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早上新世非洲季风与地中海表层生产力变化的岁差节律 被引量:3
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作者 黄恩清 田军 《地球科学(中国地质大学学报)》 EI CAS CSCD 北大核心 2007年第3期313-321,共9页
地质历史上留下了许多反映非洲季风的记录,意大利南方晚新生代的海相地层便是其中著名的一例.Cape Sper-tivento剖面位于意大利卡拉布里亚半岛,属于早上新世(5.3~4.8Ma)地中海泥灰岩-灰岩沉积物.在借鉴前人工作的基础上,重新为该剖面... 地质历史上留下了许多反映非洲季风的记录,意大利南方晚新生代的海相地层便是其中著名的一例.Cape Sper-tivento剖面位于意大利卡拉布里亚半岛,属于早上新世(5.3~4.8Ma)地中海泥灰岩-灰岩沉积物.在借鉴前人工作的基础上,重新为该剖面建立一个精度更高的天文年代标尺.反映古生产力的指标显示,早上新世在北半球夏季辐射量增大期间,地中海有机碳含量及其堆积速率增大,C/N出现高值,碳酸盐含量及其堆积速率减小,G.obliquus稳定氧碳同位素出现负偏移,这是非洲夏季风带来的降雨增强的结果.尼罗河泛滥让更多陆源营养物和淡水输入地中海.各个古环境指标的频谱分析结果存在强烈的岁差周期和丰富的半岁差周期,说明早上新世非洲季风主要受低纬过程控制. 展开更多
关键词 上新世 非洲季风 地中海 海水表层生产力 岁差
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意大利上新世古生产力的轨道驱动
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作者 丁晓辉 王汝建 +1 位作者 李建如 黄恩清 《地球科学进展》 CAS CSCD 北大核心 2007年第10期1019-1026,共8页
主要研究了意大利上新统3个剖面Punta Piccola、Cape Spertivento以及Punta Rossello蛋白石含量的变化,综合其它古环境指标对非洲季风和地中海表层生产力加以分析,研究表明,PuntaPiccola剖面和Cape Spertivento剖面各古环境指标对岁差... 主要研究了意大利上新统3个剖面Punta Piccola、Cape Spertivento以及Punta Rossello蛋白石含量的变化,综合其它古环境指标对非洲季风和地中海表层生产力加以分析,研究表明,PuntaPiccola剖面和Cape Spertivento剖面各古环境指标对岁差周期影响的响应明显而单纯,即岁差低值,对应氧同位素偏负,有机碳和蛋白石高值以及碳酸盐低值,说明地中海表层生产力明显受到岁差的驱动。岁差驱动下的北非夏季风导致尼罗河泛滥,带来的丰富营养元素使得生产力剧增,同时淡水注入,阻碍了水体的垂向交换,直接导致了海底的缺氧环境,硅藻利用深层营养产生勃发,并组成"藻席",快速沉降到海底,使得有机碳迅速埋葬和保存,从而引发了腐泥层的形成。Punta Ros-sello剖面硅藻层证实了"藻席"的存在,但是蛋白石含量并不高。 展开更多
关键词 非洲季风 地中海 古生产力 岁差 上新世
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与华北干旱相关联的全球尺度气候变化现象 被引量:29
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作者 黄刚 《气候与环境研究》 CSCD 北大核心 2006年第3期270-279,共10页
利用ERA-40再分析资料集的风、温度、水汽等再分析资料,分析了华北地区干旱以及北非萨赫勒地区干旱化的气候特征及它们之间的关联,指出在亚非季风区上空存在一个年代际的季风环流异常遥相关波列,正是由于此波列的作用,使得我国华北地区... 利用ERA-40再分析资料集的风、温度、水汽等再分析资料,分析了华北地区干旱以及北非萨赫勒地区干旱化的气候特征及它们之间的关联,指出在亚非季风区上空存在一个年代际的季风环流异常遥相关波列,正是由于此波列的作用,使得我国华北地区从1965年以后所发生的干旱与北非萨赫勒地区干旱化存在着明显的相关联。并且分析了这两地区的干旱与之相关联的全球气候变化背景,指出由于1965年之后北、南半球气温变化差异的减少导致了亚非季风系统发生了年代际减弱和南撤,从而使得华北和北非萨赫勒地区发生了持续干旱现象。 展开更多
关键词 干旱 亚非季风带 南半球 北半球 气温差
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Influence of Continental Atmospheric Forcing on the Decadal Variability of the West African Monsoon
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作者 Adjoua Moïse Landry Famien Sandrine Djakouré +3 位作者 Bi Tra Jean Claude Youan Serge Janicot Abé Delfin Ochou Arona Diedhiou 《Atmospheric and Climate Sciences》 2024年第1期1-28,共28页
The West African Monsoon (WAM) is characterized by strong decadal and multi-decadal variability and the impacts can be catastrophic for the local populations. One of the factors put forward to explain this variability... The West African Monsoon (WAM) is characterized by strong decadal and multi-decadal variability and the impacts can be catastrophic for the local populations. One of the factors put forward to explain this variability involves the role of atmospheric dynamics, linked in particular to the Saharan Heat Low (SHL). This article addresses this question by comparing the sets of preindustrial control and historical simulation data from climate models carried out in the framework of the CMIP5 project and observations data over the 20<sup>th</sup> century. Through multivariate statistical analyses, it was established that decadal modes of ocean variability and decadal variability of Saharan atmospheric dynamics significantly influence decadal variability of monsoon precipitation. These results also suggest the existence of external anthropogenic forcing, which is superimposed on the decadal natural variability inducing an intensification of the signal in the historical simulations compared to preindustrial control simulations. We have also shown that decadal rainfall variability in the Sahel, once the influence of oceanic modes has been eliminated, appears to be driven mainly by the activity of the Arabian Heat Low (AHL) in the central Sahel, and by the structure of the meridional temperature gradient over the inter-tropical Atlantic in the western Sahel. 展开更多
