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ADVANCES IN ATMOSPHERIC SCIENCES

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Unlocking Earth's ammonia mysteries: China's HIRAS/FY-3D satellite reveals first global map

Chinese scientists have established a full-physical retrieval algorithm to derive the concentration of the atmospheric ammonia from the Hyperspectral Infrared Atmospheric Sounder (HIRAS) onboard the Chinese FengYun (FY)-3D satellite, presenting the first atmospheric NH3 column global map observed by the HIRAS instrument.

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Ocean temperatures helped make 2023 the hottest year ever recorded

A multi-national team of scientists have found each year has been hotter than the prior year in the ocean.

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2023 Canadian wildfires impacted air quality as far away as Europe, China

The whole of the northern hemisphere suffered deterioration of air quality as a result of 2023’s record-setting Canadian wildfires, while Canada’s own ten-year greenhouse gas reduction plan has essentially been erased as a result of emissions from this year’s conflagration.

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Innovative climate data product reveals humidity's role in temperature extremes

The UK Met Office Hadley Centre, introduces an innovative data product, HadISDH.extremes, offering invaluable insights into temperature extremes and their humidity characteristics. This globally gridded monitoring product covers the period from January 1973 to December 2022.

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Diagnosing anthropogenic carbon emissions: a "CO2 checkup" of Earth's health

A Low-cost UAV Coordinated Carbon Observation Network (LUCCN) equipped with medium-accurate greenhouse gas sensors for CO2 measurements is established. LUCCN combines ground-based and UAV-based in-situ measurement instruments, enhancing the detection and quantification capability of point source emissions in three dimensions.

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Volume 41, No. 4 2024

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Regional climate damage quantifications and its impacts on future emission paths using the RICE model

Shili Yang,

Wenjie Dong,

.etc

doi: 10.1007/s00376-024-3193-z

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[Evolving] AI Applications in Atmospheric and Oceanic Science: Pioneering the Future

Causes, Impacts, and Predictability of Droughts for the Past, Present, and Future

2nd Special Issue on Climate Science for Service Partnership China

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The Global Energy and Water Exchanges (GEWEX) Project in Central Asia: The Case for a Regional Hydroclimate Project

Michael BRODY,

Maksim KULIKOV,

Sagynbek ORUNBAEV,

Peter J. VAN OEVELEN

doi: 10.1007/s00376-023-3384-2

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Recent Ventures in Interdisciplinary Arctic Research: The ARCPATH Project

Astrid E. J. OGILVIE,

Leslie A. KING,

Noel KEENLYSIDE,

François COUNILLON,

Brynhildur DAVIÐSDÓTTIR,

Níels EINARSSON,

Sergey GULEV,

Ke FAN,

Torben KOENIGK,

James R. MCGOODWIN,

Marianne H. RASMUSSON,

Shuting YANG

doi: 10.1007/s00376-023-3333-x

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Western North Pacific Tropical Cyclone Database Created by the China Meteorological Administration

Xiaoqin LU,

Hui YU,

Ming YING,

Bingke ZHAO,

Shuai ZHANG,

Limin LIN,

Lina BAI,

Rijin WAN

doi: 10.1007/s00376-020-0211-7

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The Record-breaking Mei-yu in 2020 and Associated Atmospheric Circulation and Tropical SST Anomalies

Yihui DING,

Yunyun LIU,

Zeng-Zhen HU

doi: 10.1007/s00376-021-0361-2

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Recent Progress in Atmospheric Chemistry Research in China: Establishing a Theoretical Framework for the “Air Pollution Complex”

Tong ZHU,

Mingjin TANG,

Meng GAO,

Xinhui BI,

Junji CAO,

Huizheng CHE,

Jianmin CHEN,

Aijun DING,

Pingqing FU,

Jian GAO,

Yang GAO,

Maofa GE,

Xinlei GE,

Zhiwei HAN,

Hong HE,

Ru-Jin HUANG,

Xin HUANG,

Hong LIAO,

Cheng LIU,

Huan LIU,

Jianguo LIU,

Shaw Chen LIU,

Keding LU,

Qingxin MA,

Wei NIE,

Min SHAO,

Yu SONG,

Yele SUN,

Xiao TANG,

Tao WANG,

Tijian WANG,

Weigang WANG,

Xuemei WANG,

Zifa WANG,

Yan YIN,

Qiang ZHANG,

Weijun ZHANG,

Yanlin ZHANG,

Yunhong ZHANG,

Yu ZHAO,

Mei ZHENG,

Bin ZHU,

Jiang ZHU

doi: 10.1007/s00376-023-2379-0

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Mongolia Contributed More than 42% of the Dust Concentrations in Northern China in March and April 2023

Siyu CHEN,

Dan ZHAO,

Jianping HUANG,

Jiaqi HE,

Yu CHEN,

Junyan CHEN,

Hongru BI,

Gaotong LOU,

Shikang DU,

Yue ZHANG,

Fan YANG

doi: 10.1007/s00376-023-3062-1

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Increased Light, Moderate, and Severe Clear-Air Turbulence in Response to Climate Change

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AAS(三角形全等的判定定理之一)_百度百科

三角形全等的判定定理之一)_百度百科 网页新闻贴吧知道网盘图片视频地图文库资讯采购百科百度首页登录注册进入词条全站搜索帮助首页秒懂百科特色百科知识专题加入百科百科团队权威合作下载百科APP个人中心AAS是一个多义词,请在下列义项上选择浏览(共7个义项)展开添加义项AAS播报讨论上传视频三角形全等的判定定理之一收藏查看我的收藏0有用+10AAS,即“角角边”判定定理,一种非常实用的三角形全等证明方法。人教版八年级上册数学教材(2013年6月修订)中的解释为:“两角分别相等且其中一组等角的对边相等的两个三角形全等。” [1]中文名角角边判定定理外文名the AAS law of congruence 别    名AAS、角角边适用领域主要在平面三角形和球面三角形应用学科几何等级划分初中数学教学等级人教版 八年级上册目录1判定定理2证明3其他重点▪区别▪注意点判定定理播报编辑角角边判定定理角角边判定定理,简写为“AAS”或“角角边”。此外,全等三角形判定定理还有"边边边”(SSS) “边角边"(SAS) "角边角"(ASA)等,直角三角形还常用到”斜边直角边“(HL或称RHS)。其中A是英文角(angle)的缩写,S是英文边(side)的缩写,H是斜边(hypotenuse)的缩写,L是直角边(leg)的缩写。证明播报编辑证明AAS:AAS,即角角边,已知两个三角形对应的两个角和其中一个角的对边,问:两个三角形是否全等?或已知两个角和其中一个角的对边,问:此三角形是否唯一?首先已知两个角,也可以算出第三个角的度数,再根据ASA证明三角形全等。证明方法如下:∵已知∠a与∠b,∠a+∠b+∠c=180°∴得知∠c∵已知∠a,线段C,∠c,所以三角形是唯一(ASA)。在AAS中,已知AA两个角,根据三角形内角和等于180°,可以证明剩下的一对角相等然后因ASA可证明三角形全等,所以AAS也可以证明三角形全等。其他重点播报编辑区别也就是方法“AAS”和“ASA”的区别。虽然这二者的证明都需要两角一边的已知条件,但是有巨大的区别:角边角是指两个角和这两个角的公共边,角边角定理可以推出全等。角角边是指两个角和另外一个非公共边,角角边也可以推出全等。两个角和他们的夹角边对应相等的两个三角形全等。注意点1.相等的边必须是对应边,否则AAS不能成立。2.对球面三角形的全等判定而言,AAS不成立,因为内角和是个不定值。新手上路成长任务编辑入门编辑规则本人编辑我有疑问内容质疑在线客服官方贴吧意见反馈投诉建议举报不良信息未通过词条申诉投诉侵权信息封禁查询与解封©2024 Baidu 使用百度前必读 | 百科协议 | 隐私政策 | 百度百科合作平台 | 京ICP证030173号 京公网安备110000020000

