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61.
北太平洋涛动与台风和飓风频次的关系研究 总被引:15,自引:1,他引:15
研究了北太平洋涛动(NPO)和西太平洋台风及热带大西洋飓风频次的联系. 结果表明, 在1949~1998年这50 a间, NPO和西太平洋台风频次的相关系数是0.37, 而和热带大西洋飓风频次的相关系数是-0.28, 都达到了95%的置信度水平. 进一步的研究揭示: 6~9月NPO的变化和西太平洋及热带大西洋区的纬向风垂直切变幅度、海平面气压以及海表面温度、区域大气辐散辐合等存在显著的关联, 而这些气候环境的变化都和台风及飓风生成与发展的热力或动力过程密切相关. 这就是NPO与台风及飓风频次相联系的原因. 还进一步研究了与NPO有关的大气遥相关以及两个区域大气环流的变化, 以便进一步理解NPO和台风及飓风活动频次的联系. 最后分析了一个海气耦合模式的积分结果, 初步印证了由观测资料所得到的结论. 相似文献
62.
大西洋位于欧洲、非洲、美洲和南极洲之间,是世界第二大洋。大西洋有多条国际航线,连接欧洲、美洲、非洲的沿岸国家,货运量居各大洋第一位。从地缘政治角度看,大西洋具有极其重要的战略意义,是世界战略资源及国际重要水上通道最密集的地区,美国、西欧和亚洲国家所需的大部分石油,都必须经过大西洋。世界许多重要的海上战略通道都在大西洋,成为西方大国争夺最激烈的地区。“因此,大西洋成为了许多国家高度重视的超级战略大洋。” 相似文献
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一种风暴轴逐日监测的方法及应用 总被引:1,自引:1,他引:0
提出了一种风暴轴逐日监测的方法, 可以获得逐日的风暴轴变化情况。并且采用了动态阈值定义了新的风暴轴的强度和位置指数, 从而可以有效对比不同层次、不同区域、不同时间的风暴轴变化情况。利用NCEP/NCAR再分析资料进行了监测结果的诊断分析。结果表明:各气象要素滤波结果都能表现出两个风暴轴主体, 但有位置上的差别。同时可以利用逐日检测的结果求得逐候、逐月的风暴轴监测结果。在不同高度的风暴轴中, 250~300 hPa高度的风暴轴强度最大, 850 hPa有极小值出现, 各层风暴轴强度呈现准正压结构。采用500 hPa高度场风暴轴监测结果做代表, 讨论了两大洋上各自的风暴轴偏强/偏弱、偏东/偏西、偏北/偏南时同期大气环流的500 hPa高度场和300 hPa纬向风场差异。 相似文献
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67.
南大西洋沉积物中多环芳香化合物的组成特征研究 总被引:1,自引:0,他引:1
10 samples of sediments obtained from the South Mid-Atlantic Ridge were measured for the abundances and distributions of polycyclic aromatic compounds(PAHs). The total concentrations of PAHs(∑PAHs) ranged from 2.768 to 9.826 μg/g dry sediment. The ∑PAHs was higher in sample 22V-TVG10 and sample 26V-TVG05 which were close to hydrothermal fields, with the lowest value in sample 22V-TVG14 which was farthest from hydrothermal fields, suggesting a probable hydrothermal origin of ∑PAHs of samples. Approximately nine kinds of PAHs were identified, and low molecular mass tricyclic and tetracyclic aromatic compounds were predominant in the samples. The concentrations of fluoranthene which were typical as hydrothermal alteration compounds were the highest among PAHs with dry weight between 0.913–3.157 μg/g. The phenanthrene homologue was most abundant in the samples, and the ratios between parent phenanthrene and methylphenanthrene which probably reflected the degree of hydrothermal alteration ranged from 0.097 to 1.602. The sample 22V-TVG10 possessing a maximum ratio value showed the intense influence of the hydrothermal alteration on this sample, which might further imply that PAHs in sediments were mainly derived from the hydrothermal alteration. 相似文献
68.
