How are storm time injections different from nonstorm time injections?     

D.-Y. Lee  J.A. Hwang  E.S. Lee  K.W. Min  W.Y. Han  U.W. Nam 《Journal of Atmospheric and Solar》2004,66(18):1715

One of the key elements of storms and substorms is the injection of energetic particles into the region of near geosynchronous orbit, that is, the sudden flux enhancement in the energy range of tens to hundreds of keV. This paper reports the observational results on how such injection features during storm times are different from those of nonstorm times. We particularly focus on the difference between proton injections and electron injections. Based on a number of storm time injection events that meet our strict selection criteria, we find a notable difference between proton injections and electron injections in the energy-spectral dependence of the flux enhancement averaged over the first 30 min after the injection onset: The average flux enhancement of many protons injections tends to be bigger at higher energy channels than at lower energy channels, but electron injections exhibit the opposite tendency for the energy-spectral dependence of flux enhancement, i.e., average flux enhancement decreasing with increasing energy. We show that this feature is almost unique only for the injection events during the storm main and early recovery phase. It is suggested that any successful scenario intended to model storm time injections should be able to explain this difference between proton injections and electron injections.  相似文献   

“0012”台风引发“8．30”特大暴雨过程的分析   总被引：4，自引：7，他引：4       下载免费PDF全文

魏建苏  赵永玲  周曾奎  王清楼 《气象科学》2003,23(1):92-99

本文应用特大暴雨出现时段相应的高空环流特征，逐时卫星云图的演变，以及最大逐时暴雨中心单站气象要素的分析，探讨了“0012”台风引发“8．30”特大暴雨的成因。可以认为不论是第一段强降水时段，还是后二段强降水时段，造成这次罕见的特大暴雨的主要成因是台风环流与中纬度西风带急流、冷槽（锋区）相互作用的结果；而第三段暴雨则是台风本身的影响。  相似文献   

渤海湾风暴潮倒灌对沿岸农田土壤盐分的影响     

张国明  顾卫  吴之正  史培军 《地球科学进展》2006,21(2):157-160

2003年10月11日渤海湾沧州范围内发生特大温带风暴潮，其摧毁沿岸养殖场后涌向沿海农田区域，海水倒灌农田浸泡持续时间达10~15 d不等。2004年5月3日，对浸泡农田土壤采样进行盐分分析，结果表明，经海水浸泡后农田全部盐碱化，且盐分主要聚集在土壤表层；46%的土地出现碱斑，0~90 cm土体内土壤含盐量较浸泡前普遍增加，0~10 cm表层含盐量高达1.134%；浸泡后0~25 cm土体内含盐离子组成较之浸泡前有显著变化，Cl－含量增加了33.3%，Na++K+含量增加了39.4%；降雨淋溶可以使土壤盐分含量明显下降，且为主要影响因素；经过一年后，土壤盐分含量降低到0.308%，而两年后，受灾土壤盐分含量降低到0.265%左右，可以种植耐盐性较强的作物。  相似文献   

2004年11月强磁暴期间武汉电离层TEC的响应和振幅闪烁特征的GPS观测   总被引：6，自引：2，他引：6       下载免费PDF全文

徐继生  朱劼  程光晖 《地球物理学报》2006,49(4):950-956

本文利用设在武汉(11436°E,3053°N,磁纬194°)的GPS电离层TEC和电波闪烁监测仪的测量数据，分析了2004年11月强磁暴期间TEC的响应以及电波闪烁和TEC起伏的特征.结果表明，在这次强磁暴期间，武汉及其邻近地区电离层TEC的响应以正暴相为主，正暴相分别出现在两次主相期间，最大正偏离达到50 TECU.这次磁暴另一个重要影响是主相期间L波段振幅闪烁的活动性及其强度显著增强.S4指数最大接近10.伴随增强的闪烁活动，多次观测到深度耗尽的等离子体泡与TEC起伏，TEC变化率的标准差ROTI指数也显著增强.分析揭示， ROTI指数与S4指数呈正相关，相关系数达到097.线性回归计算得到，ROTI和S4的比率为964.  相似文献   

中国年最大致洪暴雨落区研究   总被引：2，自引：0，他引：2       下载免费PDF全文

刘国纬  沈国昌 《水科学进展》2006,17(2):151-159

分析了1900-1999年逐年全国最大致洪暴雨落区的区域分布和年际间迁移轨迹.结果表明:中国年最大致洪暴雨落区的年际间迁移轨迹是无序的;年最大致洪暴雨可以随机地出现在中国(主要在90°E以东地区)任何地区;华中和华东地区是出现年最大致洪暴雨频次最高的地区.也分析了1470-1899年逐年的年最大洪涝中心的区域分布和年际间迁移轨迹,其结果支持20世纪中国年最大致洪暴雨落区分布和年际间迁移轨迹分析所得出的认识.上述事实表明,中国7大江河中的任何一条,每年都可能出现全国最大的暴雨洪水,而且无法预见其在年际间迁移的方向与落区.因此,中国不得不立足于此客观事实确立全国防洪战略.  相似文献   

