1961—2018年西南地区夏季干旱变化特征及其与环流异常的联系          下载免费PDF全文

吕纯月  管兆勇  黄垭飞 《大气科学学报》2021,44(4):573-584

利用1961—2018年中国西南地区312站降水观测资料、NCEP/NCAR再分析资料及海表温度资料,采用夏季SPI(Standardized Precipitation Index)指数作为干旱指数,研究了西南地区夏季干旱变化特征及其与环流异常的联系。结果表明:西南地区夏季总体呈现变干趋势,尤其在云南、四川东南部干旱化趋势显著。当西南地区夏季显著干旱时,该地区对流层低层辐散、上层辐合,且向该地区的水汽输送偏少。造成西南地区干旱维持的原因可归结为大气波动活动异常和海温异常强迫。前者通过西风带扰动向下游的能量频散,为西南地区低层辐散、上层辐合的环流异常的形成和维持提供了必要的扰动能量积聚;后者通过热带西北太平洋异常热源对大气的强迫,使得该地区对流层低层(上层)形成异常辐合(辐散),在西南地区和热带西北太平洋形成了斜向垂直环流,使西南地区受下沉气流控制,从而形成了利于降水显著偏少和干旱发生并维持的条件。  相似文献   

Intraseasonal oscillation of the southwest monsoon over Sri Lanka and evaluation of its subseasonal forecast skill          下载免费PDF全文

L.A.D.Buddika Bandurathna  Lu Wang  Xuan Zhou  Yifeng Cheng  Lin Chen 《大气和海洋科学快报》2021,14(6):7-13

斯里兰卡的雨季发生于5-9月间,主要受西南季风的控制.本文发现该地区的西南季风降水存在很强的次季节变率,主导周期为10-35天.降水的季节内变化与西传的异常气旋有关.进一步,利用S2S比较计划中欧洲中心的数值预报模式(ECMWF)提供的回报试验数据,评估了当今动力模式对斯里兰卡西南季风次季节变化的预报技巧.结果显示,对季风指数的预测技巧超过30天,而对降水指数的预测技巧大约两周,且模式的预报技巧具有明显的年际差异.分析表明,能否正确模拟出大尺度环流对热带对流的响应是影响斯里兰卡降水预测的重要因子.  相似文献   

Comparison of two types of persistent heavy rainfall events during sixteen warm seasons in the Sichuan Basin          下载免费PDF全文

Yuanchun Zhang  Jianhua Sun  Luqi Zhu  Huan Tang  Shuanglong Jin  Xiaolin Liu 《大气和海洋科学快报》2021,14(6):48-53

本文筛选出四川盆地西部(盆西型)和盆地东部(盆东型)持续性暴雨个例,深入对比两类持续性暴雨的大气环流特征和直接造成持续性暴雨的西南低涡维持的机理.四川盆地的短波槽和西太平洋副热带高压的配置有利于持续性暴雨的维持,盆东型的降水强度较盆西型个例强,高空急流位置偏南,南亚高压的强度更强,高层辐散更强,对流层中层副热带高压偏东偏南.盆西型的水汽输送主要来自南海,而盆东型的水汽输送主要来自南海和孟加拉湾.合成涡度收支的结果表明散度项是两类持续暴雨中西南涡维持的主要原因,但盆西型中,垂直平流的作用更强.  相似文献   

Groundwater characteristics and climate and ecological evolution in the Badain Jaran Desert in the southwest Mongolian Plateau     

《China Geology》2021,4(3):421-432

The Badain Jaran Desert is the third largest desert in China, covering an area of 50000 km². It lies in Northwest China, where the arid and rainless natural environment has a great impact on the climate, environment, and human living conditions. Based on the results of 1∶250000 regional hydrogeological surveys and previous researches, this study systematically investigates the circulation characteristics and resource properties of the groundwater as well as the evolution of the climate and ecological environment since the Quaternary in the Badain Jaran Desert by means of geophysical exploration, hydrogeological drilling, hydrogeochemistry, and isotopic tracing. The results are as follows. (1) The groundwater in the Badain Jaran Desert is mainly recharged through the infiltration of local precipitation and has poor renewability. The groundwater recharge in the desert was calculated to be 1.8684×10⁸ m³/a using the water balance method. (2) The Badain Jaran Desert has experienced four humid stages since the Quaternary, namely MIS 13-15, MIS 5, MIS 3, and the Early–Middle Holocene, but the climate in the desert has shown a trend towards aridity overall. The average annual temperature in the Badain Jaran Desert has significantly increased in the past 50 years. In detail, it has increased by about 2.5°C, with a higher rate in the south than in the north. Meanwhile, the precipitation amount has shown high spatial variability and the climate has shown a warming-drying trend in the past 50 years. (3) The lakes in the hinterland of the Badain Jaran Desert continuously shrank during 1973–2015. However, the vegetation communities maintained a highly natural distribution during 2000–2016, with the vegetation cover has increased overall. Accordingly, the Badain Jaran Desert did not show any notable expansion in that period. This study deepens the understanding of groundwater circulation and the climate and ecological evolution in the Badain Jaran Desert. It will provide a scientific basis for the rational exploitation of the groundwater resources and the ecological protection and restoration in the Badain Jaran Desert.© 2021 China Geology Editorial Office.  相似文献   

