电离层舒曼共振的空间观测

通过功率谱分析和波阻抗函数计算,本文证实了Aureol-3卫星在电离层高度上(>600km)观测到的极低频(ELF)波场扰动是和舒曼共振相关的电磁振荡.与舒曼共振地面观测相比较,Aureol-3观测到的舒曼共振电场分量具有很好的谐振谱结构,峰值频率和各阶舒曼共振本征频率对应;磁场分量的高阶峰值频率偏离14, 20, 26Hz等舒曼共振本征频率;随着卫星高度的改变,电场与磁场谐振的一阶最大能量峰值并不会发生在同一频率,结合本文分析的数据,分别位于7.8Hz和10Hz;水平方向的磁场分量更接近南北方向的线极化而不是地球－电离层空腔中的椭圆极化;波阻抗随频率表现出不太规则的准正弦振荡,它会随着频率增加和飞行高度上升呈现减小的趋势.虽然舒曼共振信号和电离层密度梯度间的非线性作用可以解释舒曼共振空间观测的部分特征,但需加入其他机制,如电离层不稳定性,传播模式的耦合,进一步了解电离层高度上舒曼共振各种特征产生的原因.     

基于地球-电离层空腔共振的地震电磁监测方法研究

多年来的观测研究表明,地震活动可能引发地球．电离层空腔共振异常。本文介绍了地球-电离层空腔共振的产生机理,主要的特征参数以及常用的观测方法等。总结了目前国际上对共振异常现象与地震活动关系的主要分析方法和研究结果。对地震活动引发地球-电离层空腔共振异常的下一步研究工作进行了探讨。     

基于全球集合预报的西北太平洋热带气旋预报的评估和改进

西北太平洋热带气旋在2018年7~8月间的预报,特别是在上海登陆的温比亚(2018)、安比(2018)和云雀(2018),给数值模式和预报均带来巨大的挑战.文章基于ECMWF和NCEP的集合预报对这些热带气旋的预报技巧进行了分析.结果表明,ECMWF的集合预报对热带气旋路径和强度的预报技巧高于NCEP的集合预报.对于在上海登陆的三个台风,ECMWF的集合预报对温比亚(2018)和安比(2018)的强度预报技巧优于NCEP的集合预报,但两者对云雀(2018)在峰值附近的强度预报技巧都较低.为了提高集合预报对热带气旋的预报技巧,文章提出了一种集合预报成员的适应性权重估计方法.该方法利用集合成员的预报场和分析场相对于观测的距离,适应性地估计集合成员在集合平均中的权重.当适应性权重方法应用于ECMWF和NCEP的集合预报时,二者的集合预报对热带气旋路径和强度的预报技巧都得到了改进,并且ECMWF集合预报的改进要优于NCEP集合预报.     

无参考序列条件下地面气温观测资料城市化偏差订正方法：以北京站为例

本文以北京气象站长期地面气温观测资料为例,发展了一种无早期参考序列条件下城镇站城市化偏差评价和订正方法.首先对北京站逐月平均最高、最低气温资料进行质量控制和均一化处理,并借助卫星遥感亮度温度资料遴选附近乡村站;然后利用最近3年逐时地面气温资料,计算观象台和5个乡村站各月平均地面气温的差值,把其作为北京站1915-2012年期间的城市化累积影响;最后假设城市化累积影响在整个研究时期呈匀速增长,采用线性订正法对地面月平均气温序列中的城市化偏差进行订正.分析表明：资料均一化处理后,北京站近百年最高、最低和平均气温多年平均值有所下降,气温日较差则有所提高,但三种年平均气温序列增温趋势和年平均气温日较差序列下降趋势有所增强.北京站年平均最低气温、平均气温和气温日较差序列中均存在较大的城市化累积影响,其中最低气温和平均气温四个季节均为正值,冬季最大,秋季次之,夏季最小,四季和年平均气温日较差均为较大的负值.订正城市化偏差后,最低气温和平均气温增加速率均明显下降,年平均气温日较差下降趋势则明显变弱.     