关键词 Influence of Continental Atmospheric Forcing on the Decadal Variability of the West african monsoon
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夏季青藏高原上空热力异常与其上下游大气环流联系的研究进展 被引量:5
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作者 刘舸 赵平 +2 位作者 南素兰 陈军明 王慧美 《气象学报》 CAS CSCD 北大核心 2018年第6期861-869,共9页
围绕夏季青藏高原热力异常与其上、下游大气环流在年际尺度变化上的联系,对最新的研究成果做了简要介绍。通过观测资料分析与数值试验,指出在年际尺度上夏季青藏高原热力异常与同期亚洲-太平洋涛动(APO)具有显著且稳定的联系,前者可能... 围绕夏季青藏高原热力异常与其上、下游大气环流在年际尺度变化上的联系,对最新的研究成果做了简要介绍。通过观测资料分析与数值试验,指出在年际尺度上夏季青藏高原热力异常与同期亚洲-太平洋涛动(APO)具有显著且稳定的联系,前者可能通过调节亚洲和中东太平洋热带外大尺度垂直环流异常影响后者。另外,夏季青藏高原热力异常对高原上空及更大范围上对流层温度的年际变化也有一定贡献,进而通过对上游大尺度环流的调节作用影响到同期西非萨赫勒地区的降水。夏季青藏高原热力异常只是导致其上、下游大气环流年际变化的一个原因,其他影响效应尚需进一步探讨。 展开更多
关键词 亚洲-太平洋涛动 青藏高原 数值模拟 萨赫勒 西非季风降水
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Strength of the North African monsoon in the Last Interglacial and under future warming
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作者 Jiazhi He Weiyi Sun +2 位作者 Jing Wang Bin Wang Jian Liu 《Atmospheric and Oceanic Science Letters》 CSCD 2023年第3期20-26,共7页
与人为强迫引起的全球变暖相比,末次间冰期是轨道强迫引起的过去80万年来最暖的一个间冰期,但鲜有人研究末次间冰期中北非季风的响应.因此,本文基于CMIP6多模式模拟结果对比研究了末次间冰期和SSP5-8.5情景下北非季风的响应,发现末次间... 与人为强迫引起的全球变暖相比,末次间冰期是轨道强迫引起的过去80万年来最暖的一个间冰期,但鲜有人研究末次间冰期中北非季风的响应.因此,本文基于CMIP6多模式模拟结果对比研究了末次间冰期和SSP5-8.5情景下北非季风的响应,发现末次间冰期下北非季风平均降水及其降水变率均远大于SSP5-8.5情景下的结果.轨道强迫导致的北大西洋暖于南大西洋增加了北非季风环流和平均降水,同时,南北大西洋海温梯度变化通过增强热带北大西洋的海气相互作用增大了海温梯度和撒哈拉低压的变率,从而增强了北非季风降水变率. 展开更多
关键词 北非季风 降水变率 末次间冰期 全球变暖
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On the Causes of the Minor Dry Season over the Coastal Region of the Northern Gulf of Guinea 被引量:1
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作者 Angora Aman Elisee Toualy Fidele Yoroba 《Atmospheric and Climate Sciences》 2018年第2期121-133,共13页
Along the littoral shelf of northern coast of the Gulf of Guinea (GG), a minor dry season of the rainfall regime is concomitantly observed with the occurrence of a major coastal upwelling in July-August-September (JAS... Along the littoral shelf of northern coast of the Gulf of Guinea (GG), a minor dry season of the rainfall regime is concomitantly observed with the occurrence of a major coastal upwelling in July-August-September (JAS). It was then supposed that this upwelling drives that minor dry season. But no previous studies have tried to understand this minor dry season and, this study is the first focusing on this question. The investigations undertaken to explain this dry season on the Ivorian littoral shelf with the ERA-Interim data from the European Centre for Medium Range Weather Forecasts over the 1980-2016 period have shown that the minor dry season is driven by the Northward migration of the Inter Tropical Convergence Zone (ITCZ) during this period and, enhanced by the occurrence of the major coastal upwelling of the northern GG at the same time. These two phenomena interact as follow: i) the ITCZ is located in JAS far in the north cutting off convective processes along the coast, ii) the air on the coastal region is poor in humidity, iii) the air temperature on the bordering region of the GG is cooled by the coastal upwelling to value less than 26°C and not favorable for providing convection. 展开更多
