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  1. Bring Back 1962-63

    The Arctic Thread

    THE ARCTIC THREAD This is a brand new thread for everything to do with the Arctic as well as Antarctica. I hope that many forum members will contribute on here. I have been a keen weather enthusiast for well over 50 years and have developed widespread interests in many meteorological topics. I have always been particularly fascinated by the Arctic and how it interacts with global climate patterns. We have seen a worrying decline in Arctic sea ice extent during the last 30 years and the Arctic has become the centre of the global warming and climate change debate. Whilst this is undoubtedly highly influenced by human activities, there are also some longer term natural changes in play too. I always like to examine the facts and not be overly influenced by exaggerated reports at either end of the debate which has become highly political. This thread will cover a wide range of topics including: Arctic sea ice extent - current and historic levels, rates of change, ice melt and refreezing, ice loss, ice age (new and older ice), comparisons and analysis with regular updates. Antarctica sea ice extent - as above plus features on the ice shelves and the differences between the two polar regions, facts and figures. Arctic and Antarticaa Sea surface temperatures - current, historic, trends, anomalies, reasons for changes. Arctic and Antarctica air temperatures, monitoring at certain sites, records, changes, data sets. Northern Hemisphere snow cover - seasonal changes, yearly and longer term variations, influences on regional climate and weather patterns. The Greenland ice cap - long term and current research, measurements, trends, rates of change. Glaciers - facts and figures, which ones are declining, which ones are growing, rates of change, global net ice loss. The Polar Vortex - how does this influence the Arctic climate? How does Arctic warming and ice loss influence the polar vortex? North America climate focus - how and when changes in the Arctic impact on the higher and middle latitudes (I often produce European and UK focused reports on a UK weather forum). Historic climates, research into Ice Ages and inter-glacial warmer periods. Climate change and its influence on the Arctic and Antarctica, how much, how fast, why? Global Warming Debate - assessing the extent of human impacts, separating the facts from the fiction, taking a "balanced" approach. Sudden Stratospheric Warming - impacts on the Arctic, what happens, how fast, why? The Arctic oscillation and the Antarctic oscillation - current, forecast, anomalies and historic values, links to weather patterns. Arctic and Antarctica news and events - special features and reports with comments and analysis (eg: the recent clouds of smoke covering the Arctic from vast Siberian forest fires) I will add to this list as this thread evolves. In general I would like this thread to appeal to as wide an audience as possible. I'm a great believer in keeping things simple and explaining topics in plain English. I regularly post on the "Teleconnections" thread and some of the more complex subjects such as how does the Arctic ice loss teleconnecton interact with other teleconnections may be more suitable for that thread (or perhaps both threads). There are already some excellent papers and video presentations relating to the Arctic in the "Teleconnections Research Portal" and we will be adding a lot more as winter approaches. Some of these papers may be reviewed on this thread especially when they relate to a particular post. List of Useful Links to Arctic and Antarctica Sites, Data, Facts, Charts etc: This list will gradually evolve in line with the thread (so work in progress). If you have a link that you feel is relevant, please draw this to my attentions by "replying to topic" or with a "personal message". Here's a direct link to the Teleconnections Research Portal - we have placed many Arctic related papers and presentations in there with many more being added during the coming months. National Snow and Ice Data Center (NSIDC): https://nsidc.org/arcticseaicenews/ - daily ice cover updates and monthly reports. Arctic Sea Ice graphs: https://sites.google.com/site/arcticseaicegraphs/ - this huge site with many sub links provides any extraordinary amount current and historic ice data, charts and