印度洋热含量在南海夏季风爆发中的作用     

于乐江  冯俊乔 《热带海洋学报》2011,(4)

利用Scripps海洋研究所0—400m上层海洋热含量资料和美国环境监测中心/国家大气研究中心(National Centers for Environmental Prediction/National Center for Atmospheric Research,NCEP/NCAR)的再分析资料,运用经验正交分解(empirical orthogonal function,EOF)等统计方法,研究在有ENSO影响和去除ENSO影响的情况下,前期春季印度洋热含量如何影响南海夏季风爆发。结果表明,在没有扣除ENSO信号的情况下,热带印度洋热含量EOF分解第一模态呈东西相反变化的空间分布。印度洋东部热含量为正(负)异常、西部为负(正)异常时,南海夏季风爆发较早(晚),印度洋上层热含量主要通过影响热带印度洋上空大气的垂直运动和高低层辐散辐合,进而影响季风纬向环流的强弱,来影响南海夏季风爆发的早晚。在扣除ENSO信号的情况下,印度洋热含量CEOF(conditional EOF)第一模态的空间分布类似于EOF第一模态的空间分布;第二模态表现为除小部分海区外,热带印度洋热含量呈一致变化的海盆模态。这两个模态对南海夏...  相似文献   

若干西边界潜流的气候态分布特征     

臧楠  王凡  吴德星 《中国海洋大学学报(自然科学版)》2011,41(9):1-8

"西边界潜流(WBUC)"是海洋环流中的重要现象,与表层环流相比,对次表层潜流的结构认识不足。本文利用SODA、OFES和ARGO资料,分析了北太平洋中的棉兰老潜流(MUC)和吕宋潜流(LUC)、南太平洋中的大堡礁潜流(GBRUC)和东澳大利亚潜流(EAUC)及南印度洋中的阿加勒斯潜流(AUC)的气候态空间分布特征,并且根据地转流反向的判据,分析WBUC的发生条件。  相似文献   

Spatial and temporal variations in C₃ and C₄ plant abundance over the Chinese Loess Plateau since the last glacial maximum     

Z. Yao  H. WuM. Liang  X. Shi 《Journal of Arid Environments》2011,75(10):881-889

Stable carbon isotopes of soil organic matter from 12 sites in the southern Chinese Loess Plateau are reviewed to examine spatial and temporal patterns of C₃ and C₄ plants in the arid to semiarid monsoonal region during three key periods - last glacial maximum, mid-Holocene, and modern. We have tentatively corrected the effects of atmospheric CO₂ concentrations and precipitation amounts on the δ¹³C endmembers for C₃ plants to reconstruct the relative proportion of C₄ plants because the δ¹³C values of C₃ plants are variable under different CO₂ and climate conditions. The results indicate that C₄ grasses increase from northwest to southeast spatially, which is consistent with present-day increasing precipitation and temperature patterns. This suggests that for a monsoon-dominant arid to semiarid region, such as the Loess Plateau, warm-season rainfall is a primary factor limiting C₄ plants growth, and thus C₄ grasses have been outcompeted by C₃ grasses/shrubs under cold-dry climate conditions. However, temporal fluctuations in atmospheric CO₂ concentration may also affect plant growth through altering water-use efficiency (WUE). Enhanced drought caused by decreased WUE due to low atmospheric CO₂ concentrations during glacial periods, combined with a cold-dry climate, leads to a decline in C₄ grasses, canceling out any advantages gained from lowered atmospheric CO₂ concentrations. To reconstruct accurately the abundance of C₃ and C₄ plants in an ecosystem and explore their controlling factors, process-based vegetation models integrating CO₂ and climatic parameters interactive with plant physiology are necessary.  相似文献   

Vegetation history along the eastern, desert escarpment of the Sierra San Pedro Mártir, Baja California, Mexico     

Camille A. Holmgren  Julio L. Betancourt  Kate A. Rylander 《Quaternary Research》2011,75(3):647-657