关键词 Dry Season West african monsoon GULF of GUINEA Coastal UPWELLING CONVECTIVE Rainfall
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Sensitivity Study of the RegCM4’s Surface Schemes in the Simulations of West Africa Climate
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作者 Adjon Anderson Kouassi Brahima Kone +5 位作者 Siélé Silue Alima Dajuma Toure E. N’datchoh Marcellin Adon Arona Diedhiou Véronique Yoboue 《Atmospheric and Climate Sciences》 2022年第1期86-104,共19页
Two simulations of five years (2003-2007) were conducted with the Regional Climate models RegCM4, one coupled with Land surface models BATS and the other with CLM4.5 over West Africa, where simulated air temperature a... Two simulations of five years (2003-2007) were conducted with the Regional Climate models RegCM4, one coupled with Land surface models BATS and the other with CLM4.5 over West Africa, where simulated air temperature and precipitation were analyzed. The purpose of this study is to assess the performance of RegCM4 coupled with the new CLM4.5 Land</span><span style="font-family:""> </span><span style="font-family:Verdana;">surface scheme and the standard one named BATS in order to find the best configuration of RegCM4 over West African. This study could improve our understanding of the sensitivity of land surface model in West Africa climate simulation, and provide relevant information to RegCM4 users. The results show fairly realistic restitution of West Africa’s climatology and indicate correlations of 0.60 to 0.82 between the simulated fields (BATS and CLM4.5) for precipitation. The substitution of BATS surface scheme by CLM4.5 in the model configuration, leads mainly to an improvement of precipitation over the Atlantic Ocean, however, the impact is not sufficiently noticeable over the continent. While the CLM4.5 experiment restores the seasonal cycles and spatial distribution, the biases increase for precipitation and temperature. Positive biases already existing with BATS are amplified over some sub-regions. This study concludes that temporal localization (seasonal effect), spatial distribution (grid points) and magnitude of precipitation and temperature (bias) are not simultaneously improved by CLM4.5. The introduction of the new land surface scheme CLM4.5, therefore, leads to a performance of the same order as that of BATS, albeit with a more detailed formulation. 展开更多
关键词 Regional Climate Model Land Surface Scheme West Africa Climate REGCM Precipitation West african monsoon Simulated Data
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Anomalous Atmospheric Circulation Associated with Recent West African Monsoon Rainfall Variability
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作者 Ugochukwu K. Okoro Wen Chen +1 位作者 Chidiezie Chineke Okey Nwofor 《Journal of Geoscience and Environment Protection》 2017年第12期1-27,共27页
