汶川地震前后的气象异常

有研究认为局地气象异常与地震之间存在着一定的相关性,那么震惊中外的汶川大地震前后有没有气象异常呢？应用NCEP再分析资料,以1988—2007年20年间局地气象要素的平均值和标准偏差为基准,通过构建气象异常指数对2008年5月12日汶川发生的大地震前后的日平均气温、日最高气温、日最低气温、日平均降水强度和日平均气压等5项气象要素指标的异常状况进行了分析,结果表明在地震前2个月的时间内有异常状况出现,并且其变化幅度和持续时间都比较长,在地震过后这些异常并未立即消失;从5项气象要素异常空间分异来看,汶川是气象异常的中心地带,表征了汶川地震与局地气象之间存在着一定的相关性。尽管气象异常是否是地震发生的必然前兆尚待进一步考证,但出现在汶川特大地震前后的气象异常再次给我们一个提示,即气象异常与地震的关系值得深入研究。     

芦山地震的预测

2013年4月20日中国四川省雅安市芦山县发生了7.0级地震,对于这次地震发生的时间和地点,震前有不同程度的预测。为了推动地球科学发展,提高地震预测水平,以达到最大限度地减轻地震灾害损失,特对此作一小结。2011年3月11日日本东北部海域发生9级地震以后,利用可公度性原理,分析了近年来发生在世界各地的大地震,发现这些地震发生的时间具有可公度性,且它们基本上发生在其时间轴上的可公度值点上。根据对川滇块体地震信息的可公度性分析,该研究区的可公度值是2.44年,因而2013.24年就是未来地震可能发生的时间点;根据卫星重力异常反映的地壳密度异常变化图,雅安西侧与汶川具有两个特征相同的独立的卫星重力局部高异常梯度突变区,2008年的汶川地震只是释放了龙门山断裂带东北段的能量和应力,这导致能量和应力在龙门山断裂带南西段,特别是南西端与重力异常突变位置的叠加区加速积聚和集中,因此曾佐勋多次指出四川的下一个大震将在雅安与康定之间发生。这两方面的分析都是震前的,可惜它们是彼此独立的。如果事前能将这两个方面的预测加以综合分析,则可以达到短期预测的目的。这再一次表明,地震预测必须走综合分析之路。     

2008～2009年云台等高仪时纬残差的异常波动

分析了2008～2009年间云南天文台光电等高仪的时纬资料的残差值的变化,讨论了残差异常变化与此期间云南天文台周围发生的2008年5月12日四川汶川8.0级地震、8月30日攀枝花6.1级地震以及12月26日昆明4.3级地震的可能的关系,并讨论了与该研究有关的问题。     

地球自转变化与中国大陆地震活动关系的初步分析

本文利用天文观测的日长变化时间序列和我国地震资料，统计分析了地球自转十年尺度变化、年限变化和季节性变化与中国大陆地震活动间的相关性。结果表明，中国大陆地震活动与地球自转变化在时间尺度上存在着一定的全局性联系，地球自转变化引起的附加应力可能对中国大陆地震活动起一定的触发作用，中国大陆地震活动与地球自转变化在空间尺度上存在着一定的地区性联系，以东西向的天山地震带与日长变化的相关性最为显著，南北向的中轴地震带和东西向的燕山地震带次之，而北北东向的山西地震带跟日长变化则没有确定的对应关系。分析结果表明，天文观测的地球自转资料可以为我国大陆地震预测提供一种参考依据。     

地震的发生与月球位置关系的初步讨论

本讨论了1960年－1969年共10年间在我国发生的586次震级Ms≥4.75的地震与月龄、月球时角及地月距离之间的相关性，结果表明地震的频率与月球明角、月龄无明显的相关性：当月球位于远地点附近时地震较多且与月龄无关；当月球们于地月平均距离附近时有几处发震几率较高，且地震较多发生在上下弦附近；当地月距离到最小值附近时地震都发生在朔望。     

全球大地震对ERP的影响

本探讨了1900－1986年间全球大地震和ERP之间的相关性。利用震中位置和震源参数，按Dahlen公式计算了由地震引起的地球惯性张量变化，结果表明单个地震对日长和极移变化的影响要比经典仪器测定的ERP水平小两个量级，空间技术能够获得高精度的ERP，使得有可能用来进行ERP与地震关系的研究。     

