The grain size and palinology of sediment and the frequency of ^14C dada provide an integrated reconstruction of the Holocene warm-humid phases of the North China Plain. Two clear intense and long-lasting warm-humid p...The grain size and palinology of sediment and the frequency of ^14C dada provide an integrated reconstruction of the Holocene warm-humid phases of the North China Plain. Two clear intense and long-lasting warm-humid phases were identified by comprehensive research in this region. The first phase was dated back to the early Holocene （9 000-7 000 a BP）, and the second was centered at 5 000-3 000 a BP. The warm-humid episode between 9 000 and 7 000 a BP was also recognized at other sites showing global climatic trends rather than local events. Compared with the concern to the warm-humid phase of the early Holocene, the second one was not paid enough attention in the last few decades. The compilation of the Holocene paleoclimate data suggests that perhaps the second warm-humid phase was pervasive in monsoon region of China. In perspective of environmental archaeology, much attention should be devoted to it, because the flourish and adaptation of the Neolithic cultures and the building up of the first state seem to corresponding to the general warm-humid climatic conditions of this period. In addition, a warm-humid interval at 7 20045 500 a BP was recognized by the grain size data from three sites. However, this warm-humid event was not shown in pollen assemblage and temporal distribution of ^14C data. Perhaps, the resolution for climatic reconstruction from pollen and temporal distribution of ^14C data cited here is relatively low and small-amplitude and short-period climatic events cannot be well reflected by the data. Due to the difference in locality and elevation of sampling site, as well as in resolution of proxy records, it is difficult to make precise correlation. Further work is needed in the future.展开更多
Intensified human population encourages urbanization changing the morphology and metabolism of urban environments, thus altering the local climate and outdoor thermal comfort (OTC) in public spaces. OTC is an increasi...Intensified human population encourages urbanization changing the morphology and metabolism of urban environments, thus altering the local climate and outdoor thermal comfort (OTC) in public spaces. OTC is an increasingly urgent area of research for tropical climates. This study explores the literature from the Scopus database on urban microclimate and OTC in public spaces and contrasts the studies in warm-humid cities through a bibliometric mapping of literature. The adapted methodology includes;Bibliometric Search, Scientometric Analysis, and Content analysis using VOSviewer software to identify the evolution paths, gaps, and the most recent movement of OTC assessments in urban public spaces. Results reveal five evolution paths related to all climatic regions;1) materials and cooling strategies, 2) simulation modeling and urban planning, 3) design parameters affecting thermal perception, 4) cooling effects of green infrastructure, and 5) thermal adaptation in urban design. Although urban morphology and vegetation have been received the highest attention respectively, only a few for blue infrastructure related to warm-humid cities. This review identified five research gaps;the impact of blue infrastructure on OTC, strategies to overcome the effect of reflective materials, vegetation configurations in street canyons with wind flow, OTC improvements in asymmetrical street canyons, and how local climate zone (LCZ) classification approach could be used for OTC assessments. Past empirical studies have revealed that urban