The recent West African Monsoon (WAM) wet season (May to October) rainfall’s interannual variability has been examined with emphasis on the rainfall zones of Guinea Coast (GC), Western Sudano Sahel (WSS) and Eastern ... The recent West African Monsoon (WAM) wet season (May to October) rainfall’s interannual variability has been examined with emphasis on the rainfall zones of Guinea Coast (GC), Western Sudano Sahel (WSS) and Eastern Sudano Sahel (ESS) in wet and dry years. Rainfall observations from Climate Research Unit (CRU) and Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP), and atmospheric circulation fields from National Center for Environmental Prediction (NCEP) were evaluated from 1979 to 2014. The objectives are to evaluate the trends across the zones and their linear relationship with the identified oceanic pulsations, as well as examine the evolution of the anomalous atmospheric circulation associated with the wet and dry years during the wet season months. The results show remarkable variability across the rainfall zones. The areal averaged rainfall anomalies show significant correlation values of -0.2 with Ocean Nino Index (ONI) only on WSS and ESS respectively, whereas with South Atlantic Ocean Dipole Index (SAODI) it shows significant correlation value of 0.3 only on GC, at 95% Confidence Level from a t-test. The analysis of trends in spatial and temporal patterns of the atmospheric circulation fields has extensively presented attributes associated with the wet seasonal rainfall anomalies in the wet and dry years. FGOALS-s2 model showed an outstanding simulation of the spatial and temporal patterns of these attributes, with the discrepancies noted, hence presenting itself as a viable tool in the prediction of seasonal rainfall extremes over West Africa. 展开更多
关键词 West african monsoon Wet SEASON RAINFALL Variability Atmospheric Circulation
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Study of Aerosol Direct and Indirect Effects and Auto-conversion Processes over the West African Monsoon Region Using a Regional Climate Model
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作者 Zeinab SALAH Ahmed SHALABY +3 位作者 Allison L. STEINER Ashraf S. ZAKEY Ritesh GAUTAM Mohamed M. ABDEL WAHAB 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2018年第2期182-194,共13页
This study assesses the direct and indirect effects of natural and anthropogenic aerosols (e.g., black carbon and sulfate) over West and Central Africa during the West African monsoon (WAM) period (June-July-Aug... This study assesses the direct and indirect effects of natural and anthropogenic aerosols (e.g., black carbon and sulfate) over West and Central Africa during the West African monsoon (WAM) period (June-July-August). We investigate the impacts of aerosols on the amount of cloudiness, the influences on the precipitation efficiency of clouds, and the associated radiative forcing (direct and indirect). Our study includes the implementation of three new formulations of auto-conversion parameterization [namely, the Beheng (BH), Tripoli and Cotton (TC) and Liu and Daum (R6) schemes] in RegCM4.4.1, besides the default model's auto-conversion scheme (Kessler). Among the new schemes, BH reduces the precipitation wet bias by more than 50% over West Africa and achieves a bias reduction of around 25% over Central Africa. Results from detailed sensitivity experiments suggest a significant path forward in terms of addressing the long-standing issue of the characteristic wet bias in RegCM. In terms of aerosol-induced radiative forcing, the impact of the various schemes is found to vary considerably (ranging from -5 to -25 W m-2). 展开更多
关键词 aerosol cloud West african monsoon auto-conversion REGCM
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20世纪80年代中期全球变暖前后亚非夏季风特征分析 被引量:8
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作者 宋燕 季劲钧 +1 位作者 朱临洪 张世英 《北京林业大学学报》 CAS CSCD 北大核心 2007年第2期24-33,共10页
