近震震相识别与三要素计算程序

台站地震观测中,有时会记录到在同一个近震中多个不确定震相与清楚震相并存的波形,这就需要在多个不确定近震震相中分辨出准确的震相.与《中国地区深度0.0 km近震走时表》中的理论震相到时差进行比较,两者到时差相似,说明假设的震相定位准确.     

Volcanism at the Permian-Triassic Boundary in South China and Its Effects on Mass Extinction

This paper discusses the clayrocks widespread at the Permian-Triassic boundary, which are mostly of volcanic origin. Volcanogenetic textures, structures and minerals such as high-temperature quartz are found in clayrocks at the Permian-Triassic boundary in many places. Thousands of microspherules have been collected from the Boundary clayrocks, many of which exhibit the typical features of the process from melting to cooling and solidification. indicating that they were formed by volcanic eruption or extraterrestrial impact. Volcanic effects on the Permian-Triassic mass extinction may be reflected in conodonts, algae and ammonoids. The Boundary clayrocks are found in many Permian-Triassic sections along the coast of Tethys. Their orighin remains to be studied.     

干旱与灌溉处理对冬小麦冠层内光分布的影响

为探讨北方冬麦区节水灌溉的关键时期,借助干旱和灌溉对冬小麦冠层光分布,获取本地化参数,为华北农业干旱预报模型的修正提供依据。采用美国CID公司生产的CI-110型植物冠层分析仪,对干旱和灌溉条件下冬小麦冠层内光分布进行直接测定。结果表明,干旱和灌溉条件下,无论是高氮还是低氮、中氮,平均叶面倾角(MLA)都随生育期的延长呈现出先下降再上升的趋势。高氮和低氮时,随着生育期的延长,干旱处理和灌溉处理的冬小麦散射辐射透过系数(TCDP)都呈现先下降再上升的变化趋势;中氮时,干旱处理和灌溉处理的冬小麦TCDP在开花期和灌浆期都呈现一直上升的趋势。无论高氮还是中氮、低氮,冬小麦直接辐射透过系数(TCRP)的值都随着天顶角角度的增大而减小,冬小麦TCRP的值随着冬小麦生育期的推进,都呈现出先下降、后上升的变化趋势。高、中、低氮3种情况下,干旱和灌溉处理的冬小麦每个生育期均呈现随着天顶角角度的增加,消光系数K也增大;高氮时,多数情况下,冬小麦冠层的消光系数K干旱的大于灌溉的;中氮、低氮时,多数情况下,冬小麦冠层的消光系数K干旱的小于灌溉的。干旱和灌溉对冬小麦冠层光分布的影响:灌溉增加了冬小麦的平均叶面倾角(MLA);干旱和灌溉处理条件下冬小麦的TCDP差异较小,TCDP与MLA变化趋势相似,也都呈现出先下降、再上升的变化规律;干旱和灌溉处理冬小麦TCRP,无论高氮还是中氮、低氮,都随着天顶角角度的增大而减小,在7.5°、22.5°时干旱和灌溉对冬小麦TCRP的影响较大,而在37.5°、52.5°、67.5°时对冬小麦TCRP的值影响很小;每个生育期消光系数K均随着天顶角角度的增加而增大。     

北京地区沙尘天气气溶胶飞机观测特征

利用3次沙尘天气期间的气溶胶飞机观测资料,分析了北京地区在3种沙尘天气下气溶胶垂直分布特征。结果显示:逆温层的存在对扬沙个例的垂直分布有影响。数密度谱的分布基本呈单调递减,但边界层内扬沙、浮尘和沙尘暴个例都在0.13~0.3μm间存在峰值,而扬沙个例在0.8μm,浮尘个例在6.5μm以及沙尘暴个例在2.8和6.5μm处出现次峰值。沙尘中细粒子的有效直径是人为源气溶胶粒子的4到10倍。浮尘天气整个粒子谱宽从近地面层开始随高度先增大后减小,到3000m达到最大,这与高空输送有关;扬沙个例沙尘粒子谱分布显示近地面层大于50μm段粒子谱无论数浓度还是谱宽都明显高于浮尘和沙尘暴个例,这与扬沙是局地大风扬尘引起有关;沙尘暴个例谱宽在接近云底达到最大,说明大粒子已经被携带到一定高度,与蒙古气旋云系的上升运动有关。     

