicators. Not only do natural climate variations have important socioeconomic effects, but they must be better understood before possible anthropogenic effects (from greenhouse gas emissions, for instance) can be evaluated. A topical essay introduces each of the disciplines represented, providing the nonscientist with a perspective on the field and linking the papers to the larger issues in climate research. In its conclusions section, the book evaluates progress in the different areas and makes recommendations for the direction and conduct of future climate research. This book, while consisting of technical papers, is also accessible to the interested layperson.
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Author: Jacqueline M. Grebmeier
Author: Eric T. DeWeaver
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Author: Ola M. Johannessen
Author: National Research Council
Author: Burton G. Hurdle
Author: Mary Kathleen Brennan
Author: National Research Council
Author: Christophe Kinnard