AIRS卫星温度和臭氧廓线在南极的验证分析

利用2008年中山站、Amundesen-Scott（SouthPole）站和Neumayer站为期一年的温度和臭氧探空数据,对AIRS第六版温度和臭氧垂直廓线产品在南极的精度进行了验证.结果表明,AIRS温度与探空温度总体上具有显著的一致性,其中对流层偏差最小（RMSe < 2℃）,近地面温度由于受到下垫面影响偏差略大（RMSe~2℃）,平流层偏差较大（2℃ < RMSe < 3℃）,AIRS温度平均低于探空观测且受季节变化影响显著,秋冬季偏差整体上高于春夏季.AIRS臭氧反演精度在平流层（RMSe~25%）要优于对流层（RMSe~30%）,RMSe最大值出现在UT-LS区域（可达40%）且在"臭氧洞"期间明显增大.AIRS产品精度在南极沿岸和内陆存在差异,由于南极地区探空资料较少且主要位于沿海,故在南极内陆地区进行探空观测对于提高卫星资料精度,改善该区域天气预报能力具有重大意义.     

西藏高原斜压对流边界层风、温、湿廓线特征

利用1998年夏季第2次青藏高原大气科学试验当雄观测站的边界层观测资料以及拉萨、改则和武汉等地探空资料,分析讨论西藏高原斜压对流边界层风、温、湿廓线的特征. 研究结果表明,高原地区白天对流边界层发展可高达2200m,显著超过中纬度平原地区和海面上对流边界层高度. 高原对流边界层中温度廓线具有较好的混合特征,湿度廓线有时在某一高度上出现湿度极大值. 高原对流边界层内热量和水汽收支分析表明,水平平流作用对边界层结构具有重要作用. 在对流边界层中平均风速垂直分布存在风切变现象. 水平温度梯度形成较强的斜压性是形成边界层风切变的主要原因.     

西藏高原斜压对流边界层风、温、湿廓线特征

利用1998年夏季第2次青藏高原大气科学试验当雄观测站的边界层观测资料以及拉萨、改则和武汉等地探空资料,分析讨论西藏高原斜压对流边界层风、温、湿廓线的特征. 研究结果表明,高原地区白天对流边界层发展可高达2200m,显著超过中纬度平原地区和海面上对流边界层高度. 高原对流边界层中温度廓线具有较好的混合特征,湿度廓线有时在某一高度上出现湿度极大值. 高原对流边界层内热量和水汽收支分析表明,水平平流作用对边界层结构具有重要作用. 在对流边界层中平均风速垂直分布存在风切变现象. 水平温度梯度形成较强的斜压性是形成边界层风切变的主要原因.     

人工神经网络在地震综合预报中的应用

多级判别、聚类分析等统计模式识别方法在地震综合预报中的应用已有多篇文献报道(石绍先、沈斌,1986;1990;王学仁,1982).多年预报实践表明,模式识别方法对于地震预报是有效的.随着国际上神经网络研究的兴起,该方法也被用于模式识别领域,但尚未见其用于地震综合预报方面.本研究运用“反向传播”神经网络,对滇西南地震区17个震例进行了计算机分析,建立了地震综合预报的专家系统,从而为进一步研究决定地震强度的物理因素,准确地预报将来的未知地震提供参考信息.     

电磁辐射在短临预报中的应用

本文介绍了电磁辐射对共和地震短临预报的映震效果，及时、空、强的判据，认为利用地震电磁辐射现象进行地震短临预报是一项很好的手段。     

预报预警在地质灾害防治中的应用

本文介绍了江西地质灾害气象预报模型的建立、计算方法,以及预警预报在地质灾害防治工作中获得的成功,对类似条件地区的地质灾害防治工作,具有一定的借鉴作用。     

地震非均匀度的研究及在强震中期预报中的应用

室内岩石破裂实验表明，主破裂前声发射事件在时间分布上随着应力增强存在着均匀－非均匀现象。本文据此提出了一个能够有效刻画强震前中小地震活动在时空分布上不均匀性的参量－地震非均匀度（ＧＬ值）。据对中国大陆１９２０年以来４３次Ｍｓ＞７．０大震震前５年Ｇ时间变化扫描结果，发现除少数边界附近的大震外，所有７级大震震前１－３年，在震中一定范围内５级以上地震活动显示出明显的非均匀状态（ＧＬ值大于１．０）；同时，     

