1928 research outputs found
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Evaluation of Arctic sea ice simulation of CMIP6 models from China
Full text linkNine coupled climate models from China participating in the Coupled Model Intercomparison Project Phase 6 (CMIP6) were evaluated in terms of their capability in ensemble historical Arctic sea ice simulation in the context of 56 CMIP6 models. We evaluated these nine models using satellite observations from 1980 to 2014. This evaluation was conducted comprehensively using 12 metrics covering different aspects of the seasonal cycle and long-term trend of sea ice extent (SIE) and sea ice concentration (SIC). The nine Chinese models tended to overestimate SIE, especially in March, and underestimate its long-term decline trend. There was less spread in model skill in reproducing the spatial pattern of March SIC than in reproducing the spatial pattern of September SIC. The error of March SIC simulation was distributed at the margins of sea ice cover, such as in the Nordic Seas, the Barents Sea, the Labrador Sea, the Bering Sea, and the Sea of Okhotsk. However, the error of September SIC was distributed both at the margins of sea ice cover and in the central part of the Arctic Basin. Five of these nine models had capabilities comparable with the majority of the CMIP6 models in reproducing the seasonal cycle and long-term trend of Arctic sea ice
Spatial distribution of aloricate ciliates in the stratified water of the Cosmonaut and Cooperation Seas in the Southern Ocean
Full text linkAloricate ciliates are the main component of microzooplankton. They play important roles in the circulation of materials and flow of energy in marine pelagic ecosystems. To determine the distribution pattern and structure of the aloricate ciliate community in vertically stratified waters of the Southern Ocean, we collected data on aloricate ciliates in the Cosmonaut and Cooperation Seas during the 36th Chinese National Antarctic Research Expedition. The ranges of aloricate ciliate abundance and biomass were 5–3097 ind·L−1 and 0.01–11.40 μg C·L−1, respectively. Vertically, the average abundance of aloricate ciliates decreased from the surface to 200 m, while biomass was highest in the 50-m layer. The importance of aloricate ciliates <20 μm increased along the depth gradient. Their contribution to total abundance increased from 13.04% in the surface layer to 73.71% in the 200-m layer. This is the first study to explore the distribution characteristics of the aloricate ciliate community in a stratified water column of the Southern Ocean. Our results will be helpful for understanding the variation in the pelagic community in waters of the Southern Ocean with intensified stratification
U.S. National Strategy for the Arctic Region
Full text linkThe United States seeks an Arctic region that is peaceful, stable, prosperous, and cooperative. The National Strategy for the Arctic Region articulates an affirmative U.S. agenda over the next ten years, from 2022 to 2032, to realize this vision. This strategy, an update of its 2013 predecessor, addresses the climate crisis with greater urgency and directs new investments in sustainable development to improve livelihoods for Arctic residents, while conserving the environment. It also acknowledges increasing strategic competition in the Arctic since 2013, exacerbated by Russia’s unprovoked war in Ukraine, and seeks to position the United States to both effectively compete and manage tensions
Horizontal distribution of tintinnids (Ciliophora) in surface waters of the Ross Sea and polynya in the Amundsen Sea (Antarctica) during summer 2019/2020
Full text linkInformation on tintinnid horizontal distribution in the Antarctic Continental Zone is scarce. During the summer of 2019/2020, tintinnid diversity and horizontal distribution in surface waters were investigated in the Ross Sea and Amundsen Sea polynya. Eight tintinnid species were found and the dominant species showed obvious horizontal distribution characteristics. In the Ross Sea, three tintinnid community groups were identified. Cymatocylis cristallina and Laackmanniella prolongata (group I) were dominant species and were mainly distributed in stations closer to the coast than were species in the other two groups. Codonellopsis gaussi (group II) and Cy. convallaria (group III) were mainly distributed in nearshore and offshore stations, respectively. In the Amundsen Sea polynya, the dominant species Cy. cristallina, L. prolongata and Salpingella faurei (group I) were mainly distributed in stations closer to the coast than were species in the other two groups. Cy. convallaria (group III) was mainly distributed in offshore stations. The distribution area where C. gaussi and C. cristallina were found in high abundance and abundance proportion of loricae with protoplasts was divided by the approximate boundary of the Antarctic Slope Front Current and Coastal Current in the Ross Sea. The highest abundance proportion in the Ross Sea was the 32–36 μm lorica oral diameter (LOD) size class (75.7%), and the 36–40 μm LOD size class (56.0%) was found in the Amundsen Sea polynya. Temperature– salinity–plankton diagrams of the two seas revealed that temperature may be the main reason for species distribution. Our results contribute to a better understanding of horizontal distribution of the microbial food web, and serve as a baseline for future studies of pelagic community change in the Antarctic Continental Zone
Numerical simulation of the dynamic effects of grounding icebergs on summer circulation in Prydz Bay, Antarctica
