第22周峰年强耀斑活动及持续性预报

利用１９８９ 年到１９９１ 年的观测资料, 按面积把太阳黑子群分成五类统计分析了各类黑子群的强耀斑活动（Ｉ＞ ＝ Ｍ） 结果是： Ｓｍ ＞ ＝ ５００ 的黑子群占全部黑子群的６３ ％ , 产生了５６ ％ 的强耀斑近半数的强耀斑产生于面积小于５００ 的小黑子群文中分析了小黑子群产生强耀斑的磁场位形先兆, 这些先兆有： １） 磁流浮现, （２） 磁轴垂直, （３） 反极性活动区, （４） 活动区旋转, （５）同极性磁流合并或撕裂, 但仍有相当多的小黑子群产生耀斑前无任何先兆; 用极大熵谱的ＡＲ 模式计算了四个超级活动区的强耀斑活动周期： 分析讨论了持续性预报的适用范围以及它的弊病文中指出, 发展带有更多物理意义的预报技术和方法是提高预报水平和满足用户要求的唯一可取之路     

月平滑太阳黑子相对数的预报

建国以来,不少天文工作者在太阳活动长期预报、中期和短期预报方面作了大量工作,但是,太阳活动的一至几年的中长期预报却很少有人涉足。本文试图用门限自回归模型和二次曲线方法,探讨时间长度为一年的月平滑黑子相对数的预报。并给出两种方法的综合预报结果。     

关于太阳活动预测与自然灾害预测

日地系统学中, 自然灾害与太阳活动的关系研究, 导致了自然灾害预测与太阳活动预测之间关系的探讨本文比较了太阳活动预测与自然灾害预测, 指出它们在目的、用户、观测资料的特征、预报方法以及面临的问题几方面的差异; 介绍了自然灾害预测与太阳活动预测的几点可能的关系; 简单讨论了衡量预报水平的指标问题最后列出了第２３ 黑子周特征值的一些预测结果     

电离层参数短期预报研究进展

对国内外电离层参数短期预报方法进行了综述,重点介绍了几种作者最新研究的电离层foF2参数短期预报方法.包括基于混沌时间序列分析的电离层foF2参数提前15 min(分钟)准实时预测方法、基于人工神经网络技术的提前1 h(小时)现报方法、提前1～3 d(天)的神经网络预测方法、相似日短期预报方法以及综合预报模型方法.利用中国垂测站多年的观测数据对各种算法的预测精度进行了评估,并与国内外相关算法进行了定性或定量比较,各种预报方法都在前人的预报精度基础之上有了一定的提高.其中提前15 min(分钟)预测方法平均相对误差小于4%,平均绝对误差小于0.2 MHz,可以用于实时性和精度要求较高的短波系统;提前1小时预报方法在太阳活动高年平均预测相对误差小于6%,均方根误差小于0.6 MHz,太阳活动低年平均预测相对误差小于10%,均方根误差小于0.5 MHz,平均相对误差比前人研究的自相关方法提高3个百分点左右;对于提前1～3 d(天)短期预报,综合预报模型方法充分利用了神经网络方法、自相关方法以及相似日方法的优点,获得了高于任何一种单一方法的精度,对于中国9个垂测站(海口、广州、重庆、拉萨、兰州、北京、乌鲁木齐、长春、满洲里)在不同太阳活动性条件下的历史数据进行了精度测试,提前1天和提前3天预测的平均相对误差分别小于10%和小于15%,达到了国内先进水平.此外,该方法还可以综合更多预报方法,具有进一步提高预报精度的潜力.文中提出的针对不同尺度进行电离层参数预测的方法具有一定的理论基础,且精度高、易实现,对从事电离层短期预报算法研究及相关专业的学者具有一定的参考价值.     