TSP\|203在隧道超前预报中的应用

TSP\|203系统是瑞士Amberg工程技术公司最新研制并拥有专利的隧道地震探测仪，专门为隧道超前地质预报而设计的.该系统从数据采集、处理和成果评估高度智能化，采用该系统可以预报隧道工作面前方100 m左右围岩地质体的性质、位置和规模,并可推算出其岩石物理力学参数，为确定合理的支护参数提供依据，确保隧道施工安全和质量.本文对TSP\|203系统、工作原理、数据采集及资料解释方面做了系统的阐述.     

BMA集合预报在淮河流域应用及参数规律初探

以淮河流域吴家渡水文站作为试验站点,采用基于贝叶斯平均法(BMA)的集合预报模型处理来源于马斯京根法、一维水动力学方法、BPNN(Back Propagation Neural Network)的预报流量序列,通过分析BMA的参数以及其预报结果,对各方法在淮河典型站点流量预报中的适用性进行验证与分析.经2003—2016年19场洪水模拟检验可知,BMA模型能够有效避免模型选择带来的洪水预报误差放大效应,可以提供高精度、鲁棒性强的洪水预报结果.通过进一步比较各模型统计最优的频率与BMA权重值之间的相关性,发现权重值不适用于对单场洪水预报精度评定,而适用于描述多场洪水预报中,模型为最优的统计频率;基于大量先验信息,提前获取BMA的权重等参数,将是指导模型选择、降低洪水预报不确定性、改进洪水预报技术的有效手段.     

YSU边界层参数化方案中不同地形订正方法对地面风速及温度模拟的影响

为了修正中尺度气象模式WRF(Weather Research and Forecasting model)对低层风速模拟的系统性误差,有学者在新版本WRF模式的YSU(Yonsei University)边界层参数化方案中加入了两个地形订正方法:Jiménez方法和UW(University of Washington method)方法.本文利用这两个地形订正方法,选取了两个时间段,对北京地区的地面气象要素以及气象要素垂直廓线进行了个例模拟研究,模拟结果和观测数据的比对表明在北京地区:是否采用地形订正,对地面温度的模拟几乎没有影响;采用地形订正后,模式对地面风速的模拟有明显的改进,两种方法对风速模拟的差别主要体现在山/丘陵地区;Jiménez方法在山/丘陵地区的模拟风速明显偏大,而采用UW方法进行订正后,模拟的风速减小,更接近观测值;两种方法在山谷地区对风速均有一定的过度订正.通过分析气象要素的垂直廓线发现,不同地形订正方法主要影响的是2000 m以下的低层风速.总体而言,UW地形订正方法在北京地区更为适用,采用UW方法后,模拟得到的地面气象要素的各项统计参数基本达到了统计基准值.     

中国地区电离层foF2重构方法及其在短期预报中的应用

提出了一种适合于中国地区电离层f_oF₂的重构方法——以中国参考电离层为背景的改进克里格法.该方法把f_oF₂的估计值与中国参考电离层模型值之差值的相对值作为区域化变量,引入电离层距离,采用克里格法实现区域电离层重构.与直接利用f_oF₂进行克里格重构相比,以中国参考电离层为背景场保持了电离层的区域特征,提高了重构的准确性和稳定性.利用我国电离层垂测台站网的数据对该方法应用于中国地区的重构精度进行了评估.该方法与单站预报的自相关分析法相结合可实现中国地区电离层f_oF₂短期预报.     