整点气温缺测的插补方法研究及其初步应用

长期连续完整的历史气温资料是震前气温异常判别研究的重要数据基础。本文考虑了参考站与缺测站之间的距离,建立改进的线性回归模型。利用该模型插补缺测和错误的气温整点值数据,在一定程度上解决了长期连续观测数据缺测的情况。通过对收集的唐山观测站气温整点值数据进行插补,并应用插补完整的数据分析研究了2012年5月28日唐山4.8级地震前兆异常。结果表明:①插补值与其前后观测值衔接吻合,插补后完整连续数据符合夏高冬低的年变规律;②插补误差在±0.5℃范围内的比例为60.2%,在±0.8℃范围内的比例为80.3%,其误差绝对值大于1.0℃的比例为9.6%,平均绝对误差为0.84℃,插补值与观测值的相关系数大部分在0.9以上;③从3月27日起出现增温异常,特别是震前2天增温幅度约8℃。     

CMIP6与CMIP5全球气候模式对中国东北地区气温模拟性能的比较评估

本文基于CN05.1逐月气温观测资料和CMIP6计划中34个模式资料、CMIP5中39个模式资料,利用泰勒图、技能得分(S值)、综合评级指标(M_r),系统地评估了相比于CMIP5模式,CMIP6模式对1961—2005年中国东北地区(黑龙江省、吉林省、辽宁省)气温模拟能力.结果表明：1)相较于CMIP5模式,CMIP6中大部分模式能更好地模拟出区域平均气温多年变化、年平均气温气候态空间分布及年平均气温气候倾向率的空间分布的特征,但普遍存在低估的现象;2)经过优选后得到的CMIP5与CMIP6最优模式集合平均(MME5、MME6)对年平均气温的模拟优于大部分单个模式和所有模式的集合平均模拟结果.MME6比MME5能更好地模拟出年平均气温气候态及气温多年变化趋势的空间分布特征,但对区域平均气温多年变化的模拟能力要略低.总体来说,CMIP6模式相对于CMIP5有所进步,MME6对中国东北地区气温的时空变化特征具有一定的模拟能力.

     

CMIP6模式模拟的人类活动和自然强迫对全球地表气温多尺度变化的影响

量化人类活动在气候变化中的定量贡献是气候变化检测归因研究的核心科学问题,也是提高气候变化预测和预估水平的重要科学基础.本文基于最新的第6次国际耦合模式比较计划(CMIP6)多模式历史归因模拟试验(DAMIP),检测了人为因素(ANT)和自然因素(NAT)对近百年(1915—2014年)全球地表气温多尺度变化的影响,归因了温室气体(GHG)、气溶胶(AA)、土地利用(LU)等不同人为因素对全球地表气温长期变化的相对贡献及南北半球差异.结果显示,近百年来人为因素引起的全球陆地实际增温约为1.1℃(0.8℃~1.3℃),对南北半球的贡献则分别约为0.7℃和1.2℃;全球大多数区域人为排放GHG和AA的显著作用在1960—1980年期间就能够被检测到,其中北半球AA的冷却作用要超前于GHG的增温效应;气候系统内部自然变率是调制大多数区域气温年代际(10~30年)及多年代际变率(30~60年)的主导因子,而人为和自然外强迫在全球地表气温年代际变率中的方差贡献约为5%~20%,但二者在北半球尤其在东亚和欧洲中高纬度地区地表气温多年代际变率中的方差贡献可达50%.人为因素强迫可使近50年(1965—2014)极端高温事件的发生风险概率增加3倍,其中北半球发生风险要高于南半球.

     

多离子成分空间等离子体中斜传播波的混杂共振：（Ⅱ）实验观测与波模识别

在分析ＡＲＣＳ３探空火箭记录到的由人工离子束激发的低频等离子波的特征和激发机制的过程中,提出了多离子成分冷等离子体中的一般混杂共振和一般混杂波的概念,给出了斜向传播冷等离子体波的混杂共振条件．在上述理论的基础上,考虑了电子、氧离子、氦离子和人工氩离子束的贡献,计算出ＡＲＣＳ３实验条件下的等离子体介电函数,并用等离子体波模识别的方法,识别出频率在１８０Ｈｚ。附近的最强波峰乃是Ｏ＋－Ｈｅ＋双离子混杂波．     

多离子成分空间等离子体中斜传播波的混杂共振：（Ⅱ）实验观测与波模识别

在分析ＡＲＣＳ３探空火箭记录到的由人工离子束激发的低频等离子波的特征和激发机制的过程中，提出了多离子成分冷等离子体中的一般混杂共振和一般混杂波的概念，给出了斜向传播冷等离子体波的混杂共振条件．在上述理论的基础上，考虑了电子、氧离子、氦离子和人工氩离子束的贡献，计算出ＡＲＣＳ３实验条件下的等离子体介电函数，并用等离子体波模识别的方法，识别出频率在１８０Ｈｚ。附近的最强波峰乃是Ｏ＋－Ｈｅ＋双离子混杂波．     

