Analysis of observations backing up the existence of VLF and ionospheric TEC anomalies before the Mw6.1 earthquake in Greece,January 26, 2014     

《Physics and Chemistry of the Earth》2015

The present work integrates ground-based ionosphere measurements using very-low-frequency radio transmissions with satellite measurements of the total electron content to draw common conclusions about the possible impact that the Mw6.1 earthquake that took place in Greece on January 26, 2014, had on the ionosphere.Very-low-frequency radio signals reveal the existence of an ∼4-day anomaly in the wavelet spectra of the signals received inside the earthquake preparation zone and a significant increase in the normalized variance of the signals prior to the earthquake (approximately 1 day before).Through total electron content analysis, it was possible to identify a clear anomaly from 15:00 until 20:00 UT on the day before the earthquake that appears again on the day of the earthquake between 07:00 UT and 08:00 UT. The anomalous values reach TEC1Sigma ∼4.36 and 3.11, respectively. Their spatial and temporal distributions give grounds to assume a possible link with the earthquake preparation. The geomagnetic, solar and weather conditions during the considered period are presented and taken into account.This work is an initial and original step towards a multi-parameter approach to the problem of the possible earthquake-related effects on the ionosphere joining observations made from both ground stations and satellites. A well-founded knowledge of these phenomena is clearly necessary before dealing with their application to earthquake prediction purposes.  相似文献   

强震前地气系统长波辐射（OLR）异常的成因   总被引：5，自引：2，他引：3       下载免费PDF全文

康春丽  韩延本  刘德富  曹忠权 《地球物理学进展》2008,23(6):1703-1708

本文针对2008年1月9日发生在西藏阿里地区的改则6.9级地震,分析了卫星遥感我国西部地区长波辐射(OLR)信息场的月际和日际变化特征,研究了临震前震中区附近长波辐射的显著增强与其所处大气压力变化的同步关联现象,认为震前长波辐射异常征象的成因可能源自大气而非地热,临震前的大气压力增强是改则6.9级地震发生的诱触发因素,而长波辐射变化信息可作为表征大气诱触发地震动力的一个重要指征物理量.  相似文献   

Temporal and spatial variations of <Emphasis Type="Italic">δ</Emphasis><Superscript>15</Superscript>N and <Emphasis Type="Italic">δ</Emphasis><Superscript>18</Superscript>O for atmospheric N<Subscript>2</Subscript>O above the oceanic surface from Shanghai to Antarctica     

RenBin Zhu  YaShu Liu  Hua Xu  Jing Ma  LiGuang Sun 《中国科学D辑(英文版)》2008,51(6):899-910

During the 22nd Chinese Antarctic Research Expedition (CHINARE-22), the atmospheric gas samples above the oceanic surface and near the surface were collected on the track for the scientific ship “Xuelong” and on Millor Peninsula of eastern Antarctica, respectively, using the Tedlar gas bags. Every day the sampling times were 10:00 and 22:00 (local time), respectively. In the laboratory, high-precision measurement of the isotopic compositions for N₂O in these gas samples was conducted using Thermo Finnigan MAT-253 Isotopic Mass Spectrometer with a fully automated interface for the pre-GC concentration (PreCon) of trace gases. The temporal and spatial variations of δ ¹⁵N and δ ¹⁸O in atmospheric N₂O were analyzed. The mean δ ¹⁵N and δ ¹⁸O-N₂O values above the oceanic surface were (7.21±0.50)‰ and (44.52±0.52)‰, respectively. From 30°N to Antarctica, the δ ¹⁵N (6.05‰–7.88‰) linearly increased with the rate of about 0.01‰ with the latitude while the δ ¹⁸O (43.05‰–48.78‰) showed a large fluctuation. The δ ¹⁵N negatively correlated with air temperature and N₂O concentration, and slightly positively correlated with δ ¹⁸O. The summertime variations of δ ¹⁵N and δ ¹⁸O-N₂O appeared the same trend on Millor Peninsula of eastern Antarctica. They significantly positively correlated with each other and negatively with N₂O concentration. The δ ¹⁵N and δ ¹⁸O-N₂O at different sites averaged (7.42±0.35)‰ and (44.69±0.49)‰, respectively, slightly higher than those above the oceanic surface, significantly higher than those of atmospheric N₂O in the low-latitude regions of Northern Hemisphere. The predominant factors affecting the spatial variations of δ ¹⁵N and δ ¹⁸O values were also discussed. The isotopic data given in this study can help to investigate the global and regional N₂O budgets. Supported by the National Natural Science Foundation of China (Grant Nos. 40676005 and 40406001)  相似文献   

