Influence of positive and negative Indian Ocean Dipoles on ENSO via the Indonesian Throughflow: Results from sensitivity experiments

The role of the Indonesian Throughflow(ITF) in the influence of the Indian Ocean Dipole(IOD) on ENSO is investigated using version 2 of the Parallel Ocean Program(POP2) ocean general circulation model. We demonstrate the results through sensitivity experiments on both positive and negative IOD events from observations and coupled general circulation model simulations. By shutting down the atmospheric bridge while maintaining the tropical oceanic channel, the IOD forcing is shown to influence the ENSO event in the following year, and the role of the ITF is emphasized. During positive IOD events,negative sea surface height anomalies(SSHAs) occur in the eastern Indian Ocean, indicating the existence of upwelling.These upwelling anomalies pass through the Indonesian seas and enter the western tropical Pacific, resulting in cold anomalies there. These cold temperature anomalies further propagate to the eastern equatorial Pacific, and ultimately induce a La Nia-like mode in the following year. In contrast, during negative IOD events, positive SSHAs are established in the eastern Indian Ocean, leading to downwelling anomalies that can also propagate into the subsurface of the western Pacific Ocean and travel further eastward. These downwelling anomalies induce negative ITF transport anomalies, and an El Nio-like mode in the tropical eastern Pacific Ocean that persists into the following year. The effects of negative and positive IOD events on ENSO via the ITF are symmetric. Finally, we also estimate the contribution of IOD forcing in explaining the Pacific variability associated with ENSO via ITF.     

汛期强降水过程与月内低频降水的联系及其可能机制

利用1981 2010年中国753站逐日降水观测资料、NCEP/NCAR第二套逐日再分析资料及实况天气图等,选取长江中下游32次大范围持续性强降水过程,分析了该类强降水过程与月内(10~30天)低频降水的联系,并重点讨论了形成该类强降水过程的可能机制。结果表明:(1)长江中下游夏季降水具有显著的月内低频振荡周期。大范围持续性强降水过程基本位于降水低频振荡的峰值阶段。(2)梅汛期(6 7月)月内低频降水峰值位相前期,西太平洋副热带高压(下称西太副高)西伸北进,高低空急流发展加强。在强降水过程发生期,高中低层配置出现垂直方向上的最佳耦合;而台汛期(89月)低频降水峰值位相前期,西太副高东退南撤,低空急流逐渐南落至长江中下游东南部,与高空急流相配合,为强降水过程的发生提供了有利条件。(3)梅汛期东北亚低频位势高度低值区南下,与中纬太平洋西传的低频波列在长江中下游汇合。同时西太副高发展加强,造成了长江中下游降水峰值位相南高北低的低频位势高度分布,有利于强降水过程的发生;台汛期伴随从热带西太平洋到日本海低频波列的西北向移动,菲律宾东北部的低频气旋及其北侧低频反气旋的降水峰值位相分别移至长江中下游和东北亚地区,导致暖湿、干冷气流在长江流域交汇,进而造成强降水过程。(4)菲律宾以东洋面低频强对流可作为梅汛期和台汛期强降水过程发生的前期热带信号,提前低频降水峰值位相10天左右。     

A systematic cross-search for radio/infrared counterparts of XMM-<Emphasis Type="Italic">Newton</Emphasis> sources

We present a catalog of cross-correlated radio, infrared and X-ray sources using a very restrictive selection criteria with an IDL-based code developed by us. The significance of the observed coincidences was evaluated through Monte Carlo simulations of synthetic sources following a well-tested protocol. We found 3320 coincident radio/X-ray sources with a high statistical significance characterized by the sum of error-weighted coordinate differences. For 997 of them, 2MASS counterparts were found. The percentage of chance coincidences is less than 1%. X-ray hardness ratios of well-known populations of objects were used to provide a crude representation of their X-ray spectrum and to make a preliminary diagnosis of the possible nature of unidentified X-ray sources. The results support the fact that the X-ray sky is largely dominated by Active Galactic Nuclei at high galactic latitudes (|b|≥10°). At low galactic latitudes (|b|≤10°) most of unidentified X-ray sources (∼94%) lie at |b|≤2°. This result suggests that most of the unidentified sources found toward the Milky Way plane are galactic objects. Well-known and unidentified sources were classified in different tables with their corresponding radio/infrared and X-ray properties. These tables are intended as a useful tool for researchers interested in particular identifications.     

