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91.
Dev Niyogi Hsin-I Chang Fei Chen Lianhong Gu Anil Kumar Surabi Menon Roger A. Pielke Sr. 《Natural Hazards》2007,42(2):345-359
Aerosols can affect the cloud-radiation feedback and the precipitation over the Indian monsoon region. In this paper, we propose
that another pathway by which aerosols can modulate the multi-scale aspect of Indian monsoons is by altering the land–atmosphere
interactions. The nonlinear feedbacks due to aerosol/diffuse radiation on coupled interactions over the Indian monsoon region
are studied by: (1) reviewing recent field measurements and modeling studies, (2) analyzing the MODIS and AERONET aerosol
optical depth datasets, and (3) diagnosing the results from sensitivity experiments using a mesoscale modeling system. The
results of this study suggest that the large magnitude of aerosol loading and its impact on land–atmosphere interactions can
significantly influence the mesoscale monsoonal characteristics in the Indo-Ganges Basin. 相似文献
92.
Challenges of using remote sensing and GIS in developing nations 总被引:2,自引:1,他引:2
93.
Christophe COLIN 《中国科学D辑(英文版)》2007,50(11):1674-1684
High-resolution clay mineral records combined with oxygen isotopic stratigraphy over the past 450 ka during late Quaternary from Core MD05-2901 off Middle Vietnam in the western South China Sea are re-ported to reconstruct a history of East Asian monsoon evolution. Variations in Illite, chlorite, and kaolinite contents indicate a strong glacial-interglacial cyclicity, while changes in smectite content present a higher frequency cyclicity. The provenance analysis indicates a mixture of individual clay minerals from various sources surrounding the South China Sea. Smectite derived mainly from the Sunda shelf and its major source area of the Indonesian islands. Illite and chlorite originated mainly from the Mekong and Red rivers. Kaolinite was provided mainly by the Pearl River. Spectral analysis of the kaolin-ite/(illite chlorite) ratio displays a strong eccentricity period of 100 ka, implying the ice sheet-forced win-ter monsoon evolution; whereas higher frequency changes in the smectite content show an ice sheet-forced obliquity period of 41 ka, and precession periods of 23 and 19 ka and a semi-precession period of 13 ka as well, implying the tropical-forced summer monsoon evolution. The winter monsoon evolution is generally in coherence with the glacial-interglacial cyclicity, with intensified winter monsoon winds during glacials and weakened winter monsoon winds during interglacials; whereas the summer monsoon evolution provides an almost linear response to the summer insolation of low latitude in the Northern Hemisphere, with strengthened summer monsoon during higher insolation and weakened summer monsoon during lower insolation. The result suggests that the high-latitude ice sheet and low-latitude tropical factor could drive the late Quaternary evolution of East Asian winter and summer monsoons, respectively, implying their diplex and self-contained forcing mechanism. 相似文献
94.
1991年夏季长江中下游降水和风场的低频振荡特征分析 总被引:6,自引:0,他引:6
对 1 991长江中下游地区夏季降水和风场进行 Morlet小波分析 ,结果表明 :这些要素有明显的低频特征 ,其变化具有阶段性的特点。 6月中旬之前主要表现为准双周振荡 ,6月中旬之后 3 0~ 60 d振荡逐渐明显 ;低频西风峰值超前降水峰值 2~ 4d。通过对散度场及流场的分析发现 ,7月份以后 ,低纬低频系统北传 ,同时中纬 40~50°N低频系统南传 ,两者交汇在 3 0~ 3 5°N,低频气流在长江中下游地区的辐合造成了两次大的降水过程 相似文献
95.
必须应用软件工程的方法开发GIS软件 总被引:6,自引:1,他引:6
简要介绍了GIS的软件功能,指出在软件设计中没有采用先进的软件工程方法给我国的GIS软件开发赞成了严重后果,在分析原因的基础上提出了解决建议并强调必须应用软件工程的方法开发GIS软件。 相似文献
96.
