兰州大学机构库 >资源环境学院
基于水量平衡的末次冰盛期以来全球内流区湖泊演化模拟研究
Alternative TitleLake Evolution Simulations in Global Closed Basins since the Last Glacial Maximum based on Water Balance Models
张宇欣
Subtype博士
Thesis Advisor李育
2023-05-19
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name理学博士
Degree Discipline地球系统科学
Keyword末次冰盛期 Last Glacial Maximum 全球内流区 global closed basins 湖泊模拟 lake simulation 驱动机制 driving mechanism 未来评估 future assessment
Abstract

    古气候变化作为全球变化研究的重要组成部分,一直是国际地球科学领域的研究热点。在古气候研究的诸多地质材料中,湖泊因其对气候变化的高度敏感性成为国际过去全球变化计划(Past Global Changes, PAGES)的核心研究领域之一。随着未来地球计划(Future Earth)的实施,PAGES的主要任务也从古气候研究转为基于古气候数据预测未来环境变化,因此进行古湖泊演化与气候变化研究对于评估未来全球变暖背景下的气候格局至关重要。以往研究中多使用湖泊沉积物代用指标重建沉积环境和气候条件,或采用古气候数值模拟推断气候变化的驱动机制,但是代用指标往往具有复杂性、多解性和不确定性,古气候模式又因不同子模式分辨率或参数化方案存在差异而具有多样化版本。代用指标重建与古气候数值模拟的有效结合成为了探究湖泊演化与环境变化及驱动机制的研究趋势。与此同时,现阶段古湖泊与气候模拟研究多集中于特征时期的模拟试验,长时间尺度连续性的模拟工作相对匮乏。开展长时间尺度湖泊演化与气候变化的连续模拟试验,对深入理解湖泊演化的古气候学机理和科学评估未来水文气候格局变化有重要意义。

    全球内流区约占世界陆地面积的五分之一,地理环境相对封闭,水循环相对独立,区内湖泊广泛分布,是进行长时间尺度湖泊演化研究的理想区域。本文使用古气候模式、古气候代用指标等数据,以及虚拟湖泊水量平衡模型、流域水量平衡模型等方法,基于水量平衡原理首先在全球内流区开展了末次冰盛期以来湖泊演化连续模拟以及特征时期湖泊演化片段模拟工作;同时,进一步选择六个典型内流河流域开展了古湖泊面积和流域古水文条件定量重建工作;之后将湖泊演化模拟结果与代用指标重建结果相结合,从湖泊水量平衡分量、大气环流系统及气候强迫机制三个方面综合探讨了湖泊演化的古气候学机理;在此基础上,本文尝试从古气候学视角评估了未来全球内流区的水文气候格局。本研究旨在深入理解末次冰盛期以来全球内流区的湖泊演化过程及其气候学机理,以期为评估未来水资源变化发展方向提供科学依据。本文主要结论如下:

    (1) 在全球内流区,末次冰盛期(Last Glacial Maximum, LGM)、中全新世(Mid-Holocene, MH)和工业革命前期(Preindustrial, PI)的湖泊演化片段模拟结果、LGM以来湖泊演化连续模拟结果综合显示:LGM以来中纬度和低纬度内流区湖泊演化过程呈现反相变化,整体表现为位于中纬度的北美西部、安第斯山脉和巴塔哥尼亚、南非、亚欧大陆西部内流区湖泊水位普遍在LGM时期相对全新世偏高;而位于低纬度的撒哈拉和阿拉伯半岛、东非大裂谷、亚欧大陆东部、澳大利亚内流区在早中全新世广泛发育高水位湖泊,全新世水位普遍高于LGM时期;并且在末次冰消期,大多数内流区湖泊受冷暖事件影响水位会发生剧烈波动。

    (2) 在六个典型内流河流域,古湖泊面积与流域古水文条件重建结果显示:北美洲拉洪坦湖LGM时期的面积约为13854 km2,恢复的流域降水量约为417 mm;在南美洲的的喀喀湖流域,MH时期的湖域面积约为3873 km2,流域降水量约为466 mm;而非洲乍得湖流域MH时期的湖域面积约为301787 km2,重建的流域降水量约为568 mm;在亚洲东部的青海湖流域,MH和PI时期的湖域面积分别约为5071 km2和4814 km2,MH和PI时期的流域降水量分别约为525 mm和338 mm;对于亚洲西部的凡湖流域,LGM和MH时期的湖域面积分别约为4383 km2和3813 km2,流域降水量在LGM和MH时期分别约为511 mm和650 mm;此外,大洋洲艾尔湖LGM、MH和PI时期的面积分别约为0 km2、6258 km2和790 km2,相应时期的流域降水量分别约为138 mm、428 mm和233 mm。

