共查询到20条相似文献，搜索用时 31 毫秒
1.
Aggregations of ice platelets accumulate below the annual sea ice (subice platelet layer) and on the bottom (anchor ice) to depths of 33 meters. Observations of ice platelets adhering to submerged lines support the conclusion that 33 meters is the lower limit for ice formation in the water column in this area. The rising anchor ice lifts epibenthic fauna and has a pronounced effect on the distribution of the epibenthic organisms. 相似文献
2.
南极普里兹湾关键物理海洋学问题研究进展及未来趋势 总被引：5，自引：2，他引：3
南极普里兹湾及其邻近海域关键物理海洋学问题包括水团特性、环流特征和冰架 海洋 海冰相互作用过程等。该海域水团可以分为南极表层水、绕极深层水、南极底层水、南极陆架水和南极冰架水等,受外部条件影响,这些水团时空变化显著。普里兹湾区域的环流以普里兹湾流涡,西向的沿岸流和东向的绕极流,以及两者之间的南极辐散带的环流为主要特征,地形是环流特征的关键影响因素。埃默里冰架 海洋的相互作用过程显著影响普里兹湾海域的水团特性和环流状况。冰泵机制,是埃默里冰架外海水进入冰穴,并引起冰架底部消融和冻结的重要原因。冰架 海洋 海冰相互作用形成的低温高盐水,是普里兹湾形成南极底层水的潜在因素之一。加强现场观测,并建立高分辨率的冰架 海洋 海冰耦合模型系统是研究普里兹湾海域物理海洋学关键过程和变化机制的重要手段,是南极研究的发展趋势。 相似文献
3.
Weber ME Clark PU Ricken W Mitrovica JX Hostetler SW Kuhn G 《Science (New York, N.Y.)》2011,334(6060):1265-1269
The timing of the last maximum extent of the Antarctic ice sheets relative to those in the Northern Hemisphere remains poorly understood. We develop a chronology for the Weddell Sea sector of the East Antarctic Ice Sheet that, combined with ages from other Antarctic ice-sheet sectors, indicates that the advance to and retreat from their maximum extent was within dating uncertainties synchronous with most sectors of Northern Hemisphere ice sheets. Surface climate forcing of Antarctic mass balance would probably cause an opposite response, whereby a warming climate would increase accumulation but not surface melting. Our new data support teleconnections involving sea-level forcing from Northern Hemisphere ice sheets and changes in North Atlantic deep-water formation and attendant heat flux to Antarctic grounding lines to synchronize the hemispheric ice sheets. 相似文献
4.
The melting of pure ice single crystals can be inhibited by the presence of an antifreeze glycopeptide isolated from an Antarctic fish. This inhibition effect exhibits crystallographic dependence and can result in superheating of the crystal by heat conduction across the ice-solution interface. The antifreeze molecules inhibit melting in a manner more or less symmetrical to their well-known effect of inhibiting freezing. The melting effect is best expressed at concave ice interfaces, whereas the freezing effect is best expressed at convex ones. Both are restricted to orientations near (1010) with the particular antifreeze that was used. 相似文献
5.
Manley TO Hunkins KL Villanueva JZ VAN Leer J Gascard JC Jeannin PF 《Science (New York, N.Y.)》1987,236(4800):432-434
A major component of the Fram Strait Marginal Ice Zone Experiment was the investigation of air-sea-ice interactions, processes, and circulation patterns found behind the local ice edge and on scales greater than 10 kilometers (mesoscale and large scale). Neutrally buoyant floats, ice-tethered cyclesondes, and helicopter-based measurements were used to obtain uniquely integrated and consistent views of the mesoscale ocean features beneath the ice cover of Fram Strait. Within the vicinity of the Yermak Plateau, three distinct regions of mesoscale motion were observed that coincided with the shallow topography of the plateau, the northward flowing Atlantic water over the western flank of the plateau, and the strong current-shear zone of the East Greenland Polar Front. A subice meander of the front was also observed, which was probably occluded subsequently. 相似文献
6.
340,000-year centennial-scale marine record of Southern Hemisphere climatic oscillation 总被引：1，自引：0，他引：1
In order to investigate rapid climatic changes at mid-southern latitudes, we have developed centennial-scale paleoceanographic records from the southwest Pacific that enable detailed comparison with Antarctic ice core records. These records suggest close coupling of mid-southern latitudes with Antarctic climate during deglacial and interglacial periods. Glacial sections display higher variability than is seen in Antarctic ice cores, which implies climatic decoupling between mid- and high southern latitudes due to enhanced circum-Antarctic circulation. Structural and temporal similarity with the Greenland ice core record is evident in glacial sections and suggests a degree of interhemispheric synchroneity not predicted from bipolar ice core correlations. 相似文献
7.