vegetation, surface materials, and morphological parameters are of paramount importance. Yet, the urban blue infrastructure has not received adequate research. Recently, the attention of researchers has been drawn to strategies in improving OTC using micro-meteorological simulation modelling to examine the impact of urban design interventions. Finally, comprehensive content analysis, bibliographic coupling based on documents, co-occurrence of all-keywords, are suggested for future bibliometric reviews. Finally, further research on recommended areas would assist decision-makers in planning and design to enhance livability by improving microclimate and OTC in urban spaces.展开更多
青藏高原在末次冰期晚期(30—40 ka B.P.,相当于MIS3a阶段)出现的暖湿气候事件强烈地影响了川西高原东缘河流地质生态环境。表现在深切河谷中普遍发育大型滑坡、泥石流、冲洪积扇体等灾变事件和古堰塞湖沉积。本文重点剖析了岷江上游、...青藏高原在末次冰期晚期(30—40 ka B.P.,相当于MIS3a阶段)出现的暖湿气候事件强烈地影响了川西高原东缘河流地质生态环境。表现在深切河谷中普遍发育大型滑坡、泥石流、冲洪积扇体等灾变事件和古堰塞湖沉积。本文重点剖析了岷江上游、大渡河中游大型堵江事件的地形地貌特点、沉积物发育特征、沉积年代学、新构造背景等,同时分析了黄河上游玛曲段大型冲-洪积扇体的沉积特征与时代。结果表明在川西高原东缘深切河谷普遍存在距今30—40 ka时期的堵江事件,而这一时期在黄河上游发生大型冲-洪积事件和黄河袭夺若尔盖古湖事件,二者均与青藏高原末次冰期暖湿事件同步。研究认为这期急剧气温变化增强了河谷侵蚀和卸载能力,而东缘强烈的地震断层活动又触发了突发事件的发生,暖湿气候事件与新构造运动在时空上的耦合共同塑造了晚更新世晚期川西高原东缘深切河谷系统特殊的地质生态环境及其演变。展开更多
40~30 ka BP在过去被认为是末次冰期的间冰阶,温度稍高,但仍在冰期内.20世纪90年代西昆仑山古里雅冰芯记录研究首次指出,当时气温可能高出现代4℃,即为以前所不知的间冰期.追踪同期湖泊沉积,孢粉与古生物,黄土与沙漠地区古土壤,石灰岩...40~30 ka BP在过去被认为是末次冰期的间冰阶,温度稍高,但仍在冰期内.20世纪90年代西昆仑山古里雅冰芯记录研究首次指出,当时气温可能高出现代4℃,即为以前所不知的间冰期.追踪同期湖泊沉积,孢粉与古生物,黄土与沙漠地区古土壤,石灰岩洞穴中石笋,古河道,滨海地区海相沉积等多种记录,集成研究表明,当时青藏高原与西北干旱区有许多淡水大湖,降水量远比现代丰沛,导致外流水系扩大,如青海境内的黄河上游水系形成.暖湿的气候条下,森林分布区向北向西大范围扩展,华南热带喜湿热的陆均松(Dacrydiumsp.)北界移至22°~24°N,表明当时热带气温高于现代2℃左右,降水量也有较大增加.长江下游石笋资料和北方半干旱、半湿润区的植物、古土壤、河道沉积资料均表示降水增加,森林覆盖度大.由于冰川和极地冰盖萎缩,海平面上升,给合若干地区地面沉降,海河下游、长江三角洲和珠江三角洲均出现相当规模的海侵.上述涉及全中国的特殊暖湿环境的形成与地球轨道运行岁差周期变化导致中低纬度日射增强,致使温度升高,季风区与西风带降水量都有显著增加关系密切,而植被改善又对温度和湿度有正反馈作用.展开更多
基金Supported by the Humanity and Social Sciences Research of Ministry of Education, China (No. 06JC780001)the Major Program of the National Natural Science Foundation of China (No. 40599420)
文摘The grain size and palinology of sediment and the frequency of ^14C dada provide an integrated reconstruction of the Holocene warm-humid phases of the North China Plain. Two clear intense and long-lasting warm-humid phases were identified by comprehensive research in this region. The first phase was dated back to the early Holocene （9 000-7 000 a BP）, and the second was centered at 5 000-3 000 a BP. The warm-humid episode between 9 000 and 7 000 a BP was also recognized at other sites showing global climatic trends rather than local events. Compared with the concern to the warm-humid phase of the early Holocene, the second one was not paid enough attention in the last few decades. The compilation of the Holocene paleoclimate data suggests that perhaps the second warm-humid phase was pervasive in monsoon region of China. In perspective of environmental archaeology, much attention should be devoted to it, because the flourish and adaptation of the Neolithic cultures and the building up of the first state seem to corresponding to the general warm-humid climatic conditions of this period. In addition, a warm-humid interval at 7 20045 500 a BP was recognized by the grain size data from three sites. However, this warm-humid event was not shown in pollen assemblage and temporal distribution of ^14C data. Perhaps, the resolution for climatic reconstruction from pollen and temporal distribution of ^14C data cited here is relatively low and small-amplitude and short-period climatic events cannot be well reflected by the data. Due to the difference in locality and elevation of sampling site, as well as in resolution of proxy records, it is difficult to make precise correlation. Further work is needed in the future.
