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1.
Based on temperature reconstruction and proxy data from 14 sites in the Northern Hemisphere, this paper focused on comparing the cycles of temperature variations between the Arctic and other areas, including Atlantic, Europe, China, Asia, Pacific, Indian Ocean, and America during the transition from the last Interstade to the Last Glacial Maximum, from the Last Glacial Maximum to megathermal period in Holocene and the transition of the Little Ice Age （LIA） by the methods of Singular Spectrum Analysis （SSA） and Maximum Entropy Spectrum （MES）. The results showed that environmental changes in the Arctic are most similar to that in the North American and better similar to Asia, Atlantic and Pacific, the least similar to Indian Ocean and Europe. The 1500-year oscillation of temperature existed both in Arctic and Europe. 相似文献
2.
末次盛冰期以来中国湖泊记录对环流系统及气候类型的响应 总被引：4，自引：1，他引：3
为了探讨中国长时间尺度湖泊时空演变规律和潜在的驱动机制,本文在柯本气候分区和中国季风—非季风区的划分基础上,对中国34个有明确数据的典型湖泊运行CCSM 3.0气候模拟系统和水量能量平衡模型模拟其水位变化,同时利用NCEP/NCAR再分析资料对中国按水汽输送划分的季风区进行验证。结果表明,末次盛冰期以来中国湖泊演化主要受千年尺度大气环流的驱动影响,在各个柯本气候区内没有明显的规律性。末次盛冰期以来,在季风区中国湖泊演化主要有早中全新世湖泊水位相对较高以及末次盛冰期和早全新世湖泊水位均较高2种演变规律;在东亚干旱区主要有中晚全新世期间湖泊水位相对较高以及末次盛冰期和中全新世湖泊水位均较高2种演变规律。本文为中国过去气候变化及湖泊演化机制研究提供新的证据,同时为人类全面认识末次盛冰期以来湖泊水位变化提供了新的视角。 相似文献
3.
The data from the Southern Ocean observations of World Ocean Circulation Experiment(WOCE) are used for analysis and illustration of the features and spatial distributions of Circumpolar Deep Water(CDW) in the southern Indian Ocean.It is learnt from the comparison among the vertical distributions of temperature/salinity/oxygen along the 30°E,90°E and 145°E sections respectively that some different features of CDW and the fronts can be found at those longitudes,and those differences can be attributed to the zonal transoceanic flow and the merizonal movement in the Circumpolar Deep Water.In fact,the zonal transoceanic flow is the main dynamic factor for the water exchange between the Pacific Ocean and the Indian Ocean or between the Atlantic Ocean and the Indian Ocean,and for the effects on the spatial distributions of the physical properties in CDW. 相似文献
4.
依据 1 999年 7月至 9月中国首次北极考察队在白令海、楚科奇海和南加拿大海盆的现场调查资料 ,本文分析了三个海区的水团特征 :( 1 )白令海水团主要由季节变化显著的白令海上层水团和中层水团以及深层水团组成 ;( 2 )楚科奇海水文特征受融结冰过程影响较大 ,1 999年7月和 8月差异较大 ,其水团主要为浅海变性水团 ,包括两个次级水团 ,楚科奇海夏季水和来自北太平洋以及北冰洋变性的外海入侵水 ;( 3)南加拿大海盆的水团主要由受融结冰过程影响的表层水团、源于太平洋水的次表层水、源自北大西洋的中层水团和深层水团组成 相似文献
5.
北极地区具有超过4 000亿桶油当量的待发现技术可采储量, 是未来全球油气勘探与开发的重要增长点。本文按照地理和地质构造因素将北极地区分为北冰洋海盆区和环北极含油气区（含潜在含油气盆地）,按照板块演化及盆地发育历史将后者划分为北太平洋极地盆地群、俄罗斯极地盆地群和欧洲极地盆地群。根据大量文献和IHS数据, 结合生油层、储层、盖层及圈闭特征方面的研究, 系统对比、分析北极地区石油、天然气分布特征:北太平洋极地盆地群重要烃源岩形成于侏罗纪和白垩纪, 盆地群中重要储层大部分都分布于新生界布鲁克斯层, 油气系统以构造圈闭为主。俄罗斯极地盆地群中多数盆地具有古生代基底, 受斯堪的纳维亚早古生代造山期变形、西伯利亚板块古生代西部造山变形影响, 60%以上的烃源岩产自中生界, 储层以中生界前陆、克拉通盆地沉积物为主,盖层分布较广, 以中生界居多。欧洲极地盆地群受控于北大西洋洋脊的扩张和迁移, 各盆地烃源岩分布于中生界, 大部分储层分布于上白垩统—古新系, 自生自储、古生新储为该区域盆地的主要成藏模式。其中, 俄罗斯极地盆地油气储量最多, 占北极地区总储量45%以上且勘探潜力最大。 相似文献
6.
