海洋再分析资料中IOD-ENSO遥相关的海洋通道机制分析

本文利用滞后相关分析,研究了海洋再分析资料（SODA、ORAS4和GODAS）中的IOD-ENSO滞后遥相关关系,并与观测资料进行对比。结果显示,3套再分析资料中热带东南印度洋秋季海表温度/海表高度异常和赤道太平洋冷舌次年秋季海表温度/海表高度异常之间显著相关,与观测结果一致。在次表层,观测和再分析资料均显示,热带东南印度洋秋季海表温度异常与赤道太平洋次表层海温异常之间的显著相关关系在冬季至次年秋季沿赤道太平洋垂向剖面向东移动,并于次年夏季和秋季在冷舌区上升至海表。热带东南印度洋和赤道太平洋冷舌滞后1年的相关关系是由海洋通道机制引起的,即IOD事件引起印尼贯穿流流量异常,导致赤道太平洋温跃层异常,激发赤道Kelvin波向东传播,从而影响赤道中-东太平洋冷舌海表温度异常。观测及SODA与ORAS4资料中,热带东南印度洋和赤道太平洋冷舌滞后1年的相关关系在去除ENSO信号后仍然显著,表明海洋通道机制是独立于ENSO事件的;而在GODAS资料中,这些显著相关关系在去除ENSO信号后消失。印尼贯穿流流量异常和Niño3.4及DMI（Dipole Mode Index）指数之间超前-滞后12个月的相关关系显示,在SODA和ORAS4资料中,印尼贯穿流流量同时受到ENSO和IOD的影响,与观测结果一致;而在GODAS中,印尼贯穿流流量异常仅与Niño3.4指数显著相关,极少受到IOD事件的影响,这部分解释了GODAS资料中去除ENSO信号后,IOD-ENSO滞后遥相关关系消失的原因。     

Load transfer and performance evaluation of piled beam-supported embankments

Acta Geotechnica - A ground modification technique with rigid columns and ground beams for supporting an embankment over multilayered soft soils is introduced and investigated. A fully coupled...     

Why does the IOD-ENSO teleconnection disappear in some decades?

Lag correlations between sea surface temperature anomalies(SSTA) in the southeastern tropical Indian Ocean(STIO) in fall and Nio 3.4 SSTA in the eastern equatorial Pacific in the following fall are subjected to decadal variation,with positive correlations during some decades and negative correlations during others. Negative correlations are smaller and of shorter duration than positive correlations. Variations in lag correlations suggest that the use of the Indian Ocean Dipole(IOD) as a predictor of the El Nio Southern Oscillation(ENSO) at a lead time of one year is not effective during some decades. In this study,lag correlations between IOD and ENSO anomalies were analyzed to investigate why the IOD-ENSO teleconnection disappears during decades with negative correlations. Anomalies induced by the IOD in the equatorial Pacific Ocean during decades with negative correlations are still present,but at a greater depth than in decades with positive correlations,resulting in a lack of response to oceanic channel dynamics in the cold tongue SSTA. Lag correlations between oceanic anomalies in the west Pacific warm pool in fall and the equatorial Pacific cold tongue with a one-year time lag are significantly positive during decades with negative correlations. These results suggest that oceanic channel dynamics are overwhelmed by oceanatmosphere coupling over the equatorial Pacific Ocean during decades with negative correlations. Therefore,the Indonesian throughflow is not effective as a link between IOD signals and the equatorial Pacific ENSO.     

重力波与低纬高原地区ＭβＣＳｓ地域特征的关系

利用MM5（V3.6）模式对2003年6月低纬高原地区一次大暴雨过程进行了数值模拟和地形敏感性试验,从重力波的角度研究低纬高原地区MβCSｓ生命史较短这一地域特征形成的原因。分析表明,大气稳定层结利于重力波的产生和传播,重力波的传播导致MβCSｓ的能量向两侧快速频散,使得成熟的MβCSｓ主体强度减弱,两侧有新的MβCSｓ生成并发展,中心降水也迅速减弱。地形敏感性试验表明,低纬高原地形使得大气在不稳定能量积累以后很快释放触发强降水,大气随即转化为稳定层结,利于重力波的快速传播和MβCSｓ主体能量的迅速频散,使得低纬高原地区触发暴雨的MβCSｓ生命史较短,引发的降水具有突发性强、历时短的特征。     

