Process Analysis of In-situ Strain during the Ms8.0 Wenchuan Earthquake-Data from the Stress Monitoring Station at Shandan     

PENG Hua MA Xiumin JIANG Jingjie 《《地质学报》英文版》2009,83(4)

There were huge life and property losses during the Ms8.0 Wenchuan earthquake on May 12, 2008. Strain fluctuation curves were completely recorded at stress observatory stations in the Qinghai-Tibet plateau and its surroundings in the process of the earthquake. This paper introduces the geological background of the Wenchuan earthquake and the profile of in-situ stress monitoring stations. In particular, data of 174 earthquakes (Ms4.0-Ms8.5) were processed and analyzed with various methods, which were recorded at the Shandan station from August 2007 to December 2008. The results were compared with other seismic data, and further analyses were done for the recoded strain seismic waves, co-seismic strain stepovers, pre-earthquake strain valleys, Earth's free oscillations before and after the earthquake and their physical implications. During the Wenchuan earthquake, the strainmeter recorded a huge extensional strain of 70 seconds, which shows that the Wenchuan earthquake is a rupture process predominated by thrusting. Significant precursory strain anomalies were detected 48 hours, 30 hours, 8 hours and 37 minutes before the earthquake. The anomalies are very high and their forms are very similar to that of the main shock. Similar anomalies can also be found in strain curves of other shocks greater than Ms7.0, indicating that such anomalies are prevalent before a great earthquake. In this paper, it is shown that medium aftershocks (Ms5.5-6.0) can also cause Earth's free oscillations. Study of free oscillations is of great significance to understand the internal structure of the Earth and focal mechanisms of earthquakes and to recognize slow shocks, thus providing a scientific basis for the prevention and treatment of geological disasters and the prediction of future earthquakes.  相似文献   

A Hybrid Neural Network Model for ENSO Prediction in Combination with Principal Oscillation Pattern Analyses     

Lu ZHOU  Rong-Hua ZHANG 《大气科学进展》2022,39(6):889-902

El Ni?o-Southern Oscillation(ENSO)can be currently predicted reasonably well six months and longer,but large biases and uncertainties remain in its real-time prediction.Various approaches have been taken to improve understanding of ENSO processes,and different models for ENSO predictions have been developed,including linear statistical models based on principal oscillation pattern(POP)analyses,convolutional neural networks(CNNs),and so on.Here,we develop a novel hybrid model,named as POP-Net,by combining the POP analysis procedure with CNN-long short-term memory(LSTM)algorithm to predict the Ni?o-3.4 sea surface temperature(SST)index.ENSO predictions are compared with each other from the corresponding three models:POP model,CNN-LSTM model,and POP-Net,respectively.The POP-based pre-processing acts to enhance ENSO-related signals of interest while filtering unrelated noise.Consequently,an improved prediction is achieved in the POP-Net relative to others.The POP-Net shows a high-correlation skill for 17-month lead time prediction(correlation coefficients exceeding 0.5)during the 1994-2020 validation period.The POP-Net also alleviates the spring predictability barrier(SPB).It is concluded that value-added artificial neural networks for improved ENSO predictions are possible by including the process-oriented analyses to enhance signal representations.  相似文献   

夏季青藏高原O3低值与南亚高压东西振荡的关系     

舒斯  何金海  刘毅  王永  蔡兆男  LIU Xiong 《气候与环境研究》2011,16(1):39-46

利用O3监测仪(Ozone Monitoring Instrument,OMI)卫星O3廓线资料和NCEP/NCAR再分析资料,研究了2006年夏季南亚高压偏西型和偏东型条件下青藏高原地区O3垂直结构和变化特征差异.结果表明,夏季南亚高压东西振荡与青藏高原O3分布存在密切的关系,在西(东)部型南亚高压条件下,夏季青藏高...  相似文献   

两个造成大风影响的热带气旋特征分析   总被引：6，自引：0，他引：6  

何洁琳 《广西气象》2006,27(1):10-13,16

应用NCEP／NCAR再分析资料，对造成玉林市持续长时间大风的0307号和8517号热带气旋（TC）的特点和大尺度环境特征进行对比分析，结果表明：0307号TC自身强度强，移速快；而8517号TC则移速缓慢，登陆后转向，TC中心在玉林市逗留时间长。两个TC登陆前后的大尺度环境特征不同造成其强度和运动特点的不同。  相似文献   

基于TRMM卫星降水的太行山区降水时空分布格局   总被引：2，自引：0，他引：2       下载免费PDF全文

杜军凯  贾仰文  李晓星  牛存稳  刘欢  仇亚琴 《水科学进展》2019,30(1):1-13

基于TRMM 3B42V7数据,综合采用多元线性回归、偏最小二乘回归和地理加权回归3种方法,建立了太行山区卫星降水产品的降尺度校正模型,将遥感降水信息从0.25°×0.25°降尺度到0.05°×0.05°。在结果评估和优选的基础上,分析了"像元-集水区-全区"年、月降水的多时空尺度干湿季节分布和垂向分布特征,并从机理方面论证了研究的合理性。结果表明:①地理加权回归校正效果最优,可明显降低校正降水与实测降水系列的均方根误差和平均相对偏差且提高决定系数;偏最小二乘回归可降低两项误差,但对决定系数无提升;多元线性回归最差,各项指标均无改善。②处于夏季风迎风侧的东坡和南坡降水量普遍高于500 mm,背风侧的西坡和北坡降水量较低,最大年降水量位于东南坡海拔1 300~1 500 m的地带。③研究区7-9月降水量占全年的58.7%,干湿季节降水量之比为1:18,各集水区的变化范围为1:13~1:25。④季风风向影响降水中心的移动路径,各月降水量沿高程变化梯度区间为-5.2~6.7 mm/hm,且迎风坡降水的垂向分布更复杂。  相似文献   