HUANG Wenyu WANG Bin LI Lijuan DONG Li LIN Pengfei YU Yongqiang ZHOU Tianjun LIU Li XU Shiming XIA Kun PU Ye WANG Lu LIU Mimi SHEN Si HU Ning WANG Yong SUN Wenqi DONG Fang 《大气科学进展》2014,31(1):95-109
The variability of Atlantic Meridional Overturning Circulation (AMOC) in the pre-industrial control experiment of the Flexible Global Ocean-Atmosphere-Land System model, Grid-point Version 2 (FGOALS-g2) was investigated using the model outputs with the most stable state in a 512-yr time window from the total 1500-yr period of the experiment. The period of AMOC in FGOALS-g2 is double peaked at 20 and 32 years according to the power spectrum, and 22 years according to an auto-correlation analysis, which shows very obvious decadal variability. Like many other coupled climate models, the decadal variability of AMOC in FGOALS-g2 is closely related to the convection that occurs in the Labrador Sea region. Deep convection in the Labrador Sea in FGOALS-g2 leads the AMOC maximum by 3-4 years. The contributions of thermal and haline effects to the variability of the convection in three different regions [the Labrador, Irminger and Greenland-Iceland- Norwegian (GIN) Seas] were analyzed for FGOALS-g2. The variability of convection in the Labrador and Irminger Seas is thermally dominant, while that in the colder GIN Seas can be mainly attributed to salinity changes due to the lower thermal expansion. By comparing the simulation results from FGOALS-g2 and 11 other models, it was found that AMOC variability can be attributed to salinity changes for longer periods (longer than 35 years) and to temperature changes for shorter periods. 相似文献
69.
被动陆缘原型盆地在各个地质历史时期广泛分布,是全球富油气盆地的主要盆地类型。现今被动陆缘盆地在全球主要分布在大西洋周缘、印度洋周缘、北冰洋周缘和地中海东南缘。通过对南大西洋周缘主要含油气盆地分析,将被动陆缘盆地分为伸展型和转换型两大类。根据沉积充填特征,伸展型被动陆缘盆地又可细分为含盐型、不含盐型和三角洲型。不同类型的盆地在区域上具有明显的分段特征,如可将南大西洋边缘分为南段、中段和北段。南段主要为伸展型不含盐被动陆缘盆地、中段为伸展型含盐被动陆缘盆地、北段主要为转换型被动陆缘盆地。中段尼日尔河流域还发育尼日尔三角洲高建设型被动陆缘盆地。基于已发现的被动陆缘盆地大油气田(5亿桶油当量)分析,发现这几种类型的被动陆缘盆地均具有发现大油气藏的潜力,但油气成藏特征不同。 相似文献
70.
Fresh rocks sampled from the 14.0°S hydrothermal field of the South Atlantic Ridge can be divided into two categories: olivine-gabbro and basalt. The olivine-gabbro is composed mainly of three types of minerals: olivine, clinopyroxene and plagioclase, while a multitude of melt inclusions occur in the plagioclase phenocrysts of the basalts. We analyzed the whole-rock, major and trace elements contents of the basaks, the mineral chemistry of phenocrysts and melt inclusions in the basalts, and the mineral chemistry of olivine-clinopyroxene-plagioclase in the olivine-gabbro, then simulated magma evolution within the crust using the COMAGMAT program. The whole-rock geochemistry shows that all the basalts exhibit typical N-MORB characteristics. In addition, the mineral chemistry characteristics of the olivine-gabbro (low-Fo olivine, low-Mg# clinopyroxene, high-TiO2 clinopyroxene, low-An plagioclase), show that strong magma differentiation occurred within the crust. Nevertheless, significant discrepancies between those minerals and phenocrysts in the basalts (high-Fo olivine, high-An plagioclase) reflect the heterogeneity of magma differentiation. High Mg# (-~0.72) melt inclusions isobaric partial crystallization simulations suggest that the magma differentiation occurred at the depth shallower than 13.03 km below the seafloor, and both the vertical differentiation column shows distinct discrepancies from that of a steady-state magma chamber. Instead, a series of independent magma intrusions probably occurred within the crust, and their corresponding crystallized bodies, as the primary high-temperature thermal anomalies within the off-axis crust, probably act as the heat source for the development of the 14.0°S hydrothermal system. 相似文献