Full text linkThe Regional Ocean Modeling System (ROMS) is employed to create a three-dimensional numerical model of the summer circulation in the Prydz Bay region, Antarctica. Consistent with the currents measured using an underway acoustic Doppler current profiler during a Chinese cruise, the simulated current field illustrates the major features of the Prydz Bay circulation, including the Antarctic Slope Current (ASC) along the continental shelf break, the cyclonic Prydz Bay Gyre, and the Prydz Bay Eastern Coastal Current (PBECC). The effects of grounding icebergs D15 and B15 on the circulation in Prydz Bay are investigated via numerical simulations. The results indicate that these giant grounding icebergs substantially affect the flows into and within the bay, which may differ with the different grounding locations. As grounding iceberg D15 is located close to the southwestern part of the West Ice Shelf (WIS), it cuts off the coastal current along the outer edge of the WIS, and the ASC can only enter Prydz Bay from the west side of iceberg D15, whereupon it becomes a main source of the PBECC. Iceberg D15 also weakens the circulation in the bay in general. The relatively small iceberg B15 entered Prydz Bay from 2007 to 2009 and grounded on the southwestern section of the Four Ladies Bank. The numerical experiments indicate that iceberg B15 guides the ASC flowing into the bay around its west side and reduces the width of the inflow on the eastern side of the Prydz Bay Channel. The grounding of iceberg B15 has also led to adjustments of the circulation within the bay, among which the most significant is that the outflow along the western flank of Fram Bank has shifted to the west and become more intensive
Catalogue of National Polar Programmes and Other Large-Scale Programmes
Full text linkThe polar regions are the places on earth where the human endurance and resilience are challenged the most. They are
sentinels of climate change and a proven bastion for international cooperation in research and nature protection. European researchers have made significant contributions to understand the consequences of climate change and the structure and functioning of ecosystems at both polar regions, and their global interconnections. Unifying, disseminating, and coordinating all European research actions is one of the tasks of the EU-Polar-Net 2 project. EU-PolarNet 2 – “Coordinating and co-designing the European Polar Research Area” is a Coordination and Support Action funded by the European Commission in Horizon 2020, supporting the development and implementation of future European
research actions. It comprises 25 partners representing all European and associated countries with well-developed polar research programmes and activities. EU-PolarNet 2 aims to provide a platform to co-develop strategies to advance European polar research and its contribution to policy-making processes. By involving relevant stake- and rightsholders, it supports the development of transdisciplinary and transnational polar research
actions of high societal relevance. To ensure that such an important platform is sustained after the four years of project duration, the project works with funding agencies, national polar research institutes, operators of national polar programmes, polar experts and the European polar research community to discuss and implement the identified research actions. The final goal of EU-PolarNet 2 is to create a permanent European Polar Coordination Office, which will continue the work of EU-Polar-Net 2 in a sustained way
Reindeer Husbandry - Adaptation to the Changing Arctic, Volume 1
Full text linkReindeer Husbandry: Adaptation to the Changing Arctic, Volume 1 is the first of two books published by Springer Nature. This first book consists of ten peer-reviewed chapters with each chapter reviewed by two to six renowned international researchers and scientists. The authors express their immense gratitude to the reviewers and deeply acknowledge their unique contribution.
This book addresses the critical issue faced by Indigenous peoples in the Arctic: climate change, the ways in which it affects their societies and livelihoods, environment, and economies. It is important that all available forms of knowledge – academic, traditional, Indigenous, and local – are included when addressing the adaptation and resilience of reindeer husbandry in the Circumpolar North. The two volumes provide novel insights into the Arctic Indigenous reindeer herding communities and how resilience can be built locally through the use of traditional knowledge and co-production
Distribution of transparent exopolymer particles and their response to phytoplankton community structure changes in the Amundsen Sea, Antarctica
Full text linkTo understand the response of transparent exopolymer particles (TEP) to the changes in phytoplankton communities caused by melting sea ice, we collected samples from the polynya and open ocean affected by the Antarctic circumpolar current in the Amundsen Sea. TEP, pigments, and other environmental factors were analyzed. The results showed that high TEP content was mainly found in the polynya, and was higher in the surface layer than in the deep layer. The main factor that affected TEP distribution was the phytoplankton community. In the polynya area, the phytoplankton were dominated by low-iron Haptophyta. In the Antarctic circumpolar current region affected by ice-melting water, the dominant species was diatom type II. Our results revealed that low-iron Haptophyta may be the main contributors to TEP content
Features and influencing mechanisms of gaseous elemental mercury over the equatorial Pacific and their differences with the Southern Ocean
Full text linkDue to the harmful impacts on the ecosystem and even human health, mercury (Hg) compounds in the environment deserve serious concern. Atmospheric mobilization and exchange at the air-sea interface are important processes in biogeochemical cycling of Hg. Relying on the 30th (2013/2014), 31st (2014/2015), and 33rd (2016/2017) Chinese National Antarctic Research Expedition aboard R/V Xuelong, we found significant rising gaseous elemental mercury (GEM) concentrations over the equatorial Central Indo-Pacific region. Excluding the contribution of anthropogenic, volcanic and biomass burning emissions, the enhanced GEM in marine boundary layer was likely due to the combined actions of two driving factors drove by the Inter-Tropical Conversion Zone (ITCZ): (1) intense wet deposition of Hg, followed by subsequent rapid photoreduction and vast evasion from the surface sea; and (2) the regional low-level convergence of airflow that caused the mass accumulation of GEM in air. In addition, apparently higher GEM concentration level in the equatorial Central Indo-Pacific than in the Southern Ocean was observed in one cruise. Further investigation suggests that apart from the ITCZ corresponded mechanisms, the effects of spatial differences in anthropogenic emissions and more significant GEM oxidation in Antarctic sea should play roles in this phenomenon