秋行夏令:2021年10月初北方致灾性持续暴雨及水汽极端性分析

2021年10月3—6日,我国北方地区经历了历史罕见的持续性极端强降水过程,暴雨中心稳定维持在陕西中部、山西、京津冀、辽宁等地南部和山东北部,给上述地区造成了巨大的经济损失和严重的人员伤亡。基于台站观测降水、NCEP/NCAR和ERA5再分析资料诊断了本次降水过程的极端性。结果表明,本次暴雨过程无论是降水强度、持续时长还是经向水汽输送均表现出典型北方夏季暴雨和大气环流配置特征。上述五省二市区域平均的过程累计雨量强度远远超过秋季其他暴雨个例,即使在夏季也位列第二。本次过程的极端性与强降水中心稳定在上述地区密切相关。上述五省二市区域平均降水连续4日均超过15 mm,这在秋季历史上从未出现过。除过程的极端性强外,9月山西等地降水异常偏多对10月初秋涝也起到了叠加作用。本次秋涝对应的大气环流呈现出典型的北方夏季主雨季环流型,表现为西太平洋副热带高压（副高）偏西偏北,副高西侧的经向水汽输送异常强盛,同时10月4—6日北方地区发生一次强冷空气过程,冷暖气流交汇在上述地区。水汽收支计算表明,本次过程的经向水汽输送强度为秋季历史之最,甚至超过了盛夏时期北方大部分暴雨过程水汽输送强度。上述分析结果表明,即使在仲秋时节亦可产生有利于北方极端持续暴雨的环流形势和水汽输送,并导致秋涝发生。     

Comparison of soil moisture products from microwave remote sensing,land model,and reanalysis using global ground observations

High-quality soil moisture (SM) datasets are in great demand for climate, hydrology, and other fields, but detailed evaluation of SM products from various sources is scarce. Thus, using 670 SM stations worldwide, we evaluated and compared SM products from microwave remote sensing [Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) (C- and X-bands) and European Space Agency's Climate Change Initiative (ESA CCI)], land surface model [Global Land Data Assimilation System (GLDAS)], and reanalysis data [ECMWF Re-Analysis-Interim (ERA-Interim) and National Centers for Environmental Prediction (NCEP)] under different time scales and various climates and land covers. We find that: (a) ESA CCI and GLDAS have the closest values to the in situ SM on the annual scale, whereas others overestimate the SM; ERA-Interim (averaged R = 0.58) and ESA CCI (averaged R = 0.54) correlate best with the in situ data, while GLDAS performs worst. (b) Overall, the deviations of each product vary in seasons. ESA CCI and ERA-Interim products are closer to the in situ SM at seasonal scales, and AMSR-E and NCEP perform worst in December–February and June–August, respectively. (c) Except for NCEP and ERA-Interim, others can well reflect the intermonthly variation of the in situ SM. (d) Under various climates and land covers, AMSR-E products are less effective in cold climates, whereas GLDAS and NCEP products perform poorly in arid or temperate and dry climates. Moreover, the Bias and R of each SM product differ obviously under different forest types, especially the AMSR-E products. In summary, SM from ESA CCI is the best, followed by ERA-Interim product, and precipitation is an important auxiliary data for selecting high-quality SM stations and improving the accuracy of SM from GLDAS. These results can provide a reference for improving the accuracy of the above SM products.     

Chemical Components,Variation, and Source Identification of PM1 during the Heavy Air Pollution Episodes in Beijing in December 2016

Air pollution is a current global concern. The heavy air pollution episodes(HPEs) in Beijing in December 2016 severely influenced visibility and public health. This study aims to survey the chemical compositions, sources, and formation processes of the HPEs. An aerodyne quadruple aerosol mass spectrometer(Q-AMS) was utilized to measure the non-refractory PM1(NR-PM1) mass concentration and size distributions of the main chemical components including organics, sulfate, nitrate, ammonium, and chloride in situ during 15–23 December 2016. The NR-PM1 mass concentration was found to increase from 6 to 188 μg m–3 within 5 days. During the most serious polluted episode, the PM1 mass concentration was about 2.6 times that during the first pollution stage and even 40 times that of the clean days. The formation rates of PM2.5 in the five pollution stages were 26, 22, 22, 32, and 67 μg m~(–3) h–1, respectively. Organics and nitrate occupied the largest proportion in the polluted episodes, whereas organics and sulfate dominated the submicron aerosol during the clean days. The size distribution of organics is always broader than those of other species, especially in the clean episodes. The peak sizes of the interested species grew gradually during different HPEs. Aqueous reaction might be important in forming sulfate and chloride, and nitrate was formed via oxidization and condensation processes. PMF(positive matrix factorization) analysis on AMS mass spectra was employed to separate the organics into different subtypes. Two types of secondary organic aerosol with different degrees of oxidation consisted of 43% of total organics. By contrast, primary organics from cooking, coal combustion, and traffic emissions comprised 57% of the organic aerosols during the HPEs.     