该文针对全球温度场在20世纪80年代全球明显的突然变暖事件,研究了变暖前后全球温度场和降水场的时空分布特征,以及相应季风环流圈的变化特征,并且与20世纪60年代全球变冷气候事件作了对比分析.结果表明,变暖后全球大范围增温,增温地区... 该文针对全球温度场在20世纪80年代全球明显的突然变暖事件,研究了变暖前后全球温度场和降水场的时空分布特征,以及相应季风环流圈的变化特征,并且与20世纪60年代全球变冷气候事件作了对比分析.结果表明,变暖后全球大范围增温,增温地区包括欧亚大陆大部、非洲地区大部和印度洋南部.与此同时,全球降水场也有明显的变化.1990—1995年与1980—1985年相比较,中国华北地区大部分地区、印度中南部和北非Sahel大部分地区夏季总降水量有所回升,而中国华北地区南部地区和印度北部地区降水有所减少.对比分析80年代变暖前后气候环流场,发现非洲夏季风在变暖后有所加强,印度夏季风有所减弱,东亚夏季风强度微弱加强.从海陆热力对比和华北和北非Sahel等地的夏季降水量的小波分析来看,60年代变冷气候事件以年代际信号为主,同位相叠加突出了年代际振荡的作用和强度;而80年代夏季降水量的各时间尺度年代际信号符号相反,相互抵消;与此同时,80年代年际时间尺度的信号较强,起主导作用.所以,80年代气候变暖事件与60年代气候变冷事件相比较,并不是单纯的气候年代际反位相振荡的结果,而是不同时间尺度信号相互作用下引起的气候不同的响应. 展开更多
关键词 亚非夏季风 全球变暖 年代际 年际 小波分析
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20世纪60年代中期亚非夏季风减弱的全球气候背景异常分析 被引量:5
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作者 宋燕 季劲钧 孙丹 《大气科学》 CSCD 北大核心 2009年第2期313-324,共12页
利用美国NASA格点月降水总量资料、美国CO2信息分析中心地表面温度异常月平均网格点资料、美国NCEP/NCAR再分析全球网格点资料和兰州高原大气物理研究所的台站地温观测资料分析了1960年代中期亚非夏季风环流圈年代际时间尺度的减弱及其... 利用美国NASA格点月降水总量资料、美国CO2信息分析中心地表面温度异常月平均网格点资料、美国NCEP/NCAR再分析全球网格点资料和兰州高原大气物理研究所的台站地温观测资料分析了1960年代中期亚非夏季风环流圈年代际时间尺度的减弱及其与之有关的全球气候场异常现象。结果发现,1960年代中期全球对流层大气温度和海洋温度场发生异常变化,对流层大气有明显降温,海洋主要以印度洋升温、北太平洋和北大西洋降温为主要特征,同时,我国大陆土壤温度和青藏高原温度在1960年代中期有明显的下降,导致亚洲大陆与印度洋之间的热力对比明显减弱,东风急流减弱,最终导致亚非夏季风明显减弱。 展开更多
关键词 亚非夏季风 季风环流圈 气候场异常 海陆热力对比 东风急流
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The Decadal Variation of Afro-Asian Summer Monsoon and Precipitation 被引量:1
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作者 王丽 张大为 +1 位作者 王莹 王海洋 《Meteorological and Environmental Research》 CAS 2010年第12期22-24,29,共4页
By dint of grid information from 1948 to 2007,the summer monsoon in Afro-Asian area and the precipitation in corresponding atmosphere circulation situation during the strong and weak Afro-Asian monsoon period are stud... By dint of grid information from 1948 to 2007,the summer monsoon in Afro-Asian area and the precipitation in corresponding atmosphere circulation situation during the strong and weak Afro-Asian monsoon period are studied.The results suggest that the strong or weak Afro-Asian monsoon has pretty good corresponding relation with summer precipitation in Afro-Asian area.When summer monsoon weakens year after year,precipitation also decreases every year. 展开更多
关键词 Asian-african summer monsoon PRECIPITATION Decadal variation China
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Strengthened African Summer Monsoon in the Mid-Piacenzian
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作者 Ran ZHANG Zhongshi ZHANG +3 位作者 Dabang JIANG Qing YAN Xin ZHOU Zhigang CHENG 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2016年第9期1061-1070,共10页
Using model results from the first phase of the Pliocene Model Intercomparison Project (PlioMIP) and four experiments with CAM4, the intensified African summer monsoon (ASM) in the mid-Piacenzian and corresponding... Using model results from the first phase of the Pliocene Model Intercomparison Project (PlioMIP) and four experiments with CAM4, the intensified African summer monsoon (ASM) in the mid-Piacenzian and corresponding mechanisms are analyzed. The results from PlioMIP show that the ASM intensified and summer precipitation increased in North Africa during the mid-Piacenzian, which can be explained by the increased net energy in the atmospheric column above North Africa. Further experiments with CAM4 indicated that the combined changes in the mid-Piacenzian of atmospheric CO2 concentration and SST, as well as the vegetation change, could have substantially increased the net energy in the atmospheric column over North Africa and further intensified the ASM. The experiments also demonstrated that topography change had a weak effect. Overall, the combined changes of atmospheric CO2 concentration and SST were the most important factor that brought about the intensified ASM in the mid-Piacenzian. 展开更多