    (3) 模拟结果与重建结果结合显示:拉洪坦湖LGM时期的高水位由高降水和低蒸发共同引起;高降水和低蒸发同样是的的喀喀湖LGM时期高水位发生的诱因,而高蒸发和低降水是导致MH时期水位突然下降的重要因素;低降水和高蒸发共同促成了乍得湖LGM时期和晚全新世的低水位,而高降水和低蒸发共同维持了早中全新世的高水位;长时间尺度的降水变化是控制LGM以来青海湖演化方向的决定性因素;凡湖LGM时期高水位的出现主要受低蒸发影响;低降水和高蒸发联合引发了艾尔湖LGM时期的低水位。造成LGM以来各个内流区湖泊演化及受控因素存在较大差异的原因是其对季风主导气候和西风主导气候的响应不同。低纬度内流区早中全新世普遍较高的降水和湖泊水位与此时低纬度较强的夏季风环流系统密切相关,而中纬度内流区LGM时期普遍较高的降水和湖泊水位则是对此时中纬度西风环流系统强度和位置变化的响应。地球轨道驱动的太阳辐射变化是影响LGM以来季风主导内流区湖泊演变模式的主要强迫因子,温室气体与大陆冰盖是影响LGM以来西风主导内流区湖泊演变模式的主要强迫因子,淡水注入则通过影响大西洋经向翻转环流(Atlantic Meridional Overturning Circulation, AMOC)的变化进而调控全球内流区冰消期的湖泊演化。

    (4) 近年来,北美西部内流区、撒哈拉和阿拉伯半岛内流区、亚欧大陆内流区水资源的减少可能是自然状态下千年尺度水量减少的延续,安第斯山脉和巴塔哥尼亚内流区水资源减少与东非大裂谷和南非内流区水资源增加的现象可能是暂时的。在未来全球持续变暖背景下,北美西部内流区、安第斯山脉和巴塔哥尼亚内流区北部、撒哈拉和阿拉伯半岛内流区北部、亚欧大陆内流区西南部的水资源可能将继续减少,而撒哈拉和阿拉伯半岛内流区南部、东非大裂谷内流区南部、亚欧大陆内流区东南部、澳大利亚内流区东部的水资源可能将继续增加。

Other Abstract

    As an important part of global change research, paleoclimate change has always been a research hotspot in the field of international geoscience. Among many geological materials for paleoclimate research, lakes have become one of the core research fields in the international Past Global Changes (PAGES) project due to their high sensitivity to climate change. With the implementation of the Future Earth project, the primary mission of PAGES has shifted from paleoclimate research to predicting future environmental change based on paleoclimate data, therefore, conducting studies on paleolake evolution and climate change is crucial for assessing climate patterns in the context of future global warming. Previous studies have mostly used lacustrine sediment proxies to reconstruct sedimentary environments and climate conditions, or used numerical paleoclimate simulations to infer the driving mechanisms of climate change, however, lacustrine sediment proxies are often complicated, multiple and uncertain, and paleoclimate models have diverse versions due to the differences in resolution and parameterization schemes of different submodels. The effective combination of proxy reconstruction and numerical simulation has become a research trend to explore lake evolution and environmental change and their driving mechanisms. Meanwhile, the current researches on paleolake and climate simulation are mainly focused on the characteristic periods, while the continuous simulation researches on long time scale are relatively scarce. Accordingly, it is of great significance to perform continuous simulation experiments of lake evolution and climate change on long time scale for deeply understanding the paleoclimatological mechanisms of lake evolution, and scientifically assessing the future hydroclimatic pattern change.

    Covering about one-fifth of the terrestrial surface, the global closed basins with the relatively closed geographical environment, relatively independent water cycle and widespread lakes, are an ideal region for studying lake evolution and climate change on long time scale. Using paleoclimate models, paleoclimate proxies, virtual lake water balance model and basin water balance model, according to the principle of water balance, this study first conducted the continuous simulation of lake evolution since the Last Glacial Maximum, and the time-slice simulation of lake evolution during three characteristic periods in the global closed basins. Meanwhile, six typical closed basins were further selected to perform quantitative reconstruction of paleolake area and paleohydrological conditions of the basins. Then, combining the simulation and reconstruction results, the paleoclimatological mechanism of lake evolution is comprehensively discussed from three aspects of lake water balance components, atmospheric circulation system and climate forcing mechanism. On this basis, this paper attempts to assess the future hydroclimatic pattern of closed basins from the perspective of paleoclimatology. This study aims to deeply understand the lake evolution process and its paleoclimatological mechanisms in the global closed basins since the Last Glacial Maximum, with the purpose of providing a scientific basis for assessing the future development direction of water resources change. The main conclusions of this paper are as follows:

    (1) In global closed basins, the time-slice simulation of lake evolution during the Last Glacial Maximum (LGM), Mid-Holocene (MH) and Preindustrial (PI), and the continuous simulation of lake evolution since the LGM show that: the lake evolution since the LGM presents inverse variation in the mid- and low-latitude closed basins. And the overall performance is that the lake level in the mid-latitude closed basins of Western North America, Dry Andes and Patagonia, South Africa, and western Central Eurasia during the LGM is generally higher than that in the Holocene, while higher level lakes are widely developed in the low-latitude closed basins of Sahara and Arabia, Great Rift Valley, eastern Central Eurasia, and Australia during the early-to-mid Holocene when the lake level is generally higher than that in the LGM. In addition, most of the lakes in closed basins experience significant fluctuations in water level during the last deglaciation under the influence of abrupt warm and cold events.

