Preliminary research on the transmission path of nssSO_4~(2-) and NO_3~- in Antarctic ice sheet

The main sources of nssSO 2- 4 and NO - 3 were summarized in this paper. By analyzing the spatial distribution features of major ions in Antarctic ice sheet and studying on the different time of the same volcanic event recorded by different ice cores from different regions in Antarctica, this paper intends to study the transmission path of nssSO 2- 4 and NO - 3. Results show that nssSO 2- 4 and NO - 3 are transmitted to the ice sheet through long distance and high altitude. The procedure of the transmission is that nssSO 2- 4 and NO - 3 are transmitted to the level between the top of troposphere and the bottom of stratosphere, then subsided to the ice sheet surface and spread to other regions.     

Summer sea ice characteristics of the Chukchi Sea

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.     

南极冰川学与全球变化研究新进展

南极冰川学与全球变化是最近举行的“南极与全球变化：相互作用和影响”国际学术研讨会的主题。南极冰盖净物质平衡的观测和估算，冰盖物质平衡与气候变化的预测模型；南极冰雪大气、气候和环境化学；南极深冰芯分析，及其与其它古环境记录的对比研究，是目前南极冰川学研究的几个热点、关键问题。     

甘肃临夏黄土剖面：15万年环境演变的良好记录

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。     

CONCENTRATION CHARACTERISTICS OF SOLUBLE IMPURITIES IN THE SURFACE SNOW OF COLLINS ICE CAP, KING GEORGE ISLAND, ANTARCTICA

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.     

中国第四纪冰期、地文期和黄土记录

中国第四纪冰川的发育受岩石圈运动造成的三大地貌阶梯的严格控制,主要出现在最高阶梯的青藏高原和西北山地,第二阶梯以下分布零星。把冰期、地文期和黄土记录结合起来研究会迅速提高中国第四纪冰川的研究水平。兰州附近有三次古冰川遗迹,分别可以和T₁、T₂、T₃和T₄相应。相当于氧同位素2、4、6和16阶段,即70,000—10,000aB.P.、0.15MaB.P.和0.6MaB.P.。     

基于海洋分析资料的吕宋海峡水交换的月际变化特征

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。     

南极冰盖NO－3浓度记录研究进展

综述了近年来南极冰盖雪冰中NO－ 3浓度的影响因素、NO－ 3的来源、沉积后变化及其浓度的时空变化特征的最新研究进展。尽管质子事件、超新星活动、陨石事件、火山喷发和核试验等各种突发事件都可能对南极雪冰中NO－ 3浓度产生影响,但综述和模拟结果表明中低纬度对流层闪电和极地平流层来源可能是南极雪冰中NO－ 3浓度本底的主要来源。综合研究表明,南极冰盖雪冰中记录的NO－ 3浓度可能是其来源、传输路径、沉积过程以及沉积后变化等的综合反映。     

南极海冰遥感现场对比实验

南极海冰区是影响全球气候 -环境变化的关键区域之一 ,卫星遥感资料是获取大区域海冰地球物理特征参数的最有效的手段。但是 ,在南半球晚冬-初春期间 ,卫星遥感反演的海冰资料的误差较大 ,精度较低。 2 0 0 3年 9- 1 0月 ,由澳大利亚南极局组织 ,包括中国等 7个国家 ,1 4个研究单位的科学家参加 ,以澳大利亚破冰船“南极光号”为现场工作平台 ,在东南极季节海冰带 ,通过与美国宇航局 (NASA)、日本宇宙开发促进会合作开展的卫星、飞机、船、冰站立体联合观测 ;对AMSR E等卫星遥感产生的海冰地球物理参数 (海冰密集度、雪盖厚度、海冰物理温度等 )进行地面详细验证 ,建立遥感数据与地面实测数据的统计关系 ,以发现各种卫星资料反演算式的使用范围和局限性 ,为改进卫星资料反演算式提供依据。     

北冰洋海冰/气候系统及其对全球气候的影响

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。