【干货】ICP-OES、ICP-MS、AAS傻傻分不清? - 知乎

【干货】ICP-OES、ICP-MS、AAS傻傻分不清? - 知乎切换模式写文章登录/注册【干货】ICP-OES、ICP-MS、AAS傻傻分不清?测试狗科研服务​已认证账号ICP-OES、ICP-MS、AAS傻傻分不清?你知道它们各自的特点是什么吗?在科研的过程中,又该选择哪个来作为分析方法呢?没关系,小编带你详细了解三者在检出限、干扰、容易使用度等方面的特性。珀金埃尔默的AAS、ICP-OES和ICP-MS性能优异,使用简便,快来了解一下吧!ICP-OES,即电感耦合等离子体体(ICP)光谱;而ICP-MS,则是以ICP方式离子化的质谱。有时,人们也会叫“ICP质谱”。那么他们和AAS有何区别?在选择分析方法时又该如何抉择呢?对于拥有ICP-OES技术背景的人来讲,ICP-MS是一个以质谱仪作为检测器的等离子体(ICP),而质谱学家则认为ICP-MS是一个以ICP为源的质谱仪。事实上,ICP-OES和ICP-MS的进样部分及等离子体极其相似。ICP-OES测量的是光学光谱(165~800nm),ICP-MS测量的是离子质谱,提供在3~250amu范围内每一个原子质量单位(amu)的信息,因此,ICP-MS除了元素含量测定外,还可测量同位素。和ICP-OES、ICP-MS比较,AAS是原子吸收光谱,因为只利用原子光谱中单色光照射,所以只能检测一种元素的含量,不过检测限比较低而且重现性比较好。ICP-OES是原子发射光谱,检测原子光谱中的多条谱线,检测限也比较低,而且多通道可以同时检测多种原子和离子,比较方便,重现性也不错。ICP-MS是ICP质谱联用,利用质谱检测同位素含量来检测元素的含量,检出限最低,效果最理想。适用范围:AAS用于已知元素含量的检测;ICP可以用于已知,也可以用于未知,适合多元素分析;ICP-MS由于比较贵而且检出限最低,一般是用作标准测量的时候。01.检出限ICP-MS的检出限给人极深刻的印象,其溶液的检出限大部份为ppt级(必需记牢,实际的检出限不可能优于你实验室的清洁条件),石墨炉AAS的检出限为亚ppb级,ICP-OES大部份元素的检出限为1~10ppb,一些元素在洁净的试样中也可得到令人注目的亚ppb级的检出限。必须指出,ICP-MS的ppt级检出限是针对溶液中溶解物质很少的单纯溶液而言的,若涉及固体中浓度的检出限,由于ICP-MS的耐盐量较差,ICP-MS检出限的优点会变差多达50倍。一些普通的轻元素(如S、Ca、Fe 、K、Se)在ICP-MS中有严重的干扰,也将恶化其检出限。02.干扰以上三种技术呈现了不同类型及复杂的干扰问题,为此,我们对每个技术分别予以讨论。ICP-MS的干扰:质谱干扰、基体酸干扰、双电荷离子干扰、基体效应、电离干扰、空间电荷效应。ICP-OES干扰:光谱干扰、基体效应、电离干扰。GFAAS干扰:光谱干扰、背景干扰、气相干扰、基体效应。03.容易使用度在日常工作中,从自动化来讲,ICP-OES是最成熟的,可由技术不熟练的人员来应用ICP-OES专家制定的方法进行工作。ICP-MS的操作直到现在仍较为复杂,自1993年以来,尽管在计算机控制和智能化软件方面有很大的进步,但在常规分析前仍需由技术人员进行精密调整。ICP-MS的方法研究也是很复杂及耗时的工作。GFAAS的常规工作虽然比较容易,但制定方法仍需要相当熟练的技术。04.试样中的总固体溶解量TDS在常规工作中,ICP-OES可分析10%TDS的溶液,甚至可以高至30%的盐溶液。在短时期内ICP-MS可分析0.5%的溶液,但大部分分析人员乐于采用最多0.2%TDS的溶液。当原始样品是固体时,与ICP-OES、GFAAS相比,ICP-MS需要更高倍数的稀释,其折算到原始固体样品中的检出限会显示不出很大优势,这个现象也就不令人惊奇了。05.线性动态范围LDRICP-MS具有超过105的LDR,各种方法可使其LDR开展至108。但不管如何,对ICP-MS来说:高基体浓度会导致许多问题,而这些问题的最好解决方案是稀释。正由于这个原因,ICP-MS应用的主要领域在痕量/超痕量分析。GFAAS的LDR限制在102~103,如选用次灵敏线可进行高一些浓度的分析。ICP-OES具有105以上的LDR且抗盐份能力强,可进行痕量及主量元素的测定,ICP-OES可测定的浓度高达百分含量,因此,ICP-OES外加ICP-MS,或GFAAS可以很好地满足实验室的需要。06.精密度ICP-MS的短期精密度一般是1~3% RSD,这是应用多内标法在常规工作中得到的。长期(几个小时)精密度为小于5%RSD。使用同位素稀释法可以得到很好的准确度和精密度,但这个方法的费用对常规分析来讲是太贵了。ICP-OES的短期精密度一般为0.3~2%RSD,几个小时的长期精密度小于3%RSD。GFAAS的短期精密度为0.5~5%RSD,影响长期精密度的因素不在于时间,而在于石墨管的使用次数。07.样品分析能力ICP-MS有惊人的能力来分析大量测定痕量元素的样品,典型的分析时间为每个样品小于5分钟,在某些分析情况下只需2分钟。Consulting实验室认为ICP-MS的主要优点即是其分析能力。ICP-OES的分析速度取决于是采用全谱直读型还是单道扫描型,每个样品所需的时间为2或6分钟。全谱直读型较快,一般为2分钟测定一个样品。GFAAS的分析速度为每个样品中每个元素需3~4分钟,晚上可以自动工作,这样保证对样品的分析能力。根据溶液的浓度举例如下,作参考:◆ 每个样品测定1~3个元素,元素浓度为亚或低于ppb级,如果被测元素要求能满足的情况下,GFAAS是最合适的。◆ 每个样品5~20个元素,含量为亚ppm至%,ICP-OES是最合适的。◆ 每个样品需测4个以上的元素,在亚ppb及ppb含量,而且样品的量也相当大,ICP-MS是较合适的。无人控制操作:ICP-MS、ICP-OES和GFAAS,由于现代化的自动化设计以及使用惰性气体的安全性,可以整夜无人看管工作。运行的费用:ICP-MS开机工作的费用要高于ICP-OES,因为ICP-MS的一些部件有一定的使用寿命而且需要更换,这些部件包括了涡轮分子泵、取样锥和截取锥以及检测器。对于ICP-MS和ICP-OES来讲,雾化器与炬管的寿命是相同的。如果实验室选用了ICP-OES来取代ICP-MS,那么实验室最好能配备GFAAS。GFAAS应计算其石墨管的费用。在上述三种技术中Ar气的费用是一笔相当的预算,ICP技术Ar费用远高于GFAAS。ICP-MS、ICP-OES、AAS简单比较声明:本文仅作学术分享之用,若涉及侵权等行为,请先与GO三思(kf01@ceshigo.com)联系,万分感谢!发布于 2019-09-12 16:00科研​赞同 73​​5 条评论​分享​喜欢​收藏​申请

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Advances in Atmospheric Sciences

Advances in Atmospheric Sciences

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Advances in Atmospheric Sciences, launched in 1984, aims to rapidly publish the latest achievements and developments on the dynamics, physics and chemistry of the Earth’s atmosphere and ocean.  It also aims to rapidly publish potentially high influential papers on the atmospheres of other planets and on earth system dynamics in which the atmosphere and/or ocean are involved.

