中国遥感卫星辐射校正场气溶胶光学特性观测研究

1999年6月28日~7月19日在敦煌场, 7月25日~7月31日在青海湖水面场进行了一次大规模综合野外测量试验, 其中采用3台先进的法国CIMEL太阳辐射计对两个场地大气光学特性进行了系统全面测量, 获得大量晴空天气条件下的大气光学数据。利用Langley法处理气溶胶通道数据得到气溶胶光学厚度及其光谱变化。测量结果显示550 nm波长平均气溶胶光学厚度分别为0.12、0.18, 由气溶胶光学厚度的波长变化得到气溶胶Junge参数分别为2.6、3.0, 并与几种典型气溶胶类型比较。结果表明两地在晴空天气里, 气溶胶含量较小, 符合遥感卫星传感器辐射定标的大气条件。     

千岛岛弧大震前哈佛大学矩心矩张量（CMT）解一致性的预测意义s

千岛岛弧地区属于全球地震活动最为活跃的地区之一. 本文利用哈佛大学测定的千岛岛弧地区地震的矩心矩张量（CMT）解， 分析该地区震源机制的一致性特征， 提出利用震源机制和构造应力场的一致性参数a进行地震预测的思路. 研究结果表明，MＷge;7.5地震之前， 都有一致性参数a降低的现象，a的低值起始的时间在发生大震之前的10多天至110多天， a的低值截止的日期距大震在30多天至2天. 相互之间虽然并不完全一致， 但是差别不大. 这种现象的稳定性， 尚需时间的检验， 但是设想在长达数百公里的地区， 连续发生MＷge;5.3的地震的震源机制都与构造应力场一致， 应当不是随机的现象， 而是一种具有预测意义的现象. 当积累的震例足够多时， 则有可能确定统一的评判标准和预测准则.      

Application of bivariate extreme value distribution to flood frequency analysis: a case study of Northwestern Mexico

In Mexico, poverty has forced people to live almost on the water of rivers. This situation along with the occurrence of floods is a serious problem for the local governments. In order to protect their lives and goods, it is very important to account with a mathematical tool that may reduce the uncertainties in computing the design events for different return periods. In this paper, the Logistic model for bivariate extreme value distribution with Weibull-2 and Mixed Weibull marginals is proposed for the case of flood frequency analysis. A procedure to estimate their parameters based on the maximum likelihood method is developed. A region in Northwestern Mexico with 16 gauging stations has been selected to apply the model and regional at-site quantiles were estimated. A significant improvement occurs, measured through the use of a goodness-of-fit test, when parameters are estimated using the bivariate distribution instead of its univariate counterpart. Results suggest that it is very important to consider the Mixed Weibull distribution and its bivariate option when analyzing floods generated by a␣mixture of two populations.     

Sensitivity of Mesoscale Model Forecast During a Satellite Launch to Different Cumulus Parameterization Schemes in MM5

The identification of the model discrepancy and skill is crucial when a forecast is issued. The characterization of the model errors for different cumulus parameterization schemes (CPSs) provides more confidence on the model outputs and qualifies which CPSs are to be used for better forecasts. Cases of good/bad skill scores can be isolated and clustered into weather systems to identify the atmospheric structures that cause difficulties to the forecasts. The objective of this work is to study the sensitivity of weather forecast, produced using the PSU-NCAR Mesoscale Model version 5 (MM5) during the launch of an Indian satellite on 5th May, 2005, to the way in which convective processes are parameterized in the model. The real-time MM5 simulations were made for providing the weather conditions near the launch station Sriharikota (SHAR). A total of 10 simulations (each of 48 h) for the period 25th April to 04th May, 2005 over the Indian region and surrounding oceans were made using different CPSs. The 24 h and 48 h model predicted wind, temperature and moisture fields for different CPSs, namely the Kuo, Grell, Kain-Fritsch and Betts-Miller, are statistically evaluated by calculating parameters such as mean bias, root-mean-squares error (RMSE), and correlation coefficients by comparison with radiosonde observation. The performance of the different CPSs, in simulating the area of rainfall is evaluated by calculating bias scores (BSs) and equitable threat scores (ETSs). In order to compute BSs and ETSs the model predicted rainfall is compared with Tropical Rainfall Measuring Mission (TRMM) observed rainfall. It was observed that model simulated wind and temperature fields by all the CPSs are in reasonable agreement with that of radiosonde observation. The RMSE of wind speed, temperature and relative humidity do not show significant differences among the four CPSs. Temperature and relative humidity were overestimated by all the CPSs, while wind speed is underestimated, except in the upper levels. The model predicted moisture fields by all CPSs show substantial disagreement when compared with observation. Grell scheme outperforms the other CPSs in simulating wind speed, temperature and relative humidity, particularly in the upper levels, which implies that representing entrainment/detrainment in the cloud column may not necessarily be a beneficial assumption in tropical atmospheres. It is observed that MM5 overestimates the area of light precipitation, while the area of heavy precipitation is underestimated. The least predictive skill shown by Kuo for light and moderate precipitation asserts that this scheme is more suitable for larger grid scale (>30 km). In the predictive skill for the area of light precipitation the Betts-Miller scheme has a clear edge over the other CPSs. The evaluation of the MM5 model for different CPSs conducted during this study is only for a particular synoptic situation. More detailed studies however, are required to assess the forecast skill of the CPSs for different synoptic situations.     