Implications of Japan’s long term climate mitigation target and the relevance of uncertain nuclear policy     

Diego Silva Herran  Shinichiro Fujimori  Mikiko Kainuma 《Climate Policy》2019,19(9):1117-1131

Achieving long-term climate mitigation goals in Japan faces several challenges, starting with the uncertain nuclear power policy after the 2011 earthquake, the uncertain availability and progress of energy technologies, as well as energy security concerns in light of a high dependency on fuel imports. The combined weight of these challenges needs to be clarified in terms of the energy system and macroeconomic impacts. We applied a general equilibrium energy economic model to assess these impacts on an 80% emission reduction target by 2050 considering several alternative scenarios for nuclear power deployment, technology availability, end use energy efficiency, and the price of fossil fuels. We found that achieving the mitigation target was feasible for all scenarios, with considerable reductions in total energy consumption (39%–50%), higher shares of low-carbon sources (43%–72% compared to 15%), and larger shares of electricity in the final energy supply (51%–58% compared to 42%). The economic impacts of limiting nuclear power by 2050 (3.5% GDP loss) were small compared to the lack of carbon capture and storage (CCS) (6.4% GDP loss). Mitigation scenarios led to an improvement in energy security indicators (trade dependency and diversity of primary energy sources) even in the absence of nuclear power. Moreover, preliminary analysis indicates that expanding the range of renewable energy resources can lower the macroeconomic impacts of the long term target considerably, and thus further in depth analysis is needed on this aspect.

Key policy insights

• For Japan, an emissions reduction target of 80% by 2050 is feasible without nuclear power or CCS.

• The macroeconomic impact of such a 2050 target was largest without CCS, and smallest without nuclear power.

• Energy security indicators improved in mitigation scenarios compared to the baseline.

  相似文献   

高原涡和西南涡影响的两次四川暴雨过程的对比分析     

周玉淑  颜玲  吴天贻  谢泽明 《大气科学》2019,43(4):813-830

为了进一步研究高原涡、西南涡对西南地区暴雨的影响,本文用中国气象局自动站与CMORPH降水数据融合的逐时降水资料、国家卫星气象中心的逐时FY-2E卫星的云顶亮温（TBB）资料、欧洲气象资料中心（ERA-interim）的再分析资料,通过天气学诊断分析方法以及拉格朗日轨迹模式HYSPLITv4.9,对发生在四川盆地的有高原涡东移影响西南涡发展引发暴雨的两次过程进行对比分析,发现:（1）两次暴雨过程的降水强度和分布有明显区别,并且TBB活动特征显示在过程一中有MCC（Mesoscale Convective Complex）的产生和发展,过程二则没有。（2）对于过程一,500 hPa上,高原涡逐渐减弱为高原槽并伸展到四川盆地上空,850 hPa上,在鞍型场附近有MCC的产生和发展,200 hPa上,高原涡在南亚高压北部偏西风急流下方的强辐散区内,位于南亚高压东南侧急流区下方稳定少动,偏东风急流北部有辐散中心,有利于西南涡的加强。对于过程二,500 hPa高原涡东移在四川盆地上空与西南涡耦合,形成一个稳定且深厚的系统,这也是过程二的暴雨强度比过程一强的最主要原因。200 hPa上,四川盆地始终位于南亚高压东侧的西北气流中,“抽吸作用”明显。（3）在过程一中,位涡逐渐东传且位涡增加的地方对应强降水区与MCC发展区,反映了暴雨和位涡的发展基本一致。在过程二中,中层位涡高值区从高原上东移并下传至盆地上空,两涡耦合使得上下层打通,位涡值比耦合之前单独的两涡强度更强。 MCC产生的必要条件是中层大气要有强正涡度、强辐合和强上升运动,在未产生MCC前,过程一与过程二在盆地上空的动力条件甚至是相反的;从热力条件看,过程一中有明显的干冷空气入侵,增强不稳定条件,有利于MCC的产生并引发强降水;另一方面,本文也应证了二阶位涡的水平分布与暴雨落区有较好的对应关系。（4）通过拉格朗日方法的水汽轨迹追踪模式和聚类分析方法分析可得两次暴雨过程的水汽输送源地和通道也有明显区别,过程一主要有两条水汽通道,通道一来自阿拉伯海和孟加拉湾洋面的底层,通道二来自四川南部750 m以下高度;而过程二的主要水汽输送通道有三条,通道一来自西方地中海、黑海和里海上空1500～2500 m高度附近,通道二来自阿拉伯海和印度洋的底层,通道三的水汽从孟加拉湾低层绕过云贵高原直接输送到四川盆地。  相似文献   

