Sea ice thickness estimated from passive microwave radiometers

This study presents the findings of research into the correlation between sea ice thickness and passive microwave radiation. In-situ sea ice thickness samples were obtained from video observations by the icebreaker Soya during 1996-1998 and surface feature observations in 1997 by the visible and near-infrared radiometer AVNIR mounted on the ADEOS satellite. These sea ice thickness data were binned into grid cell data of the satellite microwave radiometer SSM/I for the same location, and averaged to provide an average ice thickness for a grid cell. In order to survey the relationship between sea ice thickness and microwave radiation, two sea ice classification parameters for SSM/I were investigated as to their ability to estimate sea ice thickness. One sea ice classification parameter is the Polarization Ratio (PR), which was developed for a seasonally ice covered area and can distinguish three ice types: new ice, young ice, and first-year ice. Another parameter is the ratio between 37GHz vertical polarization and 85GHz vertical polarization (R_). It can distinguish fast ice in addition to the three ice types that can be distinguished by the PR. These parameters showed correlation coefficients with in-situ sea ice thickness, -0.77 and 0.67, respectively, in this study. Estimated sea ice thickness derived from multiple regression analysis using PR and R_ showed good correlation (R=0.81) with in-situ sea ice thickness

Unusual drift behaviour of multi-year sea ice in the Beaufort Sea during summer 2018

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Kimura, N., Tateyama, K., Sato, K., Krishfield, R. A., & Yamaguchi, H. Unusual drift behaviour of multi-year sea ice in the Beaufort Sea during summer 2018. Polar Research, 39, (2020): 3617, doi:10.33265/polar.v39.3617.In summer 2018, thick sea ice blocked the mouth of the Amundsen Gulf (AG), Canada, obstructing shipping through the North-west Passage. This study analysed multi-year ice motion to investigate the source of this thick ice and the reasons for its unusual movement. For this purpose, a daily multi-year ice distribution product was generated by ice tracking using gridded daily sea-ice velocities (2003–2018) derived from the AMSR-E and AMSR-2 data. From autumn 2017 to summer 2018, the area of multi-year ice extended westward to the Beaufort Sea and then migrated towards the AG mouth. The primary cause of the unusual ice cover was anomalous AG-ward wind in September 2018. It is known that multi-year ice has become increasingly moveable over the past decades, as indicated by the increasing wind factor (i.e., ratio of ice-drift speed and wind speed), but the unusual ice motion in the summer of 2018 cannot be explainable by the wind factor alone. Accurately, predicting monthly wind and monitoring old thick ice will reduce the risk posed by thick Arctic sea ice to shipping.This work was a part of the Arctic Challenge for Sustainability (ArCS, Program Grant Number JPMXD1300000000) and the Arctic Challenge for Sustainability II (ArCS II, Program Grant Number JPMXD1420318865) projects

Observation of the Arctic sea ice condition in 2012 summer - from JOIS2012 cruise -

第3回極域科学シンポジウム/特別セッション「これからの北極研究」11月28日（水） 国立極地研究所 2階大会議

Deterioration of perennial sea ice in the Beaufort Gyre from 2003 to 2012 and its impact on the oceanic freshwater cycle

© The Author(s), 2014. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Journal of Geophysical Research: Oceans 119 (2014): 1271-1305, doi:10.1002/2013JC008999.Time series of ice draft from 2003 to 2012 from moored sonar data are used to investigate variability and describe the reduction of the perennial sea ice cover in the Beaufort Gyre (BG), culminating in the extreme minimum in 2012. Negative trends in median ice drafts and most ice fractions are observed, while open water and thinnest ice fractions (<0.3 m) have increased, attesting to the ablation or removal of the older sea ice from the BG over the 9 year period. Monthly anomalies indicate a shift occurred toward thinner ice after 2007, in which the thicker ice evident at the northern stations was reduced. Differences in the ice characteristics between all of the stations also diminished, so that the ice cover throughout the region became statistically homogenous. The moored data are used in a relationship with satellite radiometer data to estimate ice volume changes throughout the BG. Summer solid fresh water content decreased drastically in consecutive years from 730 km3 in 2006 to 570 km3 in 2007, and to 240 km3 in 2008. After a short rebound, solid fresh water fell below 220 km3 in 2012. Meanwhile, hydrographic data indicate that liquid fresh water in the BG in summer increased 5410 km3 from 2003 to 2010 and decreased at least 210 km3 by 2012. The reduction of both solid and liquid fresh water components indicates a net export of approximately 320 km3 of fresh water from the region occurred between 2010 and 2012, suggesting that the anticyclonic atmosphere-ocean circulation has weakened.Support for Krishfield, Proshutinsky, and Timmermans, partial financial support of logistics, hydrographic observations on the board of Canadian icebreaker, and full financial coverage of all mooring instrumentation was provided by the National Science Foundation (under grants OPP-0230184, OPP-0424864, ARC-0722694, ARC-0806306, ARC- 0856531, ARC-1107277, and ARC- 1203720), and Woods Hole Oceanographic Institution internal funding. Funding for Tateyama was provided by the International Arctic Research Center – Japan Aerospace Exploration Agency (IJIS) Arctic project, and for Williams, Carmack, and McLaughlin by Fisheries and Oceans Canada

Accelerated decline of sea ice cover on the Northern Sea Route

第3回極域科学シンポジウム/特別セッション「これからの北極研究」11月28日（水） 国立極地研究所 2階大会議

changes in sea ice coverage on the Northwest Passage obtained by satellite data

第2回極域科学シンポジウム/第34回気水圏シンポジウム 11月17日（木） 統計数理研究所 3階リフレッシュフロ

Feedback effect of melt ponds on sea ice melting during summer in the Arctic

第3回極域科学シンポジウム/特別セッション「これからの北極研究」11月28日（水） 国立極地研究所 2階大会議

Arctic weather in 2012 summer and influences on Arctic Environment

第3回極域科学シンポジウム/特別セッション「これからの北極研究」11月28日（水） 国立極地研究所 2階大会議

Preliminary results for the Antarctic sea ice physics and ecosystems experiment (SIPEX-2)

第3回極域科学シンポジウム/第35回極域気水圏シンポジウム 11月29日（木） 国立国語研究所 ２階多目的