Enhancing seismic P phase arrival picking based on wavelet denoising and kurtosis picker     

Xueyi Shang  Xibing Li  Lei Weng 《Journal of Seismology》2018,22(1):21-33

P phase arrival picking of weak signals is still challenging in seismology. A wavelet denoising is proposed to enhance seismic P phase arrival picking, and the kurtosis picker is applied on the wavelet-denoised signal to identify P phase arrival. It has been called the WD-K picker. The WD-K picker, which is different from those traditional wavelet-based pickers on the basis of a single wavelet component or certain main wavelet components, takes full advantage of the reconstruction of main detail wavelet components and the approximate wavelet component. The proposed WD-K picker considers more wavelet components and presents a better P phase arrival feature. The WD-K picker has been evaluated on 500 micro-seismic signals recorded in the Chinese Yongshaba mine. The comparison between the WD-K pickings and manual pickings shows the good picking accuracy of the WD-K picker. Furthermore, the WD-K picking performance has been compared with the main detail wavelet component combining-based kurtosis (WDC-K) picker, the single wavelet component-based kurtosis (SW-K) picker, and certain main wavelet component-based maximum kurtosis (MMW-K) picker. The comparison has demonstrated that the WD-K picker has better picking accuracy than the other three-wavelet and kurtosis-based pickers, thus showing the enhanced ability of wavelet denoising.  相似文献   

中国地－气系统短波吸收辐射分布特征     

翁笃鸣 《南京气象学院学报》1995,(1)

根据ＥＲＢＥ和ＩＳＣＣＰ资料讨论了公气系统短波吸收辐射及其年较差在全国的分布，分析了其与总云量、行星和地表反射卒以及地面吸收辐射的相互关系。发现在冬季地－气系统短波吸收辐射分布主要呈南高北低型，夏季分布形势为一不对称的大鞍形场，大致与行星反射率分布反向对应。公气短波吸收辐射与总云量呈负相关，高相关区在我国东部。各站地－气短波吸收辐射与地面吸收辐射的相关系数普遍高达０．９００以上。此一特，或为从气候上利用地－气吸收辐射反演地面吸收辐射提供初步可能。  相似文献   

Optimal lake-marsh pattern determination in lake-marsh systems based on the eco-hydrological processes management     

Wuxia Bi  Baisha Weng  Denghua Yan  Meng Li  Zhilei Yu  Lin Wang  Hao Wang 《水文研究》2020,34(26):5260-5277

The major hydrological factors in lake-marsh systems are water level (depth), water surface area, and water volume. The key index for determining the lake-marsh pattern is water level, which leads to the variation of lake-marsh patterns under natural hydrological alternations. In addition, the vegetation structure also affects the lake-marsh pattern. With socioeconomic development and climate change, the ‘land use’ and ‘water use’ competitions appear more seriously between a lake-marsh system and its surrounding socioeconomic system, also inside the lake-marsh system. The possible optimal lake-marsh pattern could solve the contradictions mentioned above. As few studies focus on this issue, this study proposed an optimal lake-marsh pattern determination method with eco-hydrological management on relieving the land use and water use competitions. The optimal lake-marsh pattern determination method considers the protection objects (water depth demands), water supply (precipitation, surface water, and groundwater), and water demand (especially evapotranspiration) in the system at annual and monthly scales. Calculation and analysis were performed for the optimal pattern of the Wolonghu Wetlands as an example. The results mainly showed that the lake-marsh pattern of the Wolonghu Wetlands cannot be achieved on meeting both the maximum ecological services values and minimum water shortage amount under present natural condition. With artificial regulation measures, the possible optimal annual lake-marsh patterns can be obtained based on both ecological and hydrological objectives, with the area ratio of lake and marsh in the range of 0.650:0.350 and 0.726:0.274, the corresponding water level of lake body was of 86.85 to 87.0 m. This study could provide references for the Wolonghu Wetlands management, also for similar lake-marsh systems and other ecological systems.  相似文献   

基于数字高程模型的水系自动生成     

张渭军  王文科  孔金玲  翁晓鹏 《大地测量与地球动力学》2006,26(4):41-44

为从数字高程模型(DEM)中自动提取区域水流特征,分析了DEM中地形的形态特征,并进行洼地填充和平地抬升的预处理,应用坡面流模拟方法进行了水流方向的确定及水流方向数字阵列的生成,最后根据水流方向阵列和河流栅格网络图生成需要的水系,其结果与手工数字化的水系基本一致,证明该方法是有效的。  相似文献   

我国大气透明度系数的时间变化     

方先金  翁笃铭 《地理学报》1988,(1)

作者在文献[1]中探讨了我国大气透明度系数的空间分布及其主要影响因子。本文则探讨大气透明度系数的时间变化,特别是它的长期变化及其成因。结果发现:火山爆发可使大气透明度系数明显减小;由于人类活动影响,冬季大气透明度系数P_2、P_d有明显的减小趋势,P_2、P_d与用煤量等污染指标有很好的负相关。文中还对大气可降水含量的气候学推算方法进行了探讨。本文应用1820—1983年的地球自转变化率资料,分析出地球自转变化存在准44个月、准11年、准24年和准49年的周期。南方涛动指数的变化,大气活动中心位置的移动,赤道东太平洋海温的异常等,都能从地球自转速度变化思期中找到关系。已经发现,在地转长期(准24年和准49年周期)加(减)速时,南方涛动指数减弱(增强),大气活动中心向西北(东南)移动,非洲干旱区降水偏多(偏少);同时发现:在地转短期(准44个月周期)加(减)速时,赤道东太平洋海温降低(升高)。  相似文献   