Papers cover the subject areas including but not limited to atmospheric and oceanic theories, modelling and observations; weather and general circulation systems, numerical weather prediction, climate dynamics; satellite meteorology, remote sensing, air chemistry and the boundary layer, clouds and precipitation; earth system dynamics, particularly on interactions of the atmosphere and ocean with the biosphere, the cryosphere, and the anthroposphere. The journal encourages studies seeking universal and generalized laws from local and specific phenomena.

Advances in Atmospheric Sciences is sponsored by the Chinese Committee for International Association of Meteorology and Atmospheric Sciences (IAMAS), the Institute of Atmospheric Physics at Chinese Academy of Sciences and Chinese Meteorological Society. It is the associated journal of IAMAS.

Editors-in-Chief

Mu Mu,

Junji Cao,

Ming Xue

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Xingchao Chen,

Mike Davey,

Jun Li,

Jianhua Lü,

Augustin Vintzileos,

Yuhang Wang,

Lulin Xue

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5.8 (2022)

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4.7 (2022)

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April 2024

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Volume 41, Issue 4

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Latest articles

Spatiotemporal Characteristics of Rainfall over Different Terrain Features in the Middle Reaches of the Yangtze River Basin during the Warm Seasons of 2016–20

Qian WeiJianhua SunXiaofang Wang

Original Paper

05 March 2024

Part of 1 collection:

14th International Conference on Mesoscale Convective Systems and High-Impact Weather

The Global Energy and Water Exchanges (GEWEX) Project in Central Asia: The Case for a Regional Hydroclimate Project

