An Experiment Using the High Resolution Eta and WRF Models to Forecast Heavy Precipitation over India   总被引：1，自引：0，他引：1  

Y. V. Rama Rao  H. R. Hatwar  Ahmad Kamal Salah  Y. Sudhakar 《Pure and Applied Geophysics》2007,164(8-9):1593-1615

In the present study using the Weather Research and Forecasting (WRF) and Eta models, recent heavy rainfall events that occurred (i) over parts of Maharastra during 26 to 27 July, 2005, (ii) over coastal Tamilnadu and south coastal Andhra Pradesh during 24 to 28 October, 2005, and (iii) the tropical cyclone of 30 September to 3 October, 2004/Monsoon Depression of 2 to 5 October 2004, that developed during the withdrawal phase of the southwest monsoon season of 2004 have been investigated. Also sensitivity experiments have been conducted with the WRF model to test the impact of microphysical and cumulus parameterization schemes in capturing the extreme weather events. The results show that the WRF model with the microphysical process and cumulus parameterization schemes of Ferrier et al. and Betts-Miller-Janjic was able to capture the heavy rainfall events better than the other schemes. It is also observed that the WRF model was able to predict mesoscale rainfall more realistically in comparison to the Eta model of the same resolution.  相似文献   

Contemporary versus long‐term denudation along a passive plate margin: the role of extreme events     

K. M. Tomkins  G. S. Humphreys  M. T. Wilkinson  D. Fink  P. P. Hesse  S. H. Doerr  R. A. Shakesby  P. J. Wallbrink  W. H. Blake 《地球表面变化过程与地形》2007,32(7):1013-1031

Short‐term (contemporary) and long‐term denudation rates were determined for the Blue Mountains Plateau in the western Sydney Basin, Australia, to explore the role of extreme events (wildfires and catastrophic floods) in landscape denudation along a passive plate margin. Contemporary denudation rates were reconstructed using 40 years of river sediment load data from the Nattai catchment in the south‐west of the basin, combined with an analysis of hillslope erosion following recent wildfires. Long‐term denudation rates (10 kyr–10 Myr) were determined from terrestrial cosmogenic nuclides, apatite fission track thermochronology and post‐basalt flow valley incision. Contemporary denudation rates average several times lower than the long‐term average (5·5 ± 4 mm kyr^?1 versus 21·5 ± 7 mm kyr^?1). Erosion of sediment following wildfires accounts for only a small proportion (5%) of the contemporary rate. Most post‐fire sediment is stored on the lower slopes and valley floor, with the amount transported to the river network dependent on rainfall–run‐off conditions within the first few years following the fire. Historical catastrophic floods account for a much larger proportion (35%) of the contemporary erosion rate, and highlight the importance of these events in reworking stored material. Evidence for palaeofloods much larger than those experienced over the past 200 years suggests even greater sediment export potential. Mass movement on hillslopes along valleys incised into softer lithology appears to be a dominant erosion process that supplies substantial volumes of material to the valley floor. It is possible that a combination of infrequent mass movement events and high fluvial discharge could account for a significant proportion of the discrepancy between the contemporary and long‐term denudation rates. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

岩石矿物及粉尘中游离二氧化硅的测定     

席进萍  沈燕君等 《岩矿测试》2002,21(1):71-73

改进了游离二氧化硅（fSiO2)测定中试样的分解方法，采用硫－磷混酸替代单独使用磷酸分解试样，防止了焦磷酸盐的形成，同时，氟硼酸对fSiO2的溶解率符合测定要求。改进的方法用于标准物质中fSiO2的测定，结果与标准值或磷酸溶矿重量法相符。对于ω(fSiO2)=3.26%的标样10次测定的RSD为2．4％。  相似文献   

塔里木盆地哈得4油田成藏年代学研究   总被引：26，自引：0，他引：26  

赵靖舟  田军 《岩石矿物学杂志》2002,21(1):62-68

哈得4油田是近年来在满加尔凹陷北部发现的第一个海相油田，一直被认为是喜山期形成的油藏。然而，根据包裹体测温、伊利石K／Ar同位素测年以及油气水界面追溯等多种方法对其成藏年代重新研究表明，该油田主力油藏石碳系CⅢ油藏主杰晚海西期形成的古油藏，C5薄砂层油藏则可能为喜山期由CⅢ油藏垂向调整形成的次生油藏。  相似文献   

近50年浙江省旱、涝气候变化及特征   总被引：17，自引：4，他引：17  

顾骏强  施能  王永波 《热带气象学报》2001,17(4):429-435

用1951－1999年资料详细研究了浙江省的年、季的旱、涝气候变化特征。主要结果：浙江省夏季降水量表现出稳定的增加，其他季节（特别是秋季）的降水有不同程度的减少。每年在浙江省出现大范围旱（或涝）的可能性很大（约80％）。1985年以后浙江每年都要发生大范围的季节性的旱涝。浙江省年、季降水量旱涝有年代际变化。旱、涝发生的气候频率已经有了明显的变化，特别是夏季。奇异谱分析与最大熵谱分析的结果表明夏季、秋季与年的降水量有明显的长期趋势变化，它们还有10年左右的周期，而冬季降水的2年周期振荡特别明显。  相似文献   

Geochemistry and magnetostratigraphy of deccan flows at Anjar, Kutch     

A. D. Shukla  N. Bhandari  Sheela Kusumgar  P. N. Shukla  Z. G. Ghevariya  K. Gopalan  V. Balaram 《Journal of Earth System Science》2001,110(2):111-132

