Estimation of drag coefficient over the western desert sector of the Indian summer monsoon trough

In the estimation of momentum fluxes over land surfaces by the bulk aerodynamic method, no unique value of the drag coefficient (C _D) is found in the literature. The drag coefficient is generally estimated from special observations at different parts of the world. In this study an attempt is made to estimate drag coefficient over the western desert sector of India using data sets of Monsoon Trough Boundary Layer Experiment (MONTBLEX) during the summer monsoon season of 1990. For this purpose, the fast and slow response data sets obtained simultaneously from a 30 m high micro-meteorological tower at Jodhpur are used. All the observations used in this study are confined to a wind speed regime of 2.5–9.0 ms⁻¹. A comparison of momentum fluxes computed by eddy correlation (direct estimation) with profile and bulk aerodynamic (C _D = 3.9 × 10⁻³, Garratt, 1977) methods revealed that though the nature of variation of the fluxes by all these methods is almost similar, both the indirect methods give an under-estimated value of the fluxes. The drag coefficient is estimated as a function of wind speed and surface stability by a multiple regression approach. An average value of the estimated drag coefficient is found to be of the order of 5.43 × 10⁻³. The estimated value ofC _D is validated with a set of independent observations and found to be quite satisfactory. The recomputed momentum fluxes by bulk aerodynamic method using the estimated drag coefficient are in close agreement with the directly estimated fluxes.     

The value ofC efor the Arabian Sea during summer monsoon

We estimate, from the moisture budget the bulk aerodynamic coefficient for latent heat flux (C _e) during the monsoon season over the central Arabian Sea. The average value ofC _eunder active monsoon conditions was found to be 2.25 × 10⁻³ which is nearly 60% higher than those previously used.     

论异常地层压力在构造研究中的意义

本文将异常地层压力、压力系数及平衡深度等概念和构造研究联系起来,着重探讨压力系数在构造发育中的重要意义。     

岩石节理粗糙度系数的分形特征

岩石节理粗糙度系数JRC是估算节理抗剪强度和变形指标最重要的参数。通过对简易纵剖面仪获取的节理表面轮廓曲线的分形研究,讨论了节理表面轮廓曲线的自相似性和JRC的自相似性,并根据实测统计资料的分析,指出了分形理论研究JRC的适用条件和有效的使用方法。由实测统计资料的JRC尺寸效应自相似性分析,认为JRC尺寸效应具分形结构。本文介绍了一种确定JRC尺寸效应分维数D的方法,由此确定的分维数D具有明确的物理意义。     

补偿校正系数XRFS法七个主量元素测定的探讨

用补偿校正系数法校正X荧光光谱分析中基体效应的影响,对岩石中七个主量元素的测定结果表明该方法准确、可靠。     

攀钢,攀矿场地边坡地震稳定性研究

本文在总结分析攀钢、攀矿昔格达层滑坡基本特征的基础上,对区内滑坡进行了地震稳定性计算,给出了经不同方法治理后的滑坡的地震稳定系数;同时采用“因子迭加”方法对究研区进行边坡稳定性区划,划分出相对的稳定区、欠稳定区和不稳定区,为抗震减灾和土地的开发利用提供了科学依据。     

速度光滑对反射地震信号的影响分析

光滑处理使得单界面成为非均匀薄层,界面反射转变为层反射.为了探讨光滑处理的影响,以平面波作为入射波场,首先利用过渡层反射系数推导了反射信号的理论公式,然后就非均匀薄层下反射系数的计算问题,给出了具体的实现算法,并通过与经典Epstein过渡层反射系数解析结果的对比说明了算法的精度.最后在单界面及其被光滑后界面的对比分析中,得出了几点重要结论：随着光滑次数的增加,反射信号的到时基本保持不变,而反射信号的主频与能量呈减少趋势,其中信号能量在低光滑次数的衰减速率明显大于高光滑次数.     

新疆北天山地区中强震前单台地震波参数异常特征研究

强地震的孕育过程也是孕震介质的形成过程,在强震前震源附近小地震的地震波运动学,动力学特征的变化过程,则反映了孕震介质的变化过程,为研究地震的孕育,发展和发生的过程,采用单台地震波振幅比,尾波持续时间比,尾波衰减系数这３项地震波参数作为地震学短期前兆指标,分析其震兆特征,从而达到监测孕震介质变化的目的,研究结果表明,单台地震波参数能够有效地发现地震的前兆,但地震波参数的前兆图像复杂多变,不具有统一的     

Estimation and improvement in the geolocation accuracy of rational polynomial coefficients with minimum GCPs using KOMPSAT-3A

ABSTRACT

In this paper, we propose a method to regenerate Rational Polynomial Coefficients (RPCs) using KOMPSAT-3A imagery and to reduce the geolocation error using minimum ground control points (GCPs). To estimate the new RPCs, the physical sensor model fitted to KOMPSAT-3A imagery was utilized and virtual GCPs over the study area were created. The size of the virtual grid used was 20x20x20. To remove the sensor-related errors in physical sensor model, three different image correction models (image coordinate translation model, shift and drift model, and affine transformation model) were additionally applied. We evaluated our proposed method in two areas within Korea, one in urban (Seoul) and one in rural (Goheung) areas. The results showed that there was a significant improvement after applying the suggested approach in the two areas. The image coordinate translation model is suggested in terms of GCP requirement and expected errors estimated from the error propagation analysis using Gauss–Markov Model (GMM).     

湖陆风效应为主导的地面弱风预报方法

对博斯腾湖东南陆地风场数据进行计算,结合湖陆风效应初步建立夏半年各月风场日变化模型,得出风场日变化的4个典型时段。结果表明,区域测站一致性系数和风场有较好的对应关系,一致性系数小于50说明风向不稳定且风速较小,一致性系数大于80说明风向趋于稳定且风速一般较大,弱风时段主要出现在日出日落前后,且具有2h左右的持续时间。该方法为该地区弱风时段预报提供了思路,在稳定的高压脊形势下效果尤为明显。