Rapid simulated hydrologic response within the variably saturated near surface

Column and field experiments have shown that the hydrologic response to increases in rainfall rates can be more rapid than expected from simple estimates. Physics‐based hydrologic response simulation, with the Integrated Hydrology Model (InHM), is used here to investigate rapid hydrologic response, within the variably saturated near surface, to temporal variations in applied flux at the surface boundary. The factors controlling the speed of wetting front propagation are discussed within the Darcy–Buckingham conceptual framework, including kinematic wave approximations. The Coos Bay boundary‐value problem is employed to examine simulated discharge, pressure head, and saturation responses to a large increase in applied surface flux. The results presented here suggest that physics‐based simulations are capable of representing rapid hydrologic response within the variably saturated near surface. The new InHM simulations indicate that the temporal discretization and measurement precision needed to capture the rapid subsurface response to a spike increase in surface flux, necessary for both data‐based analyses and evaluation of physics‐based models, are smaller than the capabilities of the instrumentation deployed at the Coos Bay experimental catchment. Copyright © 2007 John Wiley & Sons, Ltd.     

Energy considerations in groundwater‐ridging mechanism of streamflow generation

Groundwater ridging is the rapid rise of a shallow water table during a rainfall event, in an environment where, in the pre‐event period, the capillary fringe extends to the ground surface. Groundwater ridging is widely cited to account for the observed significant appearance of pre‐event water in a stream stormflow hydrograph. Various hypotheses have been advanced to explain the groundwater‐ridging mechanism; and most recently, from a field study site in South Africa, an energy hypothesis was proposed, which explains that groundwater‐ridging water‐table rise is a result of rapid introduction and transmission of additional pressure head into the capillary fringe from an intense rainfall at the ground surface. However, there is a need for further analysis and evidence from other field study sites to confirm and support this newly proposed energy hypothesis. The objectives of this paper are, therefore, as follows: to review previous observations on groundwater ridging, from other study sites, in order to deduce evidence of the newly proposed energy hypothesis; to present and evaluate a one‐dimensional diffusion mathematical model that can simulate groundwater‐ridging water‐table rise, based on the newly proposed energy hypothesis; and to evaluate the importance of a capillary fringe in streamflow generation. Analysis of previous observations from other study sites generally indicated that the rate of groundwater‐ridging water‐table rise is directly related to the rainfall intensity, hence confirming and agreeing with the newly proposed energy hypothesis. Additionally, theoretical results by the mathematical model agreed fairly well with the field results observed under natural rainfall, confirming that the rapidly rainfall‐induced energy is diffusively transmitted downwards through pore water, elevating the pressure head at every depth. The results in this study also support the concept of a three‐end‐member stream stormflow hydrograph and contribute to the explanation of how catchments can store water for long periods but then release it rapidly during storm events. Copyright © 2015 John Wiley & Sons, Ltd.     

The Effect of the Warm Water and Its Weak Negative Feedback on the Rapid Intensification of Typhoon Hato (2017)

Typhoon Hato (2017) went through a rapid intensification (RI) process before making landfall in Zhuhai, Guangdong Province, as the observational data shows. Within 24 hours, its minimum sea level pressure deepened by 35hPa and its maximum sustained wind speed increased by 20m s-1. According to satellite observations, Hato encountered a large area of warm water and two warm core rings before the RI process, and the average sea surface temperature cooling (SSTC) induced by Hato was only around 0.73℃. Air-sea coupled simulations were implemented to investigate the specific impact of the warm water on its RI process. The results showed that the warm water played an important role by facilitating the RI process by around 20%. Sea surface temperature budget analysis showed that the SSTC induced by mixing mechanism was not obvious due to the warm water. Besides, the cold advection hardly caused any SSTC, either. Therefore, the SSTC induced by Hato was much weaker compared with that in general cases. The negative feedback between ocean and Hato was restrained and abundant heat and moisture were sufficiently supplied to Hato. The warm water helped heat flux increase by around 20%, too. Therefore, the warm water influenced the structure and the intensity of Hato. Although there might be other factors that also participated in the RI process, this study focused on air-sea interaction in tropical cyclone forecast and discussed the impact of warm water on the intensity and structure of a tropical cyclone.     

