冰川模型及其在古冰川模拟研究中的应用

冰川模型已广泛应用于预测未来的冰川变化。随着冰川地貌制图、测年和古气候研究的不断发展,冰川模型也逐渐用于模拟古冰川变化、估算古冰川发育时期的气候信息和探讨古冰川演化的气候驱动因素。本文综述用于古冰川模拟的两类模型：地貌-冰面剖面形态模型和物质平衡-冰川动力耦合模型,介绍不同冰川模型的原理、用于古冰川模拟的流程和利用地貌体进行模型参数校验的方法。在此基础上,以青藏高原及其周边山地为例,总结利用冰川模型恢复古冰川的范围、体积、平衡线等参数,估算不同冰川发育时期的温度和降水,以及评估测年数据及其恢复的古冰川期次和规模的案例研究。最后指出了利用冰川模型进行古冰川模拟研究存在的问题和未来发展趋势,为进一步加强和改进冰川模型在古冰川模拟研究中的应用,恢复古冰川的规模、演化过程及其气候驱动机制奠定基础。     

稻城古冰帽第四纪冰川地貌数字化研究

位于青藏高原东南部的稻城古冰帽,在第四纪时期曾发生了多次冰期并保存了丰富的古冰川遗迹,是研究第四纪冰川地貌类型特征的理想区域。目前,已有学者对冰川地貌类型划分和冰川地貌制图做了相关研究,但是古冰川地貌在空间分布特征及其量化程度有待于进一步细化。因此,本文基于Google Earth Pro遥感影像和数字高程模型(DEM),运用目视解译和野外考察相结合的方法对典型冰川地貌进行定量分析并绘制了稻城古冰帽(约3 600 km²)的第四纪冰川地貌图。本文识别了该区冰川地貌中的冰川湖、冰川谷、羊背岩和冰碛垄等四种类型,初步统计了约1 096个冰川湖、370条冰川谷、41个羊背岩及1 268列冰碛垄;空间分布上,冰川湖和羊背岩主要分布在海子山夷平面上,冰川谷以古冰帽边缘区发育为主,冰碛垄则主要形成于海子山夷平面上和东、西两侧的山谷里。本研究可为第四纪冰期规模估算、古气候重建提供基础数据,也为当地的旅游规划和自然资源调查提供一定的参考。     

青藏高原东南巴松措流域和派山谷末次冰盛期冰川与气候重建

末次冰盛期(LGM)时全球大范围降温,青藏高原冰川大规模扩张,重建LGM时期古冰川规模对认识高原冰川水资源演化及古气候条件有重要的科学意义。根据青藏高原东南巴松措流域及派山谷两地的冰川地貌及其10Be暴露年代数据,本文应用冰川纵剖面模型定量重建了两地冰川在LGM时期的范围、冰储量和平衡线高度(ELA)等参数,并通过冰川气候模型恢复了LGM时的气候条件。结果表明：巴松措流域LGM时期的冰川面积约为982.3km²,是现代冰川面积的4.5倍,冰储量约为274.4km³;派山谷无现代冰川分布,LGM时期的冰川面积达5.76km²,冰储量约为0.51km³;LGM时期两冰川的平衡线高度分别为4 460～4 547m和3 569～3 694m,与现代冰川相比分别降低了535m和1 034～1 184m。在降水减少60%的情况下,考虑LGM以来的构造剥蚀对平衡线高度变化的影响,LGM时期巴松措流域和派山谷冰川的夏季平均气温分别比现在低约2.96～4.89℃和5.09～6.99℃。     

四川康定折多山末次冰盛期古冰川重建及其气候意义

折多山位于青藏高原东缘,地势上处于由高原面向高山峡谷的过渡区,古冰川遗迹保留较好。对折多山冰川地貌进行深入研究,对揭示青藏高原东缘地形演化与古气候变化的耦合机制具有重要意义。在野外考察的基础上,结合Google Earth遥感影像、《中国第二次冰川编目》和DEM等资料,对折多山冰川地貌及其特征参数进行了识别、提取和计算。研究共识别出189条古冰川,覆盖面积为497 km²。基于研究区已有年代学资料,本区冰川地貌主要为末次冰盛期（LGM）以来冰川作用遗存。恢复研究区LGM冰川平衡线高度（ELA）,在西坡和东坡分别为4 380 m和4 110 m,相差270 m,揭示出分水岭东侧更有利于冰川发育。广泛发育的冰蚀湖、冰蚀基岩面、羊背石等,以及深切的冰川槽谷（U形谷）指示海洋性冰川作用特征;冰川作用正差、冰川朝向、冰蚀地貌的差异,揭示积累区地形条件和水汽来源对研究区冰川发育具有重要的影响。     

河西内陆河流域冰川融水近期变化

基于第一次中国冰川编目数据库,以国家气象台站的月降水与月气温资料为驱动数据,利用度日模型重建了河西内陆河流域各水系1961～2006年冰川物质平衡和融水径流序列,并与短期观测资料的对比验证表明,模型具有较高的可信度.河西内陆河流域1961～2006年平均冰川物质平衡为-49.5 mm/a,从东段石羊河流域到西段疏勒河、...     

