DETERMINISTIC ESTIMATION OF A WAVELET USING IMPEDANCE TYPE TECHNIQUE*

A new deterministic technique for estimating a wavelet suggested by Loewenthal and Jakubowicz requires measurement of both pressure and vertical particle velocity. Through construction of the impedance function a deterministic estimation of the wavelet and the reflectivity can be obtained. This idea is tested for a one-dimensional model. The test is carried out by forming a synthetic seismogram of both pressure and particle velocity and checking the formulas for obtaining the estimated wavelet under noisy conditions.     

西藏高原对其北方环流系统的影响

本文应用1956年6月到1957年5月一年内逐日亚欧500mb 天气图,计算历次高低压系统经过西藏高原以北时在强度和速度方面的改变,证明这些改变是有规则的,在地域上和季节上皆表现出独特性。     

北半球海平面气压场月偏距中心的研究

本文用统计方法研究1930—1939年期间逐月北半球气压偏距中心的活动规律.发现同一月份的气压偏距中心在北半球某些地区有集中出现的情况,这些集中地区如在阿拉斯加的南方、大西洋的东北部以及亚欧大陆的北冰洋沿岸.这些地区可以认为是北半球环流异常的关鍵性地区.绝大多数的偏距中心在逐月之间可以发现它们的联系.在过渡季节,大多数偏距中心自西向东移动.在偏距中心相互作用的基础上,本文还讨论了北半球某些地区的气候特点.     

Analysis of Determinants for an Enhanced and Long-lasting Coastal Convective System by Means of a Case Study(26 July 2011)

A precipitation system developed continuously along the western coastline of the Korean Peninsula and created considerable precipitation both along the coast and inland on 26 July 2011. In this study, the causes for this nearshore convective system are investigated from observations and the results of model experiments. Three-dimensional radar fields clearly show that a change of wind at the surface border played an important role in the development of the nearshore convection system. The simulation results, which are very similar to the observations, show that the surface border generated and maintained the convergence zone. The roughness change enhanced the convergence, and the interaction between the deepening cold pool and downward flow maintained the convergence zone. The surface mechanical discontinuity affected by the roughness change between sea and land formed the convergence (gradient of wind stress),which induced momentum transfer to the upper layer. The cold pool created a steep gradient of potential temperature and provided the reason for the propagated convergence zone with the downward flow. The maximum value of the surface change factor, which comprises the influencing factors for the long-lasting convective system, reflects the enhancement of the system at the coast.     

Incorporation of parameter uncertainty into spatial interpolation using Bayesian trans-Gaussian kriging

Quantitative precipitation estimation(QPE) plays an important role in meteorological and hydrological applications.Ground-based telemetered rain gauges are widely used to collect precipitation measurements. Spatial interpolation methods are commonly employed to estimate precipitation fields covering non-observed locations. Kriging is a simple and popular geostatistical interpolation method, but it has two known problems: uncertainty underestimation and violation of assumptions.This paper tackles these problems and seeks an optimal spatial interpolation for QPE in order to enhance spatial interpolation through appropriately assessing prediction uncertainty and fulfilling the required assumptions. To this end, several methods are tested: transformation, detrending, multiple spatial correlation functions, and Bayesian kriging. In particular, we focus on a short-term and time-specific rather than a long-term and event-specific analysis. This paper analyzes a stratiform rain event with an embedded convection linked to the passing monsoon front on the 23 August 2012. Data from a total of 100 automatic weather stations are used, and the rainfall intensities are calculated from the difference of 15 minute accumulated rainfall observed every 1 minute. The one-hour average rainfall intensity is then calculated to minimize the measurement random error. Cross-validation is carried out for evaluating the interpolation methods at regional and local levels. As a result,transformation is found to play an important role in improving spatial interpolation and uncertainty assessment, and Bayesian methods generally outperform traditional ones in terms of the criteria.     

