Intra-seasonal variations of kinetic energy of lower tropospheric zonal waves during northern summer monsoon

Space spectral analysis of zonal (u) and meridional (v) components of wind and time spectral analysis of kinetic energy of zonal waves at 850 hPa during monsoon 1991 (1st June 1991 to 31st August 1991) for the global belt between equator and 40°N are investigated. Space spectral analysis shows that long waves (wavenumbers 1 and 2) dominate the energetics of Region 1 (equator to 20°N) while over Region 2 (20°N to 40°N) the kinetic energy of short waves (wavenumbers 3 to 10) is more than kinetic energy of long waves. It has been found that kinetic energy of long waves is dominated by zonal component while both (zonal and meridional) the components of wind have almost equal contribution in the kinetic energy of short waves. Temporal variations of kinetic energy of wavenumber 2 over Region 1 and Region 2 are almost identical. The correlation matrix of different time series shows that (i) wavenumber 2 over Regions 1 and 2 might have the same energy source and (ii) there is a possibility of an exchange of kinetic energy between wavenumber 1 over Region 1 and short waves over Region 2. Wave to wave interactions indicate that short waves over Region 2 are the common source of kinetic energy to wavenumber 2 over Regions 1 and 2 and wavenumber 1 over Region 1. Time spectral analysis of kinetic energy of zonal waves indicates that wavenumber 1 is dominated by 30–45 day and bi-weekly oscillations while short waves are dominated by weekly and bi-weekly oscillations. The correlation matrix, wave to wave interaction and time spectral analysis together suggest that short period oscillations of kinetic energy of wavenumber 1 might be one of the factors causing dominant weekly (5–9 day) and bi-weekly (10–18 day) oscillations in the kinetic energy of short waves.     

比值—特征主成分混合分析提取金矿蚀变信息：以赣南遂川地区为例

在分析与金矿有关的两类蚀变岩的ＴＭ波谱特征的基础上,以赣南遂川地区为实验区,利用比值－特征主成分混合分析进行了金矿蚀变岩信息提取,为找矿预测和野外工作指明了方向。     

利用JCZ-1T地震计BB通道观测数据检测地球自由振荡

采用库尔勒台JCZ-1T地震计BB通道垂直向的观测数据,利用功率谱密度估计方法,在没有对观测资料进行任何改正的情况下,获取2016-03-02印尼苏门答腊岛海域7.8级和2016-04-17厄瓜多尔7.5级大地震激发的0S7～0S60基频球型自由振荡,并与PREM模型理论值进行对比分析。结果表明,实测值与理论值相吻合,除部分振型与理论值偏差较大以外,其余振型与理论值偏差均小于0.1％。印尼苏门答腊岛海域7.8级地震所检测的球型振荡能量频谱分布及振型与厄瓜多尔7.5级地震所检测的球型振荡有一定差别,前者所能检测的振型数量相对较多。     

内蒙古四子王旗芒和特铀矿地质特征

在铀矿航空γ能谱测量和地面放射性普查工作的基础上,通过对铀矿异常进行地表揭露和钻探工程验证,发现了芒和特铀矿床。铀矿床类型为湖沼相砂岩型沉积矿床,含铀矿岩石为古近系粉砂岩,铀矿化具有放射性强度较弱、铀含量较高和矿化分布不均匀的特点。深入分析铀矿放射性强度弱的原因,采用放射性测量结合化学样品分析的方法,能够提高找矿效率。     

基于光谱整体形态和局部吸收谷位置的高光谱遥感图像地物识别

为了精确识别高光谱遥感图像上的地物,使用交叉相关光谱匹配方法获取光谱整体形态的最大偏移量,通过对比分析吸收谷位置变化获取吸收谷位置的最大偏移量,在此基础上确定吸收谷位置的偏移范围;然后使用穷举法,进行基于整体形态和偏移范围内局部吸收谷位置的识别。在云南中甸普朗斑岩铜矿区的高光谱遥感图像的实际应用表明,该方法的识别结果比仅考虑整体形态的识别结果具有更高的可靠性,能进一步证实识别结果的准确性。     