入湖冰川物质平衡序列重建与分析--以喜马拉雅山北坡龙巴萨巴冰川为例北大核心CSCD

入湖冰川受冰湖作用影响,物质损失速率高于其他类型冰川,并导致冰湖进一步扩张,冰湖溃决风险增加。建立入湖冰川物质变化序列,对揭示不同类型冰川对气候变化的响应特征,以及评估冰湖溃决风险研究具有重要意义。基于中国地面气象要素驱动数据集和实测气象数据,采用冰川表面能量-物质平衡模型估算了冰川表面物质变化,并结合冰川流动和末端退缩特征,重建了1989-2018年龙巴萨巴冰川物质变化序列。结果表明,近30a龙巴萨巴冰川总物质损失为0.315km^(3)w.e.,平均物质变化速率为-0.114km^(3)w.e.·a^(-1)。冰川平均表面物质平衡为-0.26m w.e.·a^(-1),表面消融是冰川物质亏损的主要贡献因素。气温变化对冰川表面物质损失的影响高于降水;冰川表面物质平衡对夏季气温和降水变化的敏感性强于其他季节;表碛覆盖加速了冰川表面消融,且较薄的表碛厚度会加剧冰川表面物质损失。     

川西螺髻山清水沟倒数第二次冰期以来的冰川规模与古气候重建

川西螺髻山清水沟保存着倒数第二次冰期（MIS 6）、末次冰期早期（MIS 4）和末次冰期晚期（MIS 2）较为完好的冰川沉积序列,该序列为螺髻山地区晚第四纪古环境重建提供了直接依据。基于野外地貌考察和冰川地貌特征确定出古冰川分布范围,计算古冰川物质平衡线高度（ELA）,应用P-T模型和LR模型计算出各冰期时段的气温与降水。结果显示：清水沟MIS 6、MIS 4和MIS 2的冰川面积分别为3.44 km²、2.22 km²和1.20 km²,冰川体积分别为0.19 km³、0.12 km³和0.07 km³。各期次的古ELA分别为3 132 m、3 776 m和3 927 m,相对于现代ELA分别下降了1 716 m、1 071 m和920 m。冰川规模受气温和降水的共同影响,MIS 6气温大幅下降（8~12 ℃）是导致该阶段冰川规模最大的原因;MIS 4降水为现在的80%左右,而气温下降幅度（6~7 ℃）小于倒数第二次冰期,冰川规模小于倒数第二次冰期;MIS 2降水仅为现在的60%~80%,降温幅度（4~8 ℃）也不大,因此该阶段冰川规模最小。     

1961—2006年叶尔羌河上游流域冰川融水变化及其对径流的影响

叶尔羌河是塔里木河的主源之一,发源于喀喇昆仑山北坡,冰川融水是其主要补给.以叶尔羌河流域库鲁克栏杆水文站以上流域国家气象台站的月降水与月气温资料、90 m分辨率的数字高程模型(DEM)以及1970年代的冰川分布矢量数据为基础,利用冰川度日因子融水径流模型重建了叶尔羌河上游流域平均冰川物质平衡、冰川融水径流序列,分析了叶尔羌河上游流域冰川融水径流变化的特征、趋势及其对河流径流的影响.结果表明:1961—2006年流域冰川平均年物质平衡为-163.1 mm,累积物质平衡为-7.5 m,平衡线平均海拔为5 395.7 m.1991年之后流域冰川物质平衡呈显著负平衡,平均年物质平衡为-301.2 mm,1991—2006年与1961—1990年相比平衡线平均高度上升了64.2 m.1961—2006年流域年平均冰川融水径流深为807.7 mm,冰川融水对河流径流的补给比重为51.3%;2000年之后冰川融水对河流径流的补给比重增大到63.3%,与多年平均值相比冰川融水对河流径流的贡献在2000年后明显增大.     

