樟树市气象干旱特征及重现期分析          下载免费PDF全文

刘喆玥  韩会明  赖亮  杨立苑  徐全倩 《气象与减灾研究》2020,43(2):117-122

利用樟树市1960—2018年逐月降水和气温资料,计算标准化降水蒸散指数（SPEI）,并结合游程理论和Copula函数分析了该地区干旱特征。结果表明：樟树市干旱形势总体上趋于缓和,干旱历时和干旱烈度均呈减弱趋势,且呈现出良好的相关性;Frank-Copula函数可作为描述该地区干旱历时和干旱烈度的二维联合分布最优函数;在相同干旱历时和烈度下,“且”的重现期大于“或”的重现期,樟树市历史干旱事件的干旱历时多小于5个月,“且”的重现期小于10 a。  相似文献   

伽师近场观测地震资料的三维Q值成像     

赖晓玲  孙译 《大地测量与地球动力学》2006,26(3):28-32

为了研究震源区介质的物性特征,利用振幅谱拟合和有限差分三维Q值成像方法处理了伽师地震区临时台网的地震波形资料,获得了该地震区上地壳的S波三维Q值图像。结果表明:不同深度的Q值图像都存在低Q值带,主要展布方向为EW向、NNE向和NNW向,与研究区的柯坪断裂、羊达曼断裂和麦盖提断裂有一定的对应关系,并且NNE向的低Q值带与强震群分布和余震分布的条带位置接近,推测低Q值带可能是震源区的几条深部断裂。  相似文献   

Wave excitation in three-dimensional discs by external potential     

Hang Zhang  Dong Lai 《Monthly notices of the Royal Astronomical Society》2006,368(2):917-934

We study the excitation of density and bending waves and the associated angular momentum transfer in gaseous discs with finite thickness by a rotating external potential. The disc is assumed to be isothermal in the vertical direction and has no self-gravity. The disc perturbations are decomposed into different modes, each characterized by the azimuthal index m and the vertical index n , which specifies the nodal number of the density perturbation along the disc normal direction. The   n = 0  modes correspond to the two-dimensional density waves previously studied by Goldreich & Tremaine and others. In a three-dimensional disc, waves can be excited at both Lindblad resonances (LRs; for modes with   n = 0, 1, 2, …  ) and vertical resonances (VRs; for the   n ≥ 1  modes only). The torque on the disc is positive for waves excited at outer Lindblad/vertical resonances and negative at inner Lindblad/vertical resonances. While the   n = 0  modes are evanescent around corotation, the   n ≥ 1  modes can propagate into the corotation region where they are damped and deposit their angular momenta. We have derived analytical expressions for the amplitudes of different wave modes excited at LRs and/or VRs and the resulting torques on the disc. It is found that for   n ≥ 1  , angular momentum transfer through VRs is much more efficient than LRs. This implies that in some situations (e.g. a circumstellar disc perturbed by a planet in an inclined orbit), VRs may be an important channel of angular momentum transfer between the disc and the external potential. We have also derived new formulae for the angular momentum deposition at corotation and studied wave excitations at disc boundaries.  相似文献   

Trace element distribution during the reproductive cycle of female and male spiny and Pacific scallops, with implications for biomonitoring   总被引：1，自引：0，他引：1  

Nørum U  Lai VW  Cullen WR 《Marine pollution bulletin》2005,50(2):175-184

Trace element concentrations and contents in gills, gonad, kidneys, mantle, muscle and remainder during the reproductive cycle of female and male spiny and Pacific scallops, from the Strait of Georgia, BC, Canada, were quantified by using ICPMS. The elements investigated were chromium, manganese, iron, cobalt, nickel, selenium, molybdenum, cadmium, tin and mercury. For all ten elements, the tissue distribution was to some extent influenced by species, sex and reproductive status. The implications of the present study in relation to the design of biomonitoring programmes are: (1) care should be taken to ensure an equal/constant sex composition when making interannual comparisons of pooled samples. Preferably the sexes should be monitored separately. (2) the practice of obtaining pooled samples in the interspawn phase is applicable only to monitoring long-term trends in contaminant levels, while the reproductive status should be heeded when studying short-term changes. (3) the present study confirms that direct temporal or spatial comparisons of absolute accumulated element concentrations are only valid intraspecifically.  相似文献   