maps. NOAA National Weather Centre Environmental Modelling Centre Global Sea Surface Temperatures and Anomaly Maps: http://polar.ncep.noaa.gov/sst/ophi/ (click on the map for any region). NOAA Snow Cover Maps: https://www.ncdc.noaa.gov/snow-and-ice/snow-cover/ - current, historic and animated snow cover maps for Northern Hemisphere, North America and Eurasia. NCEP 2m Surface Temperature Anomalies by region: http://www.karstenhaustein.com/climate.php - includes forecast, current and past charts with extensive Arctic and Antarctica coverage. NASA WorldView Satellite Imagery: https://worldview.earthdata.nasa.gov/ - with many options and tools to create your own world or regional images. Polar Science Center: http://psc.apl.uw.edu/ - packed with Arctic news, research, data and links to conferences and papers (some of these are already in the Research Portal and more to add). Zachary (Zach) Labe: http://sites.uci.edu/zlabe/ - a Ph.D. student, Dept of Earth System Science, University of California; fascinating Arctic research, reports, data, charts and links to papers. Climate Reanalyzer: https://climatereanalyzer.org/wx/DailySummary/#t2 - for current weather data and analysis (northern hemisphere). many more to follow during the next few weeks Arctic Ocean Regional Map Showing All the Seas: I show an Arctic map (below) to identify the locations of all the seas that make up the Arctic Ocean so that we can comment more meaningfully on the local variations in our posts on this thread. Antarctica Map: I will kick things off with a series of short posts to give a flavour of what might follow. I'll do one on the current Arctic sea ice extent later today and two more tomorrow on Arctic sea surface temperatures and Northern Hemisphere snow cover. If I have time, I will do another one on Arctic air temperatures and also show that report on the Arctic ash cloud spreading from those Siberian forest fires. When I return from a business trip, I'll add several more posts later next week. I would really like to see other forum members getting involved on here with posts and comments and I hope that we can get some debates going too. David
  2. Key Points & Synthesis - Conference Summary Part 2 Workshop Presentation: Aspen Global Change Institute, Aspen, Colorado Workshop Programme: “Understanding the Causes and Consequences of Polar Amplification” - June 12th -16th, 2017 Presenters: James Screen, Doug Smith and Xiangdong Zhang Presentation Date: 16th June, 2017 Link to full presentation (1 hour 37 minute video): https://www.agci.org/lib/17s1/key-points-synthesis-continued Link to presentation (slides and charts only): https://www.agci.org/sites/default/files/pdfs/lib/main/AGCI synthesis_0.pdf Link to full agenda and presentations: https://www.agci.org/event/17s1
  3. Key Points & Synthesis - Conference Summary Part 1 Workshop Presentation: Aspen Global Change Institute, Aspen, Colorado Workshop Programme: “Understanding the Causes and Consequences of Polar Amplification” - June 12th -16th, 2017 Presenters: James Screen, Doug Smith and Xiangdong Zhang Presentation Date: 15th June, 2017 Link to full presentation (43 minute video): https://www.agci.org/lib/17s1/key-points-synthesis Link to presentation (slides and charts only): https://www.agci.org/sites/default/files/pdfs/lib/main/AGCI synthesis.pdf Link to full agenda and presentations: https://www.agci.org/event/17s1
  4. Bring Back 1962-63

    Causes of Antarctic Change - A Discussion

    Causes of Antarctic Change - A Discussion Workshop Presentation: Aspen Global Change Institute, Aspen, Colorado Workshop Programme: “Understanding the Causes and Consequences of Polar Amplification” - June 12th -16th, 2017 Workshop Discussion: Relating to their presentations (on the same afternoon) Presenters: John C Fyfe, Baek-Min Kim, Lorenzo Polvani, David Schneider, Karen L Smith, Laurent Terray and Xiangdong Zhang Presentation Date: 13th June, 2017 Link to full discussion (27 minute video): https://www.agci.org/lib/17s1/part-iv-discussion-causes-antarctic-change Link to full agenda and presentations: https://www.agci.org/event/17s1