黄浦江水质指标与反射光谱特征的关系分析

利用地物光谱测量技术及同步配套的常规水质采样分析实验，对上海市黄浦江全河段水体进行调查研究。共选取31个典型站位进行了光谱测量和同步水质取样，每个测点分析了9个水质指标，包括TP，TN，CODMn，CODCr，NH3-N，BOD5，DO，悬浮物浓度和浊度。各水质参数之间存在较大的相关性，以总氮（TN）和悬浮物浓度两个水质指标为例，分析了这两个水质指标与单波段归一化反射率、反射率的一阶微分、不同波段之间反射率的比值以及反射率取对数等之间的相关关系，给出了以上两个水质指标的单波段归一化反射率、一阶微分反射率识别的特征波段，以及两个波段比值的最佳波段组合。建立了常规水质参数与水体光谱反射率之间的关系模型，为利用遥感技术监测水环境提供了基础。     

Upper mantle seismic anisotropy beneath a convergent boundary: SKS waveform modeling in central Tibet

This study used SKS waveforms from the International Deep Profiling of Tibet and the Himalayas (INDEPTH) III dataset and a new 2D method for modeling seismic waves in anisotropic media to construct an image of anisotropic structures beneath central Tibet. A preferred model revealed three-segment anisotropic structures in the upper mantle beneath the study region. Waveform modeling demonstrated that the anisotropy was mainly generated by the lithosphere but not the asthenosphere, and that an anisotropic model with a flatter axis of symmetry provides a more consistent interpretation of the observations than models having steeply dipping symmetry axes. A relatively low velocity zone may underlie or intermingle with the anisotropic structures in the northern portion of the region. Synthetic tests also indicate that variations in the elastic constants and depth extent of the anisotropy assumed by the calculations do not affect the general conclusions, although trade-offs exist among certain model parameters. The modeling results suggest that the complex seismic structures in central Tibet were associated with underthrusting of the Indian lithosphere beneath the Asian lithosphere; the inferred flat symmetry axis of the anisotropy was likely generated during this collision process. If this were not the case, the inherited anisotropy would exhibit a steeply dipping axis of symmetry, parallel to the direction of underthrusting.     

Turbidity dynamics in karstic systems. Example of Ribaa and Bittit springs in the Middle Atlas (Morocco)

Abstract

The identification of the turbidity mechanisms in two karstic springs (Ribaa and Bittit) located in the Middle Atlas Plateau in Morocco was performed by means of correlation and spectral analyses applied to time series of rainfall, flow rates, and turbidity. Time series analyses of rainfall and discharges revealed high inertia and storage capacities of the karstic systems. However, the occurrence of turbidity in the springs proved independent of discharges. A causal relationship between rainfall and the occurrence of turbidity in the form of waves was established. Accordingly, turbidity was assumed to be related to the hydrodynamic conditions prevailing in the karst. Turbulent quickflows in the karst transmissive conduits, following heavy rainfall, are thought to provoke the resuspension of solid particles deposited in the conduits, as well as their transport towards outlets. An external origin has also been contemplated, concerning infiltration waters may be loaded with suspended matters washed from the watershed.     

河口表层悬浮泥沙气象卫星遥感定量模式研究

分析了HRIS光谱图像帧序列的相关性 ,并针对这一特性 ,提出了利用D2 PCM方法 ,降低光谱图像序列的谱相关和空间相关 ,减少图像中的冗余 ,从而实现光谱图像的压缩。该方法提高了压缩比和压缩效率 ,算法运算量小 ,快速。     

实际预报可预报性的时空依赖性分析

本文利用国家气象中心1990年1月1日至1992年2月29日的1～5 d、500 hPa高度场业务预报结果研究了不同球谐函数谱分量和经验正交函数(EOF)谱分量的可预报性。对球谐函数谱分量的研究表明可预报性并不是随着空间尺度的增加呈现单调的递减关系，主要表现为在总波数n等于5附近具有最大可预报性。可预报性主要依赖于总波数n，经卷大圆上的波数和纬向圆周上的波数对可预报性具有完全相同的重要意义。对EOF谱分量的分析表明，随着EOF指数(即序号数)的增大，可预报性依次减小。从EOF和球谐函数的关系发现前几个EOF分量正是对应着最可预报的球谐函数分量。进一步分析表明，最可预报的分量对应大气运动的慢变流型。这些结果对如何使用数值预报产品以及如何进行延伸预报具有重要意义。