Storm-related sea level variations along the North Sea coast as simulated by a high-resolution model 1958–2002     

Ralf Weisse  Andreas Plüβ 《Ocean Dynamics》2006,56(1):16-25

Storm-related sea level variations 1958–2002 along the North Sea coast from a high-resolution numerical hindcast are investigated and compared to the results of earlier studies. Considerable variations were found from year to year and over the entire period. The large-scale pattern of these variations is consistent with that derived from previous studies, while the magnitudes of the long-term trends differ. The latter is attributed to different analysis periods, improvements in the atmospheric forcing, and the enhanced spatial resolution of the numerical simulation. It is shown that the different analysis periods, in particular, represent an issue as the increase in storm-related sea levels was found to be weaker over the last few years that have not been included in earlier studies. These changes are consistent with observed changes of the storm climate over the North Sea. It is also shown that observed and hindcast trends may differ significantly. While the latter are in agreement with observed changes in the storm climate, it may be concluded that observed sea level changes along the North Sea coast comprise a considerable fraction that cannot be attributed to changes in the large-scale atmospheric circulation.

Ralf WeisseEmail:

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Effect of surge uncertainty on probabilistically computed dune erosion     

K.L. Roscoe  F. Diermanse 《Coastal Engineering》2011

To assess the flood protection capacity of dunes in The Netherlands, a semi-probabilistic dune-erosion prediction method is currently in use in which uncertainties in input parameters of an empirical dune erosion model were taken into account, with the exception of the uncertainty in the extreme surge distribution. Previous research has shown that the surge is by far the most influential parameter affecting erosion in the currently used erosion model, which is due both to the influence of the surge level itself and to the conditional dependence of the wave height and period on the surge level in the probabilistic model used for the assessment. Furthermore, the distribution of extreme surge levels has been shown to contain large statistical uncertainty. The inclusion of uncertainty in input variables into probabilistic models results in more extreme events (in this case erosion) for the same exceedance probability, largely due to the incorporation of higher values of the input variables. The goal of the research described in this paper was to determine the impact of the inclusion of uncertainty in the extreme surge distribution on the estimate of critical erosion (erosion associated with an exceedance frequency of 10^− 5 per year). The uncertainty in the surge distributions was estimated and parameterized, and was incorporated into the probabilistic model. A reduction in uncertainty was subsequently imposed to estimate what value a reduction in uncertainty can offer, in terms of the impact on critical erosion. The probabilistic technique first-order reliability method (FORM) was applied to determine the relative contribution of the uncertainty in the surge distribution (as well as the remaining stochastic variables) to the critical erosion. The impact of the inclusion of uncertainty in the surge distribution on the critical retreat distance was found to be substantial with increases ranging from 34% to 93% of the original estimate at five locations along the Dutch coast. The reduced uncertainty showed a more subtle impact, with increases in critical retreat distance ranging from 10% to 26% of the original estimate. The relative importance analysis showed that the uncertainty in the surge distribution has a strong influence, with the relative importance ranging from 10% to 23% for an exceedance frequency of 10^− 5 per year.  相似文献   

Suspended sediment in rapid subsurface stormflow on a large field plot     

David H. Pilgrim  Dale D. Huff 《地球表面变化过程与地形》1983,8(5):451-463

The occurrence of rapid movement of suspended sediment in subsurface stormflow on a large field plot in California is described. Concentrations of over 1000mgl^?1 were recorded in storms of only low to moderate intensity. The observed sediment was composed of uniformly fine-sized particles 4 to 8 μm in diameter. The mode of transport seems different from processes previously reported. Differences in sediment concentrations in different events, levels of ¹³⁷Cs on the sediment, and several other types of evidence indicate that the sediment was detached and entrained at the ground surface by raindrop impact and that the water and sediment flow occurred mainly through macropores in the soil. As conditions similar to those at the study site are not uncommon, it seems probable that the phenomenon may occur in many regions.  相似文献   

从熵原理得出的暴雨面积和雨量的关系   总被引：7，自引：3，他引：7  

张学文  杨秀松 《高原气象》1991,10(3):225-232

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浙江象山海滩岩的发现及其意义   总被引：8，自引：1，他引：8  

高中和  季幼庭 《地震地质》1991,13(1):28-32,T002

作者于浙江象山爵溪首次发现了全新世海滩岩,并对其岩石学特征、同位素年龄、形成环境等进行了初步研究。爵溪海滩岩目前是我国分布位置最北的全新世海滩岩,据14C年龄测出该地3400多年来海岸的相对沉降速率为0.51mm/a  相似文献