KR Arrigo DL Worthen MP Lizotte P Dixon G Dieckmann 《Science (New York, N.Y.)》1997,276(5311):394-397
A numerical model shows that in Antarctic sea ice, increased flooding in regions with thick snow cover enhances primary production in the infiltration (surface) layer. Productivity in the freeboard (sea level) layer is also determined by sea ice porosity, which varies with temperature. Spatial and temporal variation in snow thickness and the proportion of first-year ice thus determine regional differences in sea ice primary production. Model results show that of the 40 teragrams of carbon produced annually in the Antarctic ice pack, 75 percent was associated with first-year ice and nearly 50 percent was produced in the Weddell Sea. 相似文献
8.
Hughes T 《Science (New York, N.Y.)》1970,170(3958):630-633
The Antarctic surge theory of Pleistocene glaciation is reexamined in the context of thermal convection theory applied to the Antarctic ice sheet. The ice sheet surges when a water layer at the base of the ice sheet reaches the edge of the ice sheet over broad fronts and has a thickness sufficient to drown the projections from the bed that most strongly hinder basal ice flow. Frictional heat from convection flow promotes basal melting, and, as the ice sheet grows to the continental shelf of Antarctica, a surge of the ice sheet appears likely. 相似文献
9.
Thomas RH 《Science (New York, N.Y.)》1979,205(4412):1257-1258
Retreat of the margins of the West Antarctic ice sheet associated with rising sea level during the last 15,000 years is the main cause for the thinning of the ice sheet by approximately 300 meters. The West Antarctic ice sheet during the late Wisconsin was at least 30 percent wider than it is today, and Holocene retreat of its margins has added about 6 meters to the world sea level. 相似文献
10.
鳕鱼皮胶原蛋白酶解液的制备及抗氧化研究 总被引：1，自引：1，他引：0
[目的]利用酶解法从鳕鱼皮中提取胶原蛋白肽,研究其抗氧化能力。[方法]以鳕鱼鱼皮为原料,采用胃蛋白酶进行酶解,通过正交试验研究pH、水解温度、加酶量及水解时间4个因素对酶解鳕鱼皮的影响,确定胃蛋白酶酶解鳕鱼皮的最佳条件,并采用试剂盒法对酶解产物进行抗氧化活性研究。[结果]各因素对酶解鳕鱼皮的影响为水解时间〉水解温度〉加酶量〉pH,胃蛋白酶酶解鳕鱼皮的最佳工艺条件为：加酶量4%、温度37℃、pH 3、时间3 h。此条件下,蛋白质水解度可达到6.91%。胃蛋白酶酶解鳕鱼皮得到的胶原肽粗品具有一定的抗氧化能力,并对超氧阴离子自由基具有较强的清除作用。[结论]该研究为开发新的抗氧化剂提供科学参考。 相似文献
11.
A model for the process of meteorite concentration in blue ice regions of the Antarctic ice sheet is proposed based on data from near the Allan Hills and the assumptions that both meteorite influx and glacial flow have been constant. The meteorite influx is calculated to be 60 x 10(-6) kilogram per square kilometer per year, and the age of the exposed ice to be 0 to 600,000 years, varying with distance from the Allan Hills. These results are in line with other estimates of influx rate and with measurements of the terrestrial ages of the meteorites, providing support for the assumption of steady flow and meteorite influx. This may be the oldest sequence of ice in stratigraphic order yet discovered, and the results imply that this part of the east Antarctic ice sheet has been approximately steady during this time interval. 相似文献
12.
It has been suggested that as much as 90% of the discharge from the Antarctic Ice Sheet is drained through a small number of fast-moving ice streams and outlet glaciers fed by relatively stable and inactive catchment areas. Here, evidence obtained from balance velocity estimates suggests that each major drainage basin is fed by complex systems of tributaries that penetrate up to 1000 kilometers from the grounding line into the interior of the ice sheet. This finding has important consequences for the modeled or estimated dynamic response time of past and present ice sheets to climate forcing. 相似文献
13.
Mass balance of polar ice sheets 总被引：4，自引：0，他引：4
Recent advances in the determination of the mass balance of polar ice sheets show that the Greenland Ice Sheet is losing mass by near-coastal thinning, and that the West Antarctic Ice Sheet, with thickening in the west and thinning in the north, is probably thinning overall. The mass imbalance of the East Antarctic Ice Sheet is likely to be small, but even its sign cannot yet be determined. Large sectors of ice in southeast Greenland, the Amundsen Sea Embayment of West Antarctica, and the Antarctic Peninsula are changing quite rapidly as a result of processes not yet understood. 相似文献
14.
Using measurements of time-variable gravity from the Gravity Recovery and Climate Experiment satellites, we determined mass variations of the Antarctic ice sheet during 2002-2005. We found that the mass of the ice sheet decreased significantly, at a rate of 152 +/- 80 cubic kilometers of ice per year, which is equivalent to 0.4 +/- 0.2 millimeters of global sea-level rise per year. Most of this mass loss came from the West Antarctic Ice Sheet. 相似文献
15.