Geochemistry of the ophiolite and oceanic island basalt in the Kangxian-Pipasi-Nanping tectonic mélange zone,South Qinling and their tectonic significance     

Shaocong?Lai  Guowei?ZhangEmail author  Xianzhi?Pei  Haifeng?Yang 《中国科学D辑(英文版)》2004,47(2):128-137

Detailed studies indicate that Kangxian-Pipasi-Nanping tectonic zone is a complicated mélange zone which includes many tectonic slabs of different origins. Ophiolite (MORB-type basalt), oceanic island tholeiite and alkaline basalt have been identified. Moreover, this tectonic mélange zone is eastward connected with the Mianlüe suture zone. The deformation characteristics, consisting components and volcanic rock geochemical features for the Kangxian-Pipasi-Nanping tectonic mélange zone are much similar to those of the Mianlüe suture zone and Deerni ophiolite. Therefore, the Kangxian-Pipasi-Nanping tectonic mélange zone should be the westward extension part of the Mianlüe suture zone. It indicates that the Mianlüe suture zone had extended to the Nanping area.  相似文献   

中国不同区域能源消费碳足迹的时空变化(英文)   总被引：4，自引：2，他引：2  

揣小伟  赖力  黄贤金  赵荣钦  王婉晶  陈志刚 《地理学报(英文版)》2012,22(1):110-124

Study on regional carbon emission is one of the hot topics under the background of global climate change and low-carbon economic development, and also help to establish different low-carbon strategies for different regions. On the basis of energy consumption and land use data of different regions in China from 1999 to 2008, this paper established carbon emission and carbon footprint models based on total energy consumption, and calculated the amount of carbon emissions and carbon footprint in different regions of China from 1999 to 2008. The author also analyzed carbon emission density and per unit area carbon footprint for each region. Finally, advices for decreasing carbon footprint were put forward. The main conclusions are as follows: (1) Carbon emissions from total energy consumption increased 129% from 1999 to 2008 in China, but its spatial distribution pattern among different regions just slightly changed, the sorting of carbon emission amount was: Eastern China > Northern China > Central and Southern China > Southwest China > Northwest China. (2) The sorting of carbon emission density was: Eastern China > Northeast China > Central and Southern China > Northern China > Southwest China > Northwest China from 1999 to 2003, but from 2004 Central and Southern China began to have higher carbon emission density than Northeast China, the order of other regions did not change. (3) Carbon footprint increased significantly since the rapid increasing of carbon emissions and less increasing area of pro-ductive land in different regions of China from 1999 to 2008. Northern China had the largest carbon footprint, and Northwest China, Eastern China, Northern China, Central and Southern China followed in turn, while Southwest China presented the lowest area of carbon footprint and the highest percentage of carbon absorption. (4) Mainly influenced by regional land area, Northern China presented the highest per unit area carbon footprint and followed by Eastern China, and Northeast China; Central and Southern China, and Northwest China had a similar medium per unit area carbon footprint; Southwest China always had the lowest per unit area carbon footprint. (5) China faced great ecological pressure brought by carbon emission. Some measures should be taken both from reducing carbon emission and increasing carbon absorption.  相似文献   

Assessment of CMIP3 climate models and projected changes of precipitation and temperature in the Yangtze River Basin, China   总被引：1，自引：0，他引：1  

Hui Tao  Marco Gemmer  Jiahu Jiang  Xijun Lai  Zengxin Zhang 《Climatic change》2012,111(3-4):737-751

