The influence of context on lifeline behavior: Local policies under wind storm and earthquake scenarios

Local policies can play an important role in establishing a context that shapes vulnerability and influences subsequent recovery of lifelines under the natural hazards of extreme wind and seismic events. External factors, such as access availability, have long been known to influence the rate of restoration of utility systems following blackouts. Thus, since system performance takes place within a socio-technical-political context, it can be anticipated that selected local policies may also influence either the geographic extent of damage or the rate of restoration or both. This project empirically validates the assumption that selected local non-design policies establish a context that significantly (measurably) influences system functionality in terms of spatial extent and duration of outage.     

街谷环流和热力结构的数值模拟

文章介绍一种用于模拟街谷流场和温度场的动力学模式和热力学模式.应用动力模式模拟了方柱体塔楼和圆柱体塔楼形成的流场,应用动力和热力模式模拟了街谷中流场和温度场的日变化过程.计算实例表明,上述模式可用于城市街谷和建筑群风环境和热力环境研究以及街谷中空气污染物传输和扩散的计算.     

突出薄层特征的Chirp信号源浅地层剖面资料的处理研究

Chirp信号的浅地层剖面调查因其高分辨率的特点广泛应用于工程勘察、地质灾害评估、水合物调查、深海资源勘查等领域。由于Chirp信号发射频带宽度限制,互相关结果中旁瓣影响严重。常规提取包络处理能压制旁瓣,但处理后资料分辨率低。本文通过不同层厚以及不同反射系数连续薄层模型的正演、处理和定量分析,提出用线性提频处理方法压制旁瓣和提高资料的分辨率,将此方法用于理论模型和实际资料,效果显著。     

海洋飞沫及其对海—气相互作用影响的研究进展

按照海水滴生成机制和粒径大小,由海浪破碎生成的海洋飞沫分为膜滴、射滴和裂滴三大类,较小的海水滴在大气中滞留时间长,成为云的凝结核,对长期气候变化有重要影响,较大的海水滴参与海—气界面动量和热量交换过程,有利于热带气旋的形成和发展。海洋飞沫的生成与海上风速、海浪、海流和大气稳定度等因素有关,但由于缺乏观测数据,刻画海洋飞沫效应的关键物理量——海洋飞沫生成函数通常用海上风速进行参数化,忽略其他因素的影响,彼此间的差异非常大,给研究海洋飞沫对气候和海—气相互作用的影响造成困难,需要进一步开展海洋飞沫的观测,考虑风速之外的其他因素对海洋飞沫生成函数的作用,改进海洋飞沫热量和动量效应的参数化方案,进而阐明海洋飞沫对气候和海—气相互作用的影响。     

珠海三灶机场一次平流海雾的特征及成因初探

为进一步了解平流海雾的形成、发展和消散过程特点和机制,利用风廓线雷达、自动观测、探空、数值产品以及常规气象观测等资料,分析了2014年2月17—18日珠海三灶机场一次平流海雾过程的边界层温湿风三维演变特征及天气学成因。结果表明:边界层内暖湿平流输入、浅层辐合抬升、湍流加强、多层逆温结构以及夜间地面的辐射冷却有利于近地层饱和湿空气的凝结和逆温层的维持,是雾形成的主要物理机制;暖湿平流持续及湍流减弱或停歇是雾维持的原因;近地层偏北风干冷平流入侵并出现下沉气流及日间地面辐射增温使逆温层被破坏是雾消散的主要因素。     

On the contributions of atmospheric pressure and wind to daily sea level in the northern Adriatic Sea

Daily sea level variability in the Adriatic Sea is studied from different data sets using Empirical Orthogonal Functions, in connection with atmospheric pressure and wind stress. The first mode explains 56–69% of total variance and consists of uniform sea level variability all over the basin, correlated with atmospheric pressure through the inverse barometer effect. The second mode explains 13–16% of variance and accounts for an along-basin sea level gradient, which is correlated with the meridional wind stress component. The first two Principal Components are used as proxies to pressure- and wind-induced components of storm surges in the northern Adriatic. The analysis of the frequency of the most intense events in the 1957–2005 period shows that the wind contribution to storm surges has decreased, while no significant trends are found in the contribution of atmospheric pressure.     

Impact Of Dominant Waves On Sea Drag

The impact of air-flow separation from breaking dominant waves is analyzed.This impact results from the correlation of the pressure drop with theforward slope of breaking waves. The pressure drop is parameterized via thesquare of the reference mean velocity. The slope of breaking waves isrelated to the statistical properties of the wave breaking fronts describedin terms of the average total length of breaking fronts. Assuming that thedominant waves are narrow and that the length of breaking fronts is relatedto the length of the contour of the breaking zone it is shown that theseparation stress supported by dominant waves is proportional to thebreaking probability of dominant waves. The breaking probability of dominantwaves, in turn, is defined by the dominant wave steepness. With thedominant wave steepness increasing, the breaking probability is increasedand so does the separation stress. This mechanism explains wave age (youngerwaves being steeper) and finite depth (the spectrum is steeper in shallowwater) dependence of the sea drag. It is shown that dominant waves support asignificant fraction of total stress (sea drag) for young seas due to theair-flow separation that occurs when they break. A good comparison of themodel results for the sea drag with several data sets is reported.     

综合识别法去除风廓线雷达地物杂波的可行性研究

以杂波谱极小值连线的思想为基础,针对强风天气条件下的风廓线雷达地物杂波信号,提出一种综合识别杂波的去除方法,并与常规的地物杂波抑制方法相比较。结果表明:利用该方法对强风天气下的地物杂波有更好的抑制效果,水平风速得到了明显增强,与地面观测数据相比,雷达产品更趋于真实风速。     

Inferences of plasma parameters from coronal hole observations

The temperature in the acceleration region of the solar wind remains one of the most elusive parameters to measure. Knowledge of the temperature as well as its gradient in the inner corona is fundamental for placing constraints on physical mechanisms thought to be responsible for the coronal heating process, as well as for understanding the flow properties of the solar wind. Estimates of the helium abundance is essential for understanding the puzzling behavior of heavier ions in the solar wind. As an illustration of the difficulties and uncertainties involved in the inferences of plasma parameters in the wolar wind acceleration region, The inference of electron temperature and helium abundance will be described. Prospects for future observations will be briefly discussed.     

Evolution of current loops in space

Ampere's law requires that every magnetic field have an associated current. The analysis of magnetic fields in this paper begins with that current in a circular loop and calculates the forces that make the loop evolve. A circular current generates a dipole field; and a second-order, ordinary differential equation represents the evolving magetic field. The theory describes cases where the conductor shrinks as the loop increases in size. The temperature of the conducting ions and electrons then decreases. The theory also describes cases where the conductor grows as the loop grows. Then the conducting particles heat up.Analysis shows that the magnetic clouds in the solar wind belong to the first type. In the provisional model adopted, the Klein-Burlaga clouds at one astronomical unit have a toroidal shape, centered on the sun, with a conductor radius of .125 au, and temperature (same for conducting electrons and protons) of 10⁵ K. After 26 days the toroid has a radius of 7.1 au, the conductor radius is .025 au, and the temperature is 2600 K.