THE INFLUENCE OF PHOTOCHEMICAL PROCESS ON THE ATMOSPHERIC WAVE

The time damping rate of gravity wave in the range of 30-70 km is calaclated in threecircumstances:(1)adiabatic process,(2)diabatic process caused by atmospheric cooling,and(3)diabatic process resulting from atmospheric photochemical heating and cooling.The resultsindicate that the photochemical heating is as important as Newtonian cooling and its contribution tothe time damping rate of gravity wave can not he negligible.     

大气低频遥相关及其水平传播机制的解析研究

（１）利用大气对流层中部无辐散层的存在,垂直积分热力学方程,并对整个对流层的距平加热场作解析近似的描写,联立涡度方程,得到最非绝热地转的２５０ｈＰａ距平流函数方程。它的形式酷似正压涡度方程。（２）讨论了罗斯贝波列的谱平均相速和群速。证明了气候平均高度场的闭合中心,就是中高纬度大气低频振子。其两侧位相变化相反,它的能源主要来自ＣＩＳＫ凝结正反馈或海温的感热。（３）导出了低频相关射线公式,它表明低频射     

赤道不同海域对信风张弛的响应特征——对El Nio研究的启示

当均匀的纬圈风应力作用于赤道海洋时,在东、西边界附近由于平衡的物理过程不同,其响应特征也不同。当盛吹一个方向的风时,例如东风,东边界的温跃层会变浅（冷水）,而西边界的温跃层变深。当东风吹了ｔ０时间而改吹西风时,无论东边界的温跃层还是西边界的温跃层都要持续到２ｔ０时间后,才改变其发展方向。这表明边界上的物理场带有长的“惯性”或长的“记忆”。但西边界信号向东传播的速度比东边界向西传播的速度要快,且振幅也大,从这个意义上讲,ＥｌＮｉｎｏ事件先兆从西边界附近出现后,能迅速影响到西、中太平洋,也即西边界附近更易成为ＥｌＮｉｎｏ事件的源地,特别是强的ＥｌＮｉｎｏ事件。     

哀牢山变质带元江──墨江剖面岩石的纵波波速特征及其地质意义

依据研究区的地热梯度（25℃／km）,在高温高压（最高温度为1050℃,最高压力为1.2GPa）条件下系统测量了横穿红河-哀牢山断裂带的元江-墨江地质剖面上的哀牢山岩群各类变质岩（千枚岩、片岩、浅粒岩、变粒岩、大理岩和片麻岩）的纵波速度．实验结果表明,不同岩类的纵波速度随温度压力变化的趋势不同．在相当于衷牢山岩群变质岩峰期变质温度和压力条件下（P=0．4-0.8GPa,T=35-700℃）,测得大部分岩石的纵波速度为5．50－5．80km／s,这一纵波速度值与区域地球物理测深揭示的中地壳低速层的纵波速度相当因此,结合该区变质岩、地壳内热状态及地球物理测深研究成果可初步认为：组成哀牢山岩群的浅粒岩、变粒岩、酸性片麻岩以及部分千枚岩、片岩为该地区中地壳低速层的主要岩石类型．     

Impact of climate change on 24‐h design rainfall depth estimation in Qiantang River Basin,East China

The frequency and magnitude of extreme meteorological or hydrological events such as floods and droughts in China have been influenced by global climate change. The water problem due to increasing frequency and magnitude of extreme events in the humid areas has gained great attention in recent years. However, the main challenge in the evaluation of climate change impact on extreme events is that large uncertainty could exist. Therefore, this paper first aims to model possible impacts of climate change on regional extreme precipitation (indicated by 24‐h design rainfall depth) at seven rainfall gauge stations in the Qiantang River Basin, East China. The Long Ashton Research Station‐Weather Generator is adopted to downscale the global projections obtained from general circulation models (GCMs) to regional climate data at site scale. The weather generator is also checked for its performance through three approaches, namely Kolmogorov–Smirnov test, comparison of L‐moment statistics and 24‐h design rainfall depths. Future 24‐h design rainfall depths at seven stations are estimated using Pearson Type III distribution and L‐moment approach. Second, uncertainty caused by three GCMs under various greenhouse gas emission scenarios for the future periods 2020s (2011–2030), 2055s (2046–2065) and 2090s (2080–2099) is investigated. The final results show that 24‐h design rainfall depth increases in most stations under the three GCMs and emission scenarios. However, there are large uncertainties involved in the estimations of 24‐h design rainfall depths at seven stations because of GCM, emission scenario and other uncertainty sources. At Hangzhou Station, a relative change of ?16% to 113% can be observed in 100y design rainfall depths. Copyright © 2012 John Wiley & Sons, Ltd.     

