春季西亚地表热力异常与初夏东北冷涡活动年代际变化的联系

基于1979~2015年中国月平均站点温度资料,计算了初夏东北冷涡指数,分析了初夏东北冷涡活动的年代际变化特征。在此基础上,进一步探讨了东北初夏冷涡活动与春季西亚地表热力异常之间的可能联系,并初步讨论了前期西亚地表热力异常影响东北初夏冷涡活动的可能过程。结果表明:（1）1979~2015年间,初夏东北冷涡强度表现出明显的年代际变化特征,2000年前,冷涡活动总体偏强,之后总体减弱。（2）春季西亚地表热力状况在2000年前后也发生了明显的年代际转变:2000年前总体偏冷,之后明显偏暖。（3）春季西亚地区的地表热力异常与东北冷涡活动的在年代际尺度上联系密切。西亚地表异常偏冷,东北冷涡活动偏强;而西亚地表异常偏暖对应了偏弱的冷涡活动。初步分析发现,西亚地表热力因子可能通过影响大气环流分布并通过遥相关型影响我国初夏东北地区冷涡,当然相关的机理还有待深入分析。     

Digital thermal monitoring of the Amazon forest: an intercomparison of satellite and reanalysis products

Remote sensing and climate digital products have become increasingly available in recent years. Access to these products has favored a variety of Digital Earth studies, such as the analysis of the impact of global warming over different biomes. The study of the Amazon forest response to drought has recently received particular attention from the scientific community due to the occurrence of extreme droughts and anomalous warming over the last decade. This paper focuses on the differences observed between surface thermal anomalies obtained from remote sensing moderate resolution imaging spectroradiometer (MODIS) and climatic (ERA-Interim) monthly products over the Amazon forest. With a few exceptions, results show that the spatial pattern of standardized anomalies is similar for both products. In terms of absolute anomalies, the differences between the two products show a bias near to zero with a standard deviation of around 0.2?K, although the differences can be up to 1?K over particular regions and months. Despite this general agreement, the proper filtering of MODIS daily values in order to construct a new monthly product showed a dramatic reduction in the number of reliable pixels during the rainy season, while for the dry season this reduction is only seen in Northern Amazonia.     

Sea level anomalies in straits of Malacca and Singapore

This paper studies sea level anomaly (SLA) behaviour in Malacca and Singapore straits which serve part of a major maritime trade route between Indian and Pacific Ocean using both observed data and numerical model. Spatio-temporal behaviour of SLA in the region is analyzed based on 15 years of in-situ and remote sensing data. Results show that SLA signatures can be distinctly different in the two straits, with vastly opposite behaviours during certain months. By further analyzing spatial dependency of observed SLA in the region, SLA in Malacca and Singapore straits are found to be under the influence of Indian Ocean and South China Sea, respectively. Based on this insight, a numerical model is built with the appropriate non-tidal forcing derived from meteorological model and satellite dataset to properly represent SLA in Malacca and Singapore straits with Root Mean Square Error of less than 10 cm. With this well calibrated model, the effect of different types of forcing on volume flux through the straits is investigated. Combined tidal and non-tidal forcing in the model gives 4 to 7 × 10¹¹ m³ of annual net westward volume flux through the straits which is four to seven times higher than that of tidal forcing alone. Furthermore with this combined forcing, a distinct seasonal trend with westward net flow during northeast monsoon (November to March) and eastward net flow during southwest monsoon (May to September) can be observed through the straits in the model which is not observed with tidal forcing. The findings of this paper highlight the importance of these non-tidal forcing in the model to obtain accurate SLA and flow representation in the straits that is vital to environmental fate and transport modelling during operational forecast.     

Relationships Between Anomalies of Land-Sea Thermal Contrast in North Africa and Summer Flood and Drought Across the Jianghuai Region of China

The flood and drought across the Yangtze and Huaihe River(Jianghuai)areas are frequent in summer,especially in June and July.Therefore,predicting the summer flood and drought in the Jianghuai region is always one of the key topics concerned by meteorologists in China.Previous studies focused more on the skin temperature anomalies in a local area,and paid less attention to the connections between the anomalies of land-sea thermal contrast in remote continents and the summer flood and drought in Jianghuai areas of China.By using the US NCEP/NCAR monthly mean reanalysis data and the rainfall data at 743 stations in China,based on the interdecadal variation characteristics of the flood and drought index(FDI)during 51 yr(1954-2004)in the Jianghuai region of China in summer,the North African areas have been selected as the key regions for the correlation analysis.The results show that the surface temperature anomalies in the key regions have good continuity in winter,and the winter North Atlantic Oscillation(NAO)is perhaps one of the important factors that bring about the continuity of the anomalies.By a singular value decomposition(SVD)analysis between the skin temperature in the previous winter in North Africa and the summer rainfall in the Jianghuai region,it is found that when the North African continent is colder(warmer)and its northwestern sea is warmer(colder),the rainfall increases(decreases)in the Jianghuai region in summer generally.Further analysis finds that the anomaly of the surface temperature contrast between sea and land in North Africa has a good indication for the summer flood and drought in the Jianghuai areas of China.Therefore,a sea and land thermal contrast index(SLTCI)is defined to reflect the intensity of the large-scale land-sea thermal contrast.A positive correlation between the SLTCI in North Africa and the summer FDI in Jianghuai areas is identified,and it can well indicate the extreme flood and drought situations in the Jianghuai region of China.     