多离子成分空间等离子体中斜传播波的混杂共振：（Ⅱ）实验观测与波模识别

在分析ＡＲＣＳ３探空火箭记录到的由人工离子束激发的低频等离子波的特征和激发机制的过程中，提出了多离子成分冷等离子体中的一般混杂共振和一般混杂波的概念，给出了斜向传播冷等离子体波的混杂共振条件．在上述理论的基础上，考虑了电子、氧离子、氦离子和人工氩离子束的贡献，计算出ＡＲＣＳ３实验条件下的等离子体介电函数，并用等离子体波模识别的方法，识别出频率在１８０Ｈｚ。附近的最强波峰乃是Ｏ＋－Ｈｅ＋双离子混杂波．     

盐用做高温高压实验传压介质一种新方法

固体传压高温高压岩石三轴实验中，固体传压介质是影响实验结果的重要因素，ＮａＣｌ介质以它流动性好，围压均匀等特点，八十年代以来越来越受到人们青睐。本文用ＮａＣｌ介质在〈３ＧＰａ固体传压三轴流变仪〉上进行了高温高压岩石流变特性的实验研究，并达到了较高的压力（〉２ＧＰａ）和温度（〉１２００℃）；本文同时利用ＮａＣｌ介质对样品装样方式及温度、压力等相关测定方面进行了研究。     

地电短临前兆产生机理及一种新的短临预报方法（谐振预报法）

研究了地电短临震兆机理，在此基础上给出了引潮力触发地电短临前兆模式。据此从理论上分析了地电临震震兆特征，并以唐山７．８级大震为例，从实际观测中检出具有此模式特征的震兆（具有起潮力特征），从而验证了所提模式理论的客观存在的可能性。最后给出与此有关的地电短临预报方法。即，根据脆性岩石失稳的相对刚度比较准则，定义部分岩体刚度λ＝０的状态为临震阶段，分析λ＝０时起潮力引起位移的特征和规律，得出原地监测岩体刚度是否为零（进入临震阶段）的方法。因为在弹性阶段，λ为较大正值，微小的起潮力只引起微小的位移，此时的电响应甚小，通常检测不到；但随着构造力的积累，介质进入临震阶段，此时同样微小的起潮力却可引起甚大的位移（λ＝０时，位移为无穷大），从而产生可检测的电响应。由于这种电响应具有与起潮力相同的周期，故可把临震电响应同各种干扰区分开，判定为临震前兆，从而建立了地电临震前兆起潮力触发模式，并可给出相应的短临预报方法。对１９７６年唐山７．８级强震前后震中周围地电阻率及大地电场实测资料进行谱分析，发现仅在主震前二个月至半月内，两种不同物理本质的电响应分别出现与起潮力ＭＳ波与ＭＳｆ波周期相同的异常变化。这是对所提临震前兆模式和预报     

A BRIEF INTRODUCTION TO THE NEW METHOD FOR RIVER PROFILE ANALYSIS: Integral Approach

The topography and geomorphology of active orogens result from the interaction of tectonics and climate. In most orogens, a fluvial channel is most sensitive to the coupling between tectonics, lithology, and climate. Meanwhile, the related signals have been recorded by both the drainage geometry and channel longitudinal profile. Thus, how to extract tectonic information from fluvial channels has been a focused issue in geologic and geomorphologic studies. The well known stream-power river incision model bridges the gap between tectonic uplift, river incision and channel profile change, making it possible to retrieve rock uplift pattern from river profiles. In this model, the river incision rate depends on the rock erodibility, contributing drainage area and river gradient. The steady-state form of the river incision model predicts a power-law scaling between the drainage area and channel gradient. Via a linear regression to the log-transformed slope-area data, the slope and intercept are channel concavity and steepness indices, respectively. The concavity relates to lithology, climatic setting and incision process while the channel steepness can be used to map the spatial pattern of rock uplift. For its simple calculation process, the slope-area analysis has been widely used in the study of tectonic geomorphology during past decades. However, to calculate river slope, the coarse channel elevation data must be smoothed, re-sampled, and differentiated without any reasonable smooth window or rigid mathematical fundamentals. One may lose important information and derive stream-power parameters with high uncertainties. In this paper, we introduce the integral approach, a procedure that has been widely used in the latest four years and demonstrated to be a better method for river profile analysis than the traditional slope-area analysis. Via the integration to the steady-state form of the stream-power river incision equation, the river longitudinal profile can be converted into a straight line of which the independent variable is the integral quantity χ with the unit of distance and the dependent variable is the relative channel elevation. We can calculate the linear correlation coefficient between elevation and χ based on a series of concavity values and find the best linear fit to be the reasonable channel concavity index. The slope of the linear fit to the χ value and elevation is simply related to the ratio of the uplift rate to the erodibility. Without calculating channel slope, the integral approach makes up for the drawback of the slope-area analysis. Meanwhile, via the integral approach, a steady-state river profile can be expressed as a continuous function, which can provide theoretical principle for some geomorphic parameters (e.g., slope-length index, hypsometric integral). In addition, we can determine the drainage network migration direction using this method. Therefore, the integral approach can be used as a better method for tectonogeomorphic research.     

