Characteristics of dry-wet abrupt alternation events in the middle and lower reaches of the Yangtze River Basin and the relationship with ENSO

During recent decades, more frequent flood-drought alternations have been seen in China as a result of global climate change and intensive human activities, which have significant implications on water and food security. To better identify the characteristics of flood-drought alternations, we proposed a modified dry-wet abrupt alternation index (DWAAI) and applied the new method in the middle and lower reaches of the Yangtze River Basin (YRB-ML) to analyze the long-term spatio-temporal characteristics of dry-wet abrupt alternation (DWAA) events based on the daily precipitation observations at 75 rainfall stations in summer from 1960 to 2015. We found that the DWAA events have been spreading in the study area with higher frequency and intensity since 1960. In particular, the DWAA events mainly occurred in May and June in the northwest of the YRB-ML, including Hanjiang River Basin, the middle reaches of the YRB, north of Dongting Lake and northwest of Poyang Lake. In addition, we also analyzed the impact of El Niño Southern Oscillation (ENSO) on DWAA events in the YRB-ML. The results showed that around 41.04% of DWAA events occurred during the declining stages of La Niña or within the subsequent 8 months after La Niña, which implies that La Niña events could be predictive signals of DWAA events. Besides, significant negative correlations have been found between the modified DWAAI values of all the rainfall stations and the sea surface temperature anomalies in the Nino3.4 region within the 6 months prior to the DWAA events, particularly for the Poyang Lake watershed and the middle reaches of the YRB. This study has significant implications on the flood and drought control and water resources management in the YRB-ML under the challenge of future climate change.     

论CILa/CISm—CILa图解

通过对分离结晶作用和批式熔融作用C_l^y/C_l^x-C_l^y图解的数学分析,笔者认为,虽然C_l^La/C_l^sm-C_l^La图解在一定程度上能区分这两种不同岩浆作用过程,但是,Treuil等的解释是不完全的。直线的斜率和截距还极大地受参数C_o^x,C_o^y,D_x,D_y的影响。该图解并非总是有效。本文还给出了一般式C_l^y/C_l^x-C_l^y在其它方面的可能应用。     

厄尔尼诺/拉尼娜信号循环回路及其传播特性研究

基于1992～2001年卫星高度计资料分析了海面高度距平在厄尔尼诺/拉尼娜(El Niño/La Niña)现象中的演变过程,发现:(1)在El Niño过程中,海面高度正距平信号从西太平洋沿赤道海域向东传播至东海岸,然后分成南北两支,北支在10°N附近从东太平洋传回西太平洋的信号最强,到达西太沿岸海域再传回赤道,表明El Niño信号传播在北半球存在一明显循环回路.赤道以南循环圈不及赤道以北环路清晰.东太平洋的季节变化信号主要通过6°N,10°N和8°S附近的3个通道向西太平洋传播.La Niña信号主要从5°N和7°S向西传播;(2)在大洋海盆尺度快速传播信号背景下,存在波长700～800km的慢速传播信号,两类信号将信息在太平洋内传送.传播速度分析表明,慢速传播信号的相速与Rossby波相速相符,而快速传播信号应该是海洋对大气变异的响应.     

稀土钙钛矿型LaMnO3+λ系列化合物的结构计算与分析

在不同氧分压下合成了LaMnO3 λ、系列化合物,用XRD法进行了结构测定与分析,用化学滴定法测定了Mn^4 含量,由测定结果计算晶胞参数,LaMnO3 λ中系数λ值和La^3 空位率。     

牡丹江地区夏季旱涝特征及前兆信号初探

利用牡丹江地区7个测站35年(1967～2001年)夏季(6～8月)平均降水资料,用修订过的正态化Z指数变换方法,对牡丹江地区夏季降水旱涝等级进行了划分,并分析La Nina事件对夏季旱涝的影响。结果表明：牡丹江地区夏季旱涝特征明显,具有阶段性和群发性特点,较重旱涝发生的几率较大;而且对La Nina事件有明显的响应,表现在事件的增长型期间牡丹江地区夏季易发生偏旱,而在减弱型期间易发生雨涝,并认为La Nina事件可以作为预测未来牡丹江地区夏季旱涝的一个重要参考因子。     

