Monthly Antarctic Sea Ice Extent Variability Since 1957 From Reconstructions And Observations

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Monthly Antarctic Sea Ice Extent Variability Since 1957 from Reconstructions and Observations

Author : Beatrice K. Waters
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (139 download)

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Book Synopsis Monthly Antarctic Sea Ice Extent Variability Since 1957 from Reconstructions and Observations by : Beatrice K. Waters

Download or read book Monthly Antarctic Sea Ice Extent Variability Since 1957 from Reconstructions and Observations written by Beatrice K. Waters and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: As climate change continues unabated, understanding Earth’s complex climate system remains critical. The Antarctic climate system is a crucial part of this system, and the sea ice surrounding the continent is an incredibly important element. With the largest change in albedo on Earth, Antarctic sea ice is responsible for reflecting solar radiation from the region. As seen in the Arctic as a result of climate change, without sea ice this solar radiation is absorbed by the low albedo ocean causing warming and further melt of sea ice in a positive feedback loop. Antarctic sea has not responded in the same way as the Arctic. Observations of Antarctic sea ice date back to October 1978 and have shown an overall increase in sea ice. A sudden decline in sea ice extent in 2016 was an unexpected turn of events, and a new record low extent in February 2023 has further complicated this. Due to the short records of Antarctic sea ice extent and the complex nature of the regional climate system, it is difficult to isolate the impacts of climate change in the region. To expand these short records, reconstructions have been utilized. Monthly reconstructions, based on observational temperature and pressure data, were created in order to extend this record to 1957. These reconstructions were analyzed in this study in order to determine their skill and understand how Antarctic sea ice extent has changed through the 1957-2020 period. This was done for the total sea ice extent around the Antarctic continent as well as the Bellingshausen-Amundsen, East Antarctic, King Hakon, Ross, and Weddell regions. The reconstructions were analyzed using correlation, regression, and comparison of means statistical methods in order to evaluate relationships between Antarctic climate data and sea ice extent, relationships between modes of climate variability and sea ice extent, changes in the seasonal cycle of sea ice extent, and trends in sea ice extent. It was of interest to determine if there were changes between the early 1957-1978 period and the 1979-2020 observational period, as this is a likely indicator of reconstruction performance. It was found that the monthly reconstructions generally have a high level of skill. Relationships between sea ice extent and Antarctic climate data and between sea ice extent and climate modes of variability were typically maintained. Specifically, the dipole relationship (increasing versus decreasing sea ice extent) between the Bellingshausen-Amundsen and Ross regions was demonstrated in the relationships analyzed in this study. Analysis of the seasonal cycle revealed changes through time, including statistically significant changes in annual sea ice growth for the total extent, Ross, King Hakon, and Weddell regions. Trend analysis suggests that the monthly reconstructions may capture the mid-century regime shift in sea ice extent found in Fogt et al. (2022), although this is not true for all sectors, specifically Ross. Correlations between these seasonal reconstructions and the monthly reconstructions analyzed in this study were highly variable and more analysis is needed to determine the cause. This study provides a crucial initial analysis of previously unanalyzed monthly SIE reconstructions. Extending the SIE record is a critically important part of understanding the future of Antarctic climate.

Antarctic Sea Ice Extent Reconstructions Throughout the 20th Century

Author : Amanda M. Sleinkofer
Publisher :
ISBN 13 :
Total Pages : 218 pages
Book Rating : 4.:/5 (128 download)

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Book Synopsis Antarctic Sea Ice Extent Reconstructions Throughout the 20th Century by : Amanda M. Sleinkofer