一次华南强飑线过程的数值模拟及后方入流作用诊断

利用WRF中尺度模式对2014年3月30—31日发生在华南的一次强飑线过程进行数值模拟。本次飑线过程受高空槽和低涡切变线影响,水汽条件充足,低层垂直风切变较强。模拟结果表明:发展阶段,后方入流缺口开始出现,飑线逐渐呈弓形结构;成熟阶段,飑线后方入流逐渐下沉到地面并延伸至对流区前沿,冷池完全移入残留冷区并加强,配合九连山下坡过程,飑线得以加强。后方入流对本次飑线过程的发展和维持十分重要。后方入流受环境风及中层负压力扰动作用开始形成,随后受对流区后侧中低层涡旋对的影响迅速发展增强而进入发展阶段,反气旋式涡旋的北侧风场促进了后方入流的形成和发展;成熟阶段,气旋式涡旋的南侧风场使后方入流迅速增强。气旋式涡旋区域主要受涡管拉伸作用增长,反气旋式涡旋区主要受涡度倾斜增长作用。涡旋对垂直涡度主要是由低层水平涡度向上倾斜引起,而水平涡度则是由斜压作用产生。     

Adsorption kinetics and intraparticulate diffusivities of Hg, As and Pb ions on unmodified and thiolated coconut fiber

As, Hg and Pb are examples of heavy metals which are present in different types of industrial effluents responsible for environmental pollution. Their removal is traditionally made by chemical precipitation, ion-exchange and so on. However, this is expensive and not completely feasible to reduce their concentrations to the levels as low as required by the environmental legislation. Biosorption is a process in which solids of natural origin are employed for binding the heavy metal. It is a promising alternative method to treat industrial effluents, mainly because of its low cost and high metal binding capacity. The kinetics was studied for biosorption experiments using coconut fiber for As (III), Hg (II) and Pb (II) ions adsorption. The specific surface area and surface charge density of the coconut fiber are 1.186×10²⁵ (m²/g) and 5.39 ×10²⁴ (meq/m²), respectively. The maximum adsorption capacity was found to be the highest for Pb (II) followed by Hg (II) and As (III). The modification of the adsorbent by thiolation affected the adsorption capacity. Equilibrium sorption was reached for the metal ions at about 60 min. The equilibrium constant and free energy of the adsorption at 30 °C were calculated. The mechanism of sorption was found to obey the particle-diffusion model. The kinetic studies showed that the sorption rates could be described by both pseudo first-order and pseudo second-order models. The pseudo second-order model showed a better fit with a rate constant value of 1.16 × 10^?4/min. for all three metal ions. Therefore, the results of this study show that coconut fiber, both modified and unmodified, is an efficient adsorbent for the removal of toxic and valuable metals from industrial effluents.     

羌塘盆地侏罗系低渗透碎屑岩储集层特征

羌塘盆地侏罗系碎屑岩主要包括三角洲相、滨海相和河流相砂体,岩性以细砂岩和粉砂岩为主。储层经历了较强的压实作用和胶结作用,颗粒间线—凹凸接触,胶结物主要为钙质和硅质,储集空间以次生溶孔为主,包括颗粒溶孔、粒间溶孔等,溶孔以中孔和小孔为主,喉道为细喉和微喉,构造裂缝的发育对改善储层的渗透性有重要作用。物性统计表明:孔隙度大多小于5%,渗透率小于1mD,为低孔、低渗储层。结合低渗储层分类标准,将碎屑岩储集层分为3类进行了评价,认为上侏罗统雪山组储层最好,其次为中侏罗统雀莫错组,而夏里组相对较差;最有利储集层发育区主要位于北羌塘坳陷西部中央隆起带北缘和盆地东部雀莫错地区,较有利储层发育区位于北羌塘坳陷中部和东部地区,南羌塘坳陷储集层较差。压实作用和胶结作用较强,后期溶蚀作用相对较弱,是造成目前低孔低渗储层的主要因素。     