崇明异常电磁扰动与台湾7.5 级强震

2002 年3 月31 日14 时52 分在台湾以东海中发生7.5 级强地震, 地震发生前后上海市地震局崇明地震台电磁波仪器记录到了一系列强烈电磁辐射异常信息, 其中震前最早的信息出现在24 天前, 最迟的信息出现在震前5 小时且幅度最大。主震发生前电磁辐射异常信号的振荡幅度随着主震临近而增大, 主震发生后又降了下来。余震期间的电磁辐射异常信息也十分丰富。文中探讨了这些电磁辐射异常信号与强震之间的关系, 结合多种震例的记录认为这类震前电磁辐射异常信号可作为临震前的一种信息。为认识和丰富震前电磁辐射前兆异常的现象与研究增加了新的内容。     

Evaluation of temperature trends over India / Evaluation de tendances de température en Inde

Abstract

Abstract The impact of climate change is projected to have different effects within and between countries. Information about such change is required at global, regional and basin scales for a variety of purposes. An investigation was carried out to identify trends in temperature time series of 125 stations distributed over the whole of India. The non-parametric Mann-Kendall test was applied to detect monotonic trends in annual average and seasonal temperatures. Three variables related to temperature, viz. mean, mean maximum and mean minimum, were considered for analysis on both an annual and a seasonal basis. Each year was divided into four principal seasons, viz. winter, pre-monsoon, monsoon and post-monsoon. The percentages of significant trends obtained for each parameter in the different seasons are presented. Temperature anomalies are plotted, and it is observed that annual mean temperature, mean maximum temperature and mean minimum temperature have increased at the rate of 0.42, 0.92 and 0.09°C (100 year)^-1, respectively. On a regional basis, stations of southern and western India show a rising trend of 1.06 and 0.36°C (100 year)^-1, respectively, while stations of the north Indian plains show a falling trend of –0.38°C (100 year)^-1. The seasonal mean temperature has increased by 0.94°C (100 year)^-1 for the post-monsoon season and by 1.1°C (100 year)^-1 for the winter season.     

Spatial distribution of resistivity in the hydrogeological systems,and identification of the catchment area in the Rharb basin,Morocco / Répartition spatiale de la résistivité dans les systèmes hydrogéologiques et détection des zones de captages dans le bassin du Rharb,Maroc

Abstract

Abstract Geophysical results obtained in the Rharb basin, Morocco are reported. Correlations between hydrogeological well logs reveal several water-bearing Plio-Quaternary units resting on a substrate of blue marls. Geo-electrical borehole analyses were interpreted using bi-logarithmic diagrams which indicate the permeable layers of the aquifer and also its basement. Resistivity data from NE–SW and NW–SE electrical sections allow definition of the permeable/impermeable levels, and identification of ?ditches? that may be favourable sectors for hydrogeological exploitation. Resistivity anomalies were investigated by analysing maps of resistivity at 400 and 1000 m AB. Anomalies identified in the Rharb basin are related to the thickening of the permeable bodies (sand, limestone, sandstone deposits). In the coastal zone (AB = 1000 m), there is a strong decrease of the resistivity gradient (35–10 Ω m), which is probably linked to marine intrusion. Electrical anomalies allow detection of the water-bearing zones notably in the western and southwestern parts of the Rharb basin.     

内蒙古克什克腾旗黄岗山锡铜矿激电测量方法应用分析

内蒙古克什克腾旗黄岗山锡铜矿区北部及中部为第四纪冰川遗迹,在植被极其发育的地表之下为冰渍物、残坡积物等组成的碎石层,厚度多大于3m,因此开展地表地质工作有一定的难度。为提高找矿效果,开展了1：1万激电测量工作。通过对激电异常的查证分析,在DJH-1号激电异常南西侧边界,燕山早期似斑状中细粒黑云母二长花岗岩与两侧石英闪长岩、花岗斑岩的内、外接触带附近发现有多期次岩浆侵入,矿化蚀变强烈,目前共圈定锡矿体10个、铜矿体8个;圈定的矿体和发现的激电异常具有较好的对应性,为进一步开展地质勘查工作提供了重要的依据。     

应用二维经验模分解(BEMD)法提取滇东Pt、Pd 元素地球化学异常

应用二维经验模分解(BEMD)法从滇东Pt-Pd含量数据中提取2类Pt-Pd异常,即由二维内蕴模函数3(BIMF3)表征的区域Pt-Pd异常和由二维内蕴模函数2(BIMF2)表征的局部Pt-Pd异常。根据异常产出的地质特征,区域Pt-Pd异常可进一步划分为2个亚类：其一是位于受SN向小江断裂和NE向寻甸-宣威深大断裂控制的二叠纪峨眉山玄武岩分布区的异常,其特征是具有明显的浓集中心,异常强度大;其二是分布于研究区中南部的黑色岩系中的异常,异常强度弱。其中前者是滇东Pt-Pd找矿的有利地段。局部Pt-Pd异常可进一步划分为3个亚类：①分布于玄武岩区,受SN-NE向深大断裂与其次级断裂交会域控制的异常;②分布于不同地质时期黑色岩系中的异常;③哀牢山断裂北侧与基性、超基性侵入岩有关的异常。其中,分布于玄武岩区的Pt-Pd局部异常强度高、规模大,是进一步找寻Pt-Pd资源的远景地段。