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1.
Cunde Xiao Zhiheng Du Mike J Handley Paul A Mayewski Junji Cao Simon Schüpbach Tong Zhang Jean-Robert Petit Chuanjin Li Yeongcheol Han Yuefang Li Jiawen Ren 《国家科学评论(英文版)》2021,8(7)
Mineral dust can indirectly affect the climate by supplying bioavailable iron (Fe) to the ocean. Here, we present the records of dissolved Fe (DFe) and total Fe (TDFe) in North Greenland Eemian Ice Drilling (NEEM) ice core over the past 110 kyr BP. The Fe records are significantly negatively correlated with the carbon-dioxide (CO2) concentrations during cold periods. The results suggest that the changes in Fe fluxes over the past 110 kyr BP in the NEEM ice core are consistent with those in Chinese loess records because the mineral-dust distribution is controlled by the East Asian deserts. Furthermore, the variations in the dust input on a global scale are most likely driven by changes in solar radiation during the last glacial–interglacial cycle in response to Earth''s orbital cycles. In the last glacial–interglacial cycle, the DFe/TDFe ratios were higher during the warm periods (following the post-Industrial Revolution and during the Holocene and last interglacial period) than during the main cold period (i.e. the last glacial maximum (LGM)), indicating that the aeolian input of iron and the iron fertilization effect on the oceans have a non-linear relationship during different periods. Although the burning of biomass aerosols has released large amounts of DFe since the Industrial Revolution, no significant responses are observed in the DFe and TDFe variations during this period, indicating that severe anthropogenic contamination has no significant effect on the DFe (TDFe) release in the NEEM ice core. 相似文献
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近期亚洲中部高山地区湖泊变化的时空分析 总被引：3，自引：0，他引：3
亚洲中部高山地区湖泊是气候与环境变化的敏感指示器,湖泊面积与水位的变化客观地反映了该地区水资源的时空变化过程。充分认识高山地区湖泊变化的特征及驱动性因素,有利于正确评估气候变化和人类活动对湖泊变化的影响。本文针对高山地区缺乏观测资料的特点,利用遥感资料重建近期亚洲中部高山地区湖泊的水位及面积变化信息,并在此基础上分析了水位和面积对湖泊变化描述的敏感程度,分别从湖泊类型、区域分布和影响因素讨论了近期亚洲中部高山地区湖泊的时空特征。水位可以更好地描述高山湖泊变化的时空过程,10月份是中亚高山地区湖泊相对稳定的时期。对于封闭性湖泊而言,近期青藏高原北部地区的湖泊扩张明显,而天山中部的湖泊水位微弱上升或保持不变,而阿尔泰山地区的湖泊处于萎缩的状态,湖泊的变化与降水及冰川分布具有较好的相关性。吞吐型湖泊的变化按有无水坝呈两种变化趋势,出水口建有水坝的外流湖水位下降明显,而自然状态下的外流湖水位相对稳定,一定程度上反映了近年来过度向吞吐型湖泊引水与开发的趋势。 相似文献
3.