Plant macrofossils from 38 packrat middens spanning the last ~ 33,000 cal yr BP record vegetation between ~ 650 and 900 m elevation along the eastern escarpment of the Sierra San Pedro Mártir, northern Baja California. The middens span most of the Holocene, with a gap between ~ 4600 and 1800 cal yr BP, but coverage in the Pleistocene is uneven with a larger hiatus between 23,100 and 14,400 cal yr BP. The midden flora is relatively stable from the Pleistocene to Holocene. Exceptions include Pinus californiarum, Juniperus californica and other chaparral elements that were most abundant > 23,100 cal yr BP and declined after 14,400 cal yr BP. Despite being near the chaparral/woodland-desertscrub ecotone during glacial times, the midden assemblages reflect none of the climatic reversals evident in the glacial or marine record, and this is corroborated by a nearby semi-continuous pollen stratigraphy from lake sediments. Regular appearance of C₄ grasses and summer-flowering annuals since 13,600 cal yr BP indicates occurrence of summer rainfall equivalent to modern (JAS average of ~ 80–90 mm). This casts doubt on the claim, based on temperature proxies from marine sediments in the Guaymas Basin, that monsoonal development in the northern Gulf and Arizona was delayed until after 6200 cal yr BP.  相似文献   

中印度洋脊Edmond热液区黄铁矿的标型特征及其对海底成矿作用环境的指示   总被引：1，自引：0，他引：1  

王叶剑  韩喜球  金翔龙  邱中炎  朱继浩 《矿物学报》2011,31(2):173-179

对中印度洋脊Edmond热液区的丘顶和丘坡进行电视抓斗取样,获得了大量的金属硫化物等热液作用产物样品。在进行细致的矿相学分析基础上,对硫化物中黄铁矿的标型特征及其演化进行了详细研究。结果表明,Edmond热液区的黄铁矿可分3种类型,其形态标型和成分标型分别具有以下特征:Ⅰ型:呈自形立方体状,S/Fe原子数比接近于2.00,微量元素具有高Cu,低Zn、As、Pb、Ni和Ag的特点,Cu/Zn值高,平均可达4.26;Ⅱ型:呈半自形立方体状,S/Fe原子数比平均2.03,具有高Zn、Co、低Cu的特点,Cu/Zn值(平均0.04)低;Ⅲ型:主要呈胶状、莓球状,S/Fe原子数比平均2.04,具有Ag、Pb、Zn、As元素富集的特点,Cu/Zn值介于前两者之间(平均1.09)。根据硫化物中矿物共生组合关系,认为这3类黄铁矿分别对应高温、中高温和低温成矿作用,黄铁矿的形态和成分能很好地指示热液区的成矿环境和成矿条件的演变。  相似文献   

ENSO事件对云南及临近地区春末初夏降水的影响   总被引：3，自引：0，他引：3       下载免费PDF全文

杨亚力  杜岩  陈海山 《大气科学》2011,35(4):729-738

本文采用合成及相关分析的方法,应用55年中国降水资料、美国NOAA海表温度资料以及NCEP/NCAR再分析资料,研究了ENSO事件对我国云南及其邻近地区春末初夏降水的影响及物理机理.研究结果表明:(1)在El Ni(n)o (La Ni(n)a)年,云南大部分地区4～5月降水偏少(多),东部地区相关信号尤其明显;(2)...  相似文献   

与西澳州西南部冬季降水相联系的大气环流特征分析          下载免费PDF全文

李建平  李艳杰  冯娟 《大气科学》2011,35(5):801-817

西澳大利亚州西南部(SWWA)是西澳大利亚州首府Perth的所在地,也是西澳州政治、经济、文化、教育和旅游的中心.自20世纪中期以来,SWWA地区雨季降水持续减少.本文利用近60年的观测及再分析数据,分析了已知的影响澳大利亚降水的热带海洋模态:厄尔尼诺—南方涛动(ENSO)、印度洋偶极子(IOD)和ENSOModoki...  相似文献   