利用半参数核估计法预报全球电离层总电子含量

本文将半参数平差模型引入电离层球谐函数系数的预报中,建立了半参数球谐函数模型(Semiparametric-Spherical Harmonic,Semi-SH)来预测全球电离层总电子含量.首先,通过快速傅里叶变换获得球谐函数系数的周期和振幅,将振幅高的主周期归入趋势函数,振幅低的剩余周期归入随机信号,建立了半参数模型,同时利用核估计方法拟合趋势函数,解算随机信号,并在时间域上进行外推,得到了预报时间的球谐函数系数,代入15阶电离层球谐函数模型,最后得出电离层总电子含量(Total Electron Content,TEC)的预报值.本文基于欧洲定轨中心(CODE)发布的球谐函数系数进行电离层TEC长期预报和短期预报分析,其中长期预报采用四年预报两年的模式对球谐函数系数进行预报,短期预报设计了三个算例,采用前30天预报后一天的模式,分别预报1天、滑动预报7天和滑动预报30天.实验结果表明:长期预报能够较好地反映全球电离层TEC的变化趋势和波动情况,Semi-SH模型对全球电离层TEC平均值(Mean TEC global,MTECglobal)的拟合值和预报值与MTECglobal实际值的相关系数分别为0.8743和0.8010,呈现出高度相关性.短期预报中,在太阳活动高年和太阳活动低年,Semi-SH模型在中纬度地区预报精度较CODE发布的电离层TEC 1天预报产品(CODE′S 1-Day Predicted GIM,C1PG)有较大提升,在高纬度与低纬度地区两种模型预报精度相当;Semi-SH模型在太阳活动高年和太阳活动低年30天滑动预报精度的均值均高于C1PG模型.实验结果说明了Semi-SH模型预报电离层TEC值的有效性.     

浅谈地震中短期预报的科学思路与探索途径

详细论述了地震中短期预报工作的科学思路，即“给‘静态’的地质（壳）结构赋予动态属性，给前兆性异常赋予构造的涵义”；在这个思路的指导下，简要探讨了地震中短期预报的探索途径，提出了在地震中短期预报研究中应该注意的问题     

VLF电磁波能预报地震吗?

１　前言几乎所有的人都承认地震短期预报是重要的,因此,１９９７年６月文部省测地学审议会的报告提出“地震（短期）预报是不可能”的见解时,便引起很大反响。这时尤其是对致力于地震短期预报研究的学者（全世界中仅是极少数的人）们来说,是生死悠关的问题。另一方面,近年来,不同于以往地形变测量的方法,即研究电磁现象和地球化学现象的方法正在作为大有希望的短期地震预报的后补方法受到人们的关注,并进行着多方面的努力研究。相继提出了测定直流大地电流（ＶＡＮ法）或接收ＵＬＦ电磁波、ＶＬＦ／ＬＦ电磁波和ＨＦ电磁波等直接发…     

兰州形变与景泰地震的短临前兆

对比分析了兰州形变水管倾斜仪（ＦＳＱ）、水平摆倾斜仪（ＳＱ７０Ｂ）和石英伸缩仪（ＳＳＹ）于景泰地震前后观测结果中的非潮汐变化，探讨了它们对景泰地震的短期和临震前兆响应，结果表明，倾斜仪ＮＳ向于震前半月内有倾向震中的、幅度约０．１″的短临前兆显示。     

首都圈地磁无量纲参数地震前兆信息研究

为了满足地磁无量纲参数地震短期预报及多综合预报的需要,分析研究了地磁无量纲参数Ｂｉｊ方法,取得了１９９６年１０月６日唐山级地震Ｂｉｊ异常短期（三个月）追踪图象。依据Ｂｉｊ异常（测点数量、幅度、空间分布的大小和方向）时空演化过程和演变特征,可进行地震短期预测追踪的尝试。     

地震预报的社会影响及发布预报的对策

本文从我国的地震预报科学水平出发,综合几个无震虚报和有震漏报的实例,分析了一次预报变成社会行动所需付出的代价,并与地震造成的经济损失进行了对比.由此提出要全面评价地震灾害及其预报的社会经济影响. 文中根据我国几次地震所造成经济损失的资料,绘制了地震震级与经济损失关系的曲线以及预报造成损失的曲线,并引进地震代价指数进行了讨论.文章认为,为了切实有效地减少人员伤亡和经济损失,地震预报的发布,对不同震级应有所区分,地震预报的震级应有一下限,依目前地震预报的水平,六级以下地震不宜向社会发布预报,相应地应加强抗震措施。      

地震波动力学特征变化指标在短期地震预报中的应用

本文研究了地震前地震波动力学特征的变化，主要是波形和频谱的变化，并从中提取出可望在短期（半年以内）地震预报中应用的一些预报指标。这些指标包括：Ｐ波初始部分波形的时间线性度和空间线性度，初始段平均半周期，Ｓ，Ｐ波频谱的峰值频率，拐角频率，相对带宽度，相对频谱峰值，高频段的谱线斜率绝对值等。同时还研究了短周期地脉动的波形线性度及频谱特征量（峰值频率等）在大震前出现的短期（半年以内）和临震（９天以内）的     