地震的天机

2004年12月26日,印度洋发生特大地震和海啸,已造成十几万人遇难。事实上,每次大地震的袭击,都给人类留下惨痛的记忆,那种山崩地裂、海浪铺天盖地的情景,令人惊心动魄!例如1923年日本关东发生的8.2级大地震,造成东京、横滨等城市的14.3万人死亡、1994年1月17日美国洛杉矶发生6.8级地震。煤气管道泄露,引发了火灾,使一万人露宿街头。1995年日本大阪、神户发生的7.2级地震,共造     

1950年以来我国大地震与天文相关的一些特征

本文统计了近四十年来在我国发生的大地震(M≥7级)与天文相关的一些特征、并得出一些结论:(1)大地震在太阳黑子活动周谷年及这之前三年易发生、其发生的概率高于太阳活动蜂年及附近年份发生地震的概率。(2)在太阳黑子活动周的偶数周期大地震发生的次数高于在奇数周期发生的次数。(3)大地震在一年中的第一。第三季度发生的概率高于在第二,第四季度发生的概率。(4)大地震在节气日及其前二天和节气日后第五至第七天发生的概率较高。文章对产生这些相关的原因进行了初步的探讨。     

黑子半影旋涡形态和高能耀斑的相关性探讨——应用持续旋涡黑子预报太阳活动的可能性

1970年初至1972年底云南天文台的黑子细节照相资料的初步统计表明:(1)具有持续的黑子半影纤维旋涡形态历史的活动区有较高的耀斑爆发频数,平均多达55％以上.(2)它们与伴随较大地球效应的高能量耀斑有密切的相关性,达84％。(3)其中90％左右的高能耀斑发生在旋涡黑子出现以后,平均落后3.8天,反映了两个现象之间可能存在着因果联系.这三点结论都有利于磁场扭结不稳定性的耀斑理论.     

太阳活动对中国中纬度地区8级大地震的可能触发

研究了发生在中国中纬地区(20°~40)°Ms≥8的大地震与太阳活动的关系,发现地震的发生时间多处在太阳活动周的降段至谷段,并且具有统计意义,显示出太阳活动和地震活动的相关联性。联想到中纬度地区洪水与太阳活动负相关,即在太阳活动低年,降雨充沛,甚至发生水灾。作者认为大雨引起的地下水位上升,岩石被水浸泡后,耐剪强度下降,从而使已孕育的大地震容易触发。     

丽江高美古的气象观测

本文报道了１９９４年７月－１９９５年１２月期间丽江高美古的云量、风向、风速、温度、湿度和温度日较差等气象要素的观测结果。     

A Study of the γ-ray and X-ray Radiations of BL Lac Objects

The X-ray and γ-ray flux densities of 18 γ-loud BL Lac objects as well as their average spectral indices of X-ray wave band (1 keV) and γ-ray wave band (>100 MeV) are collected, and the correlations among the various quantities are examined. The results indicate: (1) The X-ray flux density and the γ-ray flux density exhibit rather strong correlations in all the states, high, low or mediate. (2) Between the mean spectral indices in X-ray and γ-ray wave bands there is a comparatively intense anti-correlation. (3) Between the average spectral indices and the X-ray and γ- flux densities there is no evident correlation either in the high or the mediate state. (4) Between the average spectral index of γ-ray wave band and the flux density of X-rays in low state there is a rather strong anticorrelation. Between the mean spectral index of X-ray wave band and the γ-flux density in low state there also exists a weak correlation. The results of our analysis support the viewpoint that both the X-ray and γ-ray emissions of BL Lac objects come from the synchrotron radiation and synchrotron self Compton (SSC) radiation with one and the same distribution of relativistic electrons.     

昭通大山包天文气象条件统计分析

采用云南省昭通市昭阳区气象局1960年到1988年间在大山包实地采集的气象数据资料,并根据优良太阳观测台址所要求的各项参数指标,对大山包29年来的气象资料进行了系统的统计分析,发现该候选址点在干季(10月到次年4月)具有年日照时间增长、云量减少、相对湿度降低、风速较小且风向稳定、气候变化具有明显的周期性等特征。考虑到交通条件便利,初步判定它是一个具有潜力的优良太阳观测候选址点。     

An analysis of heat waves in Serbia

In this study, heat waves at three meteorological stations in Serbia were analyzed based on the daily maximum temperature during the summer (June, July and August). The warmest summers as regards heat wave duration and severity occurred within the periods 1951–1952, 1987–1998 (especially 1994) and 2000–2007. The longest heat waves were recorded in 1952, lasting 16 days in Smederevska Palanka and 21 days in Ni?, while in 1994 in Belgrade lasting 18 days. The summer of 1994 in Belgrade and Smederevska Palanka, and 2003 in Ni? were characterized with the highest number of consecutive tropical days (21 and 29, respectively).The autoregressive-moving-average models were applied to generate long series of the daily maximum temperature, from which the relative frequencies of heat waves were estimated. The relationships between the longest heat waves, and the circulation conditions were analyzed using the subjective Hess–Brezowsky catalogue of weather types.     

Application of artificial neural networks to the prediction of dust storms in Northwest China

Artificial neural networks (ANN) are non-linear mapping structures analogous to the functioning of the human brain. In this study, we take the ANN approach to model and predict the occurrence of dust storms in Northwest China, by using a combination of daily mean meteorological measurements and dust storm occurrence. The performance of the ANN model in simulating dust storm occurrences is compared with a stepwise regression model. The correlation coefficients between the observed and the estimated dust storm occurrences obtained from the neural network procedure are found to be significantly higher than those obtained from the regression model with the same input data. The prediction tests show that the ANN models used in this study have the potential of forecasting dust storm occurrence in Northwest China by using conventional meteorological variables.     

Nightglow (557.7 nm of OI) in the central polar cap

The 557.7 nm OI night airglow emission was measured in the central polar cap by ground-based photometric systems at Thule Air Base, Greenland during the winter seasons from 1972–1973 to 1974–1975 and at Thule-Qanaq, Greenland during the winter season of 1973–1974. The behavior of the 557.7 nm night airglow emission in the polar cap was found to be quite different from that observed at mid and low latitudes. No diurnal variation greater than ±5% exist in the data. Large amplitude variations in the 557.7 nm daily average emission intensities can change by up to a factor of approximately 8 over periods ranging from 4 to 19 days. These long-term airglow variations cover at least a 100 km horizontal range as determined by a correlation coefficient of 0.94 between daily average 557.7 nm airglow intensities observed at Thule Air Base and Thule-Qanaq. An interplanetary magnetic field sector related behavior is evident in the daily average intensities which shows an increase of intensity in a positive (+) sector and a decrease of intensity in a negative (?) sector. No significant correlation was found between the 557.7 nm daily average intensities and Zurich sunspot number R_Z, although a season to season positive trend was evident. Correlations between the 557.7 nm daily average intensities and planetary magnetic indices ΣK_p and A_p were found to be inconclusive due to sector related effects. The Barth and Chapman mechanisms are discussed as possible source mechanisms for the 557.7 nm airglow in the central polar cap, and a hypothesis is presented to explain the airglow variations.     

Network and plage indices from Kodaikanal Ca-K data

The Ca II K filtergrams from Kodaikanal Solar Observatory have been used to study solar activity.The images are dominated by the chromospheric network and plages.Programs have been developed to obtain the network and plage indices from the daily images as functions of solar latitude and time.Preliminary results from the analysis are reported here.The network and plage indices were found to follow the sunspot cycle.A secondary peak is found during the period of declining activity in both the indices.A comparison of network indices from the northern and the southern hemispheres shows that the former is more active than the latter.However such an asymmetry is not clearly seen in the plage index.     

The link between the masses and central stellar populations of S0 galaxies

Using high signal-to-noise ratio VLT/FORS2 long-slit spectroscopy, we have studied the properties of the central stellar populations and dynamics of a sample of S0 galaxies in the Fornax cluster. The central absorption-line indices in these galaxies correlate well with the central velocity dispersions (σ₀) in accordance with what previous studies found for elliptical galaxies. However, contrary to what it is usually assumed for cluster ellipticals, the observed correlations seem to be driven by systematic age and α-element abundance variations, and not changes in overall metallicity. We also found that the observed scatter in the index–σ₀ relations can be partially explained by the rotationally supported nature of these systems. Indeed, even tighter correlations exist between the line indices and the maximum circular velocity of the galaxies. This study suggests that the dynamical mass is the physical property driving these correlations, and for S0 galaxies such masses have to be estimated assuming a large degree of rotational support. The observed trends imply that the most massive S0s have the shortest star formation time-scales and the oldest stellar populations.