Download or read book Antarctic Sea Ice Extent Reconstructions Throughout the 20th Century written by Amanda M. Sleinkofer and published by . This book was released on 2021 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to the global impacts of Antarctic sea ice and the changing climate, it is important to understand what is influencing Antarctic sea ice variability in a historical context. This is especially true since observations of Antarctic sea ice only begin around 1979. To investigate what is influencing Antarctic sea ice in a longer context, this study generated, evaluated, and analyzed new reconstructions of Antarctic sea ice extent (SIE) through statistical relationships with other long-term datasets available throughout the 20th century. A principal component regression technique that has been proven successful in other Antarctic climate reconstructions was employed in this study, using pressure and temperature observations across the Southern Hemisphere in conjunction with indices of large-scale climate variability known to influence Antarctic SIE. Ultimately, this study was conducted to determine if Antarctic SIE reconstructions are a skillful measure for understanding historical Antarctic sea ice trends and variability throughout the 20th century. The newly generated reconstructions demonstrate that skillful seasonal (extending back to 1905) and monthly (extending back to 1957) sea ice reconstructions can be produced. In comparison, the monthly reconstructions outperformed the seasonal reconstructions based on various assessments (including an independent validation approach), although both sets of reconstructions improved historical sea ice extent knowledge well beyond the use climatological mean. Although shorter in duration due to the inclusion of nearby Antarctic temperature and pressure (which begin near 1957), the monthly reconstructions also allowed for a broader analysis on sea ice extent for month-to-month variations and were useful for monitoring changes in the reconstruction skill performance that could not be seen on a seasonal level. While these new reconstructions unlock new information previously unknown about early 20th century Antarctic sea ice extent, one of the more scientifically important revelations from the new reconstructions were changes in temporal trends throughout the 20th century. Specifically, this study found that half of the reconstructions had a sign switch in the sea ice extent trends between the pre-satellite era (before 1979) and the observed satellite era (after 1979), highlighting the importance of temporal variability in the short observational sea ice record that was only hinted at in the short observational record. Overall, given their skill and connection to many physical processes, the new reconstructions will allow for an increase in the broad scale understanding of Antarctic climate variability over a much longer period than presently afforded by observations alone.

Statistical Reconstruction of 20th Century Antarctic Sea Ice

Author : Thomas Johannes Maierhofer
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (138 download)

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Book Synopsis Statistical Reconstruction of 20th Century Antarctic Sea Ice by : Thomas Johannes Maierhofer

Download or read book Statistical Reconstruction of 20th Century Antarctic Sea Ice written by Thomas Johannes Maierhofer and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The short satellite-observed period from 1979 to 2023 has seen the Antarctic sea ice changedramatically. The sea ice generally increased until 2014 then precipitously decreased from 2014 to 2017. Record lows were then observed in February 2022 and February 2023. To evaluate these recent changes in the context of anthropogenic climate change requires information on Antarctic sea ice variability over the full 20th century. However, only temporally and spatially sparse data are available before 1979, creating a need for statistical reconstructions. We create a stochastic ensemble reconstruction of monthly Antarctic sea ice extent from 1900-1979 using a novel Bayesian spatio-temporal model. This model produces a set of 2500 plausible reconstructions of sea ice extent by sector. These reconstructions improve on prior approaches with realistic month-to-month changes and interdecadal trends as well as plausible interactions between the sectors. These unique features allow the direct computation of extreme event probabilities for the pre-satellite period of the 20th century. For example, we compute a 0.44% probability of reconstructing a decline in total Antarctic sea ice extent as extreme or more extreme than the 2014-2017 decline. We compute a 16% probability of observing a sea ice minimum as low or lower than the February 2022 minimum in total sea ice extent of 2.22 mio. km2, and a probability of 4% for the February 2023 minimum of 2.04 mio. km2. We also propose a novel approach to modeling the Antarctic sea ice edge using a functional regression model. The sea ice edge on a given day is treated as a continuous set of points circling the South Pole and the latitudes of these points are modeled as a function of their longitude. This enables the estimation and visualization of a circumpolar annual cycle and interannual development of the sea ice, providing novel insight into the regionality of sea ice variability. We develop statistical techniques for reconstructing 1966-1978 Antarctic sea ice extent using early satellite images in the visible and infrared spectrum. These images have not previously been analyzed due to severe missingness and cloud cover occluding the sea ice. Combining extensive preprocessing with modern statistical methods, we produce monthly sea ice concentration maps from which we compute historic sea ice extent.