Rapid adjustment of shoreline behavior to changing seasonality of storms: observations and modelling at an open‐coast beach

An 8‐year time series of weekly shoreline data collected at the Gold Coast, Australia, is used to examine the temporal evolution of a beach, focusing on the frequency response of the shoreline to time‐varying wave height and period. Intriguingly, during 2005 the movement of the shoreline at this site changed from a seasonally‐dominated mode (annual cycle) to a storm‐dominated (~monthly) mode. This unexpected observation provides the opportunity to explore the drivers of the observed shoreline response. Utilizing the calibration of an equilibrium shoreline model to explore the time‐scales of underlying beach behavior, the best‐fit frequency response (days^?1) is shown to be an order of magnitude higher post‐2004, suggesting that a relatively subtle change in wave forcing can drive a significant change in shoreline response. Analysis of available wave data reveals a statistically significant change in the seasonality of storms, from predominantly occurring at the start of the year pre‐2005 to being relatively consistent throughout the year after this time. The observed change from one mode of shoreline variability to another suggests that beaches can adapt relatively quickly to subtle changes in the intra‐annual distribution of wave energy. Copyright © 2016 John Wiley & Sons, Ltd.     

一种新的综合物理指数构建及其在强降水预报中的应用

强降水是洪灾及相关衍生灾害的最主要原因之一,而过去单靠某一种变量诊断预报强降水,具有较大难度.本文在已有研究的基础上,根据强降水发生发展的物理机制,将引起降水的热力、动力和水汽条件综合考虑,尝试性地构建了一个新的综合指数THP(Temperature, Helicity and Precipitable water).然后针对两次强降水过程,利用NCEP/NCAR 1°×1°的再分析资料和地面常规观测资料,对THP指数进行了诊断分析,并选用2012年7月1日-8月15日的降水实况,对该指数进行了普适性检验.结果表明:(1) THP指数的变化可以有效表征强降水过程的发展和移动.对于降水落区的预报,THP指数的大值区与未来6 h的降水中心基本对应;对于降水发生时刻的预报,THP指数的位相变化超前于地面降水的变化,具有较好的指示性;(2) 对于高空槽前型降水,THP指数对降水强度也有一定的诊断意义,且普适性检验表明,该指数在我国中东部地区的盛夏期间具有良好的适用性;(3) 基于配料法的思想,THP指数将有利于强降水出现的、具有清晰物理意义的信号进行了集成,相比于表征单一物理量的指数,其稳定性得到了增强.     

Chaos hides and generates order: An application to forecasting the next eruption of Vesuvius

The poissonian and non-fractal characters generally exhibited by the most intense natural events do not allow the application of the current exponential and power law long-term hazard predictive models, and have suggested searching for a new model. This has been set up also taking into account that the random sequence (representing disorder) of these events is linked to the duration of the stationary small ones (representing order). The model, proposed in terms of the orbit of a simple non-linear hazard function, simulates the large eruptions of Vesuvius quite well and permits estimation of the next subplinian eruption to occur there around A.D. 2030. A short range forecasting model based on the tidal triggering is also provided and discussed. When large tidally triggered M₂ term in the earthquakes at Vesuvius become significant at the 0.01 level the proposed long-term hazard model will yield a more accurate estimate of the above prediction.     

1987-2017年间南极点大气风温垂直结构及趋势变化特征

本文基于1987—2017年南极点的无线电探空数据,研究了地面至30 km海拔高度的气温、风向和风速的垂直分布及变化趋势.多年平均的逐月数据表明,气温在各高度上均具有显著的季节变化,南半球夏季（冬季）对流层低层温度最高达-25℃（最低达-60℃）,分别出现于1月（7月）地面以上约500 m（近地面）.近30年来,年平均地面气温呈0.3℃/10a的增加趋势,增温趋势总体上随高度增加而减缓,至对流层上层的气温变化趋势为负,约为-0.25℃/10a.对于对流层整层平均气温,秋季上升趋势在四季中最为明显,达0.55℃/10a,而年平均气温的趋势约为0.3℃/10a.近地面全年盛行东北风,风速大多在2~10 m·s^-1范围内;对流层的低层（高层）为西北风（西南风）,在海拔6~9 km处,对流层急流可达25 m·s^-1;而平流层低层（高层）为南风（东南风）,最大风速可超过30 m·s^-1.风速和温度梯度变化特征在地面至10 km（10~30 km）高度段表现为负相关（正相关）.近30年近地面呈现北风增加东风减少的趋势,而高空南风减少,东风和北风增多.对流层整层平均风速显示,各季节平均风速均呈增加趋势,并且与温度类似,秋季的增加趋势最显著,达0.59 m·s^-1/10a,而春季趋势最为平缓,仅0.05 m·s^-1/10a.对流层整层年平均风速的线性趋势为0.24 m·s^-1/10a,地面年平均风速呈0.05 m·s^-1/10a的增加趋势.