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原子吸收光谱AAS的原理与应用 - 知乎

原子吸收光谱AAS的原理与应用 - 知乎切换模式写文章登录/注册原子吸收光谱AAS的原理与应用测试狗科研服务​已认证账号1. 原子吸收光谱分析定义原子吸收光谱(Atomic absorption spectroscopy,AAS)分析是基于物质所产生的原子蒸汽对特征谱线的吸收,来进行定量分析的一种方法。图1 石墨炉原子吸收光谱仪2. 原子吸收光谱发展历史1802年 Wollaston发现太阳光谱中存在很多暗线。1804~1820解释了暗线是太阳周围大气对太阳光辐射产生了吸收。1860年 系统研究了碱金属及碱土金属光谱,证实了Na产生的光通过Na蒸汽时会引起Na谱线的吸收,认为任何物质能发射特定的波长的辐射就能吸收该波长的辐射。1939年报道了用原子吸收法测定空气中的汞。1953年 Walsh建议使用原子吸收光谱分析法。1955年 Walsh发表了著名论文《原子吸收光谱在化学分析中的应用》奠定了原子吸收光谱分析的理论基础。由于激光、电子学、计算机等技术领域的发展,原子吸收光谱分析技术也日臻完善。3. 原子吸收光谱的原理与特点3.1 原理3.1.1 共振线和吸收线共振发射线:电子从激发态跃迁到基态所产生的发射谱线。共振吸收线:电子从基态跃迁到激发态所产生的吸收谱线。特征谱线:各种元素的原子结构和和外电子排布不同,不同元素的原子从基态激发至第一激发态(或由第一激发态跃迁返回基态)时,吸收(或发射)的能量不同,因而各种元素的共振线不同而各有其特征性,所以这种共振线是元素的特征谱线。3.1.2 吸收定律透过光的强度与原子蒸汽的厚度的关系,服从朗伯定律式中 kν是基态原子对频率为ν的光的吸收系数。3.1.3 谱线轮廓及变宽的原因1. 谱线轮廓:原子群从基态跃迁至激发态所吸收的谱线(吸收线)并不是绝对单色的几何线,而是具有一定的宽度。Kν是光源辐射频率的函数,因此透射光的强度Iν随光的频率而变化。最大吸收对应的频率V0称为峰值吸收频率或中心频率。峰值吸收处的吸收系数K0称为最大吸收系数(或峰值吸收系数)。在峰值吸收一半时(1/2K0),吸收线对应的频率范围称为谱线的半宽度。表征吸收线的轮廓特征的值:中心频率和半宽度。中心频率由原子的能级分布特征决定,而吸收线的半宽度除本身具有的自然宽度外,还受多种因素的影响。2. 谱线变宽效应(1)自然宽度(ΔνN):在无外界影响下,谱线仍具有一定的宽度,这种变宽称为自然宽度。ΔνN与原子发生能级间跃迁时激发态原子的有限寿命有关,是客观存在的。谱线的自然宽度约为ΔνN =10-5 nm,可忽略不计。(2)多普勒变宽ΔνD(Doppler Broadening)多普勒变宽是原子的热运动(无规则的)引起的,又称热变宽。式中:M——原子量; T——绝对温度; ν0——谱线中心频率;即使在较低的温度下,也比自然变宽ΔνN严重,是谱线变宽的主要因素。一般情况下:ΔνD=10-3 nm。(3)压力变宽(碰撞变宽)是由于吸收原子与蒸汽中的原子或分子相互碰撞而引起的变宽。碰撞变宽的程度随砌体的压力的增大而增大,故称压力变宽。同种粒子碰撞——赫尔兹马克(Holtzmank)变宽异种粒子碰撞——劳伦兹(Lorentz)变宽ΔνL压力变宽(碰撞变宽)为10-3 nm,也是谱线变宽的主要因素。(4)自吸变宽当基态、气态原子密度较大时产生。(5)场致变宽斯塔克变宽(Stark broadening):由于外部的电场或等离子体中离子、电子所引起的电场引起的。齐曼变宽(Zeeman broadening):由于外部的磁场影响,导致谱线的分裂,在单色器分辨率无法分辨时,也产生谱线变宽。在1000~3000 K、0.101 MPa状态下时,多普勒宽度ΔνD 和压力变宽(碰撞变宽)是谱线变宽的主要因素。火焰原子化时,ΔνL是主要的;无火焰原子化时,ΔνD是主要的。3.1.4 原子吸收的测量1. 积分吸收原子吸收的全部能量应是吸收线下面所包括的面积。原子蒸汽所吸收的全部能量称为积分吸收。积分公式:f——振子强度e——电子电荷N——单位积内的自由原子数m——电子的质量积分吸收与单位体积原子蒸汽中吸收辐射的原子数成简单的线性关系。这种关系与频率和条件无关,此式是原子吸收分析法的一个重要理论基础。2. 峰值吸收1955年Walsh提出采用锐线光源,测量谱线峰值吸收的办法。锐线光源:能发射出谱线的半宽度很窄的发射线光源。这种锐线光源使发射线的半宽度比吸收线的半宽度小得多,且发射线中心频率与吸收线中心频率一致。3. 积分吸收与峰值吸收的关系1955年澳大利亚学者沃尔森(Walsh)提出,在温度不太高的稳定火焰条件下,峰值吸收系数与火焰中被测元素的原子浓度也正比。积分吸收与火焰中基态原子数的关系为:(1)当仅考虑原子的热运动时,吸收系数的关系为:(2)把式(2)积分后,得到:(3)合并式(1)与式(3)整理后得到:整理后,得到:(4)由式(4)可以得出峰值吸收系数K0与自由原子数N成正比。若能测出峰值吸收K0,即可求出N在实际工作中,测量K0仍有一定的困难。 4.实际测量方法是以一定光强的单色光I0通过原子蒸汽,然后测出被吸收的后的光强I,此吸收符合朗伯定律。此式表明,当使用很窄的锐线光源作为原子吸收测量时,在一定条件下,测得的吸光度与原子蒸汽中待测元素的基态原子数成线性关系。3.2 原子吸收光谱仪的构成、分类及特点图2 原子吸收光谱原理图原子吸收分光光度计主要由辐射光源、原子化器、分光系统和检测系统构成。1. 原子分光光度的类型单光束:结构简单、操作方便、价格低;易漂移(零漂)、稳定性差。双光束:零漂移小、稳定性好。图3 原子吸收分光光度计光路图(a)单光束(b)双光束2. 光源(空心阴极灯)空心阴极:钨棒作为圆筒形筒内熔入被测元素阳极:钨棒装有钛、锆、钽金属做成的阳极管内充气:低压惰性气体Ne或Ar工作电压:150~300伏启动电压:300~500伏,稳流电源供电图4 空心阴极灯示意图锐线光产生原理:在高压电场下,阴极电子向阳极高速飞溅放电,并与载气原子碰撞,使之电离放出二次电子,而使场内正离子和电子增加以维持电流。载气阳离子在电场中大大加速,轰击阴极表面时可将被测元素的原子从晶格中轰出来,即溅射。溅射出的原子大量聚集在空心阴极灯内,经与其它粒子碰撞而被激发,发射出相应元素的特征谱线——共振谱线。3. 原子化器原子化器的作用:原子化实际上是破坏物质组成之间的化学键合,使各元素形成自由原子。原子化器的作用就是使试样中的待测元素转变成基态的气态原子。常见的原子化方法有火焰原子化法和非火焰原子化法。(1)火焰原子化器 火焰原子化过程图5 原子化过程示意图构造:雾化器、预混合室、燃烧室、火焰火焰的基本特性:A)作用:使待测物质分解形成基态原子。B)火焰类型:按燃气和助燃气的比例不同,分为中性火焰、富燃火焰和贫燃火焰。中性火焰:其燃助比与化学计量关系接近(1:4)。火焰层次清晰、温度高、稳定、干扰少。富燃火焰:还原性火焰,燃烧不完全,温度略低于中性火焰,其燃助比大于化学计量比(>1:3),适用于易形成难解离氧化物的元素测定,如Mo、Cr和稀土金属。