  5. The relative roles of structural uncertainty and internal variability in Antarctic climate change projections Workshop Presentation: Aspen Global Change Institute, Aspen, Colorado Workshop Programme: “Understanding the Causes and Consequences of Polar Amplification” - June 12th -16th, 2017 Presenter: David Schneider Presentation Date: 13th June, 2017 Abstract: None Link to full video presentation (27 minutes): https://www.agci.org/lib/17s1/relative-roles-structural-uncertainty-and-internal-variability-antarctic-climate-change Link to full agenda and presentations: https://www.agci.org/event/17s1
  6. The Response of the Southern Ocean and Antarctic Sea Ice to Freshwater from Ice Shelves in an Earth System Model Authors: Andrew G. Pauling, Cecelia M. Bitz, J. Smith and Patricia J. Langhorne Published: 5th December, 2015 Abstract: The possibility that recent Antarctic sea ice expansion resulted from an increase in freshwater reaching the Southern Ocean is investigated here. The freshwater flux from ice sheet and ice shelf mass imbalance is largely missing in models that participated in phase 5 of the Coupled Model Intercomparison Project (CMIP5). However, on average, precipitation minus evaporation (P − E) reaching the Southern Ocean has increased in CMIP5 models to a present value that is about greater than preindustrial times and 5–22 times larger than estimates of the mass imbalance of Antarctic ice sheets and shelves (119–544 ). Two sets of experiments were conducted from 1980 to 2013 in CESM1(CAM5), one of the CMIP5 models, artificially distributing freshwater either at the ocean surface to mimic iceberg melt or at the ice shelf fronts at depth. An anomalous reduction in vertical advection of heat into the surface mixed layer resulted in sea surface cooling at high southern latitudes and an associated increase in sea ice area. Enhancing the freshwater input by an amount within the range of estimates of the Antarctic mass imbalance did not have any significant effect on either sea ice area magnitude or trend. Freshwater enhancement of raised the total sea ice area by 1 × 106 km2, yet this and even an enhancement of was insufficient to offset the sea ice decline due to anthropogenic forcing for any period of 20 years or longer. Further, the sea ice response was found to be insensitive to the depth of freshwater injection. Link to full paper: https://journals.ametsoc.org/doi/pdf/10.1175/JCLI-D-15-0501.1
  7. Bring Back 1962-63

    Drivers of Polar Warming - Presentation

    Drivers of Polar Warming - Presentation Workshop Presentation: Aspen Global Change Institute, Aspen, Colorado Workshop Programme: “Understanding the Causes and Consequences of Polar Amplification” - June 12th -16th, 2017 Presenter: John C Fyfe Presentation Date: 13th June, 2017 Abstract: None Link to full video presentation (28 minutes): https://www.agci.org/lib/17s1/drivers-polar-warming Link to full agenda and presentations: https://www.agci.org/event/17s1
  8. Understanding the Causes and Consequences of Polar Amplification Workshops: Aspen Global Change Institute, Aspen, Colorado (mission statement: "We’re dedicated to advancing the understanding of Earth system science and global environmental change through interdisciplinary workshops, research and consulting, and education and outreach") Workshop Dates: June 12th -16th, 2017 Summary: The Arctic is warming twice as fast as the global average temperature. How these rapid changes will affect the Arctic region is critical to understand, though the significance of this understanding extends beyond the region since changes in the Arctic are increasingly understood to interact with the climate system of the Earth as a whole via atmospheric circulation and ocean currents. In particular, as climate change continues understanding how changes in the Arctic will affect weather and climate of the northern continents is a critical and timely question. Improved understanding of the mechanisms of teleconnection in these systems will shed light on how the Earth’s climate system works as it departs further from the norms of the 20th century. The ability to model these changes has the potential to better describe future climate and its ecological and societal impacts as the century unfolds. To make progress, it is imperative to consider the larger context of the causes and consequences of polar amplification in the global climate system, and examine connections between the faster pace of warming in the polar regions compared to lower latitudes. Link to full agenda and presentations: https://www.agci.org/event/17s1 Please note that some of these presentations will appear individually in this portal.