The projected changes of precipitation and temperature in the Yangtze River Basin in the 20th Century from 20 models of the CMIP3 (phase 3 of the Coupled Model Inter-comparison Project) dataset are analyzed based on the observed precipitation and temperature data of 147 meteorological stations in the Yangtze River Basin. The results show that all models tend to underestimate the annual mean temperature over the Yangtze River Basin, and to overestimate the annual mean precipitation. The temporal changes of simulated annual mean precipitation and temperature are broadly comparable with the observations, but with large variability among the results of the models. Most of the models can reproduce maximum precipitation during the monsoon season, while all models tend to underestimate the mean temperature of each month over the Yangtze River Basin. The Taylor diagram shows that the differences between modeled and observed temperature are relatively smaller as compared to differences in precipitation. For a detailed investigation of regional characteristics of climate change in the Yangtze River Basin during 2011–2050, the multi-model ensembles produced by an upgraded REA method are carried out for more reliable projections. The projected precipitation and temperature show large spatial variability in the Yangtze River Basin. Mean precipitation will increase under the A1B and B1 scenarios and decrease under the A2 scenario, with linear trends ranging from ?21 to 28.5?mm/decade. Increasing mean temperature can be found in all scenarios with linear trends ranging from 0.15 to 0.48°C/decade. Grids in the head region of the Jingshajiang catchment show distinct increasing trends for all scenarios. Some physical processes associated with precipitation are not well represented in the models.  相似文献   

An analytical investigation of a sequence of unusual springtime ozone episodes over metropolitan Taichung in 2007     

Wan-Li Cheng  Li-Wei Lai  Walter Den  Shu-Ying Wang  Pay-Liam Lin  Chueh-Ying Pai 《Meteorology and Atmospheric Physics》2012,117(3-4):153-166

This study investigated the potential factors contributing to a series of ozone (O₃) episodes in the Taichung metropolis, which occurred during the first half of May 2007. Surface data of the meteorological parameters and air pollutant concentrations, supported by Taiwan Environmental Protection Administration, and vertical data monitored via tethersonde sampling were analysed. The analyses showed that local anthropogenic activities and physical factors such as the sea–air interaction were not the main factors contributing to the O₃ events. Excluding these potential causes, the results suggest that, during the aforementioned period, the stronger Mainland High and Pacific Low may have been responsible for the long-range transport of large quantities of O₃ from Mainland China to Taiwan. Furthermore, O₃ photochemical activity also played an important role in the O₃ episodes. The faster consumption of NO lead to a more rapid increase in the O₃ concentration.  相似文献   

1901-2007年澳门地面气温变化的分析   总被引：3，自引：0，他引：3       下载免费PDF全文

冯瑞权  吴池胜  王安宇  何夏江  王婷  梁嘉静  黎婉文  梁必骐 《气候变化研究进展》2009,5(1):12-17

 利用澳门的气温观测资料, 分析了澳门1901-2007年地面气温变化的基本特征。结果表明：近107 a的升温率为0.066℃/10a, 明显低于全球平均升温率。季节平均气温的年代际变化有明显的季节差异,最大的增暖发生在春季和冬季,夏季的增暖最小;冬、夏季的变化分别有明显的时间尺度约为60 a和30 a的振动。年平均最高气温的升温率仅为最低气温的一半左右。最高气温的年代际变化呈缓慢的气候波动现象,20世纪80年代中期以后的升幅与历史上的增暖大致相当;最低气温近20多年来的增暖趋势可能是其长期（变暖）趋势的延续。年平均日较差整体来说是趋于减少的,但近30 a却趋于增加。  相似文献   

淮海地区降水周期及突变特征分析   总被引：4，自引：2，他引：2  

孙善磊  周锁铨  金博  李金建  赖安伟 《气象科学》2010,30(2):221-227

利用淮海地区1955—2004年23个气象站点的逐日降水资料,分析了淮海地区降水的主要周期振荡以及突变点,结果表明:该地区降水均有多个时间尺度的周期变化特征,降水周期变化显著,干湿交替现象明显;降水的年代际以及年际尺度的主要周期:年降水为12a、9a、5a,春季降水为14a、6a、3a,夏季为10a、4a,秋季为21a、10a、7a,冬季为18a、5a。年降水减少趋势明显,在1967年发生了突变,由相对多雨期转入相对少雨期;春季、夏季、秋季降水都有不同程度的减少趋势,而冬季降水则表现为增加的趋势。  相似文献