干扰较多、背景高。贫燃火焰:氧化性火焰,其燃助比小于化学计量比(<1:6),氧化性强、火焰温度较低、适用于易解离、易电离的元素,如碱金属、碱土金属的测定。优点:A)空气-乙炔火焰(2300℃):30多种金属元素的测定,10-4%~10%含量B)笑气-乙炔火焰(2955℃):70多种金属元素的测定,10-4%~10%含量缺点:A)同轴气动雾化器的雾化效率低,5~10%;B)火焰的原子化效率低、还伴随着复杂的火焰反应;C)原子蒸汽在光程中滞留时间短,10-4 s;D)大量气体的稀释作用,限制了检测线的降低;E)只能测液体样品。(2)石墨炉原子化器原理:利用高达数百安陪的电流,通过电阻值很高的石墨管产生高温(3000℃)以实现样品的蒸发和原子化。图6 石墨炉原子化器示意图原子化过程:样品通常以液体形式导入石墨管中,在惰性气氛中分几个升温程序进行加热,是其原子化。升温程序包括:干燥、灰化、原子化和高温净化四步。图7 升温程序优点:A)具有较高的可控温度,3400℃;B)原子蒸汽在光程中的滞留时间长,10-1~10-2 s;C)样品消耗量少(μg和μL级);D)抗干扰能力强——灰化分离;E)灵敏度高,比火焰提高2~3数量级。缺点:A)精密度、重现性差;B)存在记忆效应;C)杂散光引起的背景干扰较严重,需要校正。(4)分光系统原子吸收光度计中分光系统包括出射狭缝、入射狭缝、反射镜和色散原件。单色器的作用:将待测元素的共振线与临近的谱线分开(5)检测系统检测器的作用:将单色器分出来的光信号进行光电转换。AAS中常用光电倍增管做检测器。光电倍增管的检测原理:放大器:将光电管的输出电压信号放大对数转换器:实现的转换。图8 检测系统示意图3.3 原子吸收光谱的干扰效应和消除方法类型:光谱干扰、化学干扰、电离干扰。1. 光谱干扰产生原因:吸收线重叠,待测元素分析线与共存元素的吸收线重叠。消除方法:减少狭缝、降低灯电流、或更换其他分析线。2. 化学干扰产生原因:被测原子与共存元素发生化学反应生成的稳定化合物,影响被测元素原子化效率,统称化学干扰。消除方法:(1)选择合适原子化方法、提高原子化温度;(2)加入释放剂,如磷酸盐干扰Ca,加入La或Sr时,可释放出Ca;(3)消电离剂,加入易电离的元素K、Na、Rb、Cs其强烈的电离而消耗了能量,减少待测元素的电离;(4)保护剂:使待测元素不与干扰元素形成难挥发化合物,使待测元素被保护起来。保护剂大多是络合剂。3. 电离干扰产生原因:在高温下原子的电离使基态原子数减少,吸收下降。消除方法:加入过量消电离剂、降低火焰温度来消除干扰。3.4 原子吸收分析样品的制备方法原子吸收样品大致可以分为无机固体样品、有机固体样品和液体样品三大类。对试样溶剂的要求:溶液要澄清、无悬浮物、稳定。溶液的酸碱度要求:酸度应该在0.1%以上,一般不要超过5%,尽可能标准溶液的酸度保持一致。溶液介质:尽可能用盐酸或硝酸溶液。1. 无机试样的分解(1)水溶解:可溶性无机化合物可直接用水溶液制成测定溶液,考虑到溶液的稳定性及与标准溶液的酸度一致,往往加入一些酸。(2)酸分解:大多数无机化合物、金属、合金、矿石等式样用酸溶解。常用的溶剂有HCI、HNO3、H2SO4、H3PO4、HCIO4、HF以及它们的混合酸如HCI+HNO3、HCI+HF等。为了提高溶解效率,还可以在溶解过程中加入某些氧化剂(如H2O2),盐类(如铵盐)或有机溶剂(如酒石酸)等。在原子吸收光谱中,HNO3和HCI的干扰比较小,因此处理样品时通常使用HNO3和HCI来溶解样品。(3)高温熔融:如石英、锡石SnO、金红石、锆英石等,分解这些样品必须用碱熔融。常见的溶剂有NaOH、LiBO2、Na2O2、K2S2O7等。(4)焙烧、烧结:在低于溶剂熔点的温度下分解试样。烧结的溶剂包括:碳酸钠、碳酸钙、过氧化钠、氧化镁等。2. 有机试样的消解(1)干法灰化:使有机物燃烧,其中的金属元素转化为无机盐,然后用适当的酸溶解灰分制成稀酸溶液,用于原子吸收测定。(2)湿式消解:湿法消化是用浓无机酸或再加氧化剂,在消化过程中保持在氧化状态的条件下消化处理样品。常用的消化剂有HNO3、HNO3+HCI、HNO3+H2SO4、HNO3+HCI+H2O2等,HClO4是一种强氧化剂,但在加热时,容易分解甚至发生爆炸,因此一般不单独使用HClO4来消化有机物,它与其他消化剂混合使用(如HNO3+HCI+HClO4)非常有效。湿法消化法中样品挥发损失比干法灰化要小一些,但对于Hg、Se、Fe等易挥发金属元素仍有较大损失。(3)高压密封罐消解:加热温度一般在120~160℃,加热数小时,消化周期较长。(4)微波消解:微波消解在密封容器内加压进行,避免了挥发性元素的损失,减少了试剂消耗量,不污染环境,消解速度比传统加热消解快4~100倍,且重复性好。4. 原子吸收光谱的应用原子吸收光谱是分析化学领域中极其重要的分析方法。其已广泛应用于冶金、食品、农业、化工、环境保护和材料科学等领域。目前原子吸收已经成为金属元素分析及微量分析的工具之一。1. 元素分析中应用日本京都大学的Hiroaki Konishi等人[1]采用AAS测定了氟穿梭电池(fluoride shuttle batteries,FSB)中Pb在电解液中的溶解量。结果表明,从完全放电(1%)到完全充电(13%),电解液中Pb的含量显著增加,表明放电过程中Pb略有溶解,相反,更多在充电过程中溶解,即Pb→Pb2++2e,上述反应导致了活性物质的损失,进而导致了容量的衰减。2. 有机物分析中的应用主要是将待测的有机物直接(或将其转化为某种化合物后)与金属离子反应,然后用AAS测定反应体系中(或未反应的)过量离子,从而间接求得有机物含量[2]。GuZin Alpdogan等人采用AAS间接确定镇痛药,甲芬那酸、氟芬那酸和双氯芬酸钠的含量。该方法主要基于他们与Cu2+的络合反应,将络合物萃取到氯仿中,通过AAS测定Cu2+的含量间接测定药物浓度。参考文献[1] Hiroaki K , Taketoshi M , Takeshi A , et al. Electrochemical properties of lead fluoride electrode in fluoride shuttle battery[J]. Journal of Electroanalytical Chemistry, 2018, 826:60-64.[2] 田笠卿, 王吉德, 蒋玉琴, 李荣林, 邵名城. 原子吸收分光光度法在有机分析中的应用[A].中国分析测试协会科学技术奖发展回顾, 北京: 北京科学技术出版社, 2015, 164.[3] Güzin A. and Sidika S. Indirect determination of so-me analgesic-inflammatory drugs by AAS[J], Analytical Letters,1999, 32:14, 2799-2808.了解科研前沿,获取科研干货,公众号查询“科学10分钟”/“测试GO”,测试认准测试狗~发布于 2022-08-12 10:38物理学科学原子学​赞同 6​​添加评论​分享​喜欢​收藏​申请