中国夏季高温日数时空变化及其环流背景 总被引：8，自引：1，他引：7
本研究利用1955~2005年全国193个气象站点夏季(5~9月)逐日最高气温资料,分析了我国东部地区夏季高温日数变化的空间分布特征和时间变化规律。经验正交函数分析结果显示高温日数的变化有明显的区域特征,第一模态表现为区域整体一致的异常,中心区位于长江中下游地区,第二模态表现为江淮流域与华南反向变化的特点,第三模态表现为东南部地区与西南、华北的反向变化。这些模态与高层大气环流的变化有关。分析表明ENSO(厄尔尼诺-南方涛动)、赤道印度洋和西太平洋暖池海温,可以通过影响西太平洋和东亚地区大气环流而影响我国夏季高温日数频次,其中ENSO和西太平洋暖池区海温对高温日数变化第一模态的相关比较明显;而热带印度洋海温对第二模态有显著影响。与前期海温的关系分析可知,第一模态与前期夏季的西太平洋暖池和前期冬季赤道东太平洋海温相关关系最好,第二模态则受热带印度洋前期冬季海温影响最大,这对高温预测具有指示意义。 相似文献
7.
本文利用主成分分析法提取了川西高原北部5个样点反映气温变化的树轮宽度年表的主成分年表,其中第一主成分年表(PC1)的方差贡献率为59.52%,能够较好地代表川西高原北部地区树轮宽度变化的共同特征。在器测时段内(1961-2010年),PC1年表、6-7月区域平均气温观测序列与东亚气温场的相关分布较为一致,均与中国的西北-青藏高原一带以及西伯利亚东部呈现显著的正相关(r > 0.443,p < 0.001),表明PC1年表能够反映较大空间范围的气温变化特征。器测时期,PC1年表和观测序列与全球海温场的相关分析表明,两者均与西太平洋、印度洋及北大西洋海域显著正相关,反映了在海气相互作用过程中多个海区海表温度变化可能对研究区气温变化有一定影响;而利用PC1年表在更长时间尺度(1854-2010年)及分阶段分析则发现不同阶段对区域气温起主导作用的海区有比较明显的差异,甚至在比较大的空间范围内在不同阶段出现相反的分布型,且由相关系数反映出的海气相互作用强度也具有显著的差异,气温波动较大时,海气相互作用也比较强烈。异常年分析则反映出西北太平洋和北大西洋海温异常对研究区气温异常具有持续稳定的影响。 相似文献
8.
印度海上战略通道的新动向、动因及影响 总被引：1，自引：0，他引：1
作为印度洋沿岸的国家,随着2015年《确保海洋安全：海洋安全战略》的出台,印度进一步拓展了海上战略通道,主要体现在三个方面：重视南太平洋海上战略通道、拓展大西洋地区海上战略通道、重视北极地区这一新航道的价值。究其原因,印度追求大国地位、参与全球海洋治理的需要以及保障能源进口多元化是其拓展海上战略通道的主要动因。印度对于海上战略通道的拓展一方面将加剧大国对于海上战略通道的争夺态势,另一方面,将有助于国际社会共同建设维护海上战略通道安全的机制。 相似文献
9.