On the Taiwan Warm Current Water     

翁学传  王丛敏 《中国海洋湖沼学报》1988,6(4):320-329

With the use of historical data from their 1982-1985 special observation at the source area of the Taiwan Warm Current the authors conducted studies to clarify the temperature and salinity characteristics, variability, and origin of the Taiwan warm Current Water, and its influence on the expanding direction of the Changjiang Diluted Water.The main results are given below.(1)The Taiwan Warm Current Water can be divided into the "Surface Water of the Taiwan Warm Current" formed due to the mixing of the Kuroshio Surface Water flowing northward along the east coast of Taiwan with the Taiwan Strait Water, and the "Deep Water of the Taiwan Warm Current" originated from Kuroshio Subsurface Water to the east of Taiwan. It is characterized by stable low temperature and stable high salinity in summer. The maximum seasonal variation and maximum secular variation of temperature and salinity are 1.87℃, 0.26‰ and 2.96℃, 0.37‰, respectively.(2)The variation in strength of the Taiwan Warm Current is the main influe  相似文献   

Accumulation discrepancy of heavy metal and organic pollutants in three near-shore depositional environments, southeastern China     

Huan-Xin Weng  Yang-Ming Zhu  Ya-Chao Qin  Jian-Yu Chen  Xun-Hong Chen   《Journal of Asian Earth Sciences》2008,31(4-6):522-532

Heavy metal and organic pollutants in sediments along the coastal zone of southeastern China have been investigated. Sediment samples are retrieved from three depositional environments: coast, estuary, and tide-affected river mouth. The relative abundance of heavy metal and organic pollutants is related to their geochemical properties as well as depositional environments and anthropogenic discharge. Based on a sequential extraction method, it is revealed that anthropogenic Pb, Cr, Cu, and Cd are mainly bound to Fe–Mn oxides, suggesting that adsorption and co-precipitation of Fe–Mn oxides are in the control of their transfer processes from water column to sediment. Heavy metal bound to carbonates is also an important pool especially for Cd, Mn, and Pb. The main organic pollutants found in the study area include petroleum-related alkanes, phthalic acid ester, organic silicon, chlorophenol, phenyl ether, and amine. The accumulation of heavy metals and organics in surficial sediments has a decrease tendency from estuarine environment to coastal environment and to tide-affected river mouth.  相似文献   

CLIMATIC CHARACTERISTICS OF ATMOSPHERIC NET RADIATION OVER CHINA_*     

Weng Duming  Gao Qingxian  Yao Zhiguo 《Acta Meteorologica Sinica》1997,11(2):246-254

In terms of ERBE and ISCCP data.and measured/calculated surface net radiation,computation is performed of the climatic characteristics of ANR(atmospheric net radiation) across China alongside with the discussion and relations to other two kinds of radiation and contributing factors.Evidence suggests a high linear correlation of ANR with atmosphere-absorbed shortwave radiation.whereby can be established a general expression for ANR,which decreases more sharply as a function of altitude and increases slightly with latitude in summer,and changes uniformly in winter.Eventually,a comparison is made of the findings presented in this paper and literatures regarding the ANR pattern and magnitudes,indicating their great difference.  相似文献   

THE CALCULATION AND ANALYSIS OF SLOPE NET RADIATION IN CHINA^*     

Weng Duming  Sun Zhi''an  Shi Bing 《Acta Meteorologica Sinica》1991,5(2):242-251

By using the climatological calculating method for each component of slope surface net radiation proposed by the authors,calculations and analyses are done of the distribution features of slope net radiation in China with emphasis on the discussion of variations of slope net radiation in typical stations and sites with slope direction,slope,latitude and season.The distribution features of net radiation on the north and south slopes are,for the first time,mapped and discussed,revealing the great difference on the national basis,and thus acquiringa new interesting result that the negative-value area of winter net radiation on the north slope(20°)can reach Yunnan and Guizhou Provinces and middle and upper reaches of the Changjiang River.  相似文献   

中国坡地太阳直接辐射分布特征     

孙治安  史兵  翁笃鸣 《高原气象》1990,(4)

本文经简单变换将坡地太阳直接辐射计算式化为S_(αβ)=K(αβ)·S＇,其中S＇为水平地面太阳直接辐射日平均辐照度;K_(αβ)为坡地直接辐射换算系数。文中着重分析了K(αβ)随坡向、坡度、纬度和季节的变化特征,给出了计算南、北坡最热坡度的表达式。最后计算出我国211个站点全年各月坡地太阳直接辐射日平均辐照度,并以南、北坡20°为例分析讨论了坡地太阳直接辐射地理分布特点。  相似文献