Speciation of aluminum in the stream waters from the Susquehanna River watershed, Chesapeake Bay

 The aim of this paper was to analyze the processing and transport of aluminum speciation through the terrestrial and aquatic ecosystems of the Chesapeake Bay landscape. Stream waters were sampled in 14 different streams from the Susquehanna River watershed to the upper reach of Chesapeake Bay. The basic water quality data were documented and Al speciation was evaluated by modified MINEQL computer model. It was found that the increase in acidity in some of the stream waters near New York were closely linked with a marked decline in basic cation concentrations. In these areas, the sum of the toxic forms of Al³⁺ plus AlOH²⁺ and Al(OH)₂ ⁺ concentrations exceeds the critical level of 5 μmol l^–1. A potential threat from aluminum may occur. Received: 3 January 2000 · Accepted: 21 March 2000     

中央气象台短期降雨预报水平初步分析

该文利用1988～1993年资料，对中央气象台降雨预报水平状况进行了初步分析。结果表明:最近6年，中央气象台的有雨预报、小雨预报、中雨预报和等级综合预报的准确率和技巧水平均有不同程度的提高；暴雨和大暴雨两个等级的落点预报的准确率均超过气候概率，具有正技巧（技巧评分＞0），但技巧水平提高不明显。     

吉林省地体构造的基本特征

吉林省地体构造的一个显著特征是在早古生代以前，伊舒断裂两侧分属两个不同的大地构造单元，西侧的构造环境与华北大陆板块北缘相似，为受古蒙古洋作用的早生代活动陆缘，东侧为长白山一张广才岭地体添加带（也称联合地体（省内包括吉林－延边古生代增生褶皱带及辽吉台块。其中辽吉台块于新元古代到早寒纪位于赤道附的，以后沿巨型拆离面逐渐北移，于二叠纪末沿辉发河－古洞河拼贴带，与吉林一延边古生代陆缘增生褶皱带拼贴到一起。     

太阳P模振动理论的研究

日震学是太阳物理的一个前沿分支学科,是根据太阳振动的观测来研究太阳的内部结构与运动的一种方法学。太阳５ｍｉｎ振动频率的理论计算和实测之间存在的显著偏差和振动模的激发问题一直是困扰日震学的两大难题,经过多年的研究仍然没有解决。然而太阳的表面层内绝热假设条件与真实情况有很大的偏差,我们认为绝大多数标准太阳模型的Ｐ模频率计算忽略了非绝热效应对频率的影响,忽略了振动的激发和衰减机制以及缺乏振动与对流湍流相互作用的知识。因此,我们必须发展非绝热理论来处理太阳５ｍｉｎ的振动问题     

断层圈闭形成机制及时空配置有效性评价——以歧口凹陷歧南斜坡为例

断层的分段生长和连接控制着断层圈闭的形成,为了研究断层形成过程对圈闭形成的控制作用,应用位移/离距法和位移梯度比法判别断层相互作用阶段,落实断层圈闭的空间匹配有效性。针对空间匹配的断层圈闭,应用最大断距相减法开展断层圈闭形成时期的研究,在成藏关键时期前形成的断层圈闭是油气有利聚集的部位。本文以歧口凹陷歧南斜坡的南大港同向断层与扣村反向断层为例,开展断层圈闭时空配置有效性评价,研究结果表明油气多分布在同时具备空间和时间匹配有效的断层圈闭内,仅具备空间或时间匹配有效性的断层圈闭中未见油气聚集。因此,通过对未钻探断层圈闭开展时空匹配有效性评价,能够有效地降低勘探开发的风险。     

多层模式中臭氧加热率的计算及其对大气温度场的影响

本文介绍一个简单、经济的适用于各种多层大气环流模式中计算臭氧加热率的参数化方案,利用这一方案,可根据臭氧总量气候观测值及其垂直分布资料计算臭氧加热率,也可以在模式中加入臭氧方程,用预报的臭氧含量计算臭氧加热率.用此方案对单站气候资料试算,结果指出,随着高度的增加,臭氧吸收太阳辐射对大气太阳加热率的贡献逐渐接近、达到并在平流层50hPa附近明显超过其它物质如水汽的贡献.此方案用于九层大气环流模式时,对其辐射加热率的计算有较理想的改进,并使模拟的大气温度垂直分布更符合观测事实.     

