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81.
The regional stress field and seismic dynamics along the border zone between Fujian, Guangdong and Jiangxi Provinces are studied based on the seismo-geological data, GPS measurement, and seismicity. The results show that: (1) the principal compressional stress of the stress field is oriented in NW-SE direction and the principal extensional stress is in NE-SW direction; (2) the WNW-ward compression and collision of the Philippine Sea Plate to the eastern coast of Taiwan Island are the most direct and most important dynamic source for preparation and occurrence of strong earthquakes in the Taiwan area and along the border zone between Fujian, Guangdong and Jiangxi Provinces. 相似文献
82.
系统聚类分析在现代沉积环境划分中的应用--以崎岖列岛海区为例 总被引:5,自引:0,他引:5
根据崎岖列岛海区现代沉积物的分选系数、砂粒含量和粘粒含量 3个粒度特征参数,采用系统聚类分析方法划分现代沉积环境,与已知的沉积环境特征信息较为吻合。除水动力条件外,研究区的现代沉积环境深受物源条件和地形因素的影响。在有效划分研究区现代沉积环境的 3个粒度参数中,砂粒含量是受物源条件影响最为显著的参数,分选是对地形与流场相互作用最为敏感的参数。偏度对研究区沉积环境差异的敏感性是有限的。峰度几乎不能作为研究区沉积环境划分的粒度参数。水动力条件的特殊性值得在沉积环境的划分中予以足够重视。 相似文献
83.
Emil V. Stanev Jörg-Olaf Wolff Hans Burchard Karsten Bolding Götz Flöser 《Ocean Dynamics》2003,53(1):27-51
In this paper we use a combination of numerical modeling and data analysis to gain a better understanding of the major characteristics
of the circulation in the East Frisian Wadden Sea. In particular, we concentrate on the asymmetry of the tidal wave and its
modulation in the coastal area, which results in a complex pattern of responses to the sea-level forcing from the North Sea.
The numerical simulations are based on the 3-D primitive equation General Estuarine Transport Model (GETM) with a horizontal
resolution of 200 m and terrain-following vertical coordinates. The model is forced at its open boundaries with sea-level
data from an operational model for the German Bight (German Hydrographic Office). The validation data for our model simulations
include time series of tidal gauge data and surface currents measured at a pile in the back-barrier basin of the Island Langeoog,
as well as several ADCP transects in the Accumer Ee tidal inlet.
Circulation and turbulence characteristics are investigated for typical situations driven by spring and neap tides, and the
analysis is focused on dominating temporal and spatial patterns. By investigating the response of five back-barrier basins
with rather different morphologies to external forcing, an attempt is made to elucidate the dominating physical balances controlling
the circulation in the individual sub-basins. It is demonstrated that the friction at the seabed tends to slow down the tidal
signal in the shallow water. This leads to the establishment of flood dominance in the shallow sea north of the barrier islands.
South of the islands, where the water volume of the channels at low tide is smaller than the tidal prism, the asymmetry of
the tidal signal is shifted towards ebb dominance, a feature which is particularly pronounced at spring tide.
At the northern open boundary, the tidal wave propagating from west to east generates a sea-level difference of ∼1 m along
the boundary, and thereby triggers vigorous alongshore currents. The frictional control in the model is located in the inlets,
as well as along the northern boundary. The correlation between velocity and turbulent kinetic energy tends to the establishment
of a net southward transport, giving theoretical support to the observed accumulation of sediments on the intertidal flats.
Weak turbulence along the northern shores of the barrier islands and the small magnitude of the residual currents there promote
accumulation of suspended matter in these areas, although wave action will generally counteract this effect.
Received: 29 May 2002 / Accepted: 26 September 2002
Responsible Editor: Jean-Marie Beckers
Acknowledgements We are indebted to S. Dick for providing the data from the operational model of BSH and to B. Flemming for the useful discussions.
The topography data and Fig. 1 have been prepared in cooperation with F. Meyer. Figure 2 has been prepared by G. Brink-Spalink.
We also thank for the comments from an anonymous reviewer which helped to improve our paper. 相似文献
84.
利用NOAA AVHRR数据研究北半球雪盖气候学特征 总被引:2,自引:0,他引:2
利用NOAA卫星图像,研究了北半球、欧亚、北美和青藏高原雪盖气候学特征及其变化趋势.指出北半球、欧亚和北美雪盖气候变化趋势基本一致,年均雪盖面积在1987年前后明显下降; 而青藏高原雪盖面积在1984年后明显下降,说明青藏高原雪盖的年际变化与北半球及欧亚、北美不完全一致. 相似文献
85.