原子吸收光谱法_百度百科

光谱法_百度百科 网页新闻贴吧知道网盘图片视频地图文库资讯采购百科百度首页登录注册进入词条全站搜索帮助首页秒懂百科特色百科知识专题加入百科百科团队权威合作下载百科APP个人中心原子吸收光谱法播报讨论上传视频仪器分析法收藏查看我的收藏0有用+10本词条由“科普中国”科学百科词条编写与应用工作项目 审核 。原子吸收光谱(Atomic Absorption Spectroscopy,AAS),又称原子分光光度法,是基于待测元素的基态原子蒸汽对其特征谱线的吸收,由特征谱线的特征性和谱线被减弱的程度对待测元素进行定性定量分析的一种仪器分析的方法。 [1]中文名原子吸收光谱法外文名Atomic Absorption Spectroscopy别    名原子吸收分光光度法光线范围紫外光和可见光出现时间上世纪50年代简    称AAS测定方法标准曲线法、标准加入法目录1基本原理2谱线轮廓3仪器结构4干扰效应5主要特点▪优越性▪局限性6定量分析方法7应用8发展历史9研究展望基本原理播报编辑原子吸收光谱法 (AAS)是利用气态原子可以吸收一定波长的光辐射,使原子中外层的电子从基态跃迁到激发态的现象而建立的。由于各种原子中电子的能级不同,将有选择性地共振吸收一定波长的辐射光,这个共振吸收波长恰好等于该原子受激发后发射光谱的波长。当光源发射的某一特征波长的光通过原子蒸气时,即入射辐射的频率等于原子中的电子由基态跃迁到较高能态(一般情况下都是第一激发态)所需要的能量频率时,原子中的外层电子将选择性地吸收其同种元素所发射的特征谱线,使入射光减弱。特征谱线因吸收而减弱的程度称吸光度A,在线性范围内与被测元素的含量成正比:A=KC式中K为常数;C为试样浓度;K包含了所有的常数。此式就是原子吸收光谱法进行定量分析的理论基础由于原子能级是量子化的,因此,在所有的情况下,原子对辐射的吸收都是有选择性的。由于各元素的原子结构和外层电子的排布不同,元素从基态跃迁至第一激发态时吸收的能量不同,因而各元素的共振吸收线具有不同的特征。由此可作为元素定性的依据,而吸收辐射的强度可作为定量的依据。AAS现已成为无机元素定量分析应用最广泛的一种分析方法。该法主要适用样品中微量及痕量组分分析。谱线轮廓播报编辑原子吸收光谱线并不是严格几何意义上的线,而是占据着有限的相当窄的频率或波长范围,即有一定的宽度。原子吸收光谱的轮廓以原子吸收谱线的中心波长和半宽度来表征。中心波长由原子能级决定。半宽度是指在中心波长的地方,极大吸收系数一半处,吸收光谱线轮廓上两点之间的频率差或波长差。半宽度受到很多实验因素的影响。影响原子吸收谱线轮廓的两个主要因素:1、多普勒变宽。多普勒宽度是由于原子热运动引起的。从物理学中已知,从一个运动着的原子发出的光,如果运动方向离开观测者,则在观测者看来,其频率较静止原子所发的光的频率低;反之,如原子向着观测者运动,则其频率较静止原子发出的光的频率为高,这就是多普勒效应。原子吸收分析中,对于火焰和石墨炉原子吸收池,气态原子处于无序热运动中,相对于检测器而言,各发光原子有着不同的运动分量,即使每个原子发出的光是频率相同的单色光,但检测器所接受的光则是频率略有不同的光,于是引起谱线的变宽。2、碰撞变宽。当原子吸收区的原子浓度足够高时,碰撞变宽是不可忽略的。因为基态原子是稳定的,其寿命可视为无限长,因此对原子吸收测定所常用的共振吸收线而言,谱线宽度仅与激发态原子的平均寿命有关,平均寿命越长,则谱线宽度越窄。原子之间相互碰撞导致激发态原子平均寿命缩短,引起谱线变宽。碰撞变宽分为两种,即赫鲁兹马克变宽和洛伦茨变宽。赫鲁兹马克变宽是指被测元素激发态原子与基态原子相互碰撞引起的变宽,称为共振变宽,又称赫鲁兹马克变宽或压力变宽。在通常的原子吸收测定条件下,被测元素的原子蒸气压力很少超过10-3mmHg,共振变宽效应可以不予考虑,而当蒸气压力达到0.1mmHg时,共振变宽效应则明显地表现出来。洛伦茨变宽是指被测元素原子与其它元素的原子相互碰撞引起的变宽,称为洛伦茨变宽。洛伦茨变宽随原子区内原子蒸气压力增大和温度升高而增大。除上述因素外,影响谱线变宽的还有其它一些因素,例如场致变宽、自吸效应等。但在通常的原子吸收分析实验条件下,吸收线的轮廓主要受多普勒和洛伦茨变宽的影响。在2000-3000K的温度范围内,原子吸收线的宽度约为10-3-10-2nm。仪器结构播报编辑原子吸收光谱仪由光源、原子化系统、分光系统、检测系统等几部分组成。通常有单光束型和双光束型两类。这种仪器光路系统结构简单,有较高的灵敏度,价格较低,便于推广,能满足日常分析工作的要求,但其最大的缺点是,不能消除光源被动所引起的基线漂移,对测定的精密度和准确度有意境的影响。 [1]1、 光源。光源的功能是发射被测元素的特征共振辐射。对光源的基本要求是:发射的共振辐射的半宽度要明显小于吸收线的半宽度;辐射强度大、背景低,低于特征共振辐射强度的1%;稳定性好,30分钟之内漂移不超过1%;噪声小于0.1%;使用寿命长于5安培小时。空心阴极放电灯是能满足上述各项要求的理想的锐线光源,应用最广。2、原子化器。其功能是提供能量,使试样干燥,蒸发和原子化。 在原子吸收光谱分析中,试样中被测元素的原子化是整个分析过程的关键环节。原子化器主要有四种类型火焰原子化器、石墨炉原子化器、氢化物发生原子化器及冷蒸气发生原子化器。实现原子化的方法,最常用的有两种:火焰原子化法:是原子光谱分析中最早使用的原子化方法,至今仍在广泛地被应用;非火焰原子化法,其中应用最广的是石墨炉电热原子化法。3、分光器。它由入射和出射狭缝、反射镜和色散元件组成,其作用是将所需要的共振吸收线分离出来。分光器的关键部件是色散元件,商品仪器都是使用光栅。原子吸收光谱仪对分光器的分辨率要求不高,曾以能分辨开镍三线Ni230.003、Ni231.603、Ni231.096nm为标准,后采用Mn279.5和279.8nm代替Ni三线来检定分辨率。光栅放置在原子化器之后,以阻止来自原子化器内的所有不需要的辐射进入检测器。4、检测系统。原子吸收光谱仪中广泛使用的检测器是光电倍增管,一些仪器也采用CCD作为检测器。干扰效应播报编辑原子吸收光谱分析法与原子发射光谱分析法相比,尽管干扰较少并易于克服,但在实际工作中干扰效应仍然经常发生,而且有时表现得很严重,因此了解干扰效应的类型、本质及其抑制方法很重要。原子吸收光谱中的干扰效应一般可分为四类:物理干扰、化学干扰、电离干扰和光谱干扰。物理干扰及其抑制物理干扰指试样在前处理、转移、蒸发和原子化的过程中,试样的物理性质、温度等变化而导致的吸光度的变化。物理干扰是非选择性的,对溶液中各元素的影响基本相似。削除和抑制物理干扰常采用如下方法:(1) 配制与待测试样溶液相似组成的标准溶液,并在相同条件下进行测定。如果试样组成不详,采用标准加入法可以削除物理干扰。(2) 尽可能避免使用粘度大的硫酸、磷酸来处理试样;当试液浓度较高时,适当稀释试液也可以抑制物理干扰。化学干扰及其抑制化学干扰是指待测元素在分析过程中与干扰元素发生化学反应,生成了更稳定的化合物,从而降低了待测元素化合物的解离及原子化效果,使测定结果偏低。这种干扰具有选择性,它对试样中各种元素的影响各不相同。化学干扰的机理很复杂,消除或抑制其化学干扰应该根据具体情况采取以下具体措置措施:1、加入干扰抑制剂(1) 加入稀释剂 加入释放剂与干扰元素生成更稳定或更难挥发的化合物,从而使被测定元素从含有干扰元素的化合物中释放出来。(2) 加入保护剂 保护剂多数是有机络合物。它与被测定元素或干扰元素形成稳定的络合物,避免待测定元素与干扰元素生成难挥发化合物。(3) 加入缓冲剂 有的干扰,当干扰物质达到一定浓度时,干扰趋于稳定,这样,把被测溶液和标准溶液加入同样量的干扰物质时,干扰物质对测定就不会发生影响。2、选择合适的原子化条件提高原子化温度,化学干扰一般会减小,使用高温火焰或提高石墨炉原子化温度,可使难解离的化合物分解。3、加入基体改进剂用石墨炉原子化时,在试样中加入基体改进剂,使其在干燥或灰化阶段与试样发生化学变化,其结果可能增强基体的挥发性或改变被测元素的挥发性,使待测元素的信号区别于背景信号。当以上方法都未能消除化学干扰时,可采用化学分离的方法,如溶剂萃取、离子交换、沉淀分离等方法。电离干扰及其抑制电离干扰是指待测元素在高温原子化过程中,由于电离作用而使参与原子吸收的基态原子数目减少而产生的干扰。为了抑制这种电离干扰,可加入过量的消电离剂。由于消电离剂在高温原子化过程中电离作用强于待测元素,它们可产生大量自由电子,使待测元素的电离受到抑制,从而降低或消除了电离干扰。光谱干扰及其抑制光谱干扰是指在单色器的光谱通带内,除了待测元素的分析线之外,还存在与其相邻的其他谱线而引起的干扰,常见的有以下三种。