Derivation of a curve number and kinematic-wave based flood frequency distribution

Abstract

The physically-based flood frequency models use readily available rainfall data and catchment characteristics to derive the flood frequency distribution. In the present study, a new physically-based flood frequency distribution has been developed. This model uses bivariate exponential distribution for rainfall intensity and duration, and the Soil Conservation Service-Curve Number (SCS-CN) method for deriving the probability density function (pdf) of effective rainfall. The effective rainfall-runoff model is based on kinematic-wave theory. The results of application of this derived model to three Indian basins indicate that the model is a useful alternative for estimating flood flow quantiles at ungauged sites.     

Internal testing of a numerical model of hillslope–channel coupling using laboratory flume experiments

The numerical model COUP 2D simulates the hydrological coupling between hillslopes and the river channel during a rainfall event. In order to test the numerical model, a 1:100 scaled laboratory flume which was modified to incorporate lateral hillslope elements, was used to run a series of experiments in which hillslope angle, channel angle, hillslope discharge and channel discharge were the varying parameters. Overall, there were 18 different experimental configurations with three replicates carried out for each condition, leading to a total of 54 experiments. These conditions were then used to parameterize and run COUP 2D. Internal model outputs of flow depth and flow velocity at four cross‐sections in the channel were compared to the measurements made in the physical model for the same parameter conditions. Statistical comparisons of the measured and modelled data were carried out for each experiment and across all experiments, using two goodness‐of‐fit measures—root mean square error and Nash–Sutcliffe coefficient of efficiency—in order to assess the performance of the model over an entire simulation as well as over all the simulations. The main effects on the goodness‐of‐fit measures for flow depth of each experimental variable, as well as the interactions between variables, were evaluated using statistical modelling. The results show that the model captures flow‐depth variations in response to changing channel and hillslope parameters. Statistical modelling suggests that the main effects on model error are cross‐section position, channel angle and channel discharge. Significant interactions also occur between all the channel variables and between the channel variables and hillslope discharge. The results of the testing procedure have significant implications for the consideration of different model components and for the interaction between data‐ and model evaluation. Copyright © 2007 John Wiley & Sons, Ltd.     

The Origin and Acceleration of ~3He and Heavy Ions in the 2000 July 14 Event

1INTRODUCTIONEnrichment of3He and heavy ions(i.e.,Ne,Mg,Si and Fe),characteristic of impulsive?ares,have beenstudied for more than three decades.It is found that they are generally associated with nonthermal energeticelectron-rich events(Reames et al.1988;Reames1999and references therein;Ho et al.2001;Wang et al.2006)and are related to the peculiar ratio of charge to mass(Mazur et al.1996;Reames1999).Althoughthe abundance of3He ions is not correlated with the abundance of heavy ions,s…     

A fuzzy dynamic flood routing model for natural channels

A fuzzy dynamic flood routing model (FDFRM) for natural channels is presented, wherein the flood wave can be approximated to a monoclinal wave. This study is based on modification of an earlier published work by the same authors, where the nature of the wave was of gravity type. Momentum equation of the dynamic wave model is replaced by a fuzzy rule based model, while retaining the continuity equation in its complete form. Hence, the FDFRM gets rid of the assumptions associated with the momentum equation. Also, it overcomes the necessity of calculating friction slope (S_f) in flood routing and hence the associated uncertainties are eliminated. The fuzzy rule based model is developed on an equation for wave velocity, which is obtained in terms of discontinuities in the gradient of flow parameters. The channel reach is divided into a number of approximately uniform sub‐reaches. Training set required for development of the fuzzy rule based model for each sub‐reach is obtained from discharge‐area relationship at its mean section. For highly heterogeneous sub‐reaches, optimized fuzzy rule based models are obtained by means of a neuro‐fuzzy algorithm. For demonstration, the FDFRM is applied to flood routing problems in a fictitious channel with single uniform reach, in a fictitious channel with two uniform sub‐reaches and also in a natural channel with a number of approximately uniform sub‐reaches. It is observed that in cases of the fictitious channels, the FDFRM outputs match well with those of an implicit numerical model (INM), which solves the dynamic wave equations using an implicit numerical scheme. For the natural channel, the FDFRM outputs are comparable to those of the HEC‐RAS model. Copyright © 2009 John Wiley & Sons, Ltd.     

Study of temperature and precipitation variations in Italy based on surface instrumental observations

In this paper we present a study concerning the climatic behaviour of two principal observables, temperature and precipitation as obtained from the measurements carried out at 50 Italian meteorological stations, since 1961. Analyses of WMO Climate Normals (CliNo) from 1961 to 1990 have been performed dividing the 50 Italian stations in three different classes: mountain (11 stations), continental (17) and coastal areas (21).The comparison of the CliNo 1961–1990 with the trend of temperature and precipitation for the period 1991–2000 showed a sharp significant increase of summer temperatures over Italy starting from 1980. This phenomenon was particularly evident for mountain stations, where a significant temperature increase has been recorded also during the autumn. Moreover, the analysis of precipitation data permitted to point out that, starting from 1980, mountain stations have been affected by a significant increase of precipitation events during autumn and winter, while for the rest of the Italian territory a reduction of precipitations has been recorded during early spring.