  9. Antarctica Since The IGY (International Geophysical Year) Authors: A.P. Crary, Science and Public Affairs, "Bulletin of the Atomic Sciences" Published: December, 1970, vol 25, no. 10. (104 pages) Summary (no abstract): This excellent bulletin covers the early geographical, physical and exploration history of Antartica. For anyone studying the current and future meteorology, climate and ice extent changes, it is useful to look back. Many more recent papers on Antartica will be added to the portal and some of these will be reviewed in posts on the "Teleconnections: A More Technical Discussion" thread. Contents: Antarctica since the IGY - International Geophysical Year, 1957, Antarctic regions Antarctic research and the relevance of science - Polar research Emergence of Antarctica: the mythical land - Antarctic exploration Antarctic treaty - Antarctic Treaty (1959) Political experiment in Antarctica - Polar research Antarctica: experimental proving ground for peaceful coexistence and international collaboration - Polar research International cooperation in Antarctica, the next decade - Polar research Antarctic geology and Gondwanaland - Continental drift, Geology (Antarctic regions) Polar ice and the global climate machine - Atmospheric research, Climate, Ice (Polar regions) Antarctic meteorology - Air pollution (Antarctic regions), Meteorology (International aspects) Upper atmosphere as seen from Antarctica - Atmosphere, Upper, Polar research Drilling through the ice cap: probing climate for a thousand centuries - Drilling and boring (Ice), Polar research, Antarctic regions (Climate) Survey of Antarctic biology: life below freezing - Ecology (Antarctic regions), Wildlife (Antarctic regions) Evolution of a venture in Antarctic science; Operation Tabarin and the British Antarctic survey - Sir Vivian Fuchs; 1908-1999, Antarctic exploration Developing the U.S. Antarctic research program - Antarctic exploration, Polar research Antarctic research: a pattern of science management - National Science Foundation (U.S.), Polar research Science and logistics in Antarctica - Antarctic exploration Antarctic: any economic future? - Natural resources (Antarctic regions) Long look ahead - A.P Crary ISSN 0096-3402 Published by Educational Foundation for Nuclear Science, Inc. The Bulletin of the Atomic Scientists is the premier public resource on scientific and technological developments that impact global security. Founded by Manhattan Project Scientists, the Bulletin's iconic "Doomsday Clock" stimulates solutions for a safer world. Link to the full bulletin (click on both lines): https://books.google.co.uk/books?id=EAcAAAAAMBAJ&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false Link to all issues of the bulletin from 1945 to 1990: https://books.google.co.uk/books?id=EAcAAAAAMBAJ&source=gbs_all_issues_r&cad=1
  10. On the reproducibility of the September 2002 vortex splitting event in the Antarctic stratosphere achieved without satellite observations Authors: Shunsuke Noguchi and Chiaki Kobayashi Published: 1st November , 2017 Abstract: To highlight the impact of satellite measurements, a comparison between the Japanese 55‐year reanalysis (JRA‐55) and its equivalent without the assimilation of satellite observations (JRA‐55C; C stands for ‘conventional’ observations) was conducted. As an illustrative example of the detectability problem of extreme events, we report on the reproducibility of a stratospheric sudden warming (SSW) event that occurred in late September 2002; this event represents the first observed unique vortex splitting event in the Antarctic stratosphere. Through the data assimilation system of JRA‐55, the initial tendency of this warming event and the following recovery process were well captured even when no satellite observations were used. However, the warming in JRA‐55C does not satisfy the criteria for a major SSW event besides the lack of splitting behaviour in the polar vortex. A prominent difference between JRA‐55 and JRA‐55C during the SSW event, which was characterized by the sudden appearance of a nearly barotropic structure from the upper stratosphere to the troposphere, was found over the Western Hemisphere reflecting the geographic distribution of observational sites. Moreover, several differences in the precursory state of the polar vortex and the observational anchoring effect are consistent with the proposal that this SSW was caused by the catastrophic breakdown of a highly deformed polar vortex as suggested by some recent works. Link to full paper: https://rmets.onlinelibrary.wiley.com/doi/epdf/10.1002/qj.3193
  11. Bring Back 1962-63

    Quick Facts on Arctic Sea Ice

    Quick Facts on Arctic Sea Ice Authors: National Snow and Ice Data Center (NSIDC) Published: Regularly updated Review: For those wishing to learn the simple facts about Arctic and Antarctic sea ice, this is an excellent guide. It explains what is sea ice and why Arctic ice is important as well as ice extent and why and how it is monitored..it describes sea ice minimums and maximums. There are links to further information on the "State of the Cryosphere", "Mountain Glaciers", "Permafrost and Frozen Ground", "Ice Bergs", "Ice Shelves" and "Ice Sheets". Link to full paper: https://nsidc.org/cryosphere/quickfacts/seaice.html
