| 1. |
- Cohen, Judah, et al.
(författare)
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ARCTIC CHANGE AND POSSIBLE INFLUENCE ON MID-LATITUDE CLIMATE AND WEATHER - A US CLIVAR White Paper
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The Arctic has warmed more than twice as fast as the global average since the mid 20th century, a phenomenon known as Arctic amplification (AA). These profound changes to the Arctic system have coincided with a period of ostensibly more frequent events of extreme weather across the Northern Hemisphere (NH) mid-latitudes, including extreme heat and rainfall events and recent severe winters. Though winter temperatures have generally warmed since 1960 over mid-to-high latitudes, the acceleration in the rate of warming at high-latitudes, relative to the rest of the NH, started approximately in 1990. Trends since 1990 show cooling over the NH continents, especially in Northern Eurasia. The possible link between Arctic change and mid-latitude climate and weather has spurred a rush of new observational and modeling studies. A number of workshops held during 2013-2014 have helped frame the problem and have called for continuing and enhancing efforts for improving our understanding of Arctic-mid-latitude linkages and its attribution to the occurrence of extreme climate and weather events. Although these workshops have outlined some of the major challenges and provided broad recommendations, further efforts are needed to synthesize the diversified research results to identify where community consensus and gaps exist. Building upon findings and recommendations of the previous workshops, the US CLIVAR Working Group on Arctic Change and Possible Influence on Mid-latitude Climate and Weather convened an international workshop at Georgetown University in Washington, DC, on February 1-3, 2017. Experts in the fields of atmosphere, ocean, and cryosphere sciences assembled to assess the rapidly evolving state of understanding, identify consensus on knowledge and gaps in research, and develop specific actions to accelerate progress within the research community. With more than 100 participants, the workshop was the largest and most comprehensive gathering of climate scientists to address the topic to date. In this white paper, we synthesize and discuss outcomes from this workshop and activities involving many of the working group members.
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| 2. |
- Bäck, Daniel, 1982, et al.
(författare)
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Analysis of C-band polarimetric signatures of Arctic lead ice using data from AIRSAR and RADARSAT-1
- 2008
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Ingår i: 2008 IEEE International Geoscience and Remote Sensing Symposium - Proceedings; Boston, MA; United States; 6 July 2008 through 11 July 2008. - 9789292212209 ; :1, s. 184-187
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In December 2004 the JPL airborne synthetic aperture radar (AIRSAR) flown on the NASA DC-8 acquired fully polarimetric data in the Beaufort Sea at C, L and P-band. This work presents the backscatter coefficients (sHH, sVV, sHV), copolarized ratios (sHH/sVV) and copolarized phase differences (?HH-VV) at C-band from different young sea-ice types formed in recently frozen leads. Two weeks of RADARSAT-1 imagery from the same region as the AIRSAR data were used in order to identify when and where leads were formed and to estimate the age of the newly formed ice contained within the leads. A known empirical relationship based on freezing degree days was used to estimate the sea-ice thickness. The results indicate that some of the identified thin ice types have characteristic signatures.
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