Collating Historic Weather Observations for the East Asian Region:Challenges,Solutions,and Reanalyses

正1.Introduction Historic instrumental weather observations,made on land or at sea from as early as the 17th century(e.g.,Camuffo et al.,2010),are integral to extending our understanding of the decadal and centennial variations of Earth’s climate and for comparison with paleo-proxy data.The potential of such data is shown to best effect when used in dynamical 4D global     

Evaluation of Heavy Rainfall Model Forecasts over the Korean Peninsula Using Different Physical Parameterization Schemes and Horizontal Resolution

In this study, the accuracy of a Pennsylvania State University-National Center for Atmospheric Research mesoscale model (PSU/NCAR MM5) for predicting heavy summer precipitation over the Korean Peninsula was investigated. A total of 1800 simulations were performed using this model for 30 heavy rainfall events employing four cumulus parameterization schemes (CPS), two grid-scale resolvable precipitation schemes (GRS), and two planetary boundary layer (PBL) schemes in three model resolutions (90 km, 30 km, and 10 km). The heavy rainfall events were mesoscale convective systems developed under the influence of mid-latitude baroclinic systems with low-level moisture transport from the ocean. The predictive accuracy for maximum rainfall was approximately 80% for 10-km resolution and was 60% for 30-km resolution. The predictive accuracy for rainfall position extended to ～150 km from the observed position for both resolutions. Simulated rainfall was most sensitive to CPS, then to PBL schemes, and then to GRS. In general, the Grell (GR) scheme and the Anthes and Kuo (AK) scheme showed a better prediction capability for heavy rainfall than did the Betts-Miller (BM) scheme and the Kain-Fritsch (KF) scheme. The GR scheme also performed well in the 24-h and 12-h precipitation predictions: the parameterized convective rainfall in GR is directly related to synoptic-scale forcing. The models without CPS performed better for rainfall amounts but worse for rainfall position than those with CPS. The MM5 model demonstrated substantial predictive capacity using synoptic-scale initial conditions and lateral boundary data because heavy summer rainfall in Korea occurs in a strong synoptic-scale environment.     

多变量时间序列滑动窗口异常点的检测

针对多变量时间序列(MTS)的异常点的探测问题,提出了采用由粗到细的二次探测方案.基于滑动窗口数据的置信区间,构造了变化趋势值特征和相对变化趋势值特征分别用于二次探测,同时研究了特征的快速提取算法.通过对OPEN3000数据监测系统采集的事故发生前后某市城南变电站各设备表的数据集进行异常点探测,结果表明提出的算法能够快速准确地探测出异常点的位置.     

Aragonite in the Murray (CM2) carbonaceous chondrite: Implications for parent body compaction and aqueous alteration

Abstract— The matrix of the CM2 carbonaceous chondrite Murray contains rare micrometer‐sized prismatic crystals of aragonite that formed during late‐stage parent body aqueous alteration. The aragonite was identified by X‐ray microanalysis coupled with electron backscatter diffraction (EBSD), TEM selected area electron diffraction and cathodoluminescence spectroscopy. The sixteen crystals found all occur within loose and elongate submillimeter‐sized clusters and one cluster is present in each of the two thin sections studied. Orientation determinations using EBSD show that the c axes of aragonite crystals within each cluster lie roughly in a plane, itself aligned approximately parallel to the long axis of the host cluster. Aragonite is inferred to have crystallized after calcite but before completion of static/impact‐related compaction. The clusters developed by growth of aragonite within films of aqueous fluids that had a relatively high Mg/Ca ratio. These fluids were focused within zones of high porosity and permeability along a weak compactional fabric in the matrix and this fabric is also likely to have influenced the orientations of aragonite crystals as they grew. These results suggest that aragonite probably occurs in most of those carbonaceous chondrites that have undergone moderate degrees of parent body aqueous alteration and may provide further insights into the evolution of pore fluid compositions and volumes and the chronology of asteroidal evolution.