近代建筑文化景观形成演化与旅游开发研究——以大连旅顺太阳沟为例

人文主义地理学以"我向"角度研究人地关系。人类为逃避自然和逃向自然从而迁徙和改造自然环境,自然环境逐渐被人为改造成各类含有特定文化意义的景观,逃避的过程实际上就是景观形成演化的过程。地方感同样是人文地理研究的一个重要概念,地方感是个人情感的依恋,是文化遗产得以保护利用的重要依据。近代建筑文化景观真实记载了近代城市发展的轨迹,具有较大的历史、文化、艺术和旅游开发价值。以逃避主义与地方感为研究视角,将大连旅顺太阳沟地区建筑文化景观作为研究对象,探讨近代建筑文化景观形成演化过程及其原动力,以及逃避主义和地方感理论在太阳沟旅游开发中的具体指导和应用。     

水库渗漏水中氢氧化铁的矿化特征

对富水水库大坝渗漏水和析出物进行了分析和研究。析出物的主要成分为Fe2O3，并含少量Al2O3和SiO2，铁质析出物的XRD、IR、SEM和TEM分析表明，氢氧化铁的结晶程度较低，主要结晶相为针铁矿，其次为少量伊利石、蒙脱石和石英。电子显微分析观察到在非晶质氢氧化铁凝胶团和亚微米级微粒聚集体中存在特殊的显微管状和螺旋状针铁矿，显示出明显的生物矿化特征。     

澜沧江构造带中南段小定西组火山岩形成时代的厘定及其构造意义

三叠纪忙怀组、小定西组火山岩是澜沧江构造带中南段火山岩带的重要组成部分,是澜沧江古特提斯缝合带构造演化的产物。本文报道了小定西组巨厚玄武岩中安山岩和流纹岩夹层的岩石学、地球化学及锆石LA-ICP-MS年代学及Lu-Hf同位素特征。流纹岩锆石LA-ICP-MS U-Pb定年结果显示小定西组火山岩形成于230Ma。安山岩为高Al2O3的高钾钙碱性岩类,其较强的Nb、Sr和Ti负异常、较弱的Eu负异常、较低的Mg#、(La/Yb)N比值和Cr、Ni含量等特征与小定西组高铝玄武岩极为相似,说明安山岩岩浆与玄武岩岩浆来源相同或相似,是交代地幔物质部分熔融形成的玄武岩浆熔离分异的产物。流纹岩的过铝质特征,强烈Ba、Nb、Ta、Sr、P、Eu和Ti的负异常,与芒怀组流纹岩和临沧花岗岩极为相似,Nb/Ta、Th/Ce和Th/U比值与大陆地壳一致,以及εHf(t)值为-11.6~+9.6,峰值分布于-6.0~+2.0之间,对应的地壳模式年龄(tDM2)为658~1990Ma,大部分集中在1100~1600Ma范围内,反映其岩浆来源于中上地壳物质部分熔融的产物,并加入少量幔源组分的混合岩浆。小定西组玄武岩夹层中的安山岩和流纹岩都具有Rb、Ba、Th、U富集和Nb、Ta和Ti亏损,在微量元素构造环境判别图解上分布于陆缘弧或同碰撞岩浆岩区的特征。结合该区早三叠世地层缺失、晚三叠世磨拉石建造不整合覆盖在下伏地层之上,以及高压变质带的存在等分析认为澜沧江构造带中南段火山岩带中生代火山岩形成于同碰撞环境。在保山地块与印支地块碰撞过程中,交代地幔楔物质部分熔融形成的基性岩浆在上升过程中诱发地壳物质部分熔融形成酸性岩浆,下部基性和上部酸性两个岩浆房的岩浆间歇式喷发,形成下部以酸性火山岩为主(芒怀组),上部以基性火山岩为主(小定西组)的"双峰式"中三叠世火山岩带。