Large-Scale Environmental Influences on the Onset, Maintenance, and Dissipation of Six Sea Fog Cases over the Yellow Sea

Sea fog is typically formed and developed under a set of favorable environmental conditions, which are associated with the station pressure changes, sea level pressure, winds, temperature, water vapor supply, and sea surface temperature. Understanding of these environmental factors during the evolution of a sea fog episode is crucial for forecasting the occurrence and severity of sea fogs over the ocean and adjacent coastal areas. In this study, the large-scale environment variability of six fog events over the Yellow Sea was investigated. It was realized in the present study that the northwest Pacific Ocean high (NPH) is vital to fog formation over the Yellow Sea. In our study, six fog cases can be basically divided into two types: (1) pressure-weakening type, (2) pressure-strengthening type. The former type happened in spring and the latter type in summer. Prevailing southerly winds, accompanied with the well-positioned NPH, may supply a large amount of warm water vapor for the fog formation and maintenance. The intensity of the air temperature inversion is stronger in summer cases than that in spring ones. The wind direction change from south to north and the unstable lower atmosphere may lead to fog’s dissipation. This study may provide a comprehensive understanding of sea fog’s onset, maintenance, and dissipation over the Yellow Sea.     

A Review of some Recent Radiation Fog Prediction Studies and the Results of Integrating a Simple Numerical Model to Predict Radiation Fog over Brunei

— Several radiation fog studies with emphasis on numerical simulation and prediction are reviewed. One of the earliest attempts started with a given surface diurnal variation of temperature and water vapor, and concluded by forecasting the onset of saturation at various levels; thus fog, by examining the spread of temperature and moisture in the vertical. The one-dimensional (1-D) models are still popular. Some of the recent numerical simulations use more than 100 levels in the vertical and treat various kinds of vegetation, aerosols, and soils with moisture contents. Some also employ a mesoscale model in conjunction with a 1-D model to consider the advective effects. In the following a simple 1-D numerical model was used to predict the onset of fog at Brunei, based on a desktop computer and routine surface observations of dry bulb temperature (T), dewpoint temperature (T _d ), and wind speed at 1800 Local Time (LT). Optimism exists in improved predictions of fog and stratus as 1-D models incorporate many physical processes, and mesoscale models continue to improve in predicting advection and cloud cover.     

A Diagnostic Study of the Cyclonic Storm over the Arabian Sea during June 1994

—Based on the NCMRWF analysis over the Arabian Sea, a complete energy cycle of the severe cyclonic storm that formed in the beginning of June 1994 in the east central Arabian Sea is carried out, using the in-house developed energy package. Both barotropic and baroclinic energy conversions are responsible for the maintenance of the system, however dominance of one over the other is noticed at different stages of the system at different heights. Dynamical characteristics of synoptic scale monsoon flow surrounding the cyclonic storm are also investigated. By examining the generation and dissipation terms, it is observed that both zonal and eddy components of the synoptic scale flow act as source of energy for the cyclonic storm, both in the predeveloped and developed stages.     

Monthly Dispersion Characteristics over the South China Sea for Air Quality Modeling

— Monthly dispersion characteristics for air quality modeling over the South China Sea offshore the west coast of Borneo are studied using long-term ship measurements. It is found from monthly averages that the stability condition is nearly neutral throughout the year with the exception of April, May, and November which are slightly unstable. The lifting condensation level ranged from 338 to 450 m. The lowest value of the ventilation factor occurred in April and the highest in January. The friction velocity for each month is also provided to determine the vertical eddy diffusivity and horizontal and vertical dispersion coefficients.     

Data of Wind Field Reanalysis over the Caspian Sea for Calculating the Regime of Wind Waves

Water Resources - Calculating the regime of waves, in accordance with recommendations of the World Meteorological Organization, requires a database covering not less than 30 years. Continuous...     