Chemical analysis of nine Deccan flow basalts at Anjar, Kutch, western India, indicates that all, except the uppermost flow F-9, are alkaline. In their major and trace element composition, the alkali basalts resemble Ocean island basalts (OIB). Similarities of many diagnostic trace element ratios (e.g. Sm/Nd, Ba/Nb,Y/Nb and Zr/Nb) are similar to those found in the Réunion Island basalts. The uppermost basalt is tholeiitic and chemically resembles the least contaminated Deccan basalt (Ambenali type). The Anjar basalts have iridium concentration ranging between 2 and 178 pg/g. Some of these values are higher by about an order of magnitude compared to the Ir concentration in other basalts of the Deccan. A synthesis of chemical, palaeomagnetic and geochronologic data enables us to construct a chemical and magnetic stratigraphy for these flows. The three flows below the iridium enriched intertrappean bed (IT III) show normal magnetic polarity whereas all except one of the upper basalts show reversed magnetic polarity. The sequence seems to have started in polarity zones 31N and probably continued up to 28R or 27R. The results presented here support the view that Deccan volcanism in Kutch occurred on a time span of a few million years.  相似文献   

High iridium concentration of alkaline rocks of Deccan and implications to K/T boundary     

P. N. Shukla  N. Bhandari  Anirban Das  A. D. Shukla  J. S. Ray 《Journal of Earth System Science》2001,110(2):103-110

We report here an unusually high concentration of iridium in some alkali basalts and alkaline rocks of Deccan region having an age of about 65Ma, similar to the age of the Cretaceous-Tertiary boundary. The alkali basalts of Anjar, in the western periphery of Deccan province, have iridium concentration as high as 178pg/g whereas the alkaline rocks and basalts associated with the Amba Dongar carbonatite complex have concentrations ranging between 8 and 80 pg/g. Some of these values are more than an order of magnitude higher than the concentration in the tholeiitic basalts of Deccan, indicating the significance of alkaline magmatism in the iridium inventory at the Cretaceous-Tertiary boundary. Despite higher concentration, their contribution to the global inventory of iridium in the Cretaceous-Tertiary boundary clays remains small. The concentration of iridium in fluorites from Amba Dongar was found to be <30 pg/g indicating that iridium is not incorporated during their formation in hydrothermal activity.  相似文献   

The influence of stiffness of the true triaxial testing machine on the rupturing and acoustic emission of rocks and its correlation with seismic activities     

Zhaoyong Xu  Shirong Mei  Cantao Zhuang  Peilin Li 《地震学报(英文版)》1992,5(2):367-379

This paper introduces how the ratioR of the characteristic stiffness of rock samplevs. the stiffness of testing machines would influence the rupturing process and the acoustic emission (AE) on the part of the tested rock samples. Result of the experiment shows: WhenR>0.20, the rock sample would rupture abruptly; whereas whenR<0.20, the rock samples would rupture slowly. When the samples rupture abruptly, the time-dependent variation of the AE rate takes such a pattern:peak value—stable low values—rises to the maximum value (concentration)—drops back to the minimum value (quiescence)—(rises again)—ruptures. Moreover, smallerR-value tends to be associated with longer quiescence and vice versa. WhenR>1.50, no pre-failure quiescence is detected. When the rock samples rupture slowly, the variation pattern of the AE rate (after the stress has increased to more than 50% of the rupturing stress) is as the following:stable low (or high) values—rises (or drops) to its maximum (or minimum) values and then continues for some time—ruptures. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 223–233, 1991. This study is supported by the Chinese Joint Seismological Science Foundation.  相似文献   

松辽盆地白垩纪湖侵沉积层序与湖海沟通事件的地球化学记录          下载免费PDF全文

王璞珺  杜小弟  王东坡 《沉积与特提斯地质》1995,(4):14-20

松辽白垩纪近海陆相盆地最大湖侵期的泉头组－嫩江组时期，可能发生了三次较大规模的海水入侵事件，时间分别为泉三、四段一青一段（阿尔布期），青二、三段顶部（土仑期）和嫩一、二段（晚桑托－早坎佩尼期）。海水注入使湖盆的水文地球化学和环境地球化学条件均发生改变，并在层序中留下沉积记录。海进期主要表现为：①重同位素组份增加，直至与同期海相层序的同位素组成相同；②介质的盐度指标（Ｓｒ／Ｂａ）、碱度指标（Ｃａ＋Ｍｇ）／（Ｓｉ＋Ａｌ）、还原性指标（Ｚｎ＋Ｎｉ）／Ｇａ和硫通量指标（Ｓ归一化含量）均系统增加。相反，海退期则上述指标显著降低。根据沉积层序的同位素组成、同期海水的同位素组成和同位素分馏的质量平衡关系，可求出研究层段内同位素的海水来源与淡水来源的比例（混合度）为０－５。并由此恢复出海平面升降曲线。  相似文献   

过量酸性铬蓝K隐色光度法测定铜的研究   总被引：2，自引：0，他引：2  

黄典文 《岩矿测试》1993,12(2):93-95

在pH 4.0的微酸性介质中,酸性铬蓝K同Cu~(2+)形成稳定的红色络合物,用H_2O_2为隐色剂可以隐去过量显色剂的颜色,消除高色度背景的影响。络合物的最大吸收波长为540nm,摩尔吸光系数为1.6×10~4L·mol~(-1)·cm~(-1),Cu量在0～1.4μg/ml范围服从比尔定律。方法已应用于测定矿样中的Cu。  相似文献