冰川消融对气候变化的响应——以乌鲁木齐河源1号冰川为例

目前气候变暖导致的冰川退缩,引起了广泛关注.以新疆天山乌鲁木齐河源1号冰川为例,根据1959年以来的观测资料,研究了冰川消融对气候变化的响应.结果表明:近50 a来冰川在表面粒雪特征、成冰带、冰川温度、面积、厚度及末端位置等方面发生了显著变化,而这些变化均与气温的升高有着密切的联系;冰川的退缩自20世纪80年代后,尤其是近10 a来出现了加速趋势.其原因除夏季气温升高外,还有两个重要因素,一是冰川温度升高造成冷储的减少,二是冰川表面反射率下降导致辐射能量接收的增强.冰川物质平衡在1986年之前由气温和降水共同决定,之后主要受气温控制.     

天山庙尔沟平顶冰川的基本特征和过去24a间的厚度变化

山岳冰川在20世纪出现的全面退缩以及在最近20 a的加速消融是近年来国际冰川与全球变化研究的热点问题之一.庙尔沟平顶冰川位于天山山脉的最东段,南、北、东外围为气候十分干燥的荒漠戈壁,高山冰川是哈密绿洲主要的水资源,其冰芯记录包含有起源于这一地区的沙尘暴信息.因此,对该冰川的研究一直为人们所关注.基于2004年和2005年对庙尔沟平顶冰川的考察和取得的冰芯资料,初步探讨了庙尔沟平顶冰川的基本特征和过去24 a间的厚度变化.     

Lambert冰川流域东西两侧气候环境变化特征

During the 1992-1993 joint Australian-Chinese over-snow traverse of the western Lambert Glacier Basin (LGB), two firn cores were drilled respectively at MGA and LGB16. During the 1996-1997 and 1997-1998 austral summers, two firn cores were drilled respectively at DT001 and DT085 on the eastern LGB. Based on the measurements made during the expeditions, the climatic and environmental features on both sides of the LGB have been studied. Results show that during the past 50 years, the trends of both air temperature and accumulation rate show a slight increase on the east side of the LGB, in contrast to the west side of the LGB. The spatial trends of the accumulation rate measured by accumulation canes at 2 km intervals along the nearly 500 km of the traverse lines on both sides of the LGB are different. Moreover, correlations of δ^18O vs T10 along the two sides of the LGB are also different. In addition, the variations of sea salt ion concentrations show different trends in the past 50 years. All the evidence shows that the Lambert Glacier is a dividing region for the different climatic regimes over the East Antarctic ice sheet, which may be due to different moisture resources resulting from special local circumfluence such as cyclone activities, local terrain influences.     

西藏枪勇冰川冰下富碎屑化学沉淀特征与冰下过程

西藏枪勇冰川是我国现代大陆性冰川之一,在其外缘冰床背冰面的基岩表面和节理裂隙中发现了富碎屑化学沉淀,为研究冰岩界面的物理、化学过程提供了良好载体。对该区富碎屑化学沉淀理化特征的研究表明：枪勇冰川冰下存在压力融水,冰下碎屑,特别是陆源气溶胶粉尘来源的碎屑,能与融水及其中溶解的CO₂发生化学反应,释放出Ca⁺⁺;Ca⁺⁺随融水向下游方向迁移,在冰床背冰面,由于上覆压力减小,融水中的CO₂逸出并发生复冰作用,使融水中的Ca⁺⁺重新富集,形成CaCO₃沉淀,并将融水中的粉砂粘粒碎屑胶结,形成富碎屑化学沉淀;枪勇冰川冰下融水的存在,证明其冰下存在温度接近融点的融区,有类似于温性冰川的滑动过程。     

天山南坡科契卡尔巴西冰川物质平衡初步研究

基于2003—2005年考察期间观测的气温与降水资料,运用度日物质平衡模型模拟了天山南坡科契卡尔巴西冰川近期的物质平衡变化状况.结果表明:度日物质平衡模型模拟的冰川物质平衡值与实测值的变化趋势基本一致,模型模拟结果较为理想;2003/2004年度和2004/2005年度两个物质平衡年的平均物质平衡值分别为-494和-384 mm,平衡线高度(ELA)比20世纪70年升高了300 m左右.由此可见,在由暖干向暖湿转型的气候背景下,尽管降水增加显著,但强烈的升温导致科契卡尔巴西冰川处于强烈的物质亏损状态.     

慕士塔格卡尔塔马克冰川水文观测与特征分析

基于2003年卡尔塔马克冰川强烈消融期连续的气象与水文观测, 对卡尔塔马克冰川消融的影响因素和融水径流特征进行了分析. 结果表明: 消融期的冰川融水流量与气温之间存在着良好的相关关系, 降水过程会导致气温降低抑制冰川消融. 卡尔塔马克冰川纯冰川融水径流模数为62.4 L·s^-1·km^-2, 冰川区融水径流深为 463.5 mm. 根据现场降水损失试验, 总损失达 26%, 校正后大本营处2003年降水量为134 mm.     

Water chemistry and hydrometeorology in a glacierized catchment in the Polar Urals,Russia

This study aims to determine the relationships between local meteorological conditions,proglacial river discharge and biogeochemical processes operating in a periglacial basin located in the Polar Ural mountain range, Russia. Fieldwork was conducted in the catchment of Obruchev Glacier(13 km2) during the summer peak flow period in 2008. River discharge was dominated by snowmelt and changed from 3300 l s-1 to less than 1000 l s-1. The mean daily air temperatures of stations situated in the mountain tundra and near Obruchev Glacier from July 11 th to August 1st 2008 were 14.4°C and 10.3°C, respectively. The glacial river had low total dissolved solids varying from 4.5 to 9 mg l-1 and coefficients of correlation between Na+ and Cl-, K+ and Cl-, as well as NH4+ and Cl- were 0.94, 0.90 and 0.84, respectively. Rainfall events affected the snowmelt initiation and provided an essential part of the discharge during the intense snowmelt period, which occurred from July 11 th to July 18 th 2008. Data showed that Na+ and K+ in the surface water derived from snowmelt rather than chemical weathering of silicates. Also, it was obtained that NO3- derived from the melting snowpack, whereas ammonification occurring under the snowpacks was the primary source for NH4+.     

Extending the Place Glacier mass-balance record to AD 1585, using tree rings and wood density

Recognizing that climate influences both annual tree-ring growth and glacier mass balance, changes in the mass balance of Place Glacier, British Columbia, were documented from increment core records. Annually resolved ring-width (RW), maximum (MXD), and mean density (MD) chronologies were developed from Engelmann spruce and Douglas-fir trees sampled at sites within the surrounding region. A snowpack record dating to AD 1730 was reconstructed using a multivariate regression of spruce MD and fir RW chronologies. Spruce MXD and RW chronologies were used to reconstruct winter mass balance (Bw) for Place Glacier to AD 1585. Summer mass balance (Bs) was reconstructed using the RW chronology from spruce, and net balance was calculated from Bw and Bs. The reconstructions provide insight into the changes that snowpack and mass balance have undergone in the last 400 years, as well as identifying relationships to air temperature and circulation indices in southern British Columbia. These changes are consistent with other regional mass-balance reconstructions and indicate that the persistent weather systems characterizing large scale climate-forcing mechanisms play a significant glaciological role in this region. A comparison to dated moraine surfaces in the surrounding region substantiates that the mass-balance shifts recorded in the proxy data are evident in the response of glaciers throughout the region.