不同强度El Nino的衰减过程.Ⅰ,强El Nino的衰减过程

将1951～2004年期间的12次El Nino事件分为强、中等、较弱和弱4类,结果发现,强和较弱El Nino衰减进入La Nina,但是中等和弱El Nino衰减进入平常态.因此,El Nino的衰减结果与自身强度之间存在密切的非线性关系.进一步的研究表明,负异常信号自西太平洋向中东太平洋的东传主导了强El Nino事件向La Nina的转变过程,其具体动力过程类似于西太平洋振子理论.热带西北太平洋（WNP）大气异常反气旋在强El Nino位相转变中起核心作用,它的维持和缓慢东移是赤道东风异常维持和发展的原因,而后者通过激发Kelvin波导致了ENSO从El Nino向La Nina的转变.     

The influence of El Niño-Southern Oscillation (ENSO) cycles on wave-driven sea-floor sediment mobility along the central California continental margin

Ocean surface waves are the dominant temporally and spatially variable process influencing sea floor sediment resuspension along most continental shelves. Wave-induced sediment mobility on the continental shelf and upper continental slope off central California for different phases of El Niño-Southern Oscillation (ENSO) events was modeled using monthly statistics derived from more than 14 years of concurrent hourly oceanographic and meteorologic data as boundary input for the Delft SWAN wave model, gridded sea floor grain-size data from the usSEABED database, and regional bathymetry. Differences as small as 0.5 m in wave height, 1 s in wave period, and 10° in wave direction, in conjunction with the spatially heterogeneous unconsolidated sea-floor sedimentary cover, result in significant changes in the predicted mobility of continental shelf surficial sediment in the study area. El Niño events result in more frequent mobilization on the inner shelf in the summer and winter than during La Niña events and on the outer shelf and upper slope in the winter months, while La Niña events result in more frequent mobilization on the mid-shelf during spring and summer months than during El Niño events. The timing and patterns of seabed mobility are addressed in context of geologic and biologic processes. By understanding the spatial and temporal variability in the disturbance of the sea floor, scientists can better interpret sedimentary patterns and ecosystem structure, while providing managers and planners an understanding of natural impacts when considering the permitting of offshore activities that disturb the sea floor such as trawling, dredging, and the emplacement of sea-floor engineering structures.     

IMPACT OF LATENT HEAT FLUX ON INDIAN SUMMER MONSOON DURING EL NI(N)O/LA NI(N)A YEARS

El Ni(n)o or La Ni(n)a manifest in December over the Pacific and will serve as an index for the forecasting of subsequent Indian summer monsoon,which occurs from June to mid-September.In the present article,an attempt is made to study the variation of latent heat flux (LHF) over the north Indian Ocean during strong El Ni(n)o and strong La Ni(n)a and relate it with Indian monsoon rainfall.During strong El Ni(n)o the LHF intensity is higher and associated with higher wind speed and lower cloud amount.During E1 Ni(n)o all India rainfall is having an inverse relation with LHF.Seasonal rainfall is higher in YY+1 (subsequent year) than YY (year of occurrence).However there is a lag in rainfall during El Ni(n)o YY+1 from June to July when compared with the monthly rainfall.     

2011年4月江西降水异常偏少的初步诊断分析

利用1959-2011年北半球500 hPa高度格点资料、74项环流特征量资料和1974-2011年NOAA OLR月平均资料,结合江西83个气象观测站的1959-2011年4月降水资料,对2011年4月江西降水异常偏少成因进行了初步诊断分析.结果表明:江西省4月降水有一定的周期性,2011年4月降水处于少雨期;La ...     

地震和潮汐对气候波动变化的影响

2004年12月26日印尼地震海啸后,全球低温冻害和暴雪灾害频繁发生."潮汐调温说"和"深海巨震降温说"是一种合理的解释.根据"潮汐调温说"和"深海巨震降温说"理论,2005年以后全球气温将因为地震海啸和强潮汐南北震荡而降低.2009年11月至2010年1月低温暴雪袭击北半球,西方科学家也承认2000～2010年气候的...