1、吸收线重叠一些元素谱线与其他元素谱线重叠,相互干扰。可另选灵敏度较高而干涉少的分析线抑制干扰或采用化学分离方法除去干扰元素。2、光谱通带内的非吸收线这是与光源有关的光谱干扰,即光源不仅发射被测元素的共振线,往往发射与其邻近的非吸收线。对于这些多重发射,被测元素的原子若不吸收,它们被监测器检测,产生一个不变的背景型号,使被测元素的测定敏感度降低;若被测元素的原子对这些发射线产生吸收,将使测定结果不正确,产生较大的正误差。消除方法,可以减小狭缝宽度,使光谱通带小到可以阻挡多重发射的谱线,若波长差很小,则应另选分析线,降低灯电流也可以减少多重发射。3、背景干扰和抑制背景干扰包括分子吸收、光散射等。分子吸收是原子化过程中生成的碱金属和碱土金属的卤化物、氧化物、氢氧化物等的吸收和火焰气体的吸收,是一种带状光谱,会在一定波长范围内产生干扰。光散射是原子化过程中产生的微小固体颗粒使光产生散射,吸光度增加,造成假吸收。波长越短,散射影响越大。背景干扰都使吸光度增大,产生误差。石墨炉原子化法背景吸收干扰比火焰原子化法来得严重,有时不扣除背景会给测定结果带来较大误差。用于商品仪器的背景矫正方法主要是氘灯扣除背景、塞曼效应扣除背景。 [1]主要特点播报编辑优越性原子吸收光谱法该法具有检出限低(火焰法可达μg/cm–3级)准确度高(火焰法相对误差小于1%),选择性好(即干扰少)分析速度快,应用范围广(火焰法可分析30多种/70多种元素,石墨炉法可分析70多种元素,氢化物发生法可分析11种元素)等优点 [2]。1 选择性强。这是因为原子吸收带宽很窄的缘故。因此,测定比较快速简便,并有条件实现自动化操作。在发射光谱分析中,当共存元素的辐射线或分子辐射线不能和待测元素的辐射线相分离时,会引起表观强度的变化。而对原子吸收光谱分析来说:谱线干扰的几率小,由于谱线仅发生在主线系,而且谱线很窄,线重叠几率较发射光谱要小得多,所以光谱干扰较小。即便是和邻近线分离得不完全,由于空心阴极灯不发射那种波长的辐射线,所以辐射线干扰少,容易克服。在大多数情况下,共存元素不对原子吸收光谱分析产生干扰。在石墨炉原子吸收法中,有时甚至可以用纯标准溶液制作的校正曲线来分析不同试样。2、灵敏度高。原子吸收光谱分析法是最灵敏的方法之一。火焰原子吸收法的灵敏度是ppm到ppb级,石墨炉原子吸收法绝对灵敏度可达到10-10~10-14g。常规分析中大多数元素均能达到ppm数量级。如果采用特殊手段,例如预富集,还可进行ppb数量级浓度范围测定。由于该方法的灵敏度高,使分析手续简化可直接测定,缩短分析周期加快测量进程;由于灵敏度高,需要进样量少。无火焰原子吸收分析的试样用量仅需试液5~100?l。固体直接进样石墨炉原子吸收法仅需0.05~30mg,这对于试样来源困难的分析是极为有利的。譬如,测定小儿血清中的铅,取样只需10?l即可。3 分析范围广。发射光谱分析和元素的激发能有关,故对发射谱线处在短波区域的元素难以进行测定。另外,火焰发射光度分析仅能对元素的一部分加以测定。例如,钠只有1%左右的原子被激发,其余的原子则以非激发态存在。在原子吸收光谱分析中,只要使化合物离解成原子就行了,不必激发,所以测定的是大部分原子。应用原子吸收光谱法可测定的元素达73种。就含量而言,既可测定低含量和主量元素,又可测定微量、痕量甚至超痕量元素;就元素的性质而言,既可测定金属元素、类金属元素,又可间接测定某些非金属元素,也可间接测定有机物;就样品的状态而言,既可测定液态样品,也可测定气态样品,甚至可以直接测定某些固态样品,这是其他分析技术所不能及的。4、抗干扰能力强。第三组分的存在,等离子体温度的变动,对原子发射谱线强度影响比较严重。而原子吸收谱线的强度受温度影响相对说来要小得多。和发射光谱法不同,不是测定相对于背景的信号强度,所以背景影响小。在原子吸收光谱分析中,待测元素只需从它的化合物中离解出来,而不必激发,故化学干扰也比发射光谱法少得多。5、精密度高。火焰原子吸收法的精密度较好。在日常的一般低含量测定中,精密度为1~3%。如果仪器性能好,采用高精度测量方法,精密度为<1%。无火焰原子吸收法较火焰法的精密度低,一般可控制在15%之内。若采用自动进样技术,则可改善测定的精密度。火焰法:RSD <1%,石墨炉 3~5%。局限性1、不能多元素同时分析。测定元素不同,必须更换光源灯。2、标准工作曲线的线性范围窄(一般在一个数量级范围)。3、样品前处理麻烦。4、仪器设备价格昂贵。5、由于原子化温度比较低,对于一些易于形成稳定化合物的元素,原子化效率低,检出能力差,受化学干扰严重,结果不能令人满意。6、非火焰的石墨炉原子化器虽然原子化效率高、检出率低,但是重现性和准确度较差。7、对操作人员的基础理论和操作技术要求较高。 [3]定量分析方法播报编辑标准曲线法、直接比较法、标准加入法。应用播报编辑原子吸收光谱法已成为实验室的常规方法,能分析70多种元素,广泛应用于石油化工、环境卫生、冶金矿山、材料、地质、食品、医药等各个领域中。 [4]发展历史播报编辑1、第一阶段——原子吸收现象的发现与科学解释1802年,伍朗斯顿(W.H.Wollaston)在研究太阳连续光谱时,发现了太阳连续光谱中出现的暗线。1817年,弗劳霍费(J.Fraunhofer)再次发现了这些暗线,不了解产生这些暗线的原因,于是就将这些暗线称为弗劳霍费线。1859年,克希荷夫(G.Kirchhoff)与本生(R.Bunson解释了暗线产生的原因。2、第二阶段——空心阴极的的发现1955年,澳大利亚科学家瓦尔西(A.Walsh)发表了一片论文《原子吸收光谱在化学分析中的应用》(光谱学报)解决了原子吸收光谱的光源问题,展示了原子吸收光谱仪。3、第三阶段——电热原子化技术的提出1959年,苏联里沃夫发表了电热原子化技术大大提高了原子吸收的灵敏度。1965年英国化学家威利斯J.B.Willis氧化亚氮—乙炔火焰用于原子吸收从30个元素→60~70g个。4、第四阶段——原子吸收分析仪器的发展随着原子吸收技术的发展,推动了原子吸收仪器的不断更新和发展,而其它科学技术进步,为原子吸收仪器的不断更新和发展提供了技术和物质基础。使用连续光源和中阶梯光栅,结合使用光导摄象管、二极管阵列多元素分析检测器,设计出了微机控制的原子吸收分光光度计,为解决多元素同时测定开辟了新的前景。微机控制的原子吸收光谱系统简化了仪器结构,提高了仪器的自动化程度,改善了测定准确度,使原子吸收光谱法的面貌发生了重大的变化。联用技术(色谱-原子吸收联用、流动注射-原子吸收联用)日益受到人们的重视。色谱-原子吸收联用,不仅在解决元素的化学形态分析方面,而且在测定有机化合物的复杂混合物方面,都有着重要的用途,是一个很有前途的发展方向。国内发展1964年,蔡祖泉教授造成第一个空心阴极灯1965年,冶金部有色金属研究院组装成功第一台测量装置1971年,国内开始生产原子吸收光谱仪,随后被广泛使用研究展望播报编辑原子吸收光谱(1)用可调谐激光代替空心阴极灯光源。(2)用激光使样品原子化。它将为微区和薄膜分析提供新手段、为难熔元素的原子化提供了新方法。塞曼效应的应用,使得能在很高的背景下也能顺利地实现测定。连续光源、中阶梯光栅单色器、波长调制原子吸收法(简称CEWM-AA法)是70年代后期发展起来的一种背景校正新技术。它的主要优点是仅用一个连续光源能在紫外区到可见区全波段工作,具有二维空间色散能力的高分辨本领的中阶梯光栅单色器将光谱线在二维空间色散,不仅能扣除散射光和分子吸收光谱带背景,而且还能校正与分折线直接重叠的其他原子吸收线的干扰。使用电视型光电器件做多元素分析鉴定器,结合中阶梯光栅单色器和可调谐激光器代替元素空心阴极灯光源,设计出用电子计算机控制的测定多元素的原子吸收分光光度计,将为解决同时测定多元素问题开辟新的途径。高效分离技术气相色谱、液相色谱的引入,实现分离仪器和测定仪器联用,将会使原子吸收分光光度法的面貌发生重大变化,微量进样技术和固体直接原子吸收分析受到了人们的注意。固体直接原子吸收分析的显著优点是:省去了分解试样步骤,不加试剂,不经任何分离、富集手续,减少了污染和损失的可能性,这对生物、医药、环境、化学等这类只有少量样品供分析的领域将是特别有意义的。所有这些新的发展动向,都很值得引起我们的重视。微型电子计算机应用到原子吸收分光光度计后,使仪器的整机性能和自动化程度达到一个新的阶段。新手上路成长任务编辑入门编辑规则本人编辑我有疑问内容质疑在线客服官方贴吧意见反馈投诉建议举报不良信息未通过词条申诉投诉侵权信息封禁查询与解封©2024 Baidu 使用百度前必读 | 百科协议 | 隐私政策 | 百度百科合作平台 | 京ICP证030173号 京公网安备110000020000