A study of the kinetic energy budget of the troposphere over the Caribbean Sea and the Gulf of Mexico

Summary The budget of kinetic energy over the Caribbean Sea and the Gulf of Mexico during the winter (November–April) and Summer (May–October) half-years of 1960 is established for the finite atmospheric layers 1000/850, 850/700, 700/500, and 500/300 mb. Vertical transports, lateral outflow, and generation of kinetic energy are computed directly from twice-daily aerological soundings, while the dissipation term is obtained as a residual. The frictional dissipation in the boundary layer is independently computed from 1960 ship observations. Kinetic energy dissipation is of the order of 1·10³ ergs·cm^–2 in the layer 1000/850 mb, decreasing in the higher layers. The residual dissipation term would indicate a production of kinetic energy, particularly for the layer 500/300 mb in winter. This would appear consistent with results by other authors. Due to the uncertainties inherent in the computational procedures, however, only limited confidence can be given to the absolute values.

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Zusammenfassung Die Kinetische Energie-Bilanz über dem Amerikanischen Mittelmeer während der Winter-(November–April) und Sommerhälfte (Mai-Oktober) des Jahres 1960 wird für die Schichten 1000/350, 850/700, 700/500 und 500/300 mb untersucht. Vertikaltransporte, seitlicher Export und die Produktion von kinetischer Energie werden direkt von den zweimal täglichen Radiosondenaufstiegen berechnet, während die Vernichtung kinetischer Energie als Restglied der Energiegleichung bestimmt wird. Der Energieverbrauch in der Grenzschicht wird unabhängig auf Grund von Schiffsbeobachtungen des Jahres 1960 abgeschätzt. Die Vernichtung kinetischer Energie hat in der Schicht 1000/850 mb die Grössenordnung von 1·10³ ergs·cm^–2·sec^–1, und nimmt nach den höheren Schichten zu ab. Das Restglied der Energiegleichung zeigt eine Produktion kinetischer Energie vor allem für die Schicht 500/300 mb im Winter an. Das erscheint verträglich mit den Ergebnissen anderer Autoren. Wegen der in den Berechnungsverfahren liegenden Unsicherheiten kommt den Absolutwerten nur begrenzte Gültigkeit zu.

     

中国大陆岩石层动力学数值模型的边界条件

利用粘弹性蠕变本构关系的有限元方法,建立了中国大陆岩石层应力场及应变场的动力学模型;以中国大陆岩石层应力场的水平向最大主压应力方向的最新研究成果,以及块体水平运动的方向及速率为约束条件,用试错法得到了模型边界作用力的大小;同时分析了青藏高原重力势能对中国大陆岩石层运动格局的影响．数值模拟试验结果显示,印度洋板块对欧亚大陆的挤压作用及岩石层底部的突然剥离,是导致青藏高原目前快速抬升及正断层发育的动力源．青藏高原物质的水平侧向扩展是形成中国大陆现代构造特征的主要动力因素．模型东部所受到的边界挤压作用,主要来自太平洋板块的俯冲作用,菲律宾板块对欧亚板块的挤压作用可能非常微弱．     

A climatological data set of temperature and salinity for the Baltic Sea and the North Sea

Ocean Dynamics - A climatological monthly mean data set for temperature and salinity in the area of the North Sea and Baltic Sea is presented. More than 3.1 million temperature observations (2.9...     

A hydrologic contribution to risk assessment for the Caspian Sea

The Caspian Sea (CS), the world's largest inland sea, may also be considered as large-scale limnic system. Due to strong fluctuations of its water level during the 20th century and the flooding of vast areas in a highly vulnerable coastal zone, economic and environmental risk potentials have to be considered. Since the major water input into the CS is attributed to the Volga river, the understanding of its long-term flow process is necessary for an appropriate risk assessment for the CS and its coastal area. Therefore, a top-down approach based on statistical analyses of long-term Volga flow series is pursued. For the series of annual mean flow (MQ) of the Volga river basin during the 20th century, a complex oscillation pattern was identified. Analyses for multiple gauges in the Volga river basin and Eurasian reference basins revealed that this oscillation pattern resulted from the superposition of oscillations with periods of ∼30 years (MQ) in the western part of the Volga river basin, and ∼14 years (flow volume of snowmelt events) and ∼20 years (flow volume of summer and autumn) in the eastern part of the Volga river basin (Kama river basin). Almost synchronous minima or maxima of these oscillations occurred just in the periods of substantial changes of the Caspian Sea level (CSL). It can thus be assumed that the described mechanism is fundamental for an understanding of the CSL development during the 20th century. Regarding the global climate change, it is still difficult to predict reliably the development of the CSL for the 21st century. Consequently, we suggest an ongoing, interdisciplinary research co-operation among climatology, hydrology, hydraulics, ecology and spatial data management.     