Source mechanism and source parameters of May 28, 1998 earthquake,Egypt

On May 28, 1998, a moderate size earthquake of mb 5.5 occurred offshore the northwestern part of Egypt (latitude 31.45°N and longitude 27.64°E). It was widely felt in the northern part of Egypt. Being the largest well-recorded event in the area for which seismic data from the global digital network are available, it provides an excellent opportunity to study the tectonic process and present day stress field occurring along the offshore Egyptian coast. The source parameters of this event are determined using three different techniques: modeling of surface wave spectral amplitudes, regional waveform inversion, and teleseismic body waveform inversion. The results show a high-angle reverse fault mechanism generally trending NNW–SSE. The P-axis trends ENE–WSW consistently with the prevailed compression stress along the southeastern Hellenic arc and southwestern part of the Cyprean arc. This unexpected mechanism is most probably related to a positive inversion of the NW trending offshore normal faults and confirms an extension of the back thrusting effects towards the African margin. The estimated focal depth ranges from 22 to 25 km, indicating a lower crustal origin earthquake owing to deep-seated tectonics. The source time function indicates a single source with rise time and total rupture duration of 2 and 5 s, respectively. The seismic moment (M _o) and the moment magnitude (M _w) determined by the three techniques are 1.03 × 10¹⁷ Nm, 5.28; 1.24 × 10¹⁷ Nm, 5.33; and 1.68 × 10¹⁷ Nm, 5.42; respectively. The calculated fault radius, stress drop, and the average dislocation assuming a circular fault model are 7.2 km, 0.63 Mpa, and 0.11 m, respectively.     

Robust H∞ control for aseismic structures with uncertainties in model parameters

This paper presents a robust H∞ output feedback control approach for structural systems with uncertainties in model parameters by using available acceleration measurements and proposes conditions for the existence of such a robust output feedback controller. The uncertainties of structural stiffness, damping and mass parameters are assumed to be norm-bounded. The proposed control approach is formulated within the framework of linear matrix inequalities, for which existing convex optimization techniques, such as the LMI toolbox in MATLAB, can be used effectively and conveniently. To illustrate the effectiveness of the proposed robust H∞ strategy, a six-story building was subjected both to the 1940 El Centro earthquake record and to a suddenly applied Kanai-Tajimi filtered white noise random excitation. The results show that the proposed robust H∞ controller provides satisfactory results with or without variation of the structural stiffness, damping and mass parameters.     

半参数回归与模型精化

就一般情况给出了半参数平差的算法，并结合一种特定的情况，讨论了正规化矩阵半正定时的计算方法，给出了相应的公式，最后构造了一个模拟的平差问题，对半参数法和最小二乘法的计算结果进行了比较，计算表明，半参数法能够发现并识别模型误差或观测值中的系统误差。     

广义岭估计的直接解法

提出了广义岭估计的直接解法，该解法不需计算岭参数，可直接求得具有最小均方误差的解，并举例证实了该解法的优越性。     

闽台地震速报技术研究

本文通过系统地分析台网正式运行以来记录到主要的网内、网缘、网外地震的各种震相特征和定位参数 ,总结研究各区的震相特征、台站记录状况和震级的误差 ,力争提高台网地震速报的速度和精度。     

台湾南投“9·21”地震活动性分析

本文采用地震学方法 ,分析了台湾南投“9·2 1”地震。结果表明震前存在孕震空区和地震活动性参数异常变化