EGI OpenIR
中亚地区干湿时空演变特征及未来情景预估研究
Alternative TitleThe Analysis and Projection of Dry/Wet Climate Change in Central Asia
他志杰
Subtype博士
Thesis Advisor于瑞德
2019-06-30
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline理学博士
Keyword中亚地区 干湿变化 标准化降水蒸散指数 未来情景预估 Central Asia Dryness and wetness variation SPEI Projection
Abstract近几十年来, 随着全球气候的逐渐变暖, 极端气候事件频发, 其中造成严重损失, 持续事件较长的一种就是干旱。 对于干旱的研究一直是气候变化研究领域中的热点问题。 研究干旱的起因, 历时, 以及影响是全球气候变化研究领域中尤为重要的一个研究方向。本文以标准化降水蒸散指数作为衡量中亚地区干旱严重程度的量化指标, 首先分析了中亚地区 1961-2015 年气候干湿变化的事实, 其次讨论了中亚地区气候干湿变化与其所对应的大气环流场之间的关系, 最后预测了中亚地区未来气候变化情景下的干湿变化趋势, 最终得出以下结论:首先, 我们从众多干旱指数中选择标准化降水蒸散指数作为干旱指标, 并分析了 1961 年至 2015 年中亚干旱的时空变化特征。 结果表明: 整体上来看, 中亚地区的干旱主要发生在 1975 年和 1996 年, 哈萨克斯坦在 20 世纪 70 年代中期,90 年代后期经历了一个比较干旱的阶段。 塔吉克斯坦整体上表现出湿润的态势,历史时期比较干旱的年份是 1971 年, 干旱指数达到了-1.11, 属于中度干旱; 最湿润的年份是 1969 年, 干旱指数为 1.94, 达到严重湿润。 吉尔吉斯斯坦的气候呈现出干旱和湿润交替变化的特征, 其中比较干旱的年份是 1961 年, 1962 年,1974 年, 1975 年, 1984 年, 1995 年, 1997 年和 2007 年, 干旱程度是轻度干旱。最为湿润的年份是 1969 年和 2003 年, 为严重湿润。 土库曼斯坦和乌兹别克斯坦的干旱指数均表现出下降的趋势,干旱主要发生在 20 世纪 90 年代中后期。其次,中亚地区 1961-2015 年标准化降水蒸散指数逐月分布特征是: 整个中亚地区 20世纪 60 年代到 70 年代初比较湿润, 从 1975 年 4 月份开始出现了干旱, 干旱程度为轻旱, 5 月到 8 月干旱程度逐渐加剧, 干旱程度由轻度干旱转变为中度干旱,干旱水平在 9 月达到严重干旱, 干旱指数为-1.53。 干旱程度在 10 月得到缓解,由严重干旱转变为中度干旱状态。 这次中度干旱事件一直持续到 1976 年的 4 月份, 历时 12 个月, 干旱的严重程度, 干旱的持续时间之久都是中亚地区近 55a来罕见的。 最后, 分析了近 55a 来中亚地区的干旱面积覆盖率的变化特征。 中亚地区干旱面积覆盖率在 20 世纪 60 年代至 70 年代初, 都在 22%以下; 1975 年,中亚干旱面积覆盖率最高, 达到 60.7%。 从 20 世纪 80 年代到 90 年代初,中亚的平均干旱面积覆盖率不到 30%。 从 20 世纪 90 年代中期到 21 世纪初, 是中亚地区的干旱面积覆盖率较高的一段时期。干旱的发生往往与大规模大气环流场的异常密切相关。 因此, 本文利用正交经验函数分解(EOF) 分析了 55a 来中亚地区干湿变化的主要模态, 以及主要模态所对应的大气环流场背景。 结果表明: 中亚地区干湿变化的第一空间模态表现为中部与南北部反向变化的空间型, 中西部地区是干湿变化异常的高值中心, 这一空间分布型对应在中高纬度地区存在明显的纬向波列, 北太平洋和欧洲东部,亚洲西部地区的气压表现为异常偏低, 欧洲西岸、 贝加尔湖南部呈现异常高压,在 500 hPa 位势高度场显示出明显的欧亚太平洋遥相关型, 表明贝加尔湖阻塞高压活跃。 因此, 欧亚太平洋遥相关型可能是影响中亚地区干湿变化的一个重要环流因子。 中亚地区干湿变化的第二主要模态为南北相反变化的空间型, 中亚地区的这种干湿分布类型可能是受到了北极涛动的影响。全球气候模式是预测未来全球气候变化的重要工具。本文在分析了中亚地区近半个世纪的干湿演变事实后, 采用全球气候模式用于估计中亚地区未来的干湿变化趋势。 本文采用了 CMIP5 中 21 个全球气候模式的数据, 利用多模式集合平均的方法, 分别计算了标准化降水指数(SPI) 和标准化降水蒸散指数(SPEI) 。利用不同的干旱指数对典型浓度路径 RCP4.5 情景下的中亚地区未来的干湿变化趋势进行预测。 结果表明, 在未来全球持续变暖背景下, 未来中亚地区干旱化的趋势将延续, 变干明显的是中亚地区的西南部地区, 特别是乌兹别克斯坦和土库曼斯坦的沙漠地区。 基于 SPI1 和 SPI3 计算得出的中亚地区未来的干旱频率将呈现下降趋势, 由 SPI12 得到的干旱频率在未来时段呈现出先下降后增加的趋势。基于 SPEI1、 SPEI3、 SPEI12 的干旱频率在未来时段前期下降, 中、 后期逐渐增加。
Other AbstractIn recent decades, with the continued warming of the global climate, extremeweather events occur frequently, among which serious losses are caused. One kind ofprolonged event is drought. Therefore, the study of the causes, duration and effects ofdrought is a particularly important research direction in the study of climate change.This study takes drought as the research object, and the research area is Central Asia,and the following conclusions are drawn:Firstly, the spatial and temporal characteristics of drought in Central Asia wereanalyzed using the Standardized Precipitation Evapotranspiration index (SPEI)released by the Instituto Pirenaico de Ecología, Spanish National Research Council.The results show that, on the whole, drought in Central Asia mainly occurred in 1975and 1996. Kazakhstan experienced a relatively period of drought in the mid-1970s andlate 1990s. Tajikistan shows a wet situation. The drought index reached - 1.11 in 1971,which is a moderate drought. In 1969, the drought index reached 1.94, which is aserious humidity. Kyrgyzstan shows alternating wet and dry conditions. In the early1960s, the mid-1970s, the early 1980s, the late 1990s, and 2007 and 2008, there was aslight drought trend. The wetter years were the late 1960s, the late 1980s and the early21st century. Both the drought index of Turkmenistan and that of Uzbekistan showeda downward trend, and the drought mainly occurred in the mid and late 1990s.Secondly, from the monthly