岩性油藏地震描述技术在准噶尔盆地春光油田的应用

准噶尔盆地春光油田新近系沙湾组岩性油藏埋藏浅、厚度薄、成岩作用差,勘探效果不理想。利用层拉平切片技术确定有利储集相带、分频技术雕刻砂体、"类亮点"特征检测流体、进一步采用拟声波+电阻率反演两步法鉴别流体,这一技术方法系列在春光油田的实际应用效果良好。用拟声波+电阻率反演两步法可以检测出无亮点特征的含油砂体或含水砂体。对于不具备"类亮点"特征的滩坝砂油藏的勘探,可由原来的应用"类亮点"特征直接找油转为寻找有效圈闭,并在此基础上应用合适的流体检测技术,这同样可以发现有利的滩坝砂油藏。     

Contamination levels assessment of potential toxic metals in road dust deposited in different types of urban environment

A total of 42 samples of road dust were collected along ring road, city centre, city side, and freeway in Urumqi, China. Total concentrations of Cd, Cr, Cu, Ni, Pb, Mn, Be, Co, Zn, and U were determined by using the inductively coupled plasma-mass spectrometry in order to assess and to compare road dust contamination levels of metals among the four roads. The results show that, among the four categories of roads, mean concentrations of Co and U vary little. City centre locations show strong enrichments of Cd, Cu, Pb, and Be. Along the ring road, the highest mean concentrations were found for Cr, Ni, Mn, and Co. However, the highest concentrations of Zn and U were found along the freeway. The cluster analysis shows that three main groups can be distinguished. Every group may be associated with different main sources and concentrations of the metals. The results of contamination assessment reveal that, among all of the potential toxic metals, Cd, Cu, and Zn pollution were obviously heavier with moderate or high contamination indices for most road dust samples, while Cr, Ni, and Pb contamination were lower along the four categories of roads. Compared with the city side, Cd, Cu, Pb, Ni, and Zn contamination were heavier along the ring road, the city centre, and the freeway with high traffic density. Low Pb contamination or no contamination in all the road dust samples may be related to the increasing usage of lead-free petrol.     

XX核电厂附近海域生态环境及潜在致灾生物研究

为了了解XX核电厂周边海域的生态环境状况,筛选潜在威胁核电厂冷源安全的致灾生物,分析影响致灾生物时空分布的主要环境因素,本研究于2018年进行了四个季节的生态调查。结果表明,研究海域浮游植物密度秋季最高,春季优势种为东海原甲藻,其他季节优势种为中肋骨条藻等硅藻。浮游动物密度夏季最高,以桡足类为主,春、夏季优势种还包括球型侧腕水母和薮枝螅水母。底栖动物的密度和生物量在秋季最高,优势种主要为豆形短眼蟹、长吻沙蚕和丝异须虫。浮游植物、浮游动物和底栖动物群落均在夏季最为稳定,群落多样性水平和物种丰度较高,且分布较为均匀。浮游植物群落的细胞丰度与悬浮物和磷酸盐的浓度正相关性最高。浮游动物的密度受温度和盐度的影响较大。底栖动物的群落分布主要受悬浮物和无机营养盐的浓度影响。本研究共筛选出17种威胁XX核电厂冷源安全的潜在致灾生物。海地瓜、棘刺锚参、海葵和球型侧腕水母的风险等级较高,其分布主要受温度和盐度的影响。后续工作中,XX核电厂应根据潜在致灾生物与环境因子的关系加强暴发机制研究、提升监测预警能力,并优化驱赶消杀技术和干扰体系,为核电厂冷源安全提供理论和技术保障。     