On the 18-day quasi-periodic oscillation in the ionosphere

The presence and persistence of an 18-day quasi-periodic oscillation in the ionospheric electron density variations were studied. The data of lower ionosphere (radio-wave absorption at equivalent frequency near 1 MHz), middle and upper ionosphere (critical frequencies f₀E and f₀F2) for the period 1970–1990 have been used in the analysis. Also, solar and geomagnetic activity data (the sunspot numbers Rz and solar radio flux F10.7 cm, and a_N index respectively) were used to compare the time variations of the ionospheric with the solar and geomagnetic activity data. Periodogram, complex demodulation, auto- and cross-correlation analysis have been used. It was found that 18-day quasi-periodic oscillation exists and persists in the temporal variations of the ionospheric parameters under study with high level of correlation and mean period of 18–19 days. The time variation of the amplitude of the 18-day quasi-periodic oscillation in the ionosphere seems to be modulated by the long-term solar cycle variations. Such oscillations exist in some solar and geomagnetic parameters and in the planetary wave activity of the middle atmosphere. The high similarities in the amplitude modulation, long-term amplitude variation, period range between the oscillation of investigated parameters and the global activity of oscillation suggests a possible solar influence on the 18-day quasi-periodic oscillation in the ionosphere.     

Influence of short-term changes in solar activity on baric field perturbations in the stratosphere and troposphere

Influence of short-term changes in solar activity on baric (pressure) field perturbations is studied using such characteristics as the Sazonov index (IS), describing the intensity of meridional transfer, the Blinova index (IB), describing the intensity of zonal transfer, and ‘vorticity area index’ (VAI) describing the tropospheric cyclonic perturbations. The epoch superposition method is used to reveal effects of the solar central meridian (CM) passage of active regions, the Forbush decreases (FD) in galactic cosmic rays, and the solar proton (SP) events. The results of the analysis show that influence of short-term changes in the solar activity on baric field perturbations is the most evident in the stratosphere (30 mbar-level). The meridional circulation in case of the FD and SP events begin to increase about 5–7 days before the key date, reaches maximum nearby the key date and decays after the key date. The meridional circulation in case of the solar CM passage of active regions starts to increase after the key date and reaches the maximum by 5–6 days. Fluctuations of baric field within periods of 5–7 days typical of meridional and zonal transfers in troposphere (500 mbar-level) are evidently connected with internal dynamics of the atmosphere, not with the effects of solar activity. VAI characterizing cyclonic activity in the troposphere, shows the striking correspondence to changes of the meridional circulation in the stratosphere. Comparison of changes in the stratospheric perturbations with behavior of the UV irradiance in course of the FD and SP events show their full correspondence at the initial stage of these processes. The conclusion is made that growth of baric perturbations observed in the stratosphere in associations with the FD and SP events before the key date is caused by the solar UV irradiance increase, whereas decay of the baric perturbations after the key date is related to direct influence of the solar energetic corpuscular fluxes on the stratosphere.     

Evaluating sun–climate relationships since the Little Ice Age

From the coldest period of the Little Ice Age to the present time, the surface temperature of the Earth increased by perhaps 0.8°C. Solar variability may account for part of this warming which, during the past 350 years, generally tracks fluctuating solar activity levels. While increases in greenhouse gas concentrations are widely assumed to be the primary cause of recent climate change, surface temperatures nevertheless varied significantly during pre-industrial periods, under minimal levels of greenhouse gas variations. A climate forcing of 0.3 W m⁻² arising from a speculated 0.13% solar irradiance increase can account for the 0.3°C surface warming evident in the paleoclimate record from 1650 to 1790, assuming that climate sensitivity is 1°C W⁻¹ m⁻² (which is within the IPCC range). The empirical Sun–climate relationship defined by these pre-industrial data suggests that solar variability may have contributed 0.25°C of the 0.6°C subsequent warming from 1900 to 1990, a scenario which time dependent GCM simulations replicate when forced with reconstructed solar irradiance. Thus, while solar variability likely played a dominant role in modulating climate during the Little Ice Age prior to 1850, its influence since 1900 has become an increasingly less significant component of climate change in the industrial epoch. It is unlikely that Sun–climate relationships can account for much of the warming since 1970, not withstanding recent attempts to deduce long term solar irradiance fluctuations from the observational data base, which has notable occurrences of instrumental drifts. Empirical evidence suggests that Sun–climate relationships exist on decadal as well as centennial time scales, but present sensitivities of the climate system are insufficient to explain these short-term relationships. Still to be simulated over the time scale of the Little Ice Age to the present is the combined effect of direct radiative forcing, indirect forcing via solar-induced ozone changes in the atmosphere, and speculated charged particle mechanisms whose pathways and sensitivities are not yet specified.     