    (2) In six typical closed basins, the reconstructions of paleolake area and paleohydrological condition show that: during the LGM, the area of Lahontan Lake in North America is about 13854 km2, and the restored watershed precipitation is about 417 mm; in Titicaca Lake Basin of South America, the lake area during the MH is about 3873 km2, and the watershed precipitation is about 466 mm; while the area of Chad Lake in Africa is about 301787 km2 during the MH, and the reconstructed watershed precipitation is about 568 mm; in the eastern part of Asia, the area of Qinghai Lake during the MH and PI is about 5071 km2 and 4814 km2 respectively, and the watershed precipitation during the MH and PI is about 525 mm and 338 mm respectively; in the western part of Asia, the area of Van Lake during the LGM and MH is about 4383 km2 and 3813 km2 respectively, and the watershed precipitation during the LGM and MH is about 511 mm and 650 mm respectively; besides, the area of Eyre Lake in Oceania during the LGM, MH and PI is about 0 km2, 6258 km2 and 790 km2 respectively, and the watershed precipitation in the corresponding periods is about 138 mm, 428 mm and 233 mm respectively.

    (3) The combined results of lake evolution simulation and hydrological condition reconstruction indicate that: the high water level of Lahontan Lake during the LGM is caused by high precipitation and low evaporation; high precipitation and low evaporation also contribute to the occurrence of high water level in Titicaca Lake during the LGM, while high evaporation and low precipitation are the main factors leading to the sudden drop of water level in Titicaca Lake during the MH; low precipitation and high evaporation jointly result in the low water level of Chad Lake during the LGM and late Holocene, while high precipitation and low evaporation maintain the high water level of Chad Lake in the early-to-mid Holocene; precipitation change on long time scale is the decisive factor controlling the evolution direction of Qinghai Lake since the LGM; the occurrence of high water level in Van Lake during the LGM is mainly induced by low evaporation; the combination of low precipitation and high evaporation triggers the low water level of Eyre Lake during the LGM. The different responses to the monsoon-dominated climate and the westerly-wind-dominated climate are the reasons for the great differences in lake evolution and controlled factors in each closed basin since the LGM. More specifically, the general higher precipitation and lake level in the low-latitude closed basins during the early-to-mid Holocene are closely related to the strengthened summer monsoon circulation system in the low-latitudes, while the general higher precipitation and lake level in the mid-latitude closed basins during the LGM are in response to the changes in the intensity and position of the westerly wind circulation system in the mid-latitudes. Solar insolation change driven by the Earth's orbit is the main forcing factor affecting the lake evolution pattern in the monsoon-dominated closed basins since the LGM, and greenhouse gases and continental ice sheets are the significant forcing factors controlling the lake evolution pattern in the westerly-wind-dominated closed basins since the LGM. Besides, meltwater injection regulates the lake evolution of most closed basins through influencing the change of Atlantic Meridional Overturning Circulation (AMOC) during the last deglaciation.

    (4) Over the last few decades, the declining trend of water resource in Western North America, Sahara and Arabia, and Central Eurasia possibly has inherited the decreased water volume conditions across the millennial-scale under the natural state, while the decreasing water resource in Dry Andes and Patagonia, and the increasing water resource in Great Rift Valley and Southern Africa may be temporary. Under the continued global warming in the future, the water volume in parts of Western North America, northern Dry Andes and Patagonia, northern Sahara and Arabia, and southwestern Central Eurasia will continue to decline, while in parts of southern Sahara and Arabia, southern Great Rift Valley, southeastern Central Eurasia, and eastern Australia it will continue to rise.

MOST Discipline Catalogue理学 - 地理学
URL查看原文
Language中文
Other Code262010_120190907840
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/537099
Collection资源环境学院
Affiliation
兰州大学资源环境学院
Recommended Citation
GB/T 7714
张宇欣. 基于水量平衡的末次冰盛期以来全球内流区湖泊演化模拟研究[D]. 兰州. 兰州大学,2023.
Files in This Item:
There are no files associated with this item.
Related Services
Recommend this item
Bookmark
Usage statistics
Export to Endnote
Altmetrics Score
Google Scholar
Similar articles in Google Scholar
[张宇欣]'s Articles
Baidu academic
Similar articles in Baidu academic
[张宇欣]'s Articles
Bing Scholar
Similar articles in Bing Scholar
[张宇欣]'s Articles
Terms of Use
No data!
Social Bookmark/Share
No comment.
Items in the repository are protected by copyright, with all rights reserved, unless otherwise indicated.