Yimin Liu Mengmeng Lu Haijun Yang Anmin Duan Bian He Song Yang Guoxiong Wu 《国家科学评论(英文版)》2020,7(3):534
This paper reviews recent advances regarding land–atmosphere–ocean coupling associated with the Tibetan Plateau (TP) and its climatic impacts. Thermal forcing over the TP interacts strongly with that over the Iranian Plateau, forming a coupled heating system that elevates the tropopause, generates a monsoonal meridional circulation over South Asia and creates conditions of large-scale ascent favorable for Asian summer monsoon development. TP heating leads to intensification and westward extension (northward movement) of the South Asian High (Atlantic Intertropical Convergence Zone), and exerts strong impacts on upstream climate variations from North Atlantic to West Asia. It also affects oceanic circulation and buoyancy fields via atmospheric stationary wave trains and air–sea interaction processes, contributing to formation of the Atlantic Meridional Overturning Circulation. The TP thermal state and atmospheric–oceanic conditions are highly interactive and Asian summer monsoon variability is controlled synergistically by internal TP variability and external forcing factors. 相似文献
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Zhimian Cao Wei Yang Yangyang Zhao Xianghui Guo Zhiqiang Yin Chuanjun Du Huade Zhao Minhan Dai 《国家科学评论(英文版)》2020,7(4):786
Global coastal oceans as a whole represent an important carbon sink but, due to high spatial–temporal variability, a mechanistic conceptualization of the coastal carbon cycle is still under development, hindering the modelling and inclusion of coastal carbon in Earth System Models. Although temperature is considered an important control of sea surface pCO2, we show that the latitudinal distribution of global coastal surface pCO2 does not match that of temperature, and its inter-seasonal changes are substantially regulated by non-thermal factors such as water mass mixing and net primary production. These processes operate in both ocean-dominated and river-dominated margins, with carbon and nutrients sourced from the open ocean and land, respectively. These can be conceptualized by a semi-analytical framework that assesses the consumption of dissolved inorganic carbon relative to nutrients, to determine how a coastal system is a CO2 source or sink. The framework also finds utility in accounting for additional nutrients in organic forms and testing hypotheses such as using Redfield stoichiometry, and is therefore an essential step toward comprehensively understanding and modelling the role of the coastal ocean in the global carbon cycle. 相似文献
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河西走廊东部太阳能分布特征及指数预报 总被引：3，自引：2，他引：1
利用线性回归和线性相关分析方法对近30a年河西走廊东部民勤代表站的太阳总辐射资料进行研究。结果表明:河西走廊东部年平均太阳总辐射为6166.2MJ/m2,年平均太阳总辐射总体呈上升趋势,进入21世纪后,年太阳总辐射值稳定在(6000～6400)MJ/m2的高值区间上,说明全球增暖的气候背景下,河西走廊东部太阳能总辐射值稳定且有所增大,这为该区域内太阳能资源开发提供了有利的气候背景。太阳总辐射存在明显的季节变化,夏季最强,次强为春季,最弱的是冬季。太阳总辐射的月际变化呈单峰型,最大月份出现在6月,最小月出现在12月。尝试利用ECMWF数值预报产品作为预报因子库,采用press算子普查影响太阳总辐射变化的主要因子,对一特定地区和特定季节影响太阳总辐射变化的主要因素有温度、水汽压、相对湿度、比湿、温度露点差、露点温度等。这些因子不但与表征太阳辐射强弱的温度有关,还与空气中水汽含量的多少有关。采用最优子集回归精选因子,建立逐日太阳总辐射BP神经网络分月预报模型,并将其预报产品根据不同季节服务对象的不同划分预报等级指数,提出服务对策建议。业务试用结果表明:BP神经网络预报模型具有较强的非线性处理能力,能较好地表征日太阳总辐射的变化,预报拟合率和准确率均达较高水平,业务系统与MICAPS对接,实现全自动化,可制作一周内太阳辐射指数预报,为太阳辐射精细化预报提供了重要的技术支撑,也为开展太阳能气象指数预报提供了一种好的思路和方法。 相似文献
6.
文章回顾了近年来关于东亚季风气候系统变异和我国重大气候灾害发生机理的研究进展。通过许多观测事实分析揭示了东亚季风系统的时空变化和异常特征;并且从分析、动力理论和数值模拟研究了热带海洋、干旱/半干旱地区的陆面过程和青藏高原雪盖变化对东亚季风系统的影响及其过程,提出"东亚季风气候系统"新概念和此系统内动力学机理,并从东亚季风气候系统的年际和年代际变异提出长江流域严重洪涝发生的气候学概念模型和华北持续干旱灾害发生的气候背景;此外,本文还提出关于东亚季风气候系统亟需研究的若干科学问题。 相似文献
7.
Herman E. Seemann 《Journal of The Franklin Institute》1925,200(5):629-633
A Fery radiation pyrometer was used in relative radiation measurements during a total eclipse of the sun.The experimental curve shows that the radiation is not uniform over the sun's disc.The ratio of the energy received during full sunlight to the energy received from the corona was found to he 13,000. 相似文献
8.
构建热带西太平洋科学观测网是中科院战略性先导科技专项"热带西太平洋海洋系统物质能量交换及其影响"的重点任务之一。热带西太平洋环流系统深刻影响着暖池、厄尔尼诺/南方涛动(ENSO)和东亚季风的发展,对全球和我国气候变化研究意义重大。随着2015年15套深海潜标及数据的成功回收,世界上最大规模的热带西太平洋科学观测网的初步建成,我国科学家获得了热带西太平洋代表性海域连续一年涵盖海洋上层和中深层水体的温度、盐度和洋流等观测数据,这是世界上首次在这一地区获取高质量、高时空分辨率的定点连续数据,填补了国际上对该海域中深层环流大规模同步观测的空白,为我国大洋观测网的建设和运行积累了宝贵经验,起到了示范作用。该网络将会为我国大洋环流及其对我国气候效应的研究探索提供持续的数据支撑,将提高我国气候和海洋环境的预测能力。 相似文献
9.
全球海域波浪能资源储量分析 总被引：2，自引：0，他引：2
利用1957-2002年ECMWF的ERA-40 wave reanalysis海浪再分析资料,初次计算了全球海域波浪能资源的总储量和有效储量,为海浪发电、海水淡化等波浪能资源开发利用提供科学依据.研究发现:①全球大部分海域的年平均波浪能流密度在10kW/m以上,高值区位于南北半球西风带,呈东西带状分布,南半球西风带的能流密度能达到(60～100)kW/m,北半球西风带约(30～50)kW/m;②全球大部分海域的波浪能资源开发可用波高出现频率在90％以上,南大洋可用波高出现频率整体高于北大洋,大洋中部出现频率高于近岸海域,大洋东部近岸出现频率高于大洋西部近岸;③全球海域的波浪能资源储量可观,总储量的高值区位于南北半球西风带海域,南半球西风带海域的单位面积波浪能资源总储量基本都在50万kW/(h·m)左右,北半球西风带海域基本在(30～50)万kW/(h·m),中低纬海域在(5～30)万kW/(h·m),仅部分零星海域的总储量在5万kW/(h·m)以下,有效储量的分布特征与总储量分布特征较为一致;④综合能流密度的大小、可用波高出现频率、资源储量来看,中国海虽然并不处于全球波浪能资源的优势区域,但仍处于可用区域,相对富集区分布于南海北部、东海中南部海域. 相似文献
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1960年至2009年河西走廊东部太阳辐射变化规律及太阳能资源利用分析 总被引：2，自引：0，他引：2
利用线性回归分析和Mann-Kendall检验法,统计分析了河西走廊东部1960年-2009年近50a来的太阳总辐射和日照时数的变化规律。结果表明:河西走廊东部年平均太阳总辐射为5988.7MJ/m2,为太阳能资源丰富区,太阳总辐射存在明显的季节变化,月和日太阳总辐射变化趋势均呈单峰型。河西走廊东部年平均太阳总辐射在波动中上升,其线性倾向率为+12.7MJ(/m2·a);春、夏、秋、冬季的太阳总辐射呈不同程度的上升趋势,线性倾向率为+4.72MJ(/m2·a)、+5.69MJ(/m2·a)、+2.0MJ(/m2·a)、+0.17MJ(/m2·a)。年太阳总辐射、年日照时数的突变增大年与区域内气候开始变暖年同步,气候变暖使区域内中北部川区降水呈增多趋势,说明全球增暖的气候背景下,降水增多对空中的大气污染物有抑制作用,有利于河西走廊东部太阳能总辐射值、日照时数的增大。河西走廊东部年日照时数在空间分布呈现由北向南逐渐减少,季节分布呈现由夏-春-秋-冬季减少。研究区域太阳能资源总量丰富,有利于太阳能资源的开发利用。 相似文献
12.