Antarctic Sea Ice, 1973-1976

Author :
Publisher :
ISBN 13 :
Total Pages : 228 pages
Book Rating : 4.:/5 (318 download)

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Book Synopsis Antarctic Sea Ice, 1973-1976 by :

Download or read book Antarctic Sea Ice, 1973-1976 written by and published by . This book was released on 1983 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Arctic and Antarctic Sea Ice, 1978-1987

Author : Per Gloersen
Publisher :
ISBN 13 :
Total Pages : 324 pages
Book Rating : 4.3/5 (129 download)

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Book Synopsis Arctic and Antarctic Sea Ice, 1978-1987 by : Per Gloersen

Download or read book Arctic and Antarctic Sea Ice, 1978-1987 written by Per Gloersen and published by . This book was released on 1992 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Independent Evaluations of Seasonal Antarctic Sea Ice Extent Reconstructions During the 20th Century

Author : Riley L. McCreary
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (139 download)

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Book Synopsis Independent Evaluations of Seasonal Antarctic Sea Ice Extent Reconstructions During the 20th Century by : Riley L. McCreary

Download or read book Independent Evaluations of Seasonal Antarctic Sea Ice Extent Reconstructions During the 20th Century written by Riley L. McCreary and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Changes in Earth's cryosphere, including sea ice in both polar regions, often result in amplified climate-related impacts through positive feedback loops, making it crucial to understand how and why the cryosphere is evolving now and into the future. Observations of Antarctic sea ice are comparably short as the records have only been reliably observed since the satellite era began in 1979. Prior to the satellite era, limited data sources on Antarctic sea ice are available, including various reconstructions and discrete information in ship logbooks from expeditions and commercial vessels written in the remarks sections. This research aims to further understand how independent early sources of information can be used to evaluate the skill of seasonal Antarctic sea ice extent reconstructions (Fogt et al. 2022). Ship logbook observations of sea ice are extremely valuable because they are able to give insight into where the ice edge was prior to satellite measurement in 1979. As this is a new area of research, little is yet known on what potential data have been recovered. Not only is it important to know what data are available, but also if the ship logbooks are reliable enough to be used to evaluate Antarctic sea ice extent reconstructions. This research compiled a list of available ship logbooks at Ohio University, only a handful of which were able to be digitized in time for this project. The latitudes from the ship logbooks of the ice edge show to be within an acceptable range of the latitudes of the sea ice from reconstructions (on average within 3°), indicating the skill of the sea ice extent reconstructions, spatially and temporally, is good prior to 1979. The Antarctic sea ice extent reconstructions were also compared with estimates of early twentieth century sea ice extent from coupled climate models in terms of the ranges of variability and linear trends. Overall, the variability in the sea ice, both temporally and spatially, are similar between the coupled climate models and the reconstructions, suggesting the statistically generated reconstructions are able to produce physically plausible variations contained in the climate models. The linear trends, especially in the early twentieth century, are similar between the coupled climate models and the reconstructions, even though the end of the twentieth century in the models is showing a decreasing trend in sea ice and the reconstructions have a positive trend.

20th Century Antarctic Seasonal Sea Ice Concentration Reconstructions

Author : Nicholas Beaty
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (133 download)

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Book Synopsis 20th Century Antarctic Seasonal Sea Ice Concentration Reconstructions by : Nicholas Beaty