东亚夏季风降水和环流数值模拟对不同对流参数化方案的敏感性 总被引:4,自引:2,他引:4
A 5-level spectral AGCM (ImPKU-5LAGCM) is used to examine the sensitivity of the simulated results of the summer monsoon rainfall and circulation in East Asia to different cumulus parameterization schemes in the climatological-mean case and in the cases of weak and strong Asian summer monsoons,respectively. The results simulated with the Arakawa-Schubert's(hereafter A-S's), Kuo's and Manabe's cumulus parameterization schemes show that these simulated distributions of the summer monsoon rainfall and circulation in East Asia depend strongly on the cumulus parameterization schemes either in the climatological-mean case or in the cases of weak and strong Asian summer monsoons. From the simulated results, it might be shown that the Kuo scheme appears to be more suitable for the simulation of the summer monsoon rainfall and circulation in East Asia than the A-S scheme or the Manabe scheme, although the A-S scheme is somewhat better in the simulations of the tropical rainfall. This might be due to that the Kuo's cumulus parameterization scheme is able to reflect well the characteristics of rainfall cloud system in the East Asian summer monsoon region, where the rainfall system used to be a mixing of cumulus and stratus. 相似文献
97.
印度洋偶极子对大气环流和气候的影响 总被引:28,自引:6,他引:28
赤道印度洋SST的分析研究证实了偶极子型振荡的存在,它在9-11月较强而在1-4月较弱。若以海温西高东低为偶极子振荡正位相,以海温东高西低为负位相,则一般是正位相时振荡要强于负位相。印度洋偶极子也存在年际(主要周期为4-5年)和年代际(主要周期为25-30年)变化。分析研究表明,印度洋偶极子对亚洲季风活动有明显影响,因为亚洲地区对流层低层的风场,南亚高压和西太平洋副高强度都与印度洋偶极子有关。另外,印度洋偶极子还对北美和南印度洋(包括澳大利亚和南美)地区的大气环流和气流有影响。 相似文献
98.
Globalisation, Regionalisation and Local Voices: The Asian Development Bank and Rescaled Politics of Environment in the Mekong Region 总被引:1,自引:0,他引:1
Philip Hirsch 《Singapore journal of tropical geography》2001,22(3):237-251
Globalisation is manifested in the Mekong Region both through processes and discourses that reflect the ideology of a borderless world allowing easy passage of capital and commodities, and through resistance to such processes in an increasingly transnationalised civil society movement. However, more immediately significant supranational integrative agendas take the form of regionalisation, a process that has received less attention but which raises analogous concerns of re-scaled governance. The Asian Development Bank (ADB) has been a catalysing force for regionalisation amidst a host of regional processes and initiatives; as such it has found itself the object of critique as an institution and through the specific projects it has supported that have impacted on local communities and ecosystems. Meanwhile, local and NGO voices associated with the emergence of a vibrant civil society in Thailand and nascent civil society responses in neighbouring countries have challenged claims on resources made in the name of national development and regional integration.
This paper considers some key issues of re-scaling resource and environmental politics in the Mekong Region, and the extent to which challenges have been recast from national to regional development agendas. Politics of environment are shown to exist as a general rather than exceptional response to the region's development direction, and it is suggested that equitable and sustainable development increasingly needs to address simultaneously the re-scaling and reconfigurations of power in both environmental politics and the "infrapolitics" of environment. The paper is illustrated with case studies of dams in Laos and Thailand. 相似文献
This paper considers some key issues of re-scaling resource and environmental politics in the Mekong Region, and the extent to which challenges have been recast from national to regional development agendas. Politics of environment are shown to exist as a general rather than exceptional response to the region's development direction, and it is suggested that equitable and sustainable development increasingly needs to address simultaneously the re-scaling and reconfigurations of power in both environmental politics and the "infrapolitics" of environment. The paper is illustrated with case studies of dams in Laos and Thailand. 相似文献
99.
Quantitative measurements on the paleo-weathering intensity of the loess-soil sequences and implication on paleomonsoon 总被引:2,自引:0,他引:2
The loess-soil sequences in northern China provide a near continuous record of Quaternary paleoclimate. The pedogenetic intensity
of the sequences is closely linked with the variations of the East Asian summer monsoon. In this study, 2181 samples from
the Changwu and Xifeng loess sections are analyzed and two high-resolution paleo-weathering timeseries of the last 1.2 Ma
are generated, using the ratio of CBD extractable free Fe2O3 (FeD) versus the total iron (FeT). This new index is compared with micromorphological features, low-frequency magnetic susceptibility,
frequency-dependent magnetic susceptibility, and the Rb/Sr ratio[5,6]. The results suggest that the FeD/FeT ratio is able to better reflect the degree of soil development. Since the chemical
weathering of loess in the Loess Plateau region mainly depends upon the summer precipitation and temperature under modern
climate condition, which are closely associated with strength of summer monsoon, and the chemical weathering intensity of
loess primarily reflects the variations of the summer monsoon circulation. 相似文献
100.