  12. Influence of subtropical Rossby wave trains on planetary wave activity over Antarctica in September 2002 Authors: Takeshi Enomoto & Yoshihisa Matsuda Published: 21st may, 2015 Abstract: At the beginning of September 2002, strong convection processes over south-eastern Indonesia and over south-eastern Africa have been observed. Due to the strong upper tropospheric divergent outflow, two Rossby wave trains (RWTs) were generated. Their south-eastward propagation was controlled by the mean background flow. These two wave trains are visible in observations. It is hypothesised that these wave trains cause enhanced planetary wave activity fluxes which are a result of an amplified planetary wave 2 in the upper troposphere/lower stratosphere over Antarctica. Such a change of the planetary wave structure was diagnosed in September 2002, prior to the first observed major sudden stratospheric warming event on the Southern Hemisphere. A simplified version of GCM ECHAM4 is used to evaluate the hypothesis. Sensitivity experiments were performed for a mean background flow similar to September 2002. Furthermore, the wave maker approach was used to generate Rossby waves in the subtropical upper troposphere at two distinct locations which are corresponding to the observed regions of divergent outflow. As a main result, after about 2 weeks of model integration with wave maker forcing, we find two RWTs with a south-eastward propagation inducing a polar amplification of planetary wave 2 in the upper troposphere and lower/middle stratosphere. The poleward wave activity flux is enhanced in comparison to the control run without any wave maker forcing. The convergence of the Eliassen–Palm flux causes a 25% deceleration of zonal mean zonal wind in the model stratosphere but no wind reversal. Sensitivity runs support the robustness of these results. The obtained model results highlight the mechanism and confirm the hypothesis that enhanced planetary wave activity in austral polar region in 2002 is caused by enhanced subtropical forcing of two RWTs. Link to full paper: https://www.tandfonline.com/doi/full/10.3402/tellusa.v67.25875?scroll=top&needAccess=true
  13. The Antarctic Centennial Oscillation: A Natural Paleoclimate Cycle in the Southern Hemisphere That Influences Global Temperature Authors: W. Jackson Davis, Peter J. Taylor W. Barton Davis Published: 8th January 2018 Abstract: We report a previously-unexplored natural temperature cycle recorded in ice cores from Antarctica—the Antarctic Centennial Oscillation (ACO)—that has oscillated for at least the last 226 millennia. Here we document the properties of the ACO and provide an initial assessment of its role in global climate. We analyzed open-source databases of stable isotopes of oxygen and hydrogen as proxies for paleo-temperatures. We find that centennial-scale spectral peaks from temperature-proxy records at Vostok over the last 10,000 years occur at the same frequencies (±2.4%) in three other paleoclimate records from drill sites distributed widely across the East Antarctic Plateau (EAP), and >98% of individual ACOs evaluated at Vostok match 1:1 with homologous cycles at the other three EAP drill sites and conversely. Identified ACOs summate with millennial periodicity to form the Antarctic Isotope Maxima (AIMs) known to precede Dansgaard-Oeschger (D-O) oscillations recorded in Greenland ice cores. Homologous ACOs recorded at the four EAP drill sites during the last glacial maximum appeared first at lower elevations nearest the ocean and centuries later on the high EAP, with latencies that exceed dating uncertainty >30-fold. ACO homologs at different drill sites became synchronous, however, during the warmer Holocene. Comparative spectral analysis suggests that the millennial-scale AIM cycle declined in period from 1500 to 800 years over the last 70 millennia. Similarly, over the last 226 millennia ACO repetition period (mean 352 years) declined by half while amplitude (mean 0.67 ◦C) approximately doubled. The period and amplitude of ACOs oscillate in phase with glacial cycles and related surface insolation associated with planetary orbital forces. We conclude that the ACO: encompasses at least the EAP; is the proximate source of D-O oscillations in the Northern Hemisphere; therefore affects global temperature; propagates with increased velocity as temperature increases; doubled in intensity over geologic time; is modulated by global temperature variations associated with planetary orbital cycles; and is the probable paleoclimate precursor of the contemporary Antarctic Oscillation (AAO). Properties of the ACO/AAO are capable of explaining the current global warming signal. Link to full paper: file:///C:/Users/David/Downloads/climate-06-00003-v2.pdf
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