日本海西南陆坡全新世对马暖流演化的沉积学和地球化学记录     

徐兆凯  崔镇勇  林东日  李铁刚  李安春 《海洋地质与第四纪地质》2010,(1)

对日本海西南陆坡对马暖流主流轴下方高沉积速率沉积物柱状样,进行了沉积学和地球化学系统研究,以探讨全新世以来对马暖流在研究区的形成与演化,并得出了与附近地区古海洋学方法非常相近的结果,从而为今后研究区的对马暖流演化研究提供了沉积学和地球化学指标。据此,该柱状样中所记录的对马暖流演化可划分为5个主要阶段。全新世初期(9.6kaBP),对马暖流开始进入日本海,其强度较弱,同时,伴随着富营养东海沿岸水的影响,海底环境由还原性向氧化性转变;6.5kaBP时,对马暖流控制下的日本海南部现代对流模式最终建立起来,东海沿岸水的影响基本消失,随后,对马暖流明显减弱;3.0kaBP时,对马暖流再次增强并基本达到现在水平,且在随后的3ka里保持总体稳定,期间在2.0～0.7kaBP存在一次较弱的减弱过程。  相似文献   

中国大陆地区热流数据的分布及其初步分析          下载免费PDF全文

黄少鹏 《地震地质》1989,11(3):17

本文首次系统地收集整理了观测资料比较齐全、国内公开发表的热流数据167个,并对之进行了初步分析。这些数据的地理分布还很不均匀,热流值变化范围为25—245mWm-2,多种平均方法得到的结果表明,中国大陆区域代表性热流值范围为61—68mWm-2。作者所作的经纬度网格和条带统计还揭示,数据覆盖区内热流沿经、纬向的分布有明显的差异,纬向条带平均热流值看来具有波状起伏变化的规律。这一结果已经得到日本及其周围海域热流数据的初步印证,如果获得更广泛的证实,无疑具有深刻的地质和地球物理意义  相似文献   

赣西南下奥陶统樟木曲组笔石带的修正和补充   总被引：2，自引：0，他引：2  

肖承协  陈洪冶  谢文伟 《华东地质学院学报》1988,(3)

本文在对笔石作系统研究的基础上,对樟木曲组的笔石带进行了补充和修正。由原来的9个笔石带划分为11个笔石带,厘定了各笔石带的范围和笔石群的总体面貌,并逐带与国内外进行了对比。文内还涉及到宁国阶的顶界、上下两层下垂时笔石以及关于肿笔石与心笔石混生的问题。  相似文献   

近40年中国区域的气候型变化与北半球大气环流特征10年际时空变化的关系   总被引：3，自引：0，他引：3  

徐祥德  苗峻峰  章基嘉 《热带气象学报》1994,10(1):38-36

根据１８００－１９８９年（１１０年）的资料，分析研究了新加坡地区月平均和年平均降雨量的一些特征。主要结论是：新加坡年平均降雨量存在准２－６年和１８年的周期振荡；亚洲季风以及ＥＮＳＯ对新加坡降雨量有明显的影响。新加坡年雨量的谷值出现在西南季风期而峰值在东北季风期。在Ｅｌ Ｎｉｎｏ年，新加坡降雨量多为负距平；而在反Ｅｌ Ｎｉｎｏ年，新加坡降雨量多为正距平。  相似文献