THE EQUIVALENT SLOPE - A NEW METHOD FOR CALCULATING SOIL LOSS FROM IRREGULAR SLOPES

he slopes in field conditions are always irregular, but the supposed uniform slopes are used in most erosion models. Some studies used several uniform slopes to approximate an irregular slope for estimating soil erosion. This approximation is both time-consuming and weak in physical insights. In this paper, the concept of equivalent slope is presented based on that runoff potential on uniform slope is equal to that of irregular slope, and the equivalent uniform slope is used to estimate soil erosion instead of the irregular slopes. The estimated results of slope-length factors for convex and concave slopes are consistent with those from the method of Foster and Wischmeier, The experiments in the southern part of the Loess Plateau in China confirmed the applicability of the present method. The method is simple and has, to some extent, clear physical meanings, and is applicable for estimating soil erosion from irregular slopes.     

利用走时进行浅层反射成像及其应用

利用反射走时提出厂工程物探中浅层反射成像的新方法在局部范围内可将地层各界面视为平面,求取界面深度、速度诸参数,整个剖面的成像只需反复在局部范围内求解数值模拟表明方法具有精度高、收敛速度快等特点对清水江三板溪水电站坝址两个剖面的实际资料处理结果与现有资料吻合,表明该方法具有一定的应用前景     

LONG-TERM PERSPECTIVE ON THE NATURE OF THE AIR–WATER TEMPERATURE RELATIONSHIP: A CASE STUDY

Monthly mean data from a 90 year period relating to a small catchment (142.4 km²) in north-central Austria were used to provide a long-term perspective on the nature of the air–water temperature relationship. Annual mean values of air and water temperature were related in a relatively insensitive and scattered way (r² < 55%, b < 0.65), whereas the relationship for monthly mean values was closer and steeper (r² > 95%, b > 0.65). A separate regression equation was needed to describe the behaviour of monthly mean water temperatures as the air temperatures fell below freezing. Analysis of air–water temperature regressions for individual months revealed a series of relations which were generally more scattered and less, but variously, sensitive than the ensemble relationship of monthly mean values. Monthly mean water temperatures could be predicted from the ensemble air–water temperature relationship and from the relations for individual months with root mean square errors of > 1.0 and < 0.8°C, respectively. Segmentation of air–water temperature regressions according to air temperatures above and below freezing did not significantly improve water temperature prediction. Hysteresis in, and the relatively low slope of, the air–water temperature relationships in the study catchment reflected the importance of snowmelt in the flow regime. © 1997 by John Wiley & Sons Ltd.     

A KEY TECHNOLOGY FOR MONITORING STRESS BY TEMPERATURE: MULTICHANNEL TEMPERATURE MEASUREMENT SYSTEM WITH HIGH PRECISION AND LOW POWER CONSUMPTION

Experimental and theoretical researches have confirmed that changes in crustal stress can be monitored by the in situ bedrock temperature. Monitoring stress by temperature requires the high-precision and multi-channel temperature measurement system. We have developed such a system, based on the several refinements. The key parameters on temperature measurement system mainly include:1)the accuracy is better than 1.0mK. At the 99.5%confidence level, the accuracy reaches 0.5mK. This system can be used to detect the change of magnitude of a few tenths to several MPa. The sampling period can be set, depending on remote control. The sampling period is usually set 5 or 15 minutes. 2)A system has up to 20 channels, and commonly uses for 8 or 12 channels. 3)This system has a significant performance in low power consumption. The power is supplied by lead-acid battery with 12 volt. It is at least 2 years that a lead-acid battery, with contents of 120Ah12V, can supply the power for a system with 8 channels. In conclusion, multichannel temperature measurement system with high precision and low power consumption is designed and realized. Specially, the performance in low power consumption is of great significance, which can greatly reduce the maintenance cost after the measurement station is constructed. This temperature measurement system provides a basic technology for monitoring changes in crustal stress with bedrock temperature.     

地球深部研究—地球科学发展的挑战与机遇

本文扼要地介绍了国际地球深部研究的发展及现状，简要地讨论了地球深部研究与地球科学相关学科的关系，力图说明及时地组织和开展地球深部研究是发展我国地球科学的新机遇，是迎接未来世纪挑战的正确选择。