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731.
The influence of tropical Indian Ocean warming on the Southern Hemispheric stratospheric polar vortex 总被引:1,自引:0,他引:1
ShuangLin Li 《中国科学D辑(英文版)》2009,52(3):323-332
During the past decades, concurrent with global warming, most of global oceans, particularly the tropical Indian Ocean, have
become warmer. Meanwhile, the Southern Hemispheric stratospheric polar vortex (SPV) exhibits a deepening trend. Although previous
modeling studies reveal that radiative cooling effect of ozone depletion plays a dominant role in causing the deepening of
SPV, the simulated ozone-depletion-induced SPV deepening is stronger than the observed. This suggests that there must be other
factors canceling a fraction of the influence of the ozone depletion. Whether the tropical Indian Ocean warming (IOW) is such
a factor is unclear. This issue is addressed by conducting ensemble atmospheric general circulation model (AGCM) experiments.
And one idealized IOW with the amplitude as the observed is prescribed to force four AGCMs. The results show that the IOW
tends to warm the southern polar stratosphere, and thus weakens SPV in austral spring to summer. Hence, it offsets a fraction
of the effect of the ozone depletion. This implies that global warming will favor ozone recovery, since a warmer southern
polar stratosphere is un-beneficial for the formation of polar stratospheric clouds (PSCs), which is a key factor to ozone
depletion chemical reactions.
Supported by National Natural Science Foundation of China (Grant Nos. 40775053 and 90711004), National Basic Research Program
of China (Grant No. 2009CB421401), and Innovation Key Program of Chinese Academy of Sciences (Grant Nos. KZCXZ-YW-Q11-03,
KZCZ2-YW-Q03-08) 相似文献
732.
Early Paleozoic subduction of the Paleo-Asian Ocean: Geochronological and geochemical evidence from the Dashizhai basalts,Inner Mongolia 总被引:10,自引:0,他引:10
Zircon U-Pb results of basalt from the Dashizhai Town in Inner Mongolia, NE China, shows that the basaltic lava was erupted
at 439±3 Ma, much older than the “Permian basalts” as previously thought. These rocks show arc-type trace element patterns
(i.e., Nb-Ta depletion and light REE and large ion lithophile element enrichment) and unradiogenic Sr and highly radiogenic
Nd and Hf isotope compositions. They can be subdivided into two petrogenetic groups: Group 1 basalts have relatively high
TiO2, MgO and compatible elements and low Sr and Th, characterized by mid-oceanic ridge basalt (MORB)-type Sr-Nd-Hf isotope compositions
(87Sr/86Sr(i)=0.7028−0.7032, εNd(t)=+9.8−+11.2, εHf(t)=+16.1−+18.4). Group 2 has lower TiO2, MgO and compatible elements and higher Sr and Th, and relatively evolved Sr-Nd-Hf isotope compositions (87Sr/86Sr(i)=0.7037−0.7038, εNd(t)=+5.7−+7.3, εHf(t)=+12.6−+13.0). Both groups were interpreted as melts derived from a metasomatized mantle wedge formed during the subduction
of Paleo-Asian Ocean. The mantle source for Group 1 was probably a highly isotopically depleted oceanic mantle modified by
predominant slab fluids; whereas subducted sediments had an important contribution to the melting source for Group 2. The
petrogenesis of the Dashizhai basalts provides clear evidence for early Paleozoic subduction of the Paleo-Asian Ocean, and
the highly radiogenic Nd and Hf compositions in these rocks suggest that these lavas and their possible intrusive counterparts
were one of the important components for Phanerozoic crustal growth. Our and previous studies on the “Dashizhai Formation”
volcanic rocks yield an unrealistic eruption range of 440-270 Ma for different rock types, we thus advise to disassemble the
previously defined “Dashizhai Formation” into multiple lithologic units and to reinterpret the spatial and temporal distributions
of different volcano-sedimentary associations.
Supported by National Basic Research Program of China (Grant No. 2006CB403504) 相似文献
733.
Daisuke Sugawara Koji Minoura Naoki Nemoto Shinji Tsukawaki Kazuhisa Goto Fumihiko Imamura 《Island Arc》2009,18(3):513-525
Micropaleontological analysis of nearshore to offshore sediments recovered from the southwestern coast of Thailand was performed to clarify the submarine processes of sediment transport and deposition during the 2004 Indian Ocean tsunami. The distribution pattern of benthic foraminifers showed seaward migration after the tsunami event. Agglutinated foraminifers, which are characteristic of an intertidal brackish environment, were identified in the post-tsunami samples from foreshore to offshore zones. These suggest that sediments originally distributed in foreshore to nearshore zones were transported offshore due to the tsunami backwash. On the other hand, the distribution pattern of planktonic and benthic species living in offshore zones showed slight evidence of landward migration by the tsunami. This suggests that landward redistribution of sediments by the tsunami run-up did not occur in the offshore seafloor of the study area. Our results and a review of previous studies provide an interpretation of submarine sedimentation by tsunamis. It is possible that tsunami backwashes induce sediment flows that transport a large amount of coastal materials seaward. Thus, traces of paleotsunami backwashes can be identified in offshore sedimentary environments as the accumulation of allochthonous materials. This can be recognized as changes in benthic foraminiferal assemblages. 相似文献
734.