Non-linear predictions ofAp by activity class and numerical value

Two neural network algorithms are applied to the short-term,1 to 3 days, prediction of theAp geomagnetic index. A multi-layer, back-propagation (MBP) network is used to implement a self-prediction filter forAp and this provides a forecast of the numerical value of the index. A probabilistic neural network (PNN) is used to estimate the probability distribution of theAp index, in six activity classes, and to provide a forecast of the single most likely activity class for each day. BothAp and an index of solar activity, based on the daily reports issued by the Space Environment Services Centre (Boulder), are input to the probabilistic net. It is found that the numerical forecasts of the MBP filter are most accurate at low, non-storm, levels of activity. This non-linear method provides quantitatively better estimates of activity than are produced by an existing linear prediction filter, particularly with increasing forward forecasting lag. At high levels of the solar activity index the PNN is found to anticipate storm classAp with around 60% accuracy in 1992 and 1993. Some details of the algorithms and implementation issues are described. It is concluded that interplanetary field and solar wind data will be significant components of any of the possible future developments which are discussed.     

Improving drought predictability in Arkansas using the ensemble PDSI forecast technique

Drought prediction is important for improved water resources management and agriculture planning. Although Arkansas has suffered severe droughts and economic loss in recent years, no significant study has been done. This study proposes a local nonparametric autoregressive model with designed stochastic residual-resampling approach to produce ensemble drought forecasts with associated confidence. The proposed model utilizes historical climate records, including drought indices, temperature, and precipitation to improve the quality of the short-term forecast of drought indices. Monthly forecasts of Palmer Drought Severity Index (PDSI) in Arkansas climate divisions show remarkable skills with 2–3 month lead-time based on selected performance measure such as, Normalized Root Mean Square Error (NRMSE) and the Kuiper Skill Score (KSS). Rank histograms also show that the model captures the natural variability very well in the produced drought forecasts. The incorporation of categorical long-term precipitation prediction significantly enhances the performance of the monthly drought forecasts.     

茫崖和共和地震与断层气动态异常

观测断层气体的动态,研究它的异常变化与地震的相关性,是一种新的短临预报方法。1990年青海茫崖6.7级地震、共和6.9级地震前,断层气Rn、Hg的异常变化特点是临震突变幅度大、异常反应范围广。     

Connections between the distribution of prevailing winds in the winter Northern Hemisphere, solar/geomagnetic activity and the QBO phase

The effect of solar/geomagnetic activity and QBO phase on the distribution of winds prevailing in the winter periods (January–March) in the Northern Hemisphere at the altitude of 850 mb was studied. Analysis has shown that the zonal flow over the North Atlantic under high geomagnetic activity intensifies and under low solar/geomagnetic activity weakens. Flow deviations, associated with geomagnetic activity, are more marked under the QBO-east phase, and flow deviations, associated with solar activity, are more marked under the QBO-west phase. The results reported by Venne and Dartt (1990) concerning the wind distribution in the winter (February–March) Northern Hemisphere under high and low solar activity and a QBO-west phase, have been confirmed, and supplemented with wind distributions under high and low geomagnetic activity.     

Time evolution of cosmic-ray intensity and solar flare index at the maximum phase of cycles 21 and 22

Analysis of the time series into trigonometric series allows the investigation of cosmic-ray (CR) intensity variations in a range of periodicities from a few days to 1 year. By this technique the amplitude and the phase of all observed fluctuations can be given. For this purpose, daily CR intensity values recorded at Climax Neutron Monitor station for the time intervals 1979–1982 and 1989–1991, which correspond to the epochs of maximum activity for solar cycles 21 and 22, respectively, have been studied. The data analysis revealed the occurrence of new periodicities, common or not, in the two solar maxima. A search of our results was done by a power spectral analysis determining independently possible systematic periodic or quasi-periodic variations. Based on the fact that during these maxima the CR intensity tracks the solar flare index better than the sunspot number, the same analysis was performed on these data, which are equivalent to the total energy emitted by the solar flares. Both analyses result in periodicities with different probability of occurrence in different epochs. Occurrence at peaks of 70, 56, 35, 27, 21 and 14- days were observed in all time series, while the periods of 140–154 and 105 days are reported only in the 21st solar maximum and are of particular importance. All of the short-term periods except of those at 27 and 154-days are recorded for first time in CR data, but they had already been observed in the solar activity parameters. Moreover, each parameter studied here has a very different power spectrum distribution in periods larger than 154 days. The possible origin of the observed variations in terms of the CR interaction in the upper atmosphere and the solar cavity dynamics is also discussed here.