Impact of climatic change on streamflow in the upper reaches of the Minjiang River,China

Abstract

Characteristics of hydroclimatic change in the upper reaches of the Minjiang River are analysed using data collected over the past 50 years. The effect of autocorrelation of time series on trend analysis is removed by adopting a pre-whitening technique. Long-term hydrometeorological trend and abrupt changes are analysed by the Mann-Kendall test. The results were validated by the linear trend and Spearman methods. Correlations between runoff change with air temperature and with precipitation were studied with the Pearson method. The results clearly show that average air temperature in the upper reaches of the river is increasing, and precipitation decreasing, with differences in spatio-temporal distribution. Runoff change has a clear positive correlation with precipitation. Meteorological change, especially in precipitation, is the key governing influence of runoff volume. The annual runoff decrease, especially the decrease of inflow in spring and autumn and earlier appearance and longer duration of the low-flow season, will impact greatly on irrigation and municipal water supply. Therefore, relevant measures and further study are necessary.

Editor Z.W. Kundzewicz; Associate editor Q. Zhang

Citation Huang, X.R., Zhao, J.W., Li, W.H., and Jiang, H.X., 2013. Impact of climatic change on streamflow in the upper reaches of the Minjiang River, China. Hydrological Sciences Journal, 59 (1), 154–164.     

An Attempt to Date the Salt-mounds in the Lop Nor Playa

正1 Introduction The Lop Nor playa,located in the eastern end of the Tarim Basin,capped with a thick salt crust covering an area of approximately 5,500 km2(Ma 2007)that closely resembles a"Great Ear"in satellite images.Understanding the formation of the salt crust can provide important     

印度洋浮游生态系统的特点及其对全球变暖的响应

与太平洋和大西洋相比,印度洋有独特的季风和洋流系统和由此驱动的浮游生物分布及生产规律.在全球变暖的背景下,印度洋的变暖趋势比太平洋和大西洋更为显著,是研究变暖对海洋浮游生态系统影响的热点海区之一.文章结合国内外文献,评述印度洋浮游生态系统的现状、特点及对全球变暖的响应,包括印度洋的浮游生物地理分布、南北印度洋浮游生态系...     

基于网络药理学探讨滋补精血、温肾暖宫药物治疗卵巢功能异常疾病的作用机制

目的：基于网络药理学探讨滋补精血、温肾暖宫中药治疗卵巢功能异常疾病的作用机制。方法：采用TCMSP平台获取具有滋补精血、温肾暖宫作用的桑椹、覆盆子、小茴香的活性成分和靶点;网络药理学方法涉及“药物-成分-靶点”网络图的构建和靶点预测。运用京都基因与基因组百科全书（KEGG）数据库确定桑椹、覆盆子、小茴香与卵巢功能异常疾病集群网络的重要信号通路。采用分子对接软件对主要活性成分与核心靶点蛋白进行计算机模拟对接,预测主要成分与核心靶点的结合度。结果：筛选出欧前胡素、β-谷甾醇、槲皮素等10个有效成分,对应于桑椹、覆盆子、小茴香的196个靶点。此外,549个基因与卵巢功能异常疾病密切相关,其中87个与桑椹、覆盆子、小茴香的靶点重叠,被认为与治疗相关。KEGG通路富集分析显示桑椹、覆盆子、小茴香主要作用于卵巢功能异常疾病相关的炎症、卵巢类固醇生成及生长激素的合成分泌和作用等信号通路。分子对接结果显示主要活性成分欧前胡素、β-谷甾醇、槲皮素与靶点均能自发结合。结论：具有滋补精血、温肾暖宫作用的桑椹、覆盆子、小茴香通过多组分、多靶点和多途径协同治疗卵巢功能异常疾病,为后续进一步研究桑椹、覆盆子、小茴香的活性成分及作用机制提供了依据。     

中国1980—2019年1 m土层贮水量的时空变化特征分析

土壤剖面水分信息比表层土壤水分信息难以获取,但对全面认识整个土层的水分含量至关重要。融合多源数据是估算区域土壤剖面水分的有效途径。本文采用随机森林回归算法,利用中国实测土壤水分数据建立了不同季节的表层-深层土壤水分关系模型。据此采用ESA CCI SM遥感表层土壤水分产品估算获得了中国1980—2019年0~10、0~20、0~30、0~40、0~50、0~60、0~70、0~80、0~90和0~100 cm 共10个深度层次土壤水分的时空变化特征。ESA CCI SM产品与实测数据整体上匹配较好但普遍高估,本文提出采用饱和含水量和凋萎系数信息对其进行值域控制,有效降低了该产品的高估误差。随机森林回归模型的精度在秋季最高,夏季和春季次之,冬季最低。模型对干带土壤水分的估算最准确,暖温带和冷温带次之,青藏带准确性最低。计算了中国10个深度层次的土壤贮水量,其多年平均值和标准差分别为1.64±0.11、3.50±0.21、5.29±0.30、7.13±0.38、10.04±0.46、12.25±0.54、14.47±0.62、16.75±0.69、19.05±0.76和21.36±0.83 cm。各深度的土壤水分呈明显的分层,即波动层（0~40 cm）、跃变层（40~60 cm）和稳定层（60~100 cm）。中国1m土层贮水量呈自西北向东北和东南方向递增的分布格局,寒旱区该值较低且空间变异明显,暖湿区该值较高且空间分布更均一。热带、干带和青藏带的1 m土层贮水量在夏季最高,暖温带和冷温带该值在夏季最低。近40年来中国1m土层贮水量在空间上“湿区愈湿,干区愈干”,在时间上“湿季愈湿,干季愈干”。热带土壤在2004—2009年显著变湿,干带土壤显著变湿和变干的转折年份分别为1985—1986年和2013—2014年。中国1m土层贮水量序列最常见的周期是5年和11年。     