     

Multi-tracer assessment of seasonal water source changes in coastal water systems along the southeastern coast of Ivory Coast (West Africa)

ABSTRACT

Proper management of coastal freshwater resources depends on an understanding of processes controlling their chemistry and seasonal flowpaths. A quantitative approach involving the coupling of major solutes and isotopes (δ¹⁸O, δ²H) of 180 samples in end-member mixing analysis (EMMA) was adopted to elucidate seasonal patterns of hydraulic exchanges amongst coastal waters along the Ebrié Lagoon catchment, Ivory Coast. The results show that the Ebrié Lagoon is a hydrologically dynamic system. In the dry season, evaporation and seawater inflow are the dominating processes, while in the wet season, river discharge is the main water source in the lagoon. Regional geology plays a significant role in aquifer recharge patterns. The Quaternary aquifer responds faster to precipitation, while the Mio-Pliocene aquifer is recharged indirectly via floodplain seepages. Salinization of over 90% of wells arises from hydrological exchanges with the Ebrié Lagoon. A diluted seawater effect was recorded in wells during the wet season owing to the relative increase in freshwater inflow.     

Relations of sand trapping efficiency and migration speed of transverse dunes to wind velocity

A self‐consistent model which describes transverse dune migration in equilibrium is introduced. It shows that an equilibrium expression for dune migration speed (c _d) must take into account sand trapping efficiency (T _E), and that T _E is strongly related to the wind speedup over the windward surface. An expression for sand trapping efficiency (T _E) is analytically derived from a microscale analysis of sand grain deposition on the slip face. Sand trapping efficiency (T _E) is mainly determined by shear velocity on a level surface (u_*(−∞)), and rapidly decreases as u_*(−∞) increases. For each dune height (H), dune migration speed (c _d) first increases, and then decreases monotonically after reaching the maximum, as the shear velocity on a level surface (u_*(−∞)) increases. Dune migration speed (c _d) is not inversely proportional to dune height (H). For low dunes, small sand trapping efficiency (T _E) suppresses c _d, whereas for high dunes, wind speedup and large T _E resist the decrease of c _d. Some field data show the same tendency. The dune‐to‐plane‐bed transition observed in subaqueous and venusian bedforms could be associated with the decrease of sand trapping efficiency (T _E). Copyright © 2000 John Wiley & Sons, Ltd.     

A simultaneous interpretation,by wind speed and direction,of ambient air negative ion density in Athens,Greece

A recently developed data presentation technique, the rectangular wind frequency isopleth diagram, has been applied to examine the effect of wind speed and direction, acting simultaneously, on ambient air negative ion densities. The large negative ion concentration decreases in the majority of directions and wind speed intervals, while that of the small ions increases, as the wind speed increases. The local maxima and minima, occurring in some sectors, are properly discussed.     

Developing a large‐scale water‐balance approach to seasonal forecasting: application to the 2012 drought in Britain

Seasonal hydrological forecasts, or outlooks, can potentially provide water managers with estimates of river flows and water resources for a lead time of several months ahead. An experimental modelling tool for national hydrological outlooks has been developed which combines a hydrological model estimate of sub‐surface water storage across Britain with a range of seasonal rainfall forecasts to provide estimates of area‐wide hydrological conditions up to a few months ahead. The link is made between a deficit in sub‐surface water storage and a requirement for additional rainfall over subsequent months to enable sub‐surface water storage and river flow to return to mean monthly values. The new scheme is assessed over a recent period which includes the termination of the drought that affected much of Britain in the first few months of 2012. An illustration is provided of its use to obtain return‐period estimates of the ‘rainfall required’ to ease drought conditions; these are well in excess of 200 years for several regions of the country, for termination within a month of 1 April 2012, and still exceed 40 years for termination within three months. National maps of sub‐surface water storage anomaly show for the first time the current spatial variability of drought severity. They can also be used to provide an indication of how a drought situation might develop in the next few months given a range of possible future rainfall scenarios. © 2013 CEH/Crown and John Wiley & Sons, Ltd.