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

EVALUATING RISER INTERFERENCE FROM EXPERIMENTAL AND NUMERICAL ANALYSIS

ABSTRACT When the oil exploration and exploitation moved away from the shore to deeper ocean, the riser interference became an important issue to be addressed during platform design. It became so important, particularly, when a great numbers of rigid risers are installed on the platform. Those kinds of risers are particularly used at Spar buoy and TLP platform. A conservative approach for riser interference design can result on the oversize platform or to reduce the number of wells hanging on it. On the other hand, a non conservative approach can bring serious problems, like collision of risers, which can cause a dent on the riser wall and it may reduce its fatigue life. In order to identify the hydrodynamic behavior of one riser placed in the vicinity of other one, Petrobras R&D Center carried out some experimental and numerical studies for getting their hydrodynamic behavior when they are aligned and spaced by 2, 3, and 5 times diameter

シラセ サイヒョウ コウコウ データ ガ シメス ナンキョク リュツォ・ホルムワン テイチャクヒョウ ノ ネンネン ヘンカ

南極リュツォ・ホルム湾において毎年ほぼ同時期,同海域を航海する砕氷船「しらせ」は,海氷モニタリング・プラットフォームに適している.同湾の海氷状況の年々変化を推測するために,1983年から2002年までの間の「しらせ」砕氷航行データを解析した.主にラミング砕氷と氷厚や積雪深との関係を調べ,ラミング一回当たりの進出距離を砕氷航行の難易度の指標とすることにより,定着氷域の変化の特徴を抽出した.ラミング時の進出距離が短い1990年代前・中期は,航海が困難で厳しい氷状を反映し,氷厚や積雪深が大きい.一方,1990年代終わりから2002年までの間は,進出距離が長い傾向にあり,湾内定着氷の崩壊・流出の頻発期とも符合していることがわかった.Characteristics of sea-ice conditions in Lutzow-Holmbukta, Antarctica, have been investigated using the ice navigation log from the icebreaker Shirase, which has made a voyage almost at the same season and in the same sailing route every year since 1983. The vessel is considered as a suitable monitoring platform for sea ice. Not only basic information such as ice thickness and snow depth, but also ramming icebreaking data have been analyzed. In particular, the penetrating distances by ramming reflect difficulty in ice navigation and show distinctly interannual variations from 1983 to 2002. The periods with longer distances are consistent with those when breakup of landfast ice occurred frequently in the bay. The penetrating distances have shown a tendency to increase since the end of the 1990s, when ice breakup has been pronounced

センジョウ カンソク データ ニ モトヅク ナンキョク リュツォ・ホルムワン テイチャクヒョウ ノ カキ ニオケル ヒョウアツ オヨビ セキセツシン ブンプ トクセイ ニツイテ

南極観測船「しらせ」船上で取得された海氷観測結果をもとに,リュツォ・ホルム湾定着氷の夏季における氷厚及び積雪深分布について考察した.ビデオ観測結果から求めた各年の全氷厚(氷厚+積雪深)確率密度分布は薄氷型と厚氷型に分けられることがわかった.また大陸沿岸から約km圏内では全氷厚及び積雪深は沿岸に向かって漸減する傾向を示した.これは北東方向の卓越風による積雪輸送によると考えられる.電磁誘導法によって観測された全氷厚分布には不連続的な変化が認められた.NOAAAVHRR画像と比較した結果,不連続の位置は定着氷流出後の再結氷域における一年氷と,未流出の厚い多年氷との境界に一致することがわかった.定着氷の流出範囲は年によって大きく変動する.流出位置が沖側に後退すると厚い多年氷域の割合が多くなり厚氷型になり,沿岸に近づくと積雪影響も相まって厚い多年氷域が縮小または消滅し,薄氷型になるというメカニズムが明らかになった.Sea ice observations have been conducted onboard the Antarctic Research Vessel Shirase" since . The authors summarize these data to investigate spatial and inter-annual variability of sea ice thickness and snow depth of the summer land-fast ice in Lutzow-Holmbukta. Probability density functions of annual total thickness (ice thickness+snow depth) derived from video observations are categorized into two types, i.e. a thin-ice and a thick-ice type. The total thickness distributions observed by the electro-magnetic inductive method have a clear discontinuity, which reects the past break-up of the land-fast ice. Thin rst-year ice develops oshore of this location, while multi-year ice mostly develops onshore. Ice thickness and snow depth gradually decrease toward the coast within about km oshore, probably due to snow drift driven by the strong northeasterly wind. It is concluded that the past breakup of the land-fast ice as well as snow depth have dominant inuence on the spatial distribution of ice thickness in Lutzow-Holmbukta. The extent of break-up varies signicantly year by year. The smaller extent enhances the development of thick multi-year ice, while the larger extent, coupled with the inuence of snow drift, enhances reduction or extinction of thick multi-year ice

A Cluster of Respiratory Syncytial Virus Infections in a Hospital Ward for Adult Immunocompromised Patients

Four male patients admitted to the same ward in the first half of September 201Y were identified to have respiratory syncytial virus（RSV）infection. Their ages ranged from 49 to 85 years（median 72.5）. One patient was infected with human immunodeficiency virus and three patients had hematological malignancies. Following immuno-chromatological testing with a nasal cavity swab, RSV infection was diagnosed. Although blood and sputum cultures were performed in three patients, no significant bacteria were detected. Two cases responded to supportive therapy. However, one patient died secondary to multiple myeloma, and another patient developed pneumonia and died with an exacerbation of leukemia. RSV infections in immunocompromised hosts are associated with a poor prognosis. Early diagnosis will facilitate isolation of infected individuals to prevent hospital outbreaks

Sea ice thickness measurements with electro-magnetic inductive sounder in the pack ice zone off Syowa Station

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

Measurements of snow depth and sea ice thickness by electromagnetic-induction measurements observed by Japan and Australia in the Antarctic Ocean.

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 セミナー室

Electromagnetic-inductive Measurements for the Undeformed and Deformed Sea-ice and Snow in the East Antarctic

Indirect ice and snow thickness measurements were carried out for the winter and spring Antarctic sea ice by using the electromagneticinductive (EMI) device on the East Antarctic pack ice area. This study investigated the effect of saline slush snow layer over the sea ice and seawater-filled gap to the snow and sea ice thickness measured by EMI. A result shows underestimations of EMI thickness, which might be caused by high conductive seawater-filled gaps between ice floes, appeared on thicker ice over 3.5 m. This study improved the validity of applying a multi-rafted ice model for these ice conditions.14th (2004) International Offshore and Polar Engineering Conference. 23-28 May 2004. Toulon, France

A Computational Study of the Spreading of Oil Underneath a Sheet of Ice

The spreading of oil underneath a sheet of ice is computed using an adaptive level set method for incompressible two-fluid flow. Factors such as viscosity, surface tension, and wall adhesion are taken into account in the computations. The results of the computations agree well with previous experiments and theory. In this work, we also use a very efficient and accurate computational method for determining the final steady profile of a body of oil under ice in water. The computational models are used to make further observations regarding the dependency of the oil spreading radius on the surface energies between the oil, ice, and water. I. INTRODUCTION In recent years there has been increased oil excavation in ice covered waters 20;9 . As a result, chances are increased that an oil spill due to a tanker accident or the rupture of an oil pipeline will occur in ice covered waters. It is generally known that oil spreads over a much smaller area under the ice cover than in open waters ..