近30年中国天气预报业务进展

介绍了我国天气预报技术的发展现状，指出在大气探测技术、数值预报及可视化技术发展的推动下我国传统的天气预报向定量、定时方向发展，并系统阐述了天气预报业务发展过程和存在的问题，最后提出了对我国天气预报业务发展的思路。     

Mean, interannual variability and trends in a regional climate change experiment over Europe. II: climate change scenarios (2071–2100)

We present an analysis of climate change over Europe as simulated by a regional climate model (RCM) nested within time-slice atmospheric general circulation model (AGCM) experiments. Changes in mean and interannual variability are discussed for the 30-year period of 2071–2100 with respect to the present day period of 1961–1990 under forcing from the A2 and B2 IPCC emission scenarios. In both scenarios, the European region undergoes substantial warming in all seasons, in the range of 1–5.5°C, with the warming being 1–2°C lower in the B2 than in the A2 scenario. The spatial patterns of warming are similar in the two scenarios, with a maximum over eastern Europe in winter and over western and southern Europe in summer. The precipitation changes in the two scenarios also show similar spatial patterns. In winter, precipitation increases over most of Europe (except for the southern Mediterranean regions) due to increased storm activity and higher atmospheric water vapor loadings. In summer, a decrease in precipitation is found over most of western and southern Europe in response to a blocking-like anticyclonic circulation over the northeastern Atlantic which deflects summer storms northward. The precipitation changes in the intermediate seasons (spring and fall) are less pronounced than in winter and summer. Overall, the intensity of daily precipitation events predominantly increases, often also in regions where the mean precipitation decreases. Conversely the number of wet days decreases (leading to longer dry periods) except in the winter over western and central Europe. Cloudiness, snow cover and soil water content show predominant decreases, in many cases also in regions where precipitation increases. Interannual variability of both temperature and precipitation increases substantially in the summer and shows only small changes in the other seasons. A number of statistically significant regional trends are found throughout the scenario simulations, especially for temperature and for the A2 scenario. The results from the forcing AGCM simulations and the nested RCM simulations are generally consistent with each other at the broad scale. However, significant differences in the simulated surface climate changes are found between the two models in the summer, when local physics processes are more important. In addition, substantial fine scale detail in the RCM-produced change signal is found in response to local topographical and coastline features.     

南极臭氧洞与南极涡旋的变化——IAP模式的试验结果

通过对IAP9层全球大气环流模式试验结果的分析,讨论了1987年南极臭氧洞对平流层大气辐射加热率和温、压、风场的影响。结果表明,南半球高纬和极地平流层臭氧含量的耗损,使该地区辐射加热率明显减小,气温明显下降,等压面明显下降,南极涡旋明显加强,说明南极春季涡旋的强弱与该地区臭氧含量及其热状况有密切关系。     

EMD在广西季节降水预报中的应用

气候系统是一种耗散的、具有多个不稳定源的非线性、非平稳系统。该文利用支持向量机(SVM)算法在处理非线性问题中的优越性和经验模态分解(EMD)算法在处理非平稳信号中的优势,采用将EMD与SVM相结合的短期气候预测方法,并应用到广西季节降水预报中。选取广西88个气象观测站1957—2005年6—8月逐年降水量的距平百分率序列作为试验数据,通过EMD算法将标准化处理后的距平百分率序列分解成多个本征模态函数(IMF)分量和一个趋势分量,在分解中针对EMD算法存在的端点极值问题选择两种方法分别进行处理,对比得出极值延拓法效果更好。对每个分量构建不同的SVM模型进行预测,并通过重构形成最后的预测结果。试验中采用不经EMD处理的反向传播(BP)神经网络和SVM算法进行对比验证,结果表明:相对于直接预测方法,该文提出的方案均方误差最小,能够较为准确地反映出降水序列未来几年的变化趋势,具有更高的预测精度和较好的推广前景。     

An experimental comparison of the velocities and energies of focused spilling waves in deep water

Ocean Dynamics - It is important to achieve a better understanding of the wave energy variations occurring as a steep wave evolves towards breaking. Laboratory experiments of focused waves are...     

利用IAP九层大气环流模式模拟全球季风系统

用ＩＡＰ九层大气环流模式模拟了全球季风系统。结果表明，模式成功模拟出对流层低层的季风系统，包括经典的热季风以及副热带季风和温寒带季风。此外，模式也真实再现了对流层高层的行星季风。另一方面，平流层季风的模拟效果则较差，这与模式中西风系统性偏强有关。