1m红外太阳望远镜光电导行系统中像场旋转的分析

云南天文台1m红外太阳望远镜(YNST)光电导行系统是基于检测太阳像在面阵CMOS图像传感器上的偏移量作为反馈控制信号的高精度闭环跟踪系统[1]。由于YNST是一个地平式装置,在太阳像偏移检测量中存在着像场旋转量,为了获取稳定清晰的太阳像,必须对检测量进行消旋[2]才能达到光电导行系统的跟踪要求。根据球面天文学及天体测量学的知识并结合导行镜的光学系统,推导了光电导行系统中像场旋转的变化规律并对其进行模拟分析。     

印度季风对云南2002年6月6次大到暴雨过程影响分析

利用逐日Micaps 1°× 1°客观分析资料 ,合成分析了 2 0 0 2年 6月 6次大到暴雨过程的大尺度背景场 ,诊断分析了形成大到暴雨的水汽和动力条件。结果表明 :2 0 0 2年 6月的强降水主要由印度季风活动的影响产生 ,孟加拉湾是云南强降水的主要水汽源地 ,为其提供充沛的水汽条件 ,其水汽输送路径与云南降水落区关系密切 ,水汽通量辐合是云南产生强降水的必要条件 ,而川滇间的低涡切变是云南强降水的重要天气系统 ,提供了有利的背景条件及动力条件。     

广西氧化锰矿类型及成矿条件

本文从分析区域成矿地质背景和含锰岩系出发，全面论述了广西氧化锰矿类型，在总体各类氧化锰矿成矿机理和主要特征基础上，综合归并三类七型氧化锰矿划分对比图，其中特别指出岩溶洼地锰矿是地方特色的新类型锰矿，具有很大的找矿意义，在分析广西氧化锰矿的原岩，地质构造，地形地貌，气候及水文地质条件等成矿条件的基础上，建立了氧化锰矿成矿模式图，最后指出了广西氧化锰矿还有很大的找矿远景。     

广西东平表生富集型锰矿床地质特征及成矿条件初步研究

本文主要论述了广西东平表生富集型氧化锰矿床成矿地质环境，含锰岩系地质特征，锰矿层结构，矿石矿物成分及结构构造，矿石化学组分等特征；认为表生富集型氧化锰矿床的形成主要受原生含锰层、地质构造、地形地貌、顶盖层厚度、岩性、气候及水文地质等条件所制约。文章最后讨论了锰矿化富集特征，氧化锰矿成矿模式等并指出探采意义。     

基于IABC优化LSSVR的变形预测研究

针对最小二乘支持向量回归机(LSSVR)中惩罚参数c和核函数参数σ难以确定,以及标准人工蜂群算法(ABC)易陷入局部最优、收敛速度慢等问题,提出一种改进的人工蜂群算法(IABC)来优化LSSVR的参数并进行变形预测研究。首先,IABC算法利用反向学习策略生成正反2个种群来增加初始群体的多样性,一次迭代后对双种群的当前最优食物源进行信息交换以实现优中选优,并设计食物源自适应权重函数及适应度自适应选择函数平衡ABC的勘探和开发能力;其次,以LSSVR的预测精度为目标函数,并将其转化为IABC的适应度函数,以此构建出基于IABC优化LSSVR的预测模型;最后,以基坑监测数据为例,将IABC优化的LSSVR模型、ABC优化的LSSVR模型以及基于PSO的组合模型进行预测对比分析。结果表明,IABC增加了种群的多样性,提高了收敛精度,基于IABC优化的LSSVR模型预测的变形趋势更符合实际,预测精度高于对比模型。     

南海北部东沙岛附近海洋底层流场特征及时间变化规律

Near-bottom currents play important roles in the formation and dynamics of deep-water sedimentary systems.This study examined the characteristics and temporal variations of near-bottom currents, especially the tidal components, based on two campaigns(2014 and 2016) of in situ observations conducted southeast of the Dongsha Island in the South China Sea. Results demonstrated near-bottom currents are dominated by tidal currents, the variance of which could account for ～70% of the total current variance. Diurnal tidal currents were found stronger than semidiurnal currents for both barotropic and baroclinic components. The diurnal tidal currents were found polarized with predominantly clockwise-rotating constituents, whereas the clockwise and counterclockwise constituents were found comparable for semidiurnal tidal currents. It was established that diurnal tidal currents could induce strong current shear. Baroclinic tidal currents showed pronounced seasonal variation with large magnitude in winter and summer and weak magnitude in spring and autumn in 2014. The coherent components accounted for ～65% and ～50% of the diurnal and semidiurnal tidal current variances,respectively. The proportions of the coherent and incoherent components changed little in different seasons. In addition to tidal currents, it was determined that the passing of mesoscale eddies could induce strong nearbottom currents that have considerable influence on the deep circulation.