86.
晋北娄烦吕梁群由一套经受过两期不同性质变质作用的泥砂质岩、基性火山岩和酸性流纹岩组成。早期为吕梁期变质作用,其结果使该区地层构造形迹总体上呈NE走向;晚期为西川河韧性剪切断裂所产生的区域变质作用,其结果使该区地层走向由早期的NE向扭转为近SN向,且使地层层序发生倒转,并与递增变质带的形成关系密切。选取该区中对变质温度和压力变化反映较敏感的原岩为泥砂质岩石的袁家村组和裴家庄组地层为研究对象,采用电子探针微区分析(EPMA)对沿地层走向上连续分布的特征变质矿物及矿物共生组合特征进行研究,并利用矿物对地质温度计估算该区不同采样点的变质温度和压力条件,对研究区进行变质相带的划分,确定各变质相带的变质温、压条件,并探讨其成因。研究结果表明,袁家村组和裴家庄组为等化学系列地层。沿该地层走向上:西川河断裂以北地区,从北向南,特征变质矿物绿泥石、黑云母、石榴石、十字石和蓝晶石依次规律出现;西川河断裂以南地区,红柱石和夕线石依次规律出现。根据特征变质矿物的空间分布规律、首次出现的地点及矿物共生组合特征,划分出5个变质带:绿泥石带、黑云母带、石榴石带、十字石-蓝晶石带和红柱石-夕线石带。这一完整的递增变质带可与苏格兰高地的巴罗型相媲美。矿物对地质温度计估算结果。 相似文献
87.
利用1961~2000年柴达木盆地11个气象站的沙尘暴观测资料,分析了柴达木盆地沙尘暴天气的时空分布特征。根据1980~2000年3月至5月的40次沙尘暴天气个例,从高空环流形势、地面冷空气路径、影响因子及其预报指标4个方面进行分析,总结出柴达木盆地春季沙尘暴天气的预报方法。 相似文献
88.
利用1961~2000年中国东北地区80个测站的月降水和平均气温资料,通过计算地表最大潜在蒸发、地表干燥度指数和地表水分盈亏量,分析了东北地区及其7个不同气候区域地表干湿状况的时空分布规律及其变化趋势,并探讨了它与降水和气温的关系。结果表明,东北地区及其不同区域的地表干湿状况不仅具有较大的地域差别和年际及年代际变率,而且存在着明显的阶段性和低频变化特征,特别是20世纪90年代中期以来,东北地区呈现出较强的变干倾向,并且由于气温升高所导致的潜在蒸发的加大与降水一样对这一变干倾向也有十分重要的影响。 相似文献
89.
K. Finkele J.J. Katzfey E.A. Kowalczyk J.L. McGregor L. Zhang M.R. Raupach 《Boundary-Layer Meteorology》2003,107(1):49-79
Two land surface schemes, SCAM and CSIRO9, were used to model the measured energy fluxes during the OASIS (Observations At Several Interacting Scales) field program. The measurements were taken at six sites along a 100 km rainfall gradient. Two types of simulations were conducted: (1) offline simulations forced with measured atmospheric input data at each of the six sites, and (2) regional simulations with the two land surface schemes coupled to the regional climate model DARLAM.The two land surface schemes employ two different canopy modelling concepts: in SCAM the vegetation is conceptually above the ground surface, while CSIRO9 employs the more commonly used `horizontally tiled' approach in which the vegetation cover is modelled by conceptually placing it beside bare ground. Both schemes utilize the same below-ground components (soil hydrological and thermal models) to reduce the comparison to canopy processes only. However, the ground heat flux, soil evaporation and evapotranspiration are parameterised by the two canopy treatments somewhat differently.Both canopy concepts reproduce the measured energy fluxes. SCAM has a slightly higher root-mean standard error in the model-measurement comparison for the ground heat flux. The mean surface radiative temperature simulated by SCAM is approximately 1K lower than in the CSIRO9 simulations. However, the soil and vegetation temperatures (which contribute to the radiative temperature) varied more in the CSIRO9 simulations. These larger variations are due to the absence of a representation of the aerodynamic interactions between vegetation and ground. 相似文献
90.
应用自然正交函数分解(EOF)方法,分析了甘肃省庆阳地区春末夏初干旱的综合评价指数DH的空间分布特征及随时间演变规律;分析了春末夏初干旱对冬小麦和玉米产量的影响;应用逐步回归方法建立了春末夏初干旱的预测模型,业务使用效果良好。 相似文献