Tao Wang Ying Tong Wenjiao Xiao Lei Guo Brian F Windley Tatiana Donskaya Shan Li Narantsetseg Tserendash Jianjun Zhang 《国家科学评论(英文版)》2022,9(5)
Tracing the closure of oceans with irregular margins and the formation of an orocline are crucial for understanding plate reconstruction and continental assembly. The eastern Central Asian Orogenic Belt, where the Mongol-Okhotsk orocline is situated, is one of the world''s largest magmatic provinces. Using a large data set of U-Pb zircon ages, we updated the timing of many published igneous rocks, which allowed us to recognize tightly ‘folded’ linear Carboniferous-Jurassic magmatic belts that wrap around the Mongol-Okhotsk suture and their migrations both sutureward and suture-parallel. The new successive magmatic belts reveal a rollback, scissor-like (or zipper-like) closure of the Mongol-Okhotsk Ocean that was fundamentally controlled by coeval subduction rollback and rotation of the Siberian and Mongolian-Erguna blocks. This study also demonstrates the complex mechanisms and processes of the closure of an ocean with irregular margins and the formation of a consequent orocline. 相似文献
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W.F.G. Swann 《Journal of The Franklin Institute》1948,246(2):149-157
The paper concerns the comparison of the behavior of two magnetron systems of different sizes, all apparatus from the input terminals of the magnetron to the final radiation antenna being contemplated in the picture. The mathematical comparison of the two systems assumes a specially simple form when the electrical conductivities of the corresponding parts of the systems in the two cases are adjusted to values in the inverse ratio of the scaling in linear dimensions. A scaling of this kind is therefore studied. The conclusions reached are as follows:For an assigned potential applied to the two models, the power input is the same, the power radiated from the antenna is the same, the power dissipated in Ohm's law heating in all parts is the same, and the power dissipated in back-bombardment or at the anode is the same.As a corollary to the foregoing, it is inferred that if the corresponding parts of the two models have the same electrical conductivity, then in so far as Ohm's law heating is an important factor at all, it is more important in the small model than in the large one. 相似文献
16.
Huang Ronghui 《中国科学院院刊(英文版)》2009,23(4):222-225
The East Asian monsoon （EAM） system is an important circulation system in the global climate system, which features strong southwesterlies with wet air over East Asia in surruner and northwesterlies with dry air over North China, Northeast China, Korea and Japan and northeasterlies along the coast of Southeast China （e.g., Tao and Chen）. Influenced by the variations and anomalies of the EAM system, therefore, 相似文献
17.
Faming Wang Christian J Sanders Isaac R Santos Jianwu Tang Mark Schuerch Matthew L Kirwan Robert E Kopp Kai Zhu Xiuzhen Li Jiacan Yuan Wenzhi Liu Zhi'an Li 《国家科学评论(英文版)》2021,8(9)
Coastal tidal wetlands produce and accumulate significant amounts of organic carbon (C) that help to mitigate climate change. However, previous data limitations have prevented a robust evaluation of the global rates and mechanisms driving C accumulation. Here, we go beyond recent soil C stock estimates to reveal global tidal wetland C accumulation and predict changes under relative sea level rise, temperature and precipitation. We use data from literature study sites and our new observations spanning wide latitudinal gradients and 20 countries. Globally, tidal wetlands accumulate 53.65 (95%CI: 48.52–59.01) Tg C yr−1, which is ∼30% of the organic C buried on the ocean floor. Modeling based on current climatic drivers and under projected emissions scenarios revealed a net increase in the global C accumulation by 2100. This rapid increase is driven by sea level rise in tidal marshes, and higher temperature and precipitation in mangroves. Countries with large areas of coastal wetlands, like Indonesia and Mexico, are more susceptible to tidal wetland C losses under climate change, while regions such as Australia, Brazil, the USA and China will experience a significant C accumulation increase under all projected scenarios. 相似文献
18.
Honglin He Shaoqiang Wang Li Zhang Junbang Wang Xiaoli Ren Lei Zhou Shilong Piao Hao Yan Weimin Ju Fengxue Gu Shiyong Yu Yuanhe Yang Miaomiao Wang Zhongen Niu Rong Ge Huimin Yan Mei Huang Guoyi Zhou Yongfei Bai Zongqiang Xie Zhiyao Tang Bingfang Wu Leiming Zhang Nianpeng He Qiufeng Wang Guirui Yu 《国家科学评论(英文版)》2019,6(3):505
The carbon budgets in terrestrial ecosystems in China are strongly coupled with climate changes. Over the past decade, China has experienced dramatic climate changes characterized by enhanced summer monsoon and decelerated warming. However, the changes in the trends of terrestrial net ecosystem production (NEP) in China under climate changes are not well documented. Here, we used three ecosystem models to simulate the spatiotemporal variations in China''s NEP during 1982–2010 and quantify the contribution of the strengthened summer monsoon and warming hiatus to the NEP variations in four distinct climatic regions of the country. Our results revealed a decadal-scale shift in NEP from a downtrend of –5.95 Tg C/yr2 (reduced sink) during 1982–2000 to an uptrend of 14.22 Tg C/yr2 (enhanced sink) during 2000–10. This shift was essentially induced by the strengthened summer monsoon, which stimulated carbon uptake, and the warming hiatus, which lessened the decrease in the NEP trend. Compared to the contribution of 56.3% by the climate effect, atmospheric CO2 concentration and nitrogen deposition had relatively small contributions (8.6 and 11.3%, respectively) to the shift. In conclusion, within the context of the global-warming hiatus, the strengthening of the summer monsoon is a critical climate factor that enhances carbon uptake in China due to the asymmetric response of photosynthesis and respiration. Our study not only revealed the shift in ecosystem carbon sequestration in China in recent decades, but also provides some insight for understanding ecosystem carbon dynamics in other monsoonal areas. 相似文献
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Tuvia Blumenthal 《Research Policy》1978,7(1):63-87
This paper deals with several aspects of R & D activity in Israel's manufacturing industries on three levels — the economy, industrial branch and the firm. Relative to other industrial countries, Israel is characterized by a high share of R & D expenditure in GNP but a low level of industrial R & D. If we take registered patents as an indicator of R & D output no significant correlation is found between this measure and expenditure on R & D; this may point to a low level of success or to the nature of R & D being directed more to small improvements of existing products and processes than to new inventions. An inter-industry analysis shows that R & D expenditure is positively correlated with average firm size and capital per employee and negatively correlated with concentration ratio. A positive correlation was also found with respect to increase in sales and export per employee but not with the rate of growth of export. Although most R & D is performed by large companies there is no significant correlation between R & D expenditure and firm's size among firms engaged in R & D, nor between R & D expenditure and firm's profitability. Concerning the relationship between domestic R & D and imports of technology a tentative conclusion is that Israel does not derive sufficient benefit from the international stock of knowledge. 相似文献
20.
Roberto De A. Martins 《Journal of The Franklin Institute》1981,311(5):331-337
A paper by Macagno (3) in this Journal is discussed. The origin of the concept of physical dimensions is traced back to ideas previously used in analytic geometry. Descartes' use of the word “dimension” in the study of physical magnitudes is shown to have properties completely different from Fourier's dimensions, being therefore unimportant to the evolution of dimensional analysis. It is also shown that the principle of homogeneity was used in the derivation of physical equations sixty years prior to the publication of Fourier's work, and that the latter was aware of this paper, that may be considered the earliest publication on dimensional analysis. 相似文献