Seasonal variations in ocean structure and current in Ongul Strait, Antarctica, in 1991

Ocean structure and current were observed below fast ice in Ongul Strait, Antarctica, over a nearly full annual cycle in 1991. In the austral fall, fresh, cold and oxygen-rich water accumulates in the upper layer. This water is diffused or mixed with the lower-layer water gradually in winter. From spring to summer, warm, saline and oxygen-poor water appeared in the mid-depth and deep layers. These features seem to be common in every year. Horizontal oceanic advection is dominant in the heat and salt budget. In spite of no direct wind forcing and negligible thermohaline forcing, the current in Ongul Strait is found to be strong, with a typical velocity being 0.3m/s. The strong current is confined only to the upper 100-300m from the surface. The direction of the mean current changes drastically from southward to northward in May

A newly-developed system for countinuous measurements of atmospheric CO2 concentration at Syowa Station, Antarctica

A new apparatus for in situ continuous measurements of atmospheric CO_2 concentration at Syowa Station, Antarctica was developed using a non-dispersive infrared CO_2 analyzer with a precision better than ±0.01ppm. Standard gases employed were CO_2 in air mixtures and their concentrations were determined against special gases with absolute accuracies around ±0.1ppm, which were prepared gravimetrically using an extremely precise balance

PRELIMINARY RESULTS OF HYDROGRAPHY UNDER FAST ICE IN LUTZOW-HOLM BAY, ANTARCTICA IN 1990

Seasonal variations in water structure under fast ice in Lutzow-Holm Bay, Antarctica, were observed from April to December, 1990. Two warm and oxygen-poor waters were observed. One is warmer water with temperatures higher than 0℃, salinities of more than 34.6 and oxygen less than 6 ml/l, and is found in the bottom layer deeper than 700m in the Shirase Submarine Valley. The other is found in the upper layer with temperatures of -1.4∿ -1.5℃, salinities of around 34.2 and oxygen of 6.3-6.9ml/l. The origin of both waters is a blob of the Circumpolar Deep Water (CDW) drawn from offshore, and they are admixtures of CDW with overlying Winter Water in various proportions. Due to high density, the former is confined to the bottom layers of deep troughs; on the contrary, the latter with low density can migrate in the upper layer with the water circulation in the bay. In spring a cold and oxygen-rich water (T7.2ml/l) was observed at the intermediate depth of about 250m-350m near the top of the downslope of the submarine valley. It is probable that this water was formed by sea ice processes during winter

ナンキョク ショウワ キチ ニ オケル タイキ チュウ ノ ニサンカタンソ ノウド ノ レンゾク カンソク システム ノ アラタナ カイハツ

南極昭和基地において, 大気中の二酸化炭素濃度を高精度かつ連続的に観測するために, 非分散型赤外CO_2分析計(分析精度±0.01ppm以内)を用いた新たな計測装置を開発した。分析計の出力とCO_2濃度を関係づけるための標準ガスは, キャリアーガス効果の補正を必要としない空気と二酸化炭素の混合気体とし, その濃度は重量法によって絶対精度±0.1ppmで製造した特殊ガスを用いて検定された。A new apparatus for in situ continuous measurements of atmospheric CO_2 concentration at Syowa Station, Antarctica was developed using a non-dispersive infrared CO_2 analyzer with a precision better than ±0.01ppm. Standard gases employed were CO_2 in air mixtures and their concentrations were determined against special gases with absolute accuracies around ±0.1ppm, which were prepared gravimetrically using an extremely precise balance