This paper documents the main features of climate and climate variability across the Monte Desert for the Last Glacial Maximum, the Glacial–Interglacial transition, and the Holocene on the basis of proxy records and for the 20th century using instrumental observations. The climate in the Monte is determined by interactions between regional physiography and atmospheric circulation in the 25–45°S sectors of South America. Although arid and semi-arid conditions prevail across the Monte, its large latitudinal extent and complex topography introduce many particularities at local scales. Paleoclimatic records and model simulations of past climates suggest significant variations in the atmospheric circulation, temperature and rainfall patterns since the Last Glacial Maximum. High-resolution proxy records east of the Andes support the existence of complex climatic patterns with similar temperature changes across the whole region but opposite precipitation variations between subtropical and mid-latitude sectors in the Monte during the past millennium.The present-day climate is depicted in terms of the space and time variability of the near-surface temperature, rainfall and tropospheric wind patterns. Uneven temperature trends over the Monte were recorded for two separate (1920–44 and 1977–2001) global warming periods in the 20th century. Additional warming evidence in the region is provided by extreme temperature records. The non-homogeneous regional pattern of precipitation shows a positive long-term increase between 30 and 40°S during the interval 1985–2001. Ensemble of climate experiments accomplished with general circulation models provide the most likely changes in temperature and rainfall to occur by the end of this century in relation to present climate. Temperature increases, larger in summer than in winter, will be concurrent with more abundant precipitations in summer, but almost no changes or even small reductions in winter across the Monte. 相似文献
10.
基于野外沉积物调查、已报道的风成沉积物年代和重建的湖泊水位波动曲线,初步绘制了末次冰期冰盛期和全新世早期青海湖东岸的沙漠范围。初步认为,末次冰期冰盛期时青海湖大幅度萎缩,湖底沉积物暴露并遭受风蚀,在偏西风的搬运下,近岸粗颗粒砂堆积在日月山西侧和倒淌河河谷,形成流动沙丘,细颗粒沉积物被向东搬运沉积至河湟谷地和黄土高原。倒淌河源头的沙丘最晚是在末次冰期盛冰期(23~16ka BP)沙漠扩张时形成并残留至今的;青海湖东部日月山西侧山麓地带和倒淌河河谷中、晚全新世黄土、古土壤下部普遍沉积的风成砂是末次冰期冰盛期和全新世早期(11~9 ka BP)青海湖东岸地区大范围沙化的证据。 相似文献
11.
12.
Circulation in the Arctic Ocean 总被引：7，自引：0，他引：7
E. Peter Jones 《Polar research》2001,20(2):139-146
Much information on processes and circulation within the Arctic Ocean has emerged from measurements made on icebreaker expeditions during the past decade. This article offers a perspective based on these measurements, summarizing new ideas regarding how water masses are formed and how they circulate. Best understood at present is the circulation of the Atlantic Layer and mid-depth waters, to depths of about 1700 m, which move in cyclonic gyres in the four major basins of the Arctic Ocean. New ideas on halocline formation and circulation are directly relevant to concerns regarding changes in ice thickness. The circulation of the halocline water in part mimics that of the underlying Atlantic Layer. A number of large eddies contributing to water mass transport have been observed. The circulation of freshwater from the Pacific Ocean and from river runoff has been better delineated. Circulation within the surface layer resembles the circulation of ice, but is different in several respects. Least understood is the circulation of the deepest waters, though some information is available. Recent observed changes in the surface waters and warm Atlantic Layer have been correlated with the North Atlantic Oscillation. While these changes are dramatic, the qualitative circulation pattern may not have been altered significantly. 相似文献
13.
DEGLACIATION OF THE EASTERN FLANK OF THE NORTH PATAGONIAN ICEFIELD AND ASSOCIATED CONTINENTAL-SCALE LAKE DIVERSIONS 总被引：1，自引：1，他引：1
K.J. TURNER C.J. FOGWILL R.D. McCULLOCH D.E. SUGDEN 《Geografiska Annaler: Series A, Physical Geography》2005,87(2):363-374
ABSTRACT. We examine the deglaciation of the eastern flank of the North Patagonian Icefield between latitudes 46° and 48°S in an attempt to link the chronology of the Last Glacial Maximum moraines and those close to present-day outlet glaciers. The main features of the area are three shorelines created by ice-dammed lakes that drained eastwards to the Atlantic. On the basis of 16 14 C and exposure age dates we conclude that there was rapid glacier retreat at 15–16 ka (calendar ages) that saw glaciers retreat 90–125 km to within 20 km of their present margins. There followed a phase of glacier and lake stability at 13.6–12.8 ka. The final stage of deglaciation occurred at c. 12.8 ka, a time when the lake suddenly drained, discharging nearly 2000 km3 to the Pacific Ocean. This latter event marks the final separation of the North and South Patagonian Icefields. The timing of the onset of deglaciation and its stepped nature are similar to elsewhere in Patagonia and the northern hemisphere. However, the phase of lake stability, coinciding with the Antarctic Cold Reversal and ending during the Younger Dryas interval, mirrors climatic trends as recorded in Antarctic ice cores. The implication is that late-glacial changes in southern Patagonia were under the influence of the Antarctic realm and out of phase with those of the northern hemisphere. 相似文献
14.