自组织人工神经网络在多金属成矿预测中的应用

本文运用ＴＫｏｈｏｎｅｎ自组织人工神经网络，对鄂东南地区４４个铁帽进行计算机识别，识别成功率达１００％。结果表明，该方法性性能良好，可望成为多金属成矿预测的一种有效的辅助手段。     

Mean, interannual variability and trends in a regional climate change experiment over Europe. I. Present-day climate (1961–1990)

We present an analysis of a multidecadal simulation of present-day climate (1961–1990) over Europe with the regional climate model RegCM nested within the global atmospheric model HadAMH. Climatic means, interannual variability and trends are examined, with focus on surface air temperature and precipitation. The RegCM driven by HadAMH fields is able to reproduce the basic features of the observed mean surface climate over Europe, its seasonal evolution and the regional detail due to topographic forcing. Surface air temperature biases are mostly less than 1–2 °C and precipitation biases mostly within 10–20%. The RegCM has more intense vertical transport of temperature and water vapor than HadAMH, which results in lower surface air temperatures and greater precipitation than found in the HadAMH simulation. In some cases this is in the direction of greater agreement with observations, while in others it is in the opposite direction. The simulation shows a tendency to overestimate interannual variability of temperature and precipitation compared to observations, particularly during summer and over the Mediterranean regions. It is shown that in DJF, MAM and SON the RegCM interannual variability is primarily determined by the boundary forcing from HadAMH, while in JJA the internal model physics and resolution effects dominate over many subregions of the domain, and the RegCM has higher interannual variability than HadAMH. The precipitation trends simulated by the nested modeling system for the period 1961–1990 capture some features of the observed trends, in particular the cold season drying over the Mediterranean regions. Ensembles of simulations are, however, needed for a more robust assessment of the models capability to simulate climatic trends. Overall, this simulation is of good quality compared with previous nested RegCM experiments and will constitute the basis for the generation of climate change scenarios over the European region to be reported in future work.     

地基GPS遥感观测安徽地区水汽特征

对2002年6～7月安徽地区肥西、桐城、寿县、无为、芜湖、滁州6个GPS观测站的数据，结合相应的地面温度、气压等气象数据反演了时间间隔为30min连续变化的水汽总量。这一解算结果由解算方法分析达到1～2mm量级精度，达到了数值天气预报和气候研究的要求。利用这些资料，分析了上述地区水汽变化特征。单站水汽的持续积累和源源不断的水汽输送是强降水系统发生发展的必要条件，为了研究水汽来源及水汽量的大小，结合NCEP资料计算了一次强降雨过程中水汽通量值。     

Extreme precipitation over the Maritime Alps and associated weather regimes simulated by a regional climate model: Present-day and future climate scenarios

Summary We use the regional climate model RegCM nested within time-slice atmospheric general circulation model experiments to investigate the possible changes of intense and extreme precipitation over the French Maritime Alps in response to global climate change. This is a region with complex orography where heavy and/or extended precipitation episodes induced catastrophic floods during the last decades. Output from a 30-year simulation of present-day climate (1961–1990) is first analysed and compared with NCEP reanalysed 700 hPa geopotential heights (Z700) and daily precipitation observations from the Alpine Precipitation Climatology (1966–1999). Two simulations under forcing from the A2 and B2 IPCC emission scenarios for the period 2071–2100 are used to investigate projected changes in extreme precipitation for our region of interest. In general, the model overestimates the annual cycle of precipitation. The climate change projections show some increase of precipitation, mostly outside the warm period for the B2 scenario, and some increase in the variability of the annual precipitation totals for the A2 scenario. The model reproduces the main observed patterns of the spatial leading EOFs in the Z700 field over the Atlantic-European domain. The simulated large scale circulation (LSC) variability does not differ significantly from that of the reanalysis data provided the EOFs are computed on the same domain. Two similar clusters of LSC corresponding to heavy precipitation days were identified for both simulated and observed data and their patterns do not change significantly in the climate change scenarios. The analysis of frequency histograms of extreme indices shows that the control simulation systematically underestimates the observed heavy precipitation expressed as the 90^th percentile of rainday amounts in all seasons except summer and better reproduces the greatest 5-day precipitation accumulation. The main hydrological changes projected for the Maritime Alps consist of an increase of most intense wet spell precipitation during winters for both scenarios and during autumn for the B2 scenario. Case studies of heavy precipitation events show that the RegCM is capable to reproduce the physical mechanisms responsible for heavy precipitation over our region of interest.