Download or read book 20th Century Antarctic Seasonal Sea Ice Concentration Reconstructions written by Nicholas Beaty and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ongoing changes in the Earth's cryosphere create positive feedback loops through changing albedo, creating a spark of interest in researchers on what is happening in regions of sea ice. Despite this conviction for research, Antarctic sea ice observations have been sparsely recorded throughout human history and have only been reliably observed since the introduction of satellite measurements in approximately 1979. Recent research has shown the ability to reconstruct Antarctic pressure and sea ice extent values throughout two different studies using principal component regression techniques based primarily on temperature and pressure observations along with large-scale climate variability indices that influences Antarctic sea ice. This short historical span of sea ice concentration (SIC), a pixel-scale observation that outlines how much of the ocean area is covered in sea ice, have shown increases around much of Antarctica since 1979. This short historical record, comparatively, does not capture the full range of climate variability in one of the most isolated places on Earth. To improve the understanding of historical variations in Antarctic SIC, reconstructions of the five leading empirical orthogonal functions (EOF) have been conducted in this study to extend SIC data back to 1905. This new seasonally resolved dataset allows researchers to place current trends in a longer historical context. This study examines the skill of these seasonal Antarctic SIC reconstructions, the first of their kind, along with discussing regional changes in Antarctic sea ice since the beginning of the 20th century, and the implications these historical variations may have for further Antarctic sea ice and future research. The resultant reconstructions of SIC presented through this study outline the ability to gather skillful and meaningful results on seasonal scales through 1905 that provide overall much better skill than the climatological mean. These reconstructions allowed for analysis on sea ice concentration trends throughout the pre-satellite era spatially and temporally to understand the overall trends of Antarctic sea ice in a longer historical context than ever before, supporting previous regime changes in sea ice patterns between the pre-satellite era and observed satellite era (after 1979) suggested in previous work. In particular, the role of Pacific Ocean variability in Antarctic SIC throughout the 20th century is made even more prominent through investigating the importance of predictor networks and correlations of modes of climate variability with SIC in this study.

Antarctic Sea Ice Variability in the Southern Ocean-Climate System

Author : National Academies of Sciences, Engineering, and Medicine
Publisher : National Academies Press
ISBN 13 : 0309456037
Total Pages : 83 pages
Book Rating : 4.3/5 (94 download)

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Book Synopsis Antarctic Sea Ice Variability in the Southern Ocean-Climate System by : National Academies of Sciences, Engineering, and Medicine

Download or read book Antarctic Sea Ice Variability in the Southern Ocean-Climate System written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2017-03-24 with total page 83 pages. Available in PDF, EPUB and Kindle. Book excerpt: The sea ice surrounding Antarctica has increased in extent and concentration from the late 1970s, when satellite-based measurements began, until 2015. Although this increasing trend is modest, it is surprising given the overall warming of the global climate and the region. Indeed, climate models, which incorporate our best understanding of the processes affecting the region, generally simulate a decrease in sea ice. Moreover, sea ice in the Arctic has exhibited pronounced declines over the same period, consistent with global climate model simulations. For these reasons, the behavior of Antarctic sea ice has presented a conundrum for global climate change science. The National Academies of Sciences, Engineering, and Medicine held a workshop in January 2016, to bring together scientists with different sets of expertise and perspectives to further explore potential mechanisms driving the evolution of recent Antarctic sea ice variability and to discuss ways to advance understanding of Antarctic sea ice and its relationship to the broader ocean-climate system. This publication summarizes the presentations and discussions from the workshop.

Antarctic Sea Ice

Author : Martin O. Jeffries
Publisher : American Geophysical Union
ISBN 13 :
Total Pages : 416 pages
Book Rating : 4.:/5 (318 download)

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Book Synopsis Antarctic Sea Ice by : Martin O. Jeffries