关键词 PlioMIE mid-Piacenzian african summer monsoon vegetation change
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An Analysis of Interdecadal Variations of the Asian-African Summer Monsoon
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作者 宋燕 季劲钧 孙霞 《Acta meteorologica Sinica》 SCIE 2008年第3期317-328,共12页
The response of the Asian-African summer monsoon (AASM) to the fast global warming in the 1980s is studied based on several datasets, which span a long time period of nearly 100 yr, with two special periods 1980-198... The response of the Asian-African summer monsoon (AASM) to the fast global warming in the 1980s is studied based on several datasets, which span a long time period of nearly 100 yr, with two special periods 1980-1985 and 1990-1995 being focused on. Wavelet analyses are employed to explore the interdecadal variations of the AASM. It is found that after the mid 1980s, the global annual mean surface temperature rises more significantly and extensively over most parts of the African Continent, north of the Indian Ocean, and the Eurasian Continent excluding the Tibetan Plateau. Correspondingly, the global precipitation pattern alters with in- creased rainfall seen over the Sahel and North China in 1990-1995, though it is not recovered to the level of the rainy period before the mid-1960s. Changes of monsoonal circulations between the pre- and post-1980s periods display that, after the fast global warming of the 1980s, the African summer monsoon intensifies distinctly, the Indian summer mon- soon weakens a little bit, and the East Asian summer monsoon remains almost unchanged. The summer precipitation over the Asian-African Monsoon Belt (AAMB) does not change in phase coherently with the variations of the monsoonal circulations. Wavelet analyses of the land-sea thermal contrast and precipitation over North China and the Sahel indicate that interdecadal signals are dominant and in positive phases in the 1960s, leading to an overall enhanced interdecadal variation of the AASM, although the 1960s witnesses a global cooling. In the 1980s, however, in the context of a fast global warming, interdecadal signals are in opposite phases, and they counteract with each other, leading to a weakened interdecadal variation of the AASM. After the mid-1960s, the AASM weakened remarkably, whereas after the mid-1980s, the AASM as a whole did not strengthen uniformly and synchronously, because it is found that the interannual variations of the AASM in the 1980s are stronger than those in the 1960s, and they superimposed on the 展开更多
关键词 global warming Asian-african summer monsoon interdecadal oscillation abrupt climate change wavelet analysis
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亚非夏季风及其降水的年代际变化 被引量:1
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作者 王丽 张大为 +1 位作者 王莹 王海洋 《安徽农业科学》 CAS 北大核心 2011年第7期4302-4303,4311,共3页
利用1948~2007年格点资料对亚洲和非洲地区夏季风与相应地区的降水量进行处理分析,研究了强弱亚非夏季风时期的降水及对应的大气环流形势(高度场、气压场、温度场、风场)。结果表明,亚非夏季风的强弱与亚非夏季降水具有良好的对应关系... 利用1948~2007年格点资料对亚洲和非洲地区夏季风与相应地区的降水量进行处理分析,研究了强弱亚非夏季风时期的降水及对应的大气环流形势(高度场、气压场、温度场、风场)。结果表明,亚非夏季风的强弱与亚非夏季降水具有良好的对应关系,亚非夏季风逐年减弱时,亚非地区降水量也逐年递减。 展开更多
关键词 亚非夏季风 降水 年代际变化
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