南极绕极波(ACW)是近10年来海洋和大气科学领域研究的重要内容之一,其特征表现为一种海气耦合的年际信号在南大洋的明显东向传播。文中依据波动的基本原理,利用非线性拟合方法得到了绕极波行波的平均波速、波数和角频率和印度洋驻波的表达形式,得出行波和驻波具有相同的角频率。针对绕极波纬圈传播的不连续现象,提出了南极绕极波是行波和驻波共存系统的新见解。行波与驻波共存系统由三部分组成:在南大洋的太平洋西侧发生SLP振动,与发生在太平洋中低纬度的过程有关;在太平洋和大西洋存在传播的行波,行波在太平洋最强,到大西洋明显减弱;在印度洋SLP系统表现为局地变化,体现明显的驻波特征。三部分有共同的周期,表明三部分是统一的动力学系统,证实了行波与驻波共存系统可以很好地表达南极绕极波的时空特性和传播特征。 相似文献
15.
The localized rain rate maxima (RM) of the inner core region of intense tropical cyclones (TCs) are investigated using Version 6 of the Tropical Rainfall Measuring Mission Multi-satellite Precipitation Analysis data-set from 1998 to 2010. Specifically, this study examines the probabilities of RM exceeding 25 mm h?1 (P25) in intense TCs. The 25 mm h?1 RM is the 90th percentile of all RM observations during the study period. The descending order of P25 observed from intense TCs for the six major ocean basins is: the North Indian Ocean, the Atlantic Ocean, the Northwest Pacific Ocean, the South Pacific Ocean, the South Indian Ocean, and the East-central Pacific Ocean. The six major basins have been subdivided into 29 sub-basins to discern regional variability of RM. P25 increases with increasing TC category in all major basins, except for the South Pacific. Sub-basins with intense TCs that produce extreme rainfall rate maxima include the Bay of Bengal, the South Philippine Sea, the East China Sea, the north coast of Australia, southeast Melanesia, and the Northwest Atlantic. Sub-basins with a higher proportion of category 5 (CAT5) observations than category 3 (CAT3) observations tend to have a greater P25 beyond 60 km from the storm center. 相似文献
16.
A study on the Antarctic circumpolar wave mode-A coexistence system of standing and traveling wave 
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下载免费PDF全文 The Antarctic circumpolar wave(ACW)has become a focus of the air-sea coupled Southern Ocean study since 1996,when it was discovered as an air-sea coupled interannual signal propagating eastward in the region of the Antarctic C i rcumpolar Current(ACC).In order to analyze the mechanism of discontinuity alon g the latitudinal propagation,a new idea that ACW is a system with a traveling wave in the Southern Pacific and Atlantic Ocean and with a concurrent standing w ave in the southern Indian Ocean is proposed in this paper.Based on the ideal w ave principle,the average wave parameters of ACW is achieved using a non-linea r approximation method,by which we find that the standing part and the travelin g part possess similar radius frequency,proving their belonging to an integral s ystem.We also give the latitudinal distribution of wave speed with which we cou ld tell the reason for steady propagation during the same period.The spatial di stribution of the propagation reveals complex process with variant spatial and t emporal scales—The ENSO scale oscillation greatly impacts on the traveling process,while the result at the south of Australia indicates little connection betw een the Indian Ocean and the Pacific,which may be blocked by the vibration at t he west of the Pacific.The advective effect of ACC on the propagation process s hould be examined clearly through dynamical method. 相似文献
17.