Download or read book Antarctic Sea Ice written by Martin O. Jeffries and published by American Geophysical Union. This book was released on 1998-02-04 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt: Published by the American Geophysical Union as part of the Antarctic Research Series, Volume 74. In a 1971 Scientific Committee on Antarctic Research report that reviewed polar contrasts in sea ice, Lyn Lewis and Willy Weeks made the following observation: "People who study sea ice in the Arctic Basin are commonly asked if they have ever studied ice in Antarctica, and they answer 'why bother, it's the same old stuff." Noting this was "fortunately true to a considerable extent," they added "It is clear that future work will depend critically on the logistics facilities available to allow surface observations beyond the fast ice edge at all seasons of the year. Of almost equal importance will be the development of instruments and recording equipment suited for use in the polar environment" (Lewis, E. L., and W. F. Weeks, Sea Ice: Some Polar Contrasts, in, Antarctic Ice and Water Masses, edited by G. Deacon, Scientific Committee on Antarctic Research, Cambridge, 23-34, 1971). Lewis and Weeks made no specific mention of Earth-orbiting satellites, on which the first passive microwave sensor became operational in December 1972. Less than a year later the giant Weddell Polynya was observed for the first time. Perhaps more than any other development, this unexpected feature illustrated the potential to greatly expand our knowledge of sea ice through the application of spaceborne remote sensing. Simultaneously, it acted as a catalyst for a significant increase in the level of research.

Sea Ice

Author : David N. Thomas
Publisher : John Wiley & Sons
ISBN 13 : 1118778383
Total Pages : 666 pages
Book Rating : 4.1/5 (187 download)

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Book Synopsis Sea Ice by : David N. Thomas

Download or read book Sea Ice written by David N. Thomas and published by John Wiley & Sons. This book was released on 2017-03-06 with total page 666 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past 20 years the study of the frozen Arctic and Southern Oceans and sub-arctic seas has progressed at a remarkable pace. This third edition of Sea Ice gives insight into the very latest understanding of the how sea ice is formed, how we measure (and model) its extent, the biology that lives within and associated with sea ice and the effect of climate change on its distribution. How sea ice influences the oceanography of underlying waters and the influences that sea ice has on humans living in Arctic regions are also discussed. Featuring twelve new chapters, this edition follows two previous editions (2001 and 2010), and the need for this latest update exhibits just how rapidly the science of sea ice is developing. The 27 chapters are written by a team of more than 50 of the worlds’ leading experts in their fields. These combine to make the book the most comprehensive introduction to the physics, chemistry, biology and geology of sea ice that there is. This third edition of Sea Ice will be a key resource for all policy makers, researchers and students who work with the frozen oceans and seas.

Coupled Sea Ice and Climate Variability from Modern Observations and Proxy Reconstructions

Author : Christophe Kinnard
Publisher :
ISBN 13 :
Total Pages : 440 pages
Book Rating : 4.:/5 (871 download)

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Book Synopsis Coupled Sea Ice and Climate Variability from Modern Observations and Proxy Reconstructions by : Christophe Kinnard

Download or read book Coupled Sea Ice and Climate Variability from Modern Observations and Proxy Reconstructions written by Christophe Kinnard and published by . This book was released on 2009 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Reconstructing Arctic Sea Ice in the Common Era

Author : Mary Kathleen Brennan
Publisher :
ISBN 13 :
Total Pages : 57 pages
Book Rating : 4.:/5 (111 download)

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Book Synopsis Reconstructing Arctic Sea Ice in the Common Era by : Mary Kathleen Brennan

Download or read book Reconstructing Arctic Sea Ice in the Common Era written by Mary Kathleen Brennan and published by . This book was released on 2019 with total page 57 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Antartic Sea Ice, 1973 - 1976: Satellite Passive-microwave Observations

Author :
Publisher :
ISBN 13 :
Total Pages : 228 pages
Book Rating : 4.:/5 (317 download)

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Book Synopsis Antartic Sea Ice, 1973 - 1976: Satellite Passive-microwave Observations by :

Download or read book Antartic Sea Ice, 1973 - 1976: Satellite Passive-microwave Observations written by and published by . This book was released on 1983 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Interannual Variability and Future Changes of the Southern Ocean Sea Ice Cover

Author : Wouter Lefebvre
Publisher : Presses univ. de Louvain
ISBN 13 : 9782874630958
Total Pages : 254 pages
Book Rating : 4.6/5 (39 download)

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Book Synopsis Interannual Variability and Future Changes of the Southern Ocean Sea Ice Cover by : Wouter Lefebvre

