长江三角洲地区人体舒适度时空变化特征北大核心CSCD     

张春阳  李正泉  肖晶晶  周良女  方贺  张立波  张含 《气候与环境研究》2022,27(5):669-678

基于1981~2020年ERA5逐小时再分析资料,采用通用热气候指数(Universal Thermal Climate Index,UTCI)计算方法,分析了气候变化背景下长江三角洲地区人体生理热响时空变化特征。研究表明:近40年长江三角洲地区人体无冷热胁迫气候条件的出现频率约为43.77%、热胁迫和冷胁迫出现频率分别约为22.42%和33.81%,其中,显著热胁迫和显著冷胁迫出现频率分别约为8.38%和1.58%;在空间分布上,长江三角洲地区无冷热胁迫气候条件的出现频率总体表现为南多北少地带性分布,兼有山区多平原少、沿海多内陆少分布特征,显著热胁迫主要出现在皖西和皖南的平原以及浙江的嘉绍平原和金衢盆地,显著冷胁迫主要出现在苏北、皖北和舟山以北的沿海岸区;在全球气候变暖背景下,长江三角洲地区UTCI值的年代际变化呈上升趋势,由1981~1990年13.83℃增加至2011~2020年14.75℃,人体生理热响应表征为冷胁迫减少、热胁迫增加、无冷热胁迫基本不变,春季无冷热胁迫时长的增加基本抵消了夏季无冷热胁迫时长的减少。  相似文献   

Climatology of Shear Line and Related Rainstorm over the Southern Yangtze River Valley Based on an Improved Intelligent Identification Method     

刘金卿  陈鹤  徐靖宇 《热带气象学报(英文版)》2022,28(4):413-424

Based on four reanalysis datasets including CMA-RA, ERA5, ERA-Interim, and FNL, this paper proposes an improved intelligent method for shear line identification by introducing a second-order zonal-wind shear. Climatic characteristics of shear lines and related rainstorms over the Southern Yangtze River Valley (SYRV) during the summers (June-August) from 2008 to 2018 are then analyzed by using two types of unsupervised machine learning algorithm, namely the t-distributed stochastic neighbor embedding method (t-SNE) and the k-means clustering method. The results are as follows: (1) The reproducibility of the 850 hPa wind fields over the SYRV using China’s reanalysis product CMA-RA is superior to that of European and American products including ERA5, ERA-Interim, and FNL. (2) Theory and observations indicate that the introduction of a second-order zonal-wind shear criterion can effectively eliminate the continuous cyclonic curvature of the wind field and identify shear lines with significant discontinuities. (3) The occurrence frequency of shear lines appearing in the daytime and nighttime is almost equal, but the intensity and the accompanying rainstorm have a clear diurnal variation: they are significantly stronger during daytime than those at nighttime. (4) Half (47%) of the shear lines can cause short-duration rainstorms (≥20 mm (3h)-1 ), and shear line rainstorms account for one-sixth (16%) of the total summer short-duration rainstorms. Rainstorms caused by shear lines are significantly stronger than that caused by other synoptic forcing. (5) Under the influence of stronger water vapor transport and barotropic instability, shear lines and related rainstorms in the north and middle of the SYRV are stronger than those in the south.  相似文献   

Decreasing predictability as a precursor indicator for abrupt climate change     

He  Wenping  Xie  Xiaoqiang  Mei  Ying  Wan  Shiquan  Zhao  Shanshan 《Climate Dynamics》2021,56(11):3899-3908

Abrupt climate change has an important impact on sustainable economic and social development, as well as ecosystem. However, it is very difficult to predict abrupt climate changes because the climate system is a complex and nonlinear system. In the present paper, the nonlinear local Lyapunov exponent (NLLE) is proposed as a new early warning signal for an abrupt climate change. The performance of NLLE as an early warning signal is first verified by those simulated abrupt changes based on four folding models. That is, NLLE in all experiments showed an almost monotonous increasing trend as a dynamic system approached its tipping point. For a well-studied abrupt climate change in North Pacific in 1976/1977, it is also found that NLLE shows an almost monotonous increasing trend since 1970 which give up to 6 years warning before the abrupt climate change. The limit of the predictability for a nonlinear dynamic system can be quantitatively estimated by NLLE, and lager NLLE of the system means less predictability. Therefore, the decreasing predictability may be an effective precursor indicator for abrupt climate change.