Modeling helioseismic modes in the magnetic atmosphere of the Sun     

B. Pintr 《Astronomische Nachrichten》2007,328(8):738-742

The pulsation of the solar surface is caused by acoustic waves traveling in the solar interior. Thorough analyses of observational data indicate that these f and p helioseismic oscillation modes are not bounced back completely at the surface but they partially penetrate into the atmosphere. Atmospheric effects and their possible observational application are investigated in one‐dimensional magnetohydrodynamic models. It is found that f and p mode frequencies are shifted of the order of μHz due to the presence of an atmospheric magnetic field. This shift varies with the direction of the wave propagation.Resonant coupling of global helioseismic modes to local Alfvén and slow waves reduce the life time of the global modes. The resulting line width of the frequency line is of the order of nHz, and it also varies with propagation angle. These features enable us to use helioseismic observations in magnetic diagnostics of the lower atmosphere. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

A FLUID EXPERIMENT OF GRAVITY INTERNAL WAVE INDUCED BY TERRAIN          下载免费PDF全文

刘辉志  桑建国  张伯寅  洪钟祥  胡非 《Acta Meteorologica Sinica》2000,(2)

The mountain wave induced by a ridge in two-layer stratified fluid has been successfullysimulated in a tank.The wave pattern is qualitatively similar to that calculated with linear theory.  相似文献   

未来海平面变化趋势     

冯浩鉴  方爱平 《测绘科学》2000,25(4):5-10

根据气候和海平面在整个历史长河中的变化规律 ,结合当前各国科学家对气候变化所做的实验、分析 ,讨论了最近 10 0多年全球气候变暖原因和未来海平面变化趋势。海平面在今后百年尺度里 ,随气候变暖继续上升一段时间之后 ,将会随气候变冷而下降。这种时高时低现象可能会持续数百年 ,变幅不会超过 3米  相似文献   

BAROTROPIC AND BAROCLINIC PATTERNS OF ATMOSPHERIC CIRCULATIONS RELATED TO MONSOON TYPES^*          下载免费PDF全文

ZHU Qiangen  LIU Xuanfei 《Acta Meteorologica Sinica》2000,14(4):433-441

In the context of 1982-1994 NCEP/NCAR wind at 12-level isobaric surfaces on a global basis calculation is made of the barotropic(mass-weighed vertical mean) and baroclinic components(difference between the actual wind at each level and barotropic component) of atmospheric flow fields,followed by dealing with the distribution features of barotropic and baroelinie patterns globally in winter and summer,alongside with the classification of global monsoons according to the surface barotropic/baroclinic patterns.Evidence suggests that the seasonal variation of both components will lead to the reversal of a prevailing wind between winter and summer,thus causing a related monsoon:the baroclinie flow pattern is indicative of a thermal circulation driven by atmospheric inhomogeneous heating chiefly from land-sea thermal contrast whilst the barotropic counterpart represents the result mainly from dynamic effects,which is helpful to the understanding of monsoon nature.And further study shows that the classical monsoon regions in tropical Asia,Africa and South America fall into a baroclinic category,those in the bi-hemispheric subtropical Pacific into a barotropic type and the East Asian subtropical monsoon generated underthe joint action of both the patterns falls into a mixed category.  相似文献   

青藏高原云对地气系统短波吸收辐射强迫的气候研究   总被引：3，自引：3，他引：0  

刘艳  翁笃鸣 《南京气象学院学报》2000,23(1):124-129

利用地球辐射平衡试验（ＥＲＢＥ）和国际卫星云气候计划（ＥＳＣＣＰ）提供的总云量、得星反射率资料,计算并分析了青藏高原地气系统年、月平均云对太阳短波吸收辐射的强迫,揭示了其与总云量的关系。结果表明：高原的短事射云强迫与总云量有较好的非线性相关,呈幂指数形式,且季节变化明显;短波辐射云强迫的地理分布与高原云的分产好,高原主体和北部是短波辐射云强迫的低值区,高原东南部和西部边缘迎风部位为强迫的高值区。  相似文献   

青藏高原云对地气系统长波射出辐射(OLR)强迫的气候研究   总被引：6，自引：1，他引：5  

刘艳  翁笃鸣 《南京气象学院学报》2000,23(2):270-276

利用地球辐射平衡试验（ＥＲＢＥ）和国际卫星云气修计划（ＩＳＣＣＰ）提供的地气系统长波射出辐射（ＯＬＲ）和云量资料,计算并讨论了青藏高原地气系统各季和年平均总云量对ＯＬＲ的强迫及其所产生的温室效应,揭示了高、低示了高、低云对ＯＬＲ强迫的特点。结果表明：高原的ＯＬＲ云强迫与总云量、高云量都有较好的相关关系,且季节变化明显;ＯＬＲ云强迫和云温室效应的地理分布与高原总云量的分布较为一致;云强迫的年变化一同  相似文献   

广西早春旱预报的全部可能回归模型方法     

古文保  覃丹宇 《南京气象学院学报》2000,23(2):288-293

研究了广西春旱天气的前期大气环流及要素场的异常特征发现,冬季５００ｈＰａ高度场,月平均降水、温度,冬季海温、极涡强度指数,亚欧续向环流等与广西早春旱关系密切。用建立的广西早基旱预报模型对１９９８年春季降水进行了试报。  相似文献