基于冰川钻孔温度的古气候重建研究进展北大核心CSCD

冰川内部温度与过去冰面温度变化密切相关,因此可以利用冰川钻孔温度对过去冰面温度变化过程进行重建。耦合的热传导-冰流物理模型与相关反演算法,是基于冰川钻孔温度进行古气候重建研究的理论基础和关键。论文收集了过去三十多年基于冰川钻孔温度进行古气候重建的研究文献,从冰川钻孔温度对气候变化的响应和古气候重建等方面进行了概述,并简要讨论了不同反演算法的优劣性和适用条件。尽管很多因素(如太阳辐射、融水等)都会对冰川钻孔温度造成影响,但两极或高纬地区的冷冰川钻孔温度能较好地反映气候变化历史。目前已通过这些不同地区的冰川钻孔温度,重建了末次冰期冰盛期以来不同时间尺度的气候变化历史,同时可与对应的冰芯记录相互印证。此外,通过冰川钻孔温度可以研究冰川与气温的耦合作用,并进一步预测冰川对未来气候变化的响应。利用中纬度冷冰川钻孔温度开展古气候重建的研究较少,未来加深这一方面的研究将有助于揭示中纬度高海拔地区的气候变化状况。     

冰筏沉积与古气候,古地理

冰筏沉积物，是古气候，古地理的有效记录。对冰筏沉积的研究，可用于研究冰川发育时期，范围，重建冰川发史，重塑地质历史时期的古气候。通过冰筏沉积物中的砾石和砂级颗粒的成分分析，可了解古冰川发育区母岩的岩性组合。     

Modelling Last Glacial Maximum ice cap with the Parallel Ice Sheet Model to infer palaeoclimate in south-west Turkey

Modelling palaeoglaciers in mountainous terrain is challenging due to the need for detailed ice flow computations in relatively narrow and steep valleys, high-resolution climate estimations, knowledge of pre-ice topography, and proxy-based palaeoclimate forcing. The Parallel Ice Sheet Model (PISM), a numerical model that approximates glacier sliding and deformation to simulate large ice sheets such as Greenland and Antarctica, was recently adapted to alpine environments. In an attempt to reconstruct the climate conditions during the Last Glacial Maximum (LGM) on Mount Dedegöl in SW Turkey, we used PISM and explored palaeoglacier dynamics at high spatial resolution (100 m) in a relatively small domain (225 km²). Palaeoice-flow fields were modelled as a function of present temperature and precipitation. Nine different palaeoclimate simulations were run to reach the steady-state glacier extents and the modelled glacial areas were compared with the field-based and chronologically well-established ice extents. Although our results provide a non-unique solution, best-fit scenarios indicate that the LGM climate on Mount Dedegöl was between 9.2 and 10.6 °C colder than today, while precipitation levels were the same as today. More humid (20% wetter) or arid (20% drier) conditions than today bring the palaeotemperature estimates to 7.7–8.8 or 11.5–13.2 °C lower than present, respectively.     

Recognition and palaeoclimatic implications of late Quaternary niche glaciation in eastern Lesotho

Geomorphic evidence of former glaciation in the high Drakensberg of southern Africa has proven controversial, with conflicting glacial and non‐glacial interpretations suggested for many landforms. This paper presents new geomorphological, sedimentological and micromorphological data, and glacier mass‐balance modelling for a site in the Leqooa Valley, eastern Lesotho, preserving what are considered to be moraines of a former niche glacier that existed during the Last Glacial Maximum (LGM). The geomorphology and macro‐sedimentology of the deposits display characteristics of both active and passive transport by glacial processes. However, micromorphological analyses indicate a more complex history of glacial deposition and subsequent reworking by mass movement processes. The application of a glacier reconstruction technique to determine whether this site could have supported a glacier indicates a reconstructed glacier equilibrium line altitude (ELA) of 3136 m a.s.l. and palaeoglacier mass balance characteristics comparable with modern analogues, reflecting viable, if marginal glaciation. Radiocarbon dates obtained from organic sediment within the moraines indicate that these are of LGM age. The reconstructed palaeoclimatic conditions during the LGM suggest that snow accumulation in the Drakensberg was significantly higher than considered by other studies, and has substantial relevance for tuning regional climate models for southern Africa during the last glacial cycle. Copyright © 2009 John Wiley & Sons, Ltd.     

Chronology of the Last Glacial Maximum in the Salzach palaeoglacier area (Eastern Alps)

