Preliminary study of the transition of sea ice during the melting process

In order to understand the transition in sea ice, snow transformation, and temperature variations, we carried out tank experiments in a cold room. In the melting experiment of bare ice, the transition of the condition of the ice surface was observed through visual observations and reflectance measurements. The first change was manifested in the surface becoming wet and acquiring a rough texture. Subsequently, a porous layer was formed under the ice surface. Since this layer scattered the incident light, it appeared as a bright surface. The reflectance of this surface was high as compared with that measured during the initial stages of melting. However, this thin scattering layer disappeared as the melting progressed. As a result, the reflectance was reduced to its value during the initial stage of melting. In the melting experiments on snow covered sea ice, the structure of snow-ice became porous and mechanically weak before the thickness reduction commenced. The temperature gradients of bare ice and snow covered ice were small during the melting process compared to those during the growth period

ANALYSIS OF THE TRANSFORMATION OF THE VELOCITY OF THE CENTER OF GRAVITY IN RUNNING SINGLE LEG HORIZONTAL JUMP

The purpose of this study was to analyze the transformation of the center of gravity (CG) in the running single leg horizontal jump and to investigate the influence of the forward rotation of the takeoff leg in achieving vertical CG velocity. The subjects were 98 male long jumpers, whose mean best official jump among their recorded trials was 7.16 ± 0.66 m. Their takeoff motion was videotaped with two high-speed cameras. Horizontal CG velocity at touchdown and vertical CG velocity at toe-off had significantly positive correlations with jumping distance; the decrease in horizontal CG velocity during the takeoff phase was significantly and negatively correlated with jumping distance. Forward rotation of the spring-mass model did not contribute to an increase in vertical CG velocity, although it did contribute to an increase in horizontal CG velocity just before toe-off

変動する北極雪氷圏と温暖化

第6回極域科学シンポジウム特別セッション：[S] 北極温暖化とその影響 ―GRENE 北極気候変動プロジェクトと新しい方向性―11月18日（水）　国立極地研究所 2階 大会議

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

Surface mass balance in Suntar Khayata Range of North-Eastern Siberia

第6回極域科学シンポジウム分野横断セッション：[IA] 急変する北極気候システム及びその全球的な影響の総合的解明―GRENE北極気候変動研究事業研究成果報告2015―11月19日（木）　国立極地研究所１階交流アトリウ

Investigation of retrieved snow depth by microwave remote sensing with in-situ field data

AMSR-E/AMSR2 is provided the brightness temperature data with more channels, higher spatial resolution and frequent coverage. New snow algorism techniques of remote sensing for snow depth and snow-melting area can be carried out using these in-situ data. We have conducted snow survey from 2006 to now, which is mainly on March and occasionally on January and April/May when seasonal snow melts. The sites are located at an interval of ca. 32-km along the Dalton Highway (Fig. 1). Snow density, snow depth and temperature were measured in snow-pit wall observation at each site. Snow water equivalent (SWE) was calculated by multiplying snow-column snow density by snow depth. As the results, the response of SWE to snow depth showed a positively linear relationship (R2 > 0.90).This research was conducted under the IARC-JAXA Information System (IJIS project) with funding provided by the Japan Aerospace Exploration Agency (JAXA) under a grant to the International Arctic Research Center (IARC). These archived data is stored in ADS (Arctic Data archive System) of the NIPR (National Institute of Polar Research, Japan)

Activity of GRENE-Arctic Climate Change Research Project

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