The case for intensity targets

Abstract

While most of the world has pursued absolute emission limits for greenhouse gases, the Bush administration has proposed an alternative policy formulation based, among other things, on reducing emissions intensity—that is, emissions per dollar of real gross domestic product (GDP). Critics of this formulation have denounced the general idea of an intensity-based emission target, along with its voluntary nature and modest targets. This raises the question of whether intensity-based emission limits, distinct from the other features of the Bush initiative, offer a useful alternative to absolute emission limits. This essay makes the case that they do, based on how emission targets are framed. The argument draws on four key observations: greenhouse gas emissions will continue to rise over the near term; absolute targets emphasize zero or declining emissions growth while intensity targets do not; developing countries' economic development is integrally tied to emissions growth for the foreseeable future; and intensity targets need not be any more complicated to administer than absolute targets.     

Changes in Global Vegetation Distribution and Carbon Fluxes in Response to Global Warming: Simulated Results from IAP-DGVM in CAS-ESM2

Terrestrial ecosystems are an important part of Earth systems, and they are undergoing remarkable changes in response to global warming. This study investigates the response of the terrestrial vegetation distribution and carbon fluxes to global warming by using the new dynamic global vegetation model in the second version of the Chinese Academy of Sciences (CAS) Earth System Model (CAS-ESM2). We conducted two sets of simulations, a present-day simulation and a future simulation, which were forced by the present-day climate during 1981–2000 and the future climate during 2081–2100, respectively, as derived from RCP8.5 outputs in CMIP5. CO₂ concentration is kept constant in all simulations to isolate CO₂-fertilization effects. The results show an overall increase in vegetation coverage in response to global warming, which is the net result of the greening in the mid-high latitudes and the browning in the tropics. The results also show an enhancement in carbon fluxes in response to global warming, including gross primary productivity, net primary productivity, and autotrophic respiration. We found that the changes in vegetation coverage were significantly correlated with changes in surface air temperature, reflecting the dominant role of temperature, while the changes in carbon fluxes were caused by the combined effects of leaf area index, temperature, and precipitation. This study applies the CAS-ESM2 to investigate the response of terrestrial ecosystems to climate warming. Even though the interpretation of the results is limited by isolating CO₂-fertilization effects, this application is still beneficial for adding to our understanding of vegetation processes and to further improve upon model parameterizations.     

Investigation of the relationship between Euro-Atlantic and West Asia blockings and major stratospheric sudden warmings in the period of 1959–2018

The main aim of this paper is to investigate and compare the possible connection between tropospheric blocking events and major stratospheric sudden warmings (SSWs) in the two periods of 1959−1988 and 1989−2018 to present a dynamical insight into the blocking formation and behaviors. After identifying and characterizing two types of SSWs including wavenumber-1 (W₁) and wavenumber-2 (W₂) in both the periods, the behaviors of blocking events coincided with major SSWs are examined and compared in the two periods. Then, the relationship between blockings and major SSWs is discussed applying the Empirical Orthogonal Function (EOF) method.In general, 18 and 16 major SSW events were identified in the first and second periods, respectively. The investigation of planetary wave activities indicates that the maximum anomalies of geopotential height amplitude and meridional eddy heat flux in the PRE-SSW phase of both types of SSWs, particularly major W₂ warmings, in the second period occurred earlier than those in the first period. The peaks of blocking activities in the second period have also been moved eastward compared with the first period in both prior to and after the onset of SSWs. Moreover, the frequency of blocking event during the PRE-SSW phase of major W₁ warmings in Euro-Atlantic and a large part of West Asia in the second period is less than that of the first period, while the occurrence of blocking during the PRE-SSW phase of major W₂ warmings in Eastern Europe and West Asia has been increased in the second period. In the POST-SSW phase, blocking activity associated with major W₂ warmings is enhanced in West Asia during the second period. In addition, the maximum blocking activities preceding major SSWs in the second period was occurred 5-days prior to the first period. The results of cross-correlation coefficients between blockings and SSWs show significant relationship between them with time lag of about 10-days prior to the onset of warmings in both the periods, especially in the recent years.     

甘肃平凉地区约80万年以来的植被与气候变迁*

将该地约80万年以来的植被发展和气候变化历史划分为14个大的阶段.其中距今约80-78万年、20-14万年、10-1万年三个阶段的植被主要为荒漠草原,气候干冷;距今约78-64、55-46、14-10万年三个阶段植被主要为落叶阔林,气候温暖湿润;其它阶段的植被和气候处于上述二者之间.全新世早、中期,本区气候较现代温湿,晚期趋于温凉半干旱.     

中国西部生态环境变化与对策建议

中国西部地区生态环境的历史演变过程与未来可能变化趋势是科学界面对的一大难题,正确认识西部地区生态环境的演变过程与变化趋势,是西部地区社会经济可持续发展必须面对的课题,是正确制定西部大开发战略方针的重要科学基础。依托中国科学院牵头完成的《中国西部环境演变评估》研究成果,介绍了中国西部地区生态环境演变的主要特征与基本事实,主要强调近50年来全球变暖与人类活动在西部生态环境演变中的重要作用;指出未来的气候与环境变化对西部地区的经济社会发展将产生重要影响;提出了西部地区生态保护与可持续发展的对策与建议,指出西部地区的生态建设必须综合治理、突出重点,特别强调要强化对西部地区的科学研究,为西部大开发服务。