海冰是海洋-大气交互系统的重要组成部分,与全球气候系统间存在灵敏的响应和反馈机制。本文选用欧洲空间局发布的1992—2008年海冰密集度数据分析了南北极海冰在时间和空间上的变化规律与趋势,并结合由美国环境预报中心(National Centers for Environmental Prediction,NCEP)和美国大气研究中心(National Center for Atmospheric Research, NCAR)联合制作的NCEP/NCAR气温数据和ENSO指数探讨了南北极海冰变化的影响因素。结果表明,北极海冰面积呈明显的减少趋势,其中夏季海冰最小月的减少更快。北冰洋中央海盆区、巴伦支海、喀拉海、巴芬湾和拉布拉多海的减少最明显。南极海冰面积呈微弱增加趋势,罗斯海、太平洋扇区和大西洋扇区的海冰增加。北极海冰面积与气温有显著的滞后1个月的负相关关系(P0.01)。北极升温显著,北冰洋中央海盆区、喀拉海、巴伦支海、巴芬湾和楚科奇海升温趋势最大,海冰减少很明显。南极在南大西洋、南太平洋呈降温趋势,海冰增加。北极海冰减少与39个月之后ONI的下降、40个月之后SOI的上升密切相关;南极海冰增加与7个月之后ONI的下降、6个月之后SOI的上升存在很好的响应关系。南北极海冰变化与三次ENSO的强暖与强冷事件有很好的对应关系。 相似文献
18.
David E. Wilkins 《自然地理学》2013,34(5):460-477
Western North American hemiarid basins situated along a climate boundary zone, or threshold, that separates regions of different climate regimes exhibit greater variability to changes in hydroclimatic variables. The Trans-Pecos Closed Basin study examines how global paleoclimatic factors and intrinsic geographic controls act in determining the threshold between states of hydroclimatic equilibria. Geomorphic, radiocarbon, and limnetic evidence identifies four major highstands for late Pleistocene Lake King during the Last Glacial Maximum (LGM). Patterns in the resulting model limnograph for Lake King suggest that runoff contributions from basin catchments to the inundated area were limited by precipitation rather than evaporation. Timing of the onset of lacustrine transgressive events corresponds with the later stages of cooling events recorded in the Greenland ice and North Atlantic deep-sea sedimentary record. Correlation of Trans-Pecos lacustrine environments with North Atlantic cooling implies that full pluvial conditions in the basin were limited to those periods when those cooling events resulted in extreme equatorward shifts of the LGM subpolar winter storm tracks, providing a moisture source to the basin. By comparing timing, intensity, and direction of climate change over a widely spaced array of hemiarid basins, the global implications of climatic events are better understood. [Key words: Last Glacial Maximum, paleolakes, Pleistocene, Trans-Pecos Closed Basin, New Mexico, Texas.] 相似文献
19.
Modeling Arctic Ocean heat transport and warming episodes in the 20th century caused by the intruding Atlantic Water 下载免费PDF全文
下载免费PDF全文 Jun Takahashi Tatsuo Suzuki Igor V Polyakov Kohei Mizobata Moto Ikeda Fancois J.Saucier Markus Meier 《极地研究》2008,19(2):159-167
This study investigates the Arctic Ocean warming episodes in the 20th century using both a high-resolution coupled global climate model and historical observations .The model,with no flux adjustment,reproduces well the Atlantic Water core temperature(AWCT) in the Arctic Ocean and shows that four largest decadal-scale warming episodes occurred in the 1930s,70s,80s,and 90s,in agreement with the hydrographic observational data.The difference is that there was no pre-warming prior to the 1930s episode,while there were two pre-warming episodes in the 1970s and 80s prior to the 1990s,leading the 1990s into the largest and prolonged warming in the 20th century.Over the last century,the simulated heat transport via Fram Strait and the Barents Sea was estimated to be,on average,31.32 TW and 14.82 TW,respectively,while the Bering Strait also provides 15.94 TW heat into the western Arctic Ocean.Heat transport into the Arctic Ocean by the Atlantic Water via Fram Strait and the Barents Sea correlates significantly with AWCT(C=0.75 ) at 0- lag.The modeled North Atlantic Oscillation(NAO) index has a significant correlation with the heat transport(C=0.37).The observed AWCT has a significant correlation with both the modeled AWCT(C=0.49) and the heat transport(C=0.41). However,the modeled NAO index does not significantly correlate with either the observed AWCT(C=0.03) or modeled AWCT(C=0.16) at a zero-lag,indicating that the Arctic climate system is far more complex than expected. 相似文献
20.
1 IntroductionIthas been accepted thatthe glacialextentin the early stage w as largerthan thatin the late stagein Eastern A sia during the Last G laciation and w as different from Europe and N orth A m erica(Li, 1992; Cui et al., 2000). M any scholars hav… 相似文献