distribution of SPEI in Central Asia from 1961 to 2015, itcan be seen that the Central Asia was relatively humid from 1960s to early 1970s.Drought began to appear in April 1975, and the degree of drought was light. Thedegree of drought intensified from May to August, reaching mid-drought. The degreeof drought in September reached serious drought. The SPEI value was -1.53. Thedrought alleviated in October from severe to moderate. This moderate drought eventlasted until April 1976. It lasted 12 months. The severity of drought and the durationof drought were rare in Central Asia in recent 55 years. Finally, the change of drought area coverage in Central Asia in the past 55 years was analyzed. The drought areacoverage in Central Asia was below 22% from 1960s to early 1970s. In 1975, thedrought area coverage in Central Asia was the highest, reaching 60.7%. From the1980s to the early 1990s, the drought area coverage remained below 30%. From thelate 1990s to the early 21st century, the drought area coverage in Central Asia wasrelatively high.The large-scale atmospheric circulation anomaly often leads to the occurrence ofdrought. Therefore, in this study, Empirical Orthogonal Function (EOF) was used toanalyze the main modes of dry and wet changes in 55a in Central Asia, as well as thelarge-scale atmospheric circulation background corresponding to each mode. Theresults show that: the first spatial mode shows the reverse change of the middle andthe north and south in CA. The central and western regions is high value center ofdrought-wet change. This spatial pattern corresponds to the existence of obvious zonalwave train in the middle and high latitudes. The pressure over the north Pacific andeastern Europe and western Asia is unusually low. The pressure on the west coast ofEurope and the south of Lake Baikal is unusually high. The 500 hPa geopotentialheight field shows an obvious Eurasian-Pacific teleconnection pattern, indicating thatthe Lake Baikal blocking high is active. Therefore, the Eurasian Pacific telecorrelationmay be an important circulation factor for the dry-wet change in central Asia. Thesecond main mode is the spatial pattern of north-south opposite changes. Thedistribution of dry and wet type may be influenced by the arctic oscillation.Global climate models are important tools for predicting future global climatechange.After analyzing the evolution of dry and wet in Central Asia for nearly half acentury, the global climate model is used to estimate the future dry and wet trends incentral Asia.In this study, the 21 global climate models were used, and thestandardized precipitation index (SPI) and the standardized precipitationevapotranspiration index (SPEI) were calculated by using the method of multi-modelensemble. Different drought indexes were used to predict the future dry and wet variation trends in Central Asia under the scenario of RCP 4.5.The results show thatunder the background of global warming in the future, the trend of dryness in CentralAsia will continue, especially in the desert areas of Uzbekistan and Turkmenistan.Thefuture drought frequency of Central Asia calculated based on SPI1 and SPI3 willdecrease, and the drought frequency of SPI12 will first decrease and then increase inthe future.The drought frequency based on SPEI1, SPEI3 and SPEI12 decreased in theearly period and increased in the middle and late period.
Subject Area自然地理学
Language中文
Document Type学位论文
Identifierhttp://ir.xjlas.org/handle/365004/15356
Collection中国科学院新疆生态与地理研究所
研究系统
Affiliation中国科学院新疆生态与地理研究所
First Author Affilication中国科学院新疆生态与地理研究所
Recommended Citation
GB/T 7714
他志杰. 中亚地区干湿时空演变特征及未来情景预估研究[D]. 北京. 中国科学院大学,2019.
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