Soil and vegetation seasonal changes in the grazing Andean Mountain grasslands

Andean grasslands ecosystems are fragile environments with rigorous climatologic conditions and low and variable food for the grazing. The Apolobamba area is located in the Bolivian Andean Mountains. Its high grasslands provide a natural habitat for wild and domestic camelids such as vicuna（Vicugna vicugna） and alpaca（Lama pacos）. The botanical diversity plays an essential role in maintaining vital ecosystem functions. The objectives of this research were to determine the seasonal changes in soil properties, to study the vegetation changes during the wet and dry seasons and the influence of soil properties and camelid densities on the vegetation in the Apolobamba grasslands. Four zones with different vicuna populations were selected to be studied. The following soil parameters were determined： total organic carbon, total nitrogen, available phosphorous, cation exchange capacity, exchangeable cations, pH and texture. The vegetation season changes were studied through botanical identification, above-ground biomass, plant cover and species richness. Results showed that some soil properties such as C/N ratio, CEC, silt and clay percentages kept stable against the seasonal changes. Generally, soil nutrients were relatively higher during the dry season in the surface and subsurface. The results did not point out the predominant vegetation growth during the wet season. The seasonal vegetation growth depended on each species. Thegood soil fertility corresponded to the highest plant cover. Soil fertility presented no influence on the above-ground biomass of the collected species. The negative influence of camelid grazing on soil properties could not be assessed. However, overgrazing could affect some plant species. Therefore, protection is needed in order to preserve the biodiversity in the Andean mountain grasslands.     

一次陕西关中强暴雨环境条件及中尺度系统分析

综合利用T213再分析资料和高时空分辨率观测资料包括地面区域逐时加密观测资料,对2007年8月8—9日陕西关中特大暴雨过程的环境条件和中尺度系统进行了分析。天气学分析表明:500 h Pa西太平洋副热带高压和青藏高原高压形成的高压坝在陕西中部断裂形成东北—西南向切变线、250 h Pa西风急流入口区右侧发散场和700 h Pa东西向切变线相互配合是特大暴雨形成的有利环境条件;低层风向快速变化使关中暴雨区低空水汽经历了减小—突然增加—快速减小的过程,关中周围水汽通过偏东气流输送至暴雨区为暴雨的发生提供了水汽和位势不稳定条件,而水汽的快速变化又形成关中暴雨的突发性和历时短而强的特征;高空反气旋涡度的发展形成强烈的"抽吸作用"、双圈垂直次级环流和强垂直上升运动及其两侧的弱下沉运动形成的不对称结构是暴雨形成的动力机制。强降水的中尺度特征分析显示:强暴雨是由一个中α尺度对流系统(MαCS)的发生发展产生的,MαCS又是由2个中β尺度对流系统(MβCS)合并发展而成,其内部对流单体的发展合并和独立加强形成岐山、礼泉和高陵3个大暴雨中心,这些对流单体的发展是由地面中尺度辐合系统产生的,强降水的强弱与地面中尺度辐合系统的强弱有很好的对应关系,地面中尺度辐合系统的形成和加强可能是强降水的触发机制和增幅原因之一。     

Spectrum Analysis of Wind Profiling Radar Measurements

Unlike previous studies on wind turbulence spectrum in the planetary boundary layer, this investigation focuses on high-altitude （1-5 km） wind energy spectrum and turbulence spectrum under various weather conditions. A fast Fourier transform （FFT） is used to calculate the wind energy and turbulence spectrum density at high altitudes （1-5 km） based on wind profiling radar （WPR） measurements. The turbulence spectrum under stable weather conditions at high altitudes is expressed in powers within a frequency range of 2 × 10-5-10-3 s-1, and the slope b is between -0.82 and -1.04, indicating that the turbulence is in the transition from the energetic area to the inertial sub-range. The features of strong weather are reflected less obviously in the wind energy spectrum than in the turbulence spectrum, with peaks showing up at different heights in the latter spectrum. Cold windy weather appears over a period of 1.5 days in the turbulence spectrum. Wide-range rainstorms exhibit two or three peaks in the spectrum over a period of 15-20 h, while in severe convective weather conditions, there are two peaks at 13 and 9 h. The results indicate that spectrum analysis of wind profiling radar measurements can be used as a supplemental and helpful method for weather analysis.     

哈密地区平原区与山区气候变化差异性分析

利用水文气象站点数据采用线性趋势分析法和Mann-kendall检验法分析了哈密地区与水资源息息相关的山区与平原区气候要素变化的差异性。结果表明：山区与平原区实测站点气候要素多年平均月系列变化规律与趋势基本一致,在量上存在一定的差异;气象站点与水文站点降水要素均呈波动增加的趋势,总体不明显,山区与平原无明显的差别,相对以头道沟站降水增加较明显;气温均呈波动升高的趋势,并且受所处的地理位置影响较大,在相近经度方向上山区气温的升高幅度高于平原区;哈密气象站与头道沟水文站点降水以上世纪70年代增幅最明显,而伊吾气象站和苇子峡水文站以上世纪80-90年代降水增幅最明显;气温除伊吾气象站上世纪90年代升温明显外,其他各站点均以70-80年代升温最明显。