Download or read book Interannual Variability and Future Changes of the Southern Ocean Sea Ice Cover written by Wouter Lefebvre and published by Presses univ. de Louvain. This book was released on 2007 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: The interannual variability of the sea ice in the Southern Ocean and its evolution projected for the end of the 21st century are investigated using observations and different types of models. First of all, none of the known atmospheric modes of variabilit

Antarctic Sea Ice Response to Weather and Climate Modes of Variability

Author : Tsubasa Kohyama
Publisher :
ISBN 13 :
Total Pages : 51 pages
Book Rating : 4.:/5 (948 download)

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Book Synopsis Antarctic Sea Ice Response to Weather and Climate Modes of Variability by : Tsubasa Kohyama

Download or read book Antarctic Sea Ice Response to Weather and Climate Modes of Variability written by Tsubasa Kohyama and published by . This book was released on 2016 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt: The relationship between climate modes and Antarctic sea ice is explored by separating the variability into intraseasonal, interannual, and decadal time scales. Cross spectral analysis shows that geopotential height and Antarctic sea ice extent are most coherent at periods between about 20 and 40 days (the intraseasonal time scale). In this period range, where the atmospheric circulation and the sea ice extent are most tightly coupled, sea ice variability responds strongly to Rossby waves with the structure of the Pacific-South American (PSA) pattern. The PSA pattern in this time scale is not directly related to the El Niño Southern Oscillation (ENSO) nor the Southern Annular Mode (SAM), which have received much attention for explaining Antarctic sea ice variability. On the interannual time scale, ENSO and SAM are important, but a large fraction of sea ice variance can also be explained by Rossby wave-like structures in the Drake Passage region. After regressing out the sea ice extent variability associated with ENSO, the observed positive sea ice trends in Ross Sea and Indian Ocean during the satellite era become statistically insignificant. Regressing out SAM makes the sea ice trend in the Indian Ocean insignificant. Thus, the positive trends in sea ice in the Ross Sea and the Indian Ocean sectors may be explained by the variability and decadal trends of known interannual climate modes.

Reconstructing Arctic Sea Ice in the Instrumental Era

Author : Mary Kathleen Brennan
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (135 download)

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Book Synopsis Reconstructing Arctic Sea Ice in the Instrumental Era by : Mary Kathleen Brennan

Download or read book Reconstructing Arctic Sea Ice in the Instrumental Era written by Mary Kathleen Brennan and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Arctic sea ice has undergone rapid declines in recent decades. Given the short satellite record (1979–present), disentangling the relative role of natural variability and anthropogenic forcing on recent declines remains an important unresolved problem. In order to acquire a longer, reliable record of Arctic sea ice we employ data assimilation to combine temperature observations and climate model output. This technique results in fully gridded spatial fields of various climate variables throughout the Instrumental Era (1850-present). Specifically, the goal of this research is to reconstruct Arctic sea ice coverage and thickness on both annual and monthly timescales. We first reconstruct Arctic sea ice on annual timescales using an offline approach where each time step is independent from one another. This work reveals larger declines in total Arctic sea ice extent during the early 20th century (1900–1940) than previously estimated. Next, we build a Linear Inverse Model to forecast Arctic sea ice and other climate conditions on monthly timescales. We find that the Linear Inverse Model is able to skillfully forecast Arctic climate conditions during statistically stable time periods and is thus most useful when used as a model emulator. We then embed the Linear Inverse Model into a data assimilation scheme to produce monthly reconstructions of Arctic climate throughout the Instrumental Era.

Seasonal to Decadal Predictions of Arctic Sea Ice

Author : National Research Council
Publisher : National Academies Press
ISBN 13 : 0309265266
Total Pages : 93 pages
Book Rating : 4.3/5 (92 download)

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Book Synopsis Seasonal to Decadal Predictions of Arctic Sea Ice by : National Research Council

Download or read book Seasonal to Decadal Predictions of Arctic Sea Ice written by National Research Council and published by National Academies Press. This book was released on 2013-01-03 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.