Monaghan AJ Bromwich DH Fogt RL Wang SH Mayewski PA Dixon DA Ekaykin A Frezzotti M Goodwin I Isaksson E Kaspari SD Morgan VI Oerter H Van Ommen TD Van der Veen CJ Wen J 《Science (New York, N.Y.)》2006,313(5788):827-831
Antarctic snowfall exhibits substantial variability over a range of time scales, with consequent impacts on global sea level and the mass balance of the ice sheets. To assess how snowfall has affected the thickness of the ice sheets in Antarctica and to provide an extended perspective, we derived a 50-year time series of snowfall accumulation over the continent by combining model simulations and observations primarily from ice cores. There has been no statistically significant change in snowfall since the 1950s, indicating that Antarctic precipitation is not mitigating global sea level rise as expected, despite recent winter warming of the overlying atmosphere. 相似文献
16.
The portion of the West Antarctic ice sheet that flows into the Ross Sea is thinning in some places and thickening in others. These changes are not caused by any current climatic change, but by the combination of a delayed response to the end of the last global glacial cycle and an internal instability. The near-future impact of the ice sheet on global sea level is largely due to processes internal to the movement of the ice sheet, and not so much to the threat of a possible greenhouse warming. Thus the near-term future of the ice sheet is already determined. However, too little of the ice sheet has been surveyed to predict its overall future behavior. 相似文献
17.
澳洲龙纹斑生物学特征及其繁养殖技术研究进展 总被引：1，自引：0，他引：1
澳洲龙纹斑Maccullochellapeeliipeelii是原产于澳大利亚墨瑞河的一种经济鱼类,是澳大利亚乃至世界上品质优良及种群类型较大的淡水鱼类之一。近年澳洲龙纹斑已经引入中国并开始驯化开发。其作为一项新兴的水产养殖产业,给人们带来新的开发途径,但开发者也将面临许多新的技术问题,如何有效地人工繁殖,保障健康养殖与有效防控病害等。本文就澳洲龙纹斑的生物学特性、人工繁殖养殖技术、经济价值和养殖技术以及疾病防控等方面进行综述介绍,同时结合先期的养殖实践,提出若干发展对策与建议。 相似文献
18.
Bornemann A Norris RD Friedrich O Beckmann B Schouten S Damsté JS Vogel J Hofmann P Wagner T 《Science (New York, N.Y.)》2008,319(5860):189-192
The Turonian (93.5 to 89.3 million years ago) was one of the warmest periods of the Phanerozoic eon, with tropical sea surface temperatures over 35 degrees C. High-amplitude sea-level changes and positive delta18O excursions in marine limestones suggest that glaciation events may have punctuated this episode of extreme warmth. New delta18O data from the tropical Atlantic show synchronous shifts approximately 91.2 million years ago for both the surface and deep ocean that are consistent with an approximately 200,000-year period of glaciation, with ice sheets of about half the size of the modern Antarctic ice cap. Even the prevailing supergreenhouse climate was not a barrier to the formation of large ice sheets, calling into question the common assumption that the poles were always ice-free during past periods of intense global warming. 相似文献
19.
The reactions of dinitrogen pentoxide (N(2)O(5)) with H(2)O and hydrochloric acid (HCl) were studied on ice surfaces in a Knudsen cell flow reactor. The N(2)O(5) reacted on ice at 185 K to form condensed-phase nitric acid (HNO(3)). This reaction may provide a sink for odd nitrogen (NO(x)) during the polar winter, a requirement in nearly all models of Antarctic ozone depletion. A lower limit to the sticking coefficient, gamma, for N(2)O(5) on ice is 1 x 10(-3). Moreover, N(2)O(5) reacted on HCl-ice surfaces at 185 K, with gamma greater than 3 x 10(-3). This reaction, which produced gaseous nitryl chloride (ClNO(2)) and condensed-phase HNO(3), proceeded until all of the HCl within the ice was depleted. The ClNO(2), which did not react or condense on ice at 185 K, can be readily photolyzed in the Antarctic spring to form atomic chlorine for catalytic ozone destruction cycles. The other photolysis product, gaseous nitrogen dioxide (NO(2)), may be important in the partitioning of NO(x) between gaseous and condensed phases in the Antarctic winter. 相似文献
20.
Glacier surge after ice shelf collapse 总被引：2，自引：0，他引：2
The possibility that the West Antarctic Ice Sheet will collapse as a consequence of ice shelf disintegration has been debated for many years. This matter is of concern because such an event would imply a sudden increase in sea level. Evidence is presented here showing drastic dynamic perturbations on former tributary glaciers that fed sections of the Larsen Ice Shelf on the Antarctic Peninsula before its collapse in 1995. Satellite images and airborne surveys allowed unambiguous identification of active surging phases of Boydell, Sj?gren, Edgeworth, Bombardier, and Drygalski glaciers. This discovery calls for a reconsideration of former hypotheses about the stabilizing role of ice shelves. 相似文献