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AAS publishes original articles, letters, comments and responses, data description articles, research highlight, meeting summaries and reviews. AAS also includes a News & Views section, featuring research news and project reports. Please refer to the Guide to Referees for the requirements for the different types of articles. Authors are required to submit on-line via http://mc03.manuscriptcentral.com/aasiap . An article constitutes an outstanding and solid advancement in our understanding on an aspect of atmospheric sciences, including physical oceanography and geophysics, as well as the theoretical and applied areas of these disciplines. The main text (excluding references) should be less than 6000 words, or 22 double-spaced pages of text (Times New Roman, 12 point). Shorter manuscripts are preferred. Articles should have no more than 10 display items (figures and/or tables). The abstract is limited to 250 words and must be unreferenced. 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ADVANCES IN ATMOSPHERIC SCIENCES

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2024-4 Contents

2024,

41(4):

1-1.

[Abstract](30)

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News & Views

Severe Global Environmental Issues Caused by Canada’s Record-Breaking Wildfires in 2023

Zhe WANG,

Zifa WANG,

Zhiyin ZOU,

Xueshun CHEN,

Huangjian WU,

Wending WANG,

Hang SU,

Fang LI,

Wenru XU,

Zhihua LIU,

Jiaojun ZHU

2024,

41(4):

565-571.

doi: 10.1007/s00376-023-3241-0

[Abstract](422)

[FullText HTML]

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Due to the record-breaking wildfires that occurred in Canada in 2023, unprecedented quantities of air pollutants and greenhouse gases were released into the atmosphere. The wildfires had emitted more than 1.3 Pg CO2 and 0.14 Pg CO2 equivalent of other greenhouse gases (GHG) including CH4 and N2O as of 31 August. The wildfire-related GHG emissions constituted more than doubled Canada’s planned cumulative anthropogenic emissions reductions in 10 years, which represents a significant challenge to climate mitigation efforts. The model simulations showed that the Canadian wildfires impacted not only the local air quality but also that of most areas in the northern hemisphere due to long-range transport, causing severe PM2.5 pollution in the northeastern United States and increasing daily mean PM2.5 concentration in northwestern China by up to 2 μg m–3. The observed maximum daily mean PM2.5 concentration in New York City reached 148.3 μg m–3, which was their worst air quality in more than 50 years, nearly 10 times that of the air quality guideline (i.e., 15 μg m–3) issued by the World Health Organization (WHO). Aside from the direct emissions from forest fires, the peat fires beneath the surface might smolder for several months or even longer and release substantial amounts of CO2. The substantial amounts of greenhouse gases from forest and peat fires might contribute to the positive feedback to the climate, potentially accelerating global warming. To better understand the comprehensive environmental effects of wildfires and their interactions with the climate system, more detailed research based on advanced observations and Earth System Models is essential.

CAS-ESM2.0 Successfully Reproduces Historical Atmospheric CO2 in a Coupled Carbon−Climate Simulation

Jiawen ZHU,

Juanxiong HE,

Duoying JI,

Yangchun LI,

He ZHANG,

Minghua ZHANG,

Xiaodong ZENG,

Kece FEI,

Jiangbo JIN

2024,

41(4):

572-580.

doi: 10.1007/s00376-023-3172-9

[Abstract](670)

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(412)

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The atmospheric carbon dioxide (CO2) concentration has been increasing rapidly since the Industrial Revolution, which has led to unequivocal global warming and crucial environmental change. It is extremely important to investigate the interactions among atmospheric CO2, the physical climate system, and the carbon cycle of the underlying surface for a better understanding of the Earth system. Earth system models are widely used to investigate these interactions via coupled carbon–climate simulations. The Chinese Academy of Sciences Earth System Model version 2 (CAS-ESM2.0) has successfully fixed a two-way coupling of atmospheric CO2 with the climate and carbon cycle on land and in the ocean. Using CAS-ESM2.0, we conducted a coupled carbon–climate simulation by following the CMIP6 proposal of a historical emissions-driven experiment. This paper examines the modeled CO2 by comparison with observed CO2 at the sites of Mauna Loa and Barrow, and the Greenhouse Gases Observing Satellite (GOSAT) CO2 product. The results showed that CAS-ESM2.0 agrees very well with observations in reproducing the increasing trend of annual CO2 during the period 1850–2014, and in capturing the seasonal cycle of CO2 at the two baseline sites, as well as over northern high latitudes. These agreements illustrate a good ability of CAS-ESM2.0 in simulating carbon–climate interactions, even though uncertainties remain in the processes involved. This paper reports an important stage of the development of CAS-ESM with the coupling of carbon and climate, which will provide significant scientific support for climate research and China’s goal of carbon neutrality.

Will the Globe Encounter the Warmest Winter after the Hottest Summer in 2023?

Fei ZHENG,

Shuai HU,

Jiehua MA,

Lin WANG,

Kexin LI,

Bo WU,

Qing BAO,

Jingbei PENG,

Chaofan LI,

Haifeng ZONG,

Yao YAO,

Baoqiang TIAN,

Hong CHEN,

Xianmei LANG,

Fangxing FAN,

Xiao DONG,

Yanling ZHAN,

Tao ZHU,

Tianjun ZHOU,

Jiang ZHU

2024,

41(4):

581-586.

doi: 10.1007/s00376-023-3330-0

[Abstract](541)

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(231)

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Abstract:

In the boreal summer and autumn of 2023, the globe experienced an extremely hot period across both oceans and continents. The consecutive record-breaking mean surface temperature has caused many to speculate upon how the global temperature will evolve in the coming 2023/24 boreal winter. In this report, as shown in the multi-model ensemble mean (MME) prediction released by the Institute of Atmospheric Physics at the Chinese Academy of Sciences, a medium-to-strong eastern Pacific El Niño event will reach its mature phase in the following 2−3 months, which tends to excite an anomalous anticyclone over the western North Pacific and the Pacific-North American teleconnection, thus serving to modulate the winter climate in East Asia and North America. Despite some uncertainty due to unpredictable internal atmospheric variability, the global mean surface temperature (GMST) in the 2023/24 winter will likely be the warmest in recorded history as a consequence of both the El Niño event and the long-term global warming trend. Specifically, the middle and low latitudes of Eurasia are expected to experience an anomalously warm winter, and the surface air temperature anomaly in China will likely exceed 2.4 standard deviations above climatology and subsequently be recorded as the warmest winter since 1991. Moreover, the necessary early warnings are still reliable in the timely updated medium-term numerical weather forecasts and sub-seasonal-to-seasonal prediction.

Southern Hemisphere Volcanism Triggered Multi-year La Niñas during the Last Millennium

Shangrong ZHOU,

Fei LIU

2024,

41(4):

587-592.

doi: 10.1007/s00376-023-3254-8

[Abstract](484)

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Abstract:

To explain the recent three-year La Niña event from 2020 to 2022, which has caused catastrophic weather events worldwide, