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51.
During August 1999, we investigated sea ice characteristics; its distribution, surface feature, thickness, ice floe movement, and the temperature field around inter-borders of air/ice/seawater in the Chukchi Sea. Thirteen ice cores were drilled at 11 floe stations in the area of 72°24′ 77°18′N, 153°34′ 163°28′W and the ice core structure was observed. From field observation, three melting processes of ice were observed; surface layer melting, surface and bottom layers melting, and all of ice melting. The observation of temperature fields around sea ice floes showed that the bottom melting under the ice floes were important process. As ice floes and open water areas were alternately distributed in summer Arctic Ocean; the water under ice was colder than the open water by 0.4 2.8℃. The sun radiation heated seawater in open sea areas so that the warmer water went to the bottom when the ice floes move to those areas. This causes ice melting to start at the bottom of the ice floes. This process can balance effectively the temperature fluctuating in the sea in summer. From the crystalline structure of sea ice observed from the cores, it was concluded that the ice was composed of ice crystals and brine-ice films. During the sea ice melting, the brine-ice films between ice crystals melted firstly; then the ice crystals were encircled by brine films; the sea ice became the mixture of ice and liquid brine. At the end of melting, the ice crystals would be separated each other, the bond between ice crystals weakens and this leads to the collapse of the ice sheet. 相似文献
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甘肃临夏黄土剖面:15万年环境演变的良好记录 总被引:13,自引:1,他引:13
历经15万年的甘肃临夏北塬黄土剖面,沉积速率大、古土壤序列完整。特别是在距今14—8万年的末次间冰期形成的三层古土壤,末次冰期间冰段形成的数层弱成土型古土壤,其特征优于其它黄土剖面。对北塬剖面磁化率、孢粉、粒度、地球化学特征的综合研究表明,该剖面完整地记录了15万年以来的环境变化,为检验以往从大陆冰盖和深海沉积中得出的环境变化模式提供了途径。 相似文献
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CONCENTRATION CHARACTERISTICS OF SOLUBLE IMPURITIES IN THE SURFACE SNOW OF COLLINS ICE CAP, KING GEORGE ISLAND, ANTARCTICA 下载免费PDF全文
Measurements carried out for the upper 10m firn/ice obtained at the main dome of Collins Ice Cap, King George Island, Antarctica revealed the direct relation of soluble impurities of snow mass to the composition of atmosphere aerosols. It was indicated that sea salt source dominates the atmosphere aerosol around Collins Ice Cap. The simultaneous variation shown by the concentration profiles of Na~+, K~+, Mg~(2+), Ca~(2+), SO_4~(2-), CI~-, Br~- and very close EF values (≈1) suggested their common marine source and similar deposition process. Besides the possible surface contamination,NH_4~+varied uniformly along deeper part of the core in concentration, which could be considered as background value of ammonium. A satisfactory explanation for NO_3~- concentration profile has not reached at present. 相似文献
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利用1993—2006年1~12月AIPO(The joining area of Asia and Indian-Pacific Ocean)流场数据,分析了吕宋海峡120°E断面水交换流速结构的平均月际变化特征,并计算了通过该断面的水通量,探讨了水通量及其垂向结构的月际和季节变化特征。结果表明:1在断面的南北方向,西向流和东向流分别大致以19.5°N和21.5°N线为界,二者交替相间分布,呈"两进(西向流入南海)两出(东向流出南海)"的结构;21.5°N以南的300 m以深和21.5°N以北的1 000 m以浅海域,常年存在南海水东向流入太平洋。2上层、深层和整个断面的净水通量几乎均为西向流,净水通量冬季最大,春季和秋季次之,夏季最小。中层除12月外,其他各月的净水通量均为东向流出南海,净水通量春季最大,夏季和秋季次之,冬季最小。3整个断面的净水通量,1~5月和8~11月呈"三明治"结构,6~7月呈2层结构;12月呈单层结构,年平均呈"三明治"结构。 相似文献
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结合前人对北冰洋海冰、气候系统的研究成果和 1 999年 8月在北冰洋对海冰的现场观测 ,本文综述了海冰分布、厚度的变化 ,海冰表面特征、积雪变化及北冰洋天气、气候特征和分区。讨论了北极海冰与南极海冰的差异。文章认为 ,北冰洋与周围地区气候变化趋势的不一致 ,主要是由于夏季在北冰洋海冰与开阔水域的相间分布、海冰漂移、融化吸热 ,均衡了周围大气、海洋温度的变化。 相似文献
59.
Ship-based sea ice observation data (concentrations,ice thickness,topography and overlying snow cover) were collected from Middle Weddell Sea to Prydz Bay,Antarctic during the period of 4 to 17 Jan 2003.Antarctic ice chart of first week of Jan 2003 was derived from National Ice Center (NIC).The compared analysis of sea ice concentrations and thickness distributions were conducted though in situ data and NIC chart.Results from sea ice concentration-analysis indicated the presence of large-scale open water between 2000 and 4100 km along transit route resulted from sea ice drifting.We describe the existence of mostly smooth first-year sea ice in study region ranged between 30 and 120 era.We also display the derived overlying snow coverage.Our results reveal the strong correspondence between ship-based observations and remotely sensed ice charts whatever in ice concentrations and ice thickness distributions. 相似文献
60.
极地海冰的研究及其在气候变化中的作用 总被引:4,自引:2,他引:2
极地海冰作为全球气候系统的一个重要组成部分,通过影响大洋表面的辐射平衡、物质平衡、能量平衡以及大洋温、盐流的形成和循环而影响全球气候变化.从最初研究极地海冰的强度和承载力到目前海/冰/气相互作用全球气候耦合模型的建立,使海冰变化和全球气候变化紧密结合起来.这些研究领域主要有:海冰及其表层雪的物理特性和过程、海冰区域生态特征、海冰区与气候相关的反照率和物质平衡研究以及海冰气候耦合模型等大的领域.模拟显示,21世纪因为全球变暖,南北极海冰都将减少.海冰和全球气候系统其它要素之间的相互作用问题、极地海冰的厚度季节性区域性分布问题、极地海冰边界及范围变化趋势问题、生消关键过程及其影响因素问题、冰间湖的作用以及海气相互作用等将是未来重要的研究方向. 相似文献