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The asymmetric impacts of ENSO modoki on boreal winter climate over the Pacific and its rim     

He  Linqiang  Hao  Xin  Han  Tingting 《Climate Dynamics》2021,56(1):29-44

Climate Dynamics - The El Niño–Southern Oscillation (ENSO) Modoki phenomenon has a substantial influence on regional climate. In this study, the results derived from observational and...  相似文献   

2018年春季北京一次沙尘天气边界层特征及来源分析     

桂海林  秦贺  赵培涛  王飞  唐志军  王继康  朱媛媛  褚旸晰 《气象与环境学报》2021,37(4):18-25

2018年3月27-28日,内蒙古中东部、中国东北地区、华北等地出现一次大范围沙尘天气。28日凌晨,沙尘进入北京,受此影响北京出现了严重的污染天气。本文利用中国气象局地面常规观测资料、气溶胶激光雷达、风廓线雷达资料、生态环境部大气成分等资料分析了北京沙尘天气前后边界层特征、沙尘来源以及沙尘天气前后大气污染特征。结果表明：此次沙尘天气期间,北京沙尘气溶胶退偏振比约为0.25-0.40,退偏振比数据显示此次沙尘首先从高空进入北京,比地面提前6 h。此次影响北京的沙尘主要来自于北路,东路沙尘有一定补充;沙尘影响时段,北京Ca、Fe、Na、K、Mn等元素浓度显著升高,与该物质地壳丰度相当,污染物元素Cu、Zn、Pb、Cd、As等浓度有所降低,丰度远大于该物质在地壳中丰度。  相似文献   

An analytical model for evaluating the dynamic response of a tunnel embedded in layered foundation soil with different saturations     

Di  Honggui  Guo  Huiji  Zhou  Shunhua  Wang  Binglong  He  Chao  Zhang  Xiaohui 《地震工程与工程振动(英文版)》2022,21(3):663-681

Earthquake Engineering and Engineering Vibration - This paper proposes an analytical model for evaluating the dynamic response of an underground railway tunnel in layered foundation soil with...  相似文献   

Projection of droughts and their socioeconomic exposures based on terrestrial water storage anomaly over China     

Yin  Jiabo  Guo  Shenglian  Yang  Yan  Chen  Jie  Gu  Lei  Wang  Jun  He  Shaokun  Wu  Boyang  Xiong  Jinghua 《中国科学:地球科学(英文版)》2022,65(9):1772-1787

Science China Earth Sciences - Global warming has altered the thermodynamic and dynamic environments of the climate system, thus affecting the energy budget and water cycle process of the...  相似文献   

2021年青海玛多Mw7.5地震的同震变形及断层滑动模型研究     

张岚  李琦  唐河  孙文科 《地球物理学报》2022,65(3):1044-1056

2021年5月22日,中国青海玛多县发生了M_W7.5地震.针对此次地震,国内外多家机构发布的震源机制解和有限断层滑动模型结果大都是基于半无限空间地球模型的位错理论反演得到的,未考虑地球曲率和层状效应的影响.该影响的量级以及其是否可以忽略目前仍是一个未知问题,值得研究.为此,本文利用美国地质调查局(USGS)、中国科学院青藏高原研究所以及中国地震局地球物理研究所提供的三个断层模型,基于弹性半无限空间、均质球、PREM三种地球模型的位错理论,分别计算了地表同震位移场和应变场,并对比分析了这些结果的差异.我们发现基于PREM位错理论的同震位移场与半无限空间模型的对应值差异约为3~28 cm,占PREM位错理论值的10%~30%,应变场差异更大,表明地球曲率和层状效应的影响不可忽略.此外,理论同震形变结果与GNSS和InSAR形变观测数据对比发现,基于PREM模型的理论位移场最接近于观测值.利用InSAR数据和三种地球模型反演得到的有限断层滑动模型存在差异,说明了地球模型的选择对断层模型的反演具有一定影响.本文的结果为今后对此次地震的观测数据物理解释和断层滑动反演提供了理论参考.  相似文献   

Subglacial Meltwater Recharge in the Dongkemadi River Basin,Yangtze River Source Region     

Qiule He  Xingxing Kuang  Jiachang Chen  Jiu Jimmy Jiao  Sihai Liang  Chunmiao Zheng 《Ground water》2022,60(3):434-450

Glaciers on the Tibetan Plateau play an important role in the local hydrological cycle. However, there are only few studies on groundwater in the alpine basins in the Tibetan Plateau which considered the effects of glaciers. Glaciers are extensively distributed in the Dongkemadi River Basin, which is a representative alpine basin in the Yangtze River source region. This study focuses on building a numerical groundwater flow model with glaciations using HydroGeoSphere (HGS) to simulate subglacial meltwater recharge to groundwater in the Dongkemadi River Basin in response to future climate changes. Effects of hydraulic conductivity, precipitation, and temperature on subglacial meltwater recharge to groundwater were discussed. Glacier changes in the future 50 years were predicted under different climate change scenarios. Results show that: (1) the average thickness of the glacier will change significantly; (2) the simulated rate of annual mean subglacial meltwater recharge to groundwater is 4.58 mm, which accounts for 6.33% of total groundwater recharge; and (3) hydraulic conductivity has the largest influence on subglacial meltwater recharge to groundwater, followed by temperature and precipitation. Results of this study are also important to sustainable water resource usage in the Yangtze River source region.  相似文献   

Directional Support Method for Tunnel Jointed Rock Mass     

Wu  Xu  Xu  Jinliang  Zhang  Liyuan  Sun  Jinglai  He  Zhengyu  Gao  Jun 《Geotechnical and Geological Engineering》2022,40(8):4171-4182

Geotechnical and Geological Engineering - In order to explore the directional support method of jointed rock mass and ensure the stable operation of roadway, the support effect of jointed rock mass...  相似文献