A chronostratigraphy based on luminescence data was established at a key loess profile (Duttendorf) in the northern alpine foreland of Austria. The data help to constrain the timing and duration of the Last Glacial Maximum (LGM) in the area of one of the largest east Alpine piedmont glaciers, the Salzach palaeoglacier. Climate deterioration and maximum advance of this glacier were coeval with the beginning of the main loess accumulation phase in the glacier forefield at ～29–30 ka. A late LGM‐outwash gravel layer deposited on top of the loess profile marks the end of the LGM glacier activity at ～20 ka. The geomorphological setting around the loess profile provides evidence of a major glacier oscillation during the course of the LGM, a phenomenon qualitatively known from other alpine palaeoglaciers but never interpreted in terms of palaeoclimate. A LGM glacier oscillation similar to that of the Salzach palaeoglacier was reported recently from the south Alpine Tagliamento palaeoglacier, suggesting a common forcing. The onset of loess deposition at Duttendorf and the tentatively contemporal advance of the Salzach palaeoglacier reflect, as do other data, the drastic cooling in Europe as a result of Heinrich event 3. The first glacier maximum is not well constrained in the study area but a correlation with the better dated Tagliamento amphitheatre suggests a possible response to Heinrich 2. The second re‐advance occurred synchronously (within dating uncertainties) in both palaeoglaciers forefields (at ～21 ka) but the forcing mechanism remains unknown. Copyright © 2011 John Wiley & Sons, Ltd.     

A case for a downwasting mountain glacier during Termination I,Verçenik valley,northeastern Turkey

Field evidence of palaeoglacial records in the Verçenik valley in the Eastern Black Sea Mountains was examined and 19 samples for surface exposure dating with cosmogenic ¹⁰Be were collected with the aim of increasing knowledge on the amplitude and frequency of palaeoglacier advances in Anatolia. Glacial erosional features were mapped and the flow directions of the palaeoglaciers were determined. The Verçenik palaeoglacier advanced before 26.1 k ± 1.2 k yr. The Last Glacial Maximum (LGM) advance continued until 18.8 k ±1.0 k yr. The Verçenik palaeoglacier collapsed during Termination I. After 17.7 k ± 0.8 k yr there was no more ice in the main valley. The Verçenik palaeoglacier most probably then separated into five small glaciers that were restricted to the tributary valleys. Among these, the Hem?in palaeoglacier completed its recession around 15.7 k ± 0.8 k yr. On the basis of glacial erosion features, a Lateglacial glacier advance can be identified. Evidence of the Little Ice Age advance appears to be absent. The results from this valley system seem to be consistent with the first results from the adjacent Kavron valley and with the Anatolian LGM palaeoclimate, the sea surface temperature minima in the western Mediterranean, the deposition of red clay layers in the Black Sea and deposition of the Heinrich‐1 layer in the North Atlantic. Copyright © 2007 John Wiley & Sons, Ltd.     

Late Pleistocene climate of the northern Iberian Peninsula: New insights from palaeoglaciers at Fuentes Carrionas (Cantabrian Mountains)

New ¹⁰Be dates for glacial landforms in the Fuentes Carrionas area (Cantabrian Mountains, nothern Spain) are presented. Mapped and dated landforms in Fuentes Carrionas made possible a palaeoglacier reconstruction for four glacial stages. Results were compared to other nearby palaeoenvironmental proxies, so a final approximation on the mean annual temperature and annual precipitation that caused the four glacial advance stages is proposed. Glaciers reached their maximum extension at 36 ka, in a cold and dry environment. A second advance stage took place between 18.5 and 19.5 ka, during the Last Glacial Maximum (LGM), when glaciers advanced in a wet environment, with positive rainfall anomalies. A third glacial advance was dated during the Oldest Dryas, in which climate shifted to extremely cold and dry conditions. Finally, a last stage has been identified and proposed to the Younger Dryas, in which precipitation anomalies are negligible. Our results confirm some of the previously made palaeoglacial and palaeoenvironmental inferences for the Iberian Peninsula, as well as provide valuable and accurate anomalies, which are useful for climate modelling.     

Svalbard glaciers re‐advanced during the Pleistocene–Holocene transition

Despite warming regional conditions and our general understanding of the deglaciation, a variety of data suggest glaciers re‐advanced on Svalbard during the Lateglacial–early Holocene (LGEH). We present the first well‐dated end moraine formed during the LGEH in De Geerbukta, NE Spitsbergen. This landform was deposited by an outlet glacier re‐advancing into a fjord extending 4.4 km beyond the late Holocene (LH) maximum. Comparing the timing of the De Geerbukta glacier re‐advance to a synthesis of existing data including four palaeoclimate records and 15 other proposed glacier advances from Svalbard does not suggest any clear synchronicity in glacial and climatic events. Furthermore, we introduce six additional locations where glacier moraines have been wave‐washed or cut by postglacial raised marine shorelines, suggesting the landforms were deposited before or during high relative sea‐level stands, thus exhibiting a similar LGEH age. Contrary to current understanding, our new evidence suggests that the LGEH glaciers were more dynamic, exhibited re‐advances and extended well beyond the extensively studied LH glacial expansion. Given the widespread occurrence of the LGEH glacier deposits on Svalbard, we suggest that the culmination of the Neoglacial advances during the Little Ice Age does not mark the maximum extent of most Svalbard glaciers since deglaciation; it is just the most studied and most visible in the geological record.