Comparison of Different Methods for a Moho Modeling Under Oceans and Marginal Seas: A Case Study for the Indian Ocean

Surveys in Geophysics - Since marine seismic studies are relatively sparse and unevenly distributed, detailed tomographic images of the Moho geometry under large parts of the world’s oceans...     

用超速CT机检测99例无症状香港中国人降低钙指数

回顾分析Ｍａｔｉｌｄａ医院超速ＣＴ室筛选首批病人中９９例中国人资料，很明显从通常采用１３０－１００Ｈｏｕｎｓｆｉｅｌｄ单位作为检出冠状血管钙化的基数应用至中国人身上其阈值数目需要降低，同时，我们也发现如果病人年龄按每１０年范围分组（２１－３０，３０－４０，４１－５０，５１－６０）而计算其超速ＣＴ的钙化指数会较随机男女一起按平均计算更易区分其差异．进一步分析显示，男性中年时候超速ＣＴ指数已达最高值，而女性则晚１０年方达最高值，因此，为了更易探测冠脉循环内钙化倾向应作出超速ＣＴ检出钙化的指数数目．这些实践经验对动脉粥样硬化过程的预测或预防有实际意义．     

A Procedure for Calculating Extreme Characteristics of the Northern Caspian Sea Level

A procedure is proposed for calculating extreme characteristics of the level of a sea with allowance for positive and negative setups. Analysis is made of past storm events in the Northern Caspian Sea that have caused strong setups. Sixty-three storm weather patterns are chosen from a period of 45 years. Time ring synoptic maps are used to digitize the atmospheric pressure fields and calculate the field of its gradient and the wind near water surface. Based on these data, the sea level values and currents are calculated through two- and three-dimensional hydrodynamic models. A probabilistic model along with computer-aided data treatment procedures are used to calculate the fields of extreme characteristics of the sea level at the Lagan gage with the occurrence of once per N years at the average Caspian Sea level of 27 m below SL.     

A model for tides and currents in the English Channel and southern North Sea

The amplitude and phase of 11 tidal constituents for the English Channel and southern North Sea are calculated using a frequency domain, finite element model. The governing equations — the shallow water equations — are modifed such that sea level is calculated using an elliptic equation of the Helmholz type followed by a back-calculation of velocity using the primitive momentum equations. Triangular elements with linear basis functions are used. The modified form of the governing equations provides stable solutions with little numerical noise. In this field-scale test problem, the model was able to produce the details of the structure of 11 tidal constituents including O₁, K₁, M₂, S₂, N₂, K₂, M₄, MS₄, MN₄, M₆, and 2MS₆.     

滇西实验场地震中短临动态跟踪综合预测方案及其实践运用

对滇西实验场1992年以来地下流体前兆观测资料进行分析研究,选取应震效果通过R信度检验（对应MS≥5.0级地震）的8条单项前兆指标。综合考虑单项前兆指标虚报率和漏报率对指标信度的影响,对单项前兆指标利用数学模型进行综合处理,减少了虚报和漏报的次数,预测效果明显提高。利用分级预警模式分别建立了中期（T≤6个月）和短临（T≤3个月）预测模型。综合预测方案还提供了地点判定原则和震级估算原则。最终提供地震短临预测三要素。运用本综合预测方案对2011年腾冲5级双震、2013年洱源5级双震和德钦两次5级地震作用了较为成功的短临预测。     

A 48-kyr-long slip rate history for the Jordan Valley segment of the Dead Sea Fault

We investigate the late Quaternary active deformation along the Jordan Valley segment of the left-lateral Dead Sea Fault and provide new insights on the behaviour of major continental faults. The 110-km-long fault segment shows systematic offsets of drainage systems surveyed at three sites along its southern section. The isotopic dating of six paleoclimatic events yields a precise chronology for the onset of six generations of gully incisions at 47.5 ka BP, 37.5 ka BP, 13 ka BP, 9 ka BP, 7 ka BP, and 5 ka BP. Additionally, detailed mapping and reconstructions provide cumulative displacements for 20 dated incisions along the fault trace. The individual amounts of cumulative slip consistently fall into six distinct classes. This yields: i) an average constant slip rate of 4.7 to 5.1 mm/yr for the last 47.5 kyr and ii) a variable slip rate ranging from 3.5 mm/yr to 11 mm/yr over 2-kyr- to 24-kyr-long intervals. Taking into account that the last large earthquake occurred in AD 1033, we infer 3.5 to 5 m of present-day slip deficit which corresponds to a Mw  7.4 earthquake along the Jordan Valley fault segment. The timing of cumulative offsets reveals slip rate variations critical to our understanding of the slip deficit and seismic cycle along major continental faults.     