Impact of Different Intensity Tropical Cyclones on Precipitation Changes in China     

Hui Yang  Fumin Ren  Ming-Jen Yang 《地球科学进展》2019,34(7):747-756

Based on the daily precipitation data of more than 2 000 meteorological stations from 1960 to 2017 and the tropical cyclone (TC) best-track data of the China Meteorological Administration, the TC precipitation was identified by the Objective Synoptic Analysis Technique (OSAT). The research shows that the TC precipitation in China has a significant downward trend, which is slower than that of the research results 12 years ago. The TC precipitation in the peaking season (July to Sepember) accounted for 78.5% of the total TC precipitation. Both TC precipitation in peaking season and other months showed a significant downward trend. The TC precipitation climate trend is mainly characterized by reduction in spatial distribution, and shows obvious regional differences. From south to north, there is a distribution of “decreasing-increasing-decreasing”, and the decreasing trend centers are located in Guangdong and Hainan. According to the maximum intensity in the TC influence period, we classified TCs into three levels (weak TCs, medium intensity TCs and strong TCs) and studied the variations of TC precipitation in different intensities. The results show that the strong TC precipitation shows a significant decrease trend, which mainly determines the influence range and trend of TC total precipitation. Further analysis found that the frequency of affecting TC showed a significant reduction trend during the time period of 1960-2017 and an abrupt shift occurred in 1995. A comparative study of the two periods before and after 1995 showed that compared with the previous period (1960-1994), the frequency of TCs in the latter period (1995-2017) showed a significant decreasing trend in the south of 20°N. The maximum decreasing center was located in the northern part of the South China Sea, and this feature was mainly affected by the strong TC. It was decided that this trend of strong TC led to a decrease trend in the number of precipitation days in South China, especially in Guangdong and Hainan, which led to a decrease trend in TC precipitation.  相似文献   

Non-adiabatic effects in the solar p-mode oscillations     

Shao-lan Bi  Ru-feng Li 《Chinese Astronomy and Astrophysics》1997,21(4):474-480

Non-adiabatic effects associated with radiative loss and convective transfer add small imaginary parts to solar p-mode eigenfrequencies. An asymptotic approximation is developed to study the non-adiabatic effects. For the outermost layer where the approximation is not valid, an exact solution of the equation of non-adiabatic oscillation which results in an cigenfunction equation, is used. The inclusion of the non-adiabatic effects reduces the discrepancy between the theory and observations particularly for frequencies above 3.1 mHz.  相似文献   

利用雷达回波特征和地面资料确定0312号台风"科罗旺"强度     

刘丽君 《气象研究与应用》2003,24(4):24-27

通过分析0312号台风"科罗旺"过程的雷达回波特征和地面资料,应用"热带气旋强度综合判据表"的办法,确定该台风的强度,并分析其大风分布的特点.为将来雷达探测台风业务,分析回波资料积累一些经验和方法,从而能更好的利用雷达回波应用于台风预报业务.  相似文献   

关于东亚夏季风变化及其成因的最近研究进展   总被引：55，自引：10，他引：45  

HUANG Ronghui  ZHOU Liantong  CHEN Wen 《大气科学进展》2003,20(1):55-69

东亚夏季风变化是中国、日本和韩国的重要研究课题。回顾了关于东亚季风(尤其是东亚夏季风)的季节内变化、年际和年代际变化及其这些变化成因的最近研究进展,特别是系统地回顾了厄尔尼诺、南方涛动(ENSO)循环、西太平洋暖池、青藏高原和陆面过程对东亚夏季风的季节内变化、年际和年代际变化的作用。  相似文献   

SST日变化对西太平洋暖池海表热通量季节内变化的影响(英文)   总被引：2，自引：0，他引：2  

李薇  宇如聪  刘海龙  俞永强 《大气科学进展》2001,(5)

基于利用日最大太阳辐射、日平均海面风和日降水量近似计算海表温度（SST）日变化的振幅的方法,发展了一个计算SST日循环的参数化方案。利用周平均SST强迫美国国家大气研究中心（NCAR）的CCM3大气模式进行了有、无考虑SST日变化的比较试验。热带海洋与全球大气计划之耦合海气响应实验（TOGA COARE）的强化观测期间 IMET浮标的逐时海表观测资料不仅验证了该参数化方案的合理性,也表明了利用参数化方案对强迫场SST迭加日变化使CCM3较真实地模拟出西太平洋暖池海表热通量的季节内变化的位相结构。  相似文献