文摘Intensified human population encourages urbanization changing the morphology and metabolism of urban environments, thus altering the local climate and outdoor thermal comfort (OTC) in public spaces. OTC is an increasingly urgent area of research for tropical climates. This study explores the literature from the Scopus database on urban microclimate and OTC in public spaces and contrasts the studies in warm-humid cities through a bibliometric mapping of literature. The adapted methodology includes;Bibliometric Search, Scientometric Analysis, and Content analysis using VOSviewer software to identify the evolution paths, gaps, and the most recent movement of OTC assessments in urban public spaces. Results reveal five evolution paths related to all climatic regions;1) materials and cooling strategies, 2) simulation modeling and urban planning, 3) design parameters affecting thermal perception, 4) cooling effects of green infrastructure, and 5) thermal adaptation in urban design. Although urban morphology and vegetation have been received the highest attention respectively, only a few for blue infrastructure related to warm-humid cities. This review identified five research gaps;the impact of blue infrastructure on OTC, strategies to overcome the effect of reflective materials, vegetation configurations in street canyons with wind flow, OTC improvements in asymmetrical street canyons, and how local climate zone (LCZ) classification approach could be used for OTC assessments. Past empirical studies have revealed that urban vegetation, surface materials, and morphological parameters are of paramount importance. Yet, the urban blue infrastructure has not received adequate research. Recently, the attention of researchers has been drawn to strategies in improving OTC using micro-meteorological simulation modelling to examine the impact of urban design interventions. Finally, comprehensive content analysis, bibliographic coupling based on documents, co-occurrence of all-keywords, are suggested for future bibliometric reviews. Finally, further research on recommended areas would assist decision-makers in planning and design to enhance livability by improving microclimate and OTC in urban spaces.
文摘青藏高原在末次冰期晚期(30—40 ka B.P.,相当于MIS3a阶段)出现的暖湿气候事件强烈地影响了川西高原东缘河流地质生态环境。表现在深切河谷中普遍发育大型滑坡、泥石流、冲洪积扇体等灾变事件和古堰塞湖沉积。本文重点剖析了岷江上游、大渡河中游大型堵江事件的地形地貌特点、沉积物发育特征、沉积年代学、新构造背景等,同时分析了黄河上游玛曲段大型冲-洪积扇体的沉积特征与时代。结果表明在川西高原东缘深切河谷普遍存在距今30—40 ka时期的堵江事件,而这一时期在黄河上游发生大型冲-洪积事件和黄河袭夺若尔盖古湖事件,二者均与青藏高原末次冰期暖湿事件同步。研究认为这期急剧气温变化增强了河谷侵蚀和卸载能力,而东缘强烈的地震断层活动又触发了突发事件的发生,暖湿气候事件与新构造运动在时空上的耦合共同塑造了晚更新世晚期川西高原东缘深切河谷系统特殊的地质生态环境及其演变。
文摘40~30 ka BP在过去被认为是末次冰期的间冰阶,温度稍高,但仍在冰期内.20世纪90年代西昆仑山古里雅冰芯记录研究首次指出,当时气温可能高出现代4℃,即为以前所不知的间冰期.追踪同期湖泊沉积,孢粉与古生物,黄土与沙漠地区古土壤,石灰岩洞穴中石笋,古河道,滨海地区海相沉积等多种记录,集成研究表明,当时青藏高原与西北干旱区有许多淡水大湖,降水量远比现代丰沛,导致外流水系扩大,如青海境内的黄河上游水系形成.暖湿的气候条下,森林分布区向北向西大范围扩展,华南热带喜湿热的陆均松(Dacrydiumsp.)北界移至22°~24°N,表明当时热带气温高于现代2℃左右,降水量也有较大增加.长江下游石笋资料和北方半干旱、半湿润区的植物、古土壤、河道沉积资料均表示降水增加,森林覆盖度大.由于冰川和极地冰盖萎缩,海平面上升,给合若干地区地面沉降,海河下游、长江三角洲和珠江三角洲均出现相当规模的海侵.上述涉及全中国的特殊暖湿环境的形成与地球轨道运行岁差周期变化导致中低纬度日射增强,致使温度升高,季风区与西风带降水量都有显著增加关系密切,而植被改善又对温度和湿度有正反馈作用.
