东南极伊利莎白公主地LGB65点的雪层密度与剖面特征  

Snow Density and Stratigraphy at LGB65 in Princess Elizabeth Land, East Antarctica

作　　者：温家洪 康建成 汪大立 孙波 李忠勤[2] 李军 

机构地区：[1]中国极地研究所,上海200129 [2]中国科学院寒区旱区环境与工程研究所,甘肃兰州730000 [3]Antarctic CRC and Australian Antarctic Division

出　　处：《冰川冻土》2001年第2期156-163,共8页Journal of Glaciology and Geocryology

基　　金：国家科技攻关计划项目! (98 92 7 0 1 0 5 );国家自然科学基金项目!(497710 2 2 ) ;国家海洋局青年海洋科学基金项目! (9860 3 ;9760

摘　　要：对东南极冰盖伊利莎白公主地LGB6 5点的 5 0m雪芯及雪坑进行了雪层密度与剖面分析 ,结果表明 ,该处雪的密实化过程属冷型密实化类型 ,第一和第二临界密度深度分别为 10 4m和 6 0 4m .深霜不发育 ,雪层中为数不多的雏形深霜层厚度仅几厘米 ,多分布在冰壳层的上、下两侧 .16 0m以上 ,雪芯透光性的变化不明显 ,之下 ,透光性逐渐表现出韵律变化 .雪层中辐射壳和风壳频繁出现 ,其中辐射壳可作为划分年层的重要依据 .综合雪层内的各种层位特征 ,初步划分出LGB6 5雪芯的年层约为 2 43a,总的年平均积累率为 131 9mm .2 0世纪 6 0年代年积累率低于平均水平 ,70年代中期以后 ,积累率出现大幅度增加 .近 2 5 0a来该处的年积累率呈增大趋势 .Snow density measurement and stratigraphic observation of a 50 m firn-core and a snow-pit at LGB65 in Princess Elizabeth Land, East Antarctica, were conducted. The major conclusions were obtained as follows: (1) Densification of snow/firn belongs to cold type one. The depths of the first and the second critical density are 10.4 m and 60.4 m respectively. (2) Depth hoar is not well developed. There are only a few embryo depth hoar layers, several centimeters in thickness, and most of them overlie or underlie ice crusts. (3) Thirteen grain-size classes, from fine to coarse, are divided according to their size and size ratios. Grain-size depth profile of the snow/firn layers at the LGB65 can be divided into four sections: 0～7 76 m, 7 76～18 35 m, 18 35～41 19 m, 41 19 m to the bottom of the core. Grain-size variations are mainly controlled by seasonal or interannual changes of climate factors. (4) The relative light-transmission of the core varies less above 16.0 m, but varies rhythmically bellow 16 0 m, which can be considered as an indicator for differentiating annual layers. (5) Relatively abundant ice crusts can be recognized in the snow stratigraphic profile, 7 crusts per meter on an avarage. However, there are two firn sections, 5 21m in length, without ice crust. Ice crusts can mainly divided into three types: radiation crust, wind crust and multi-layer crust. Among them, radiation crust is of importance for determining annual layer boundaries. (6) The process of firnification at the LGB65 has been examined with two empirical models established by Craven and Allison 〔21〕 and Kameda and others 〔22〕. The results show that the LGB65 is not located in the strong katabatic-wind and low accumulation rate area. The LS model established by Craven and Allison 〔21〕 has wider applicability and higher reliability. In the shallow layer of the LGB65 firn core, the annual accumulation rate derived by the LS model is consistent with the result from firn core dating through the stratigraphic

关 键 词：雪芯 雪层剖面 年积累率 东南极冰盖 雪层密度 雪坑 

分 类 号：P343.6[天文地球—水文科学] P426.63[天文地球—地球物理学]