Distribution and abundance of thaliaceans in the northwest continental shelf of South China Sea, with response to environmental factors driven by monsoon   总被引：3，自引：0，他引：3  

Kaizhi LiJianqiang Yin  Liangmin HuangJianlin Zhang  Shumin LianCuimei Liu 《Continental Shelf Research》2011,31(9):979-989

The distribution and abundance of thaliaceans were studied in relation to physical and biological variables during summer and winter in the northwest continental shelf of South China Sea. Based on the topography and water mass of the surveyed region, it was divided into three subregions: region I (onshore waters of the east Leizhou Peninsula), region II (onshore waters of the east and southeast Hainan Island) and region III (offshore waters from Leizhou Peninsula to Hainan Island). During summer due to a strong southwest monsoon, a cold eddy and coastal upwelling dominated in regions I and II, respectively, whereas the onshore and offshore waters were vertically mixed during winter due to a strong northeast monsoon. A total of 18 thaliacean species (including 3 subspecies) were collected. The mean species richness was higher in summer compared to winter, with the occurrence of higher values during summer and winter at region II and region III, respectively. The average thaliacean abundance is also higher in summer than in winter, with higher values at region I in summer and no significant difference among three subregions in winter. Doliolum denticulatum and Thalia democratica were the dominant species during summer and winter. The results suggested that the seasonal and spatial distribution of thaliacean richness was considered to be the result of physical factors such as temperature and ocean current in summer and winter. Spatial distribution of thaliacean abundance was affected by chlorophyll a concentration increased by the occurrence of coastal upwelling and cold eddy in summer. Southwest and northeast monsoons are shown to play an important role in shaping the distribution of species richness and abundance of thaliaceans in the northwest continental shelf of South China Sea.  相似文献   

热带气旋“碧利斯”与南海季风相互作用的强水汽特征数值研究   总被引：2，自引：0，他引：2  

叶成志  李昀英 《气象学报》2011,69(3):496-507

强热带风暴碧利斯(0604)登陆后其低压环流较长时间地维持,并与南海季风相互作用,造成湖南省东南部发生历史罕见的特大致洪暴雨。文中应用多种常规、非常规细网格观测资料及NECP再分析资料,结合暴雨中尺度数值预报模式AREM对该暴雨过程的强水汽场特征进行了数值模拟和诊断分析,并设计水汽敏感性试验,进一步揭示造成湘东南特大暴雨的水汽通道和水汽来源。结果表明:碧利斯低压环流南侧的西南气流对湘东南暴雨区起到了主要水汽输送作用,且随着碧利斯逆时针旋转,水汽沿着环流中心东侧的强风速带夹卷到环流北侧,并通过增强的东北风源源不断地输送至湘东南。这南北两支主要水汽通道在湘东南长时间交汇,形成了湘东南暴雨区深厚的湿层和强水汽辐合,对碧利斯低压环流较长时间的维持及对湘东南特大暴雨的形成和发展有重要的作用。  相似文献   

北印度洋—南海海面风速和有效波高的年代际变化     

周林  梅勇  王慧娟  郑崇伟 《南京气象学院学报》2011,34(5):547-554

采用1958年1月—2001年12月ECMWF ERA-40的10m风场资料,以及由该风场资料驱动WAVEWATCHⅢ得到的北印度洋—南海海域44a的海浪场资料,通过EOF分析、正交小波分析和M-K检测方法,分析了北印度洋—南海海域海面风场和有效波高的年代际变化特征。结果表明：北印度洋—南海海域存在3个大风、大浪区,其中亚丁湾以东洋面风力最强,有效波高最高;表面风场和有效波高存在35、15和3a的主周期变化,并自20世纪70年代中期以来,年平均风场和有效波高均存在明显增强趋势,1977年为突变起始年;年平均海表10m风速和有效波高随时间增大主要是由冬季和春季海表10m风速和有效波高随时间增大引起的;冬、秋季海面风场与有效波高的年际、年代际变化周期较一致,冬季以35～40a的周期为主,秋季以11～12a的周期为主。  相似文献