超级台风‘玛莉亚’的对流爆发特征及与快速加强的关系

利用数值模拟结果,该研究探讨了超级台风‘玛莉亚’的对流爆发(CBs)特征及与快速加强(RI)的关系。发现,(1)切变相对象限的内核CBs表现为由顺切变到逆切变的气旋式旋转,这有利于台风快速加强;(2)CBs的突然增长为即将到来的RI提供了预示性特征信号,同时,台风玛莉亚的RI过程引发剧烈的深对流;(3)自对流层底向上的对流增长角度分析,发现对流爆发与边界层高对流有效位能,次级环流的向上深层发展,增强的动量通量辐合等有关。     

Relationship of Rapid Intensification of Tropical Cyclones to Dynamical/Thermodynamical Parameters

Many avenues of research are currently being tried for understanding and predicting hurricane intensity forecasts. We have listed several such research avenues being pursued by the research community. This article addresses the use of high-resolution aircraft reconnaissance datasets used for daily data assimilation over three years of hurricane histories that cover rapid intensification cases. We show a number of dynamical and thermodynamical parameters, derived from these datasets, which seem to hold promise for future use in short range statistical forecasts on rapid intensification. These include the vertical differential of heating in the complete potential vorticity equation, the conversion of divergent kinetic energy to rotational kinetic energy, the transformation of shear vorticity to curvature vorticity, and the advection of the earth's and the relative angular momentum into the inner core of hurricanes. We find a rapid growth in the time history of each of these parameters as the rapid intensification occurs. These are demonstrated for a number of recent hurricanes.     

一种结合重心法和GIS技术的机场抢修预置物资仓库选址模型

如何科学、合理地进行预置物资仓库的选址是保证机场抢修时效性的关键问题.本文在分析总结传统重心选址法存在的问题的基础上,结合GIS技术,建立了基于道路距离的改进重心法最优选址模型,提高了机场抢修预置物资仓库选址的效率和实用性.     

应用快速光曲线方法研究两株海洋超微型真核藻光合特性的差异

超微型浮游植物是海洋中重要的初级生产者,浮游植物吸收的光一部分用于光合作用,另一部分以荧光或热的形式耗散.本文利用调制叶绿素荧光仪（Pulse-Amplitude-Modulation,PAM）测定2株海洋超微型真核藻：细小微胞藻（Micromonas pusilla）和梨形脂金藻（Pinguiochrysis pyriformis）在不同光强下的叶绿素荧光和快速光曲线.结果表明细小微胞藻和梨形脂金藻在不同光强下的光系统II（PS II）的最大光量子产量（Fv/Fm）分别为0.572-0.634和0.624-0.426;最大相对电子传递速率（rETRmax）分别为61.58-163.56和76.69-143.17μmol/m2·s-1;半饱和光强（Ik）分别为212.37-946.00和307.44-671.28μmol·m-2·s-1;光能利用效率（α）分别为0.29-0.17和0.25-0.21.细小微胞藻和梨形脂金藻分别属于高光型和低光型的超微型浮游植物,光照条件会显著影响超微型浮游植物的光合特性,但不同类型的超微型浮游植物的光合特性对光的响应存在差异.     

Seismic response evaluation of the linked column frame system

The linked column frame (LCF) system is proposed as a seismic load resisting system that uses conventional components to limit seismic damage to relatively easily replaced elements. The LCF features a primary lateral system, denoted the linked column, which is made up of dual columns connected with replaceable links, and a secondary flexible moment frame system with beams having fully restrained connections at one end and simple connections at the other. The linked columns are designed to limit seismic forces and provide energy dissipation via link yielding, while preventing damage to the moment frame under certain earthquake hazard levels. A design procedure is proposed that ensures plastic hinges develop in the links of the linked columns at a significantly lower story drift than when plastic hinges develop in the moment frame beams. The large drift difference helps enable design of this system for two distinct performance states: rapid return to occupancy, where only link damage occurs and relatively simple link replacement is possible, and collapse prevention, where both the links and the beams of the moment frame may be damaged. A series of 3‐story, 6‐story, and 9‐story prototype LCF buildings were designed using the proposed design approach. Nonlinear models were developed for the designs with the link models validated using recent experimental results. The seismic response of these systems was investigated for ground motions representing various seismic hazard levels. Results show that the LCF system not only provides collapse prevention, but also has the capability of limiting economic loss by reducing structural damage and allowing for rapid return to occupancy following earthquakes with shorter return periods. Copyright © 2012 John Wiley & Sons, Ltd.     

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星际闪烁和BLO 0716＋71的快速射电变化

利用星际介质的折射闪烁理论解释在ＢＬＬａｃ天体０７１６＋７１中观测到的射电快速变化的结构函数，确定了对射电源结构和散射介质特性所提出的条件。为了解释这个源内观测到的射电变化的“快模式”和“慢模式”的转换，必须考虑时电源内致密结构的角径或运动状态的快速变化。射电变化和光学变化的相关性仍然是析射闪烁解释的一个难于克服的困难。