Environmental decision-making under uncertainty using intuitionistic fuzzy analytic hierarchy process (IF-AHP) 总被引:1,自引:0,他引:1
Rehan Sadiq Solomon Tesfamariam 《Stochastic Environmental Research and Risk Assessment (SERRA)》2009,23(1):75-91
Analytic hierarchy process (AHP) is a utility theory based decision-making technique, which works on a premise that the decision-making
of complex problems can be handled by structuring them into simple and comprehensible hierarchical structures. However, AHP
involves human subjective evaluation, which introduces vagueness that necessitates the use of decision-making under uncertainty. The vagueness is commonly handled through fuzzy sets theory, by assigning degree of membership. But, the environmental decision-making
problem becomes more involved if there is an uncertainty in assigning the membership function (or degree of belief) to fuzzy pairwise comparisons, which is referred to as ambiguity (non-specificity). In this paper, the concept of intuitionistic fuzzy set is applied to AHP, called IF-AHP to handle both vagueness and ambiguity
related uncertainties in the environmental decision-making process. The proposed IF-AHP methodology is demonstrated with an
illustrative example to select best drilling fluid (mud) for drilling operations under multiple environmental criteria. 相似文献
735.
把建好的海洋碳模式应用于印度洋区域,模拟得到了印度洋中与碳有关各化学量的表层分布、垂直分布和沿子午线面的等值线分布。与实测的GEOSECS(GeochemicalOcean—Sectinn Study)数据作对比,模式较好地再现了印度洋上营养盐浓度、总碳浓度、总碱度和溶解氧的二维分布。通过模拟还发现,在稳定状态下,大气和海洋中总碳含量的分布依赖于发生在海洋中的各种物理化学过程及边界条件,水平扩散系数Kh和光合作用常数率Kg对各化学量的分布有较大影响(以前有学者认为不太重要,如 Baes[1]);南印度洋中纬地区 10°S至 30°S是14C的重要向下渗透区域,人为排放的CO2可通过这片渗透区从海洋的表层输入海洋的深层。 相似文献
736.
An integrated model for predicting rainfall-induced landslides 总被引:2,自引:0,他引:2
This study proposes a novel method that combines a deterministic slope stability model and a statistical model for predicting rainfall-induced landslides. The method first uses the deterministic model to derive the rainfall rate critical to induce slope failure for each land unit. Then it calculates the difference between the critical rainfall threshold and estimated rainfall intensity. Using the difference and estimated rainfall duration as explanatory variables, the method derives a logit (integrated) model to compute landslide occurrence probabilities. To demonstrate the effectiveness of this method, the study used radar rainfall estimates and landslides associated with a typhoon (tropical cyclone) to develop the integrated model and the same types of data associated with another typhoon to validate the model. The model had a modified success rate of 84.0% for predicting landslides and stable areas, and model validation yielded a modified success rate of 87.4%. Both rates were better than those from the critical rainfall model. The main advantage of the integrated model lies in its use of rainfall variables that are not included in calculating the critical rainfall. Also, as a probabilistic model, the integrated model is better suited for decision-making in watershed management. This study has advanced the method for predicting rainfall-triggered landslides. 相似文献
737.
Projections of ocean climate for northwestern Pacific Ocean 总被引:1,自引:1,他引:0
The long-term adjustment processes of atmosphere and ocean in response to gradually increased atmospheric CO2 concentration have been analyzed in 70 and 140a integrations with NCAR fully-coupled climate system model (CSM). In these experiments the CO2 concentration has been increased to double and quadruples the initial concentration, respectively. After 70a, at the time of CO2 doubling, the model predicts surface air temperature rises by 1.2 and 1.5K for the globe and the northwestern Pacific Ocean, respectively. The behavior of the quadrupling run is similar: each global and regional mean surface air temperatures increase by 2.8 and 3.0K at the time of CO2 quadrupling. From the experiments, surface air temperature changes in the northwestern Pacific Ocean will be more distinctive compared with the global average, mainly due to exceptionally large warming and sea level change near the entrance of the Kuroshio extension. 相似文献
738.
基于GIS组件和Surfer软件的海洋调查数据等值线绘制方法 总被引:5,自引:0,他引:5
论文讨论了利用海洋调查数据自动绘制等值线图的方法。该方法采用组件化GIS实现研究站位的交互选取,根据交互选取的站位信息访问后台数据库取得站位数据,使用Surfer软件作为后台服务器接收站位数据并绘制等值线图。该方法集成了GIS组件的交互选取功能和Surfer软件的空间插值和绘图功能,实现了海洋空间要素分布图的自动绘制,而且操作简单、直观,等值线图效果好。文章给出了该方法的主要步骤和调用Surfer实现插值和绘图的关键VB语句,并给出了该方法的一个具体应用实例。 相似文献
739.
针对华北地区农业生产水平和农业干旱特点 ,于 1 996~ 1 998年进行了农业干旱监测预测、秸秆覆盖、底墒科学利用、有限水胁迫效应、深松、多功能防旱剂和有限灌溉等单项农业干旱防御技术试验研究 .在它们的防旱机理、功能和操作技术方面取得了较好的效果 .在此基础上 ,在干旱严重的 1 998~ 1 999年冬小麦生育期内 ,在河南郑州郊区、山东泰安郊区和河北固城 ,根据各地条件因地制宜地对上述技术进行组装配套集成示范试验 .结果表明 ,综合应用这些技术具有较显著的抗旱增产效能 ,小麦增产 1 0 .1 %~ 36.0 % ,耗水量减少 1 .0 %~ 1 9.0 % ,水分利用效率提高 1 0 .6%~ 60 .0 % . 相似文献
740.