A theoretical model for the intrusion of the Kuroshio across the continental shelf of East China Sea

Here we use a two-layer model to study the dynamics of the intrusion of the Kuroshio onto the continental shelf. Results show that the interaction of the Kuroshio water and shelf water produces a stable upwelling zone above 100 m depth northeast of Taiwan, which provides a dynamical explanation to the presence of the cold core previously observed by satellite. The affected shelf water from the interaction has an onshore portion, which turns right and becomes a northward alongshore flow when it moves closer to shore. This implies that the Kuroshio water cannot penetrate deep onto the inner part of the continental shelf, but it generates a strong northward jet that is formed mainly by the shelf water.     

一种基于投影变换的旋转型CL重建算法

相对于传统计算机断层成像(CT),计算机层析成像(CL)对于扁平状物体的检测具有独特的优势。旋转型CL不严格满足滤波反投影(FBP)算法的条件,针对这一问题本文提出了一种基于投影变换的旋转型CL FBP重建算法。首先介绍了旋转型CL的扫描结构;然后阐述了该结构下投影的生成方法及基于投影变换的投影数据重构方法;最后利用重构后投影数据进行滤波反投影,并通过仿真重建实验验证了算法的有效性。     

A new fish-based multi-metric assessment index for cyprinid streams in the Iranian Caspian Sea Basin

A major issue for water resource management is the assessment of environmental degradation of lotic ecosystems. The overall aim of this study is to develop a multi-metric fish index for the cyprinid streams of the Caspian Sea Basin (MMICS) in Iran. As species diversity and composition as well as population structure in the studied streams are different to other regions, there is a substantial need to develop a new fish index. We sampled fish and environmental data of 102 sites in medium sized streams. We analysed human pressures at different spatial scales and determined applicable fish metrics showing a response to human pressures. In total, five structural and functional types of metrics (i.e. biodiversity, habitat, reproduction, trophic level and water quality sensitivity) were considered. In addition, we used 29 criteria describing major anthropogenic human pressures at sampling sites and generated a regional pressure index (RPI) that accounted for potential effects of multiple human pressures.For the MMICS development, we first defined reference sites (least disturbed) and secondly quantified differences of fish metrics between reference and impaired sites. We used a Generalised Linear Model (GLM) to describe metric responses to natural environmental differences in least disturbed conditions. By including impaired sites, the residual distributions of these models described the response range of each metric to human pressures, independently of natural environmental influence.Finally, seven fish metrics showed the best ability to discriminate between impaired and reference sites. The multi-metric fish index performed well in discriminating human pressure classes, giving a significant negative linear response to a gradient of the RPI. These methods can be used for further development of a standardised monitoring tool to assess the ecological status and trends in biological condition for streams of the whole country, considering its complex and diverse geology and climate.     

西藏地区复杂地形下的降水空间分布估算模型

本文提供了一个描述西藏地区年、季降水量空间分布的估算模型.利用卫星遥测数字化地形高程资料和西藏地区仅有的27个常规气象站的多年平均降水整编资料,根据地形坡向站点分为三类.再采用多元逐步回归方法,建立西藏地区的年、季降水量和经度、纬度、海拔高度、坡度、坡向、遮蔽度等6个地理、地形因子之间的关系模型,估算西藏地区降水量的空间分布.结果表明,此方法建立的关于西藏地区降水量与诸因子之间方程的相关性显著,平均绝对误差、相对误差分别为0.93mm和1.16%,对估算模型进行F检验,均通过置信度为0.95的相关检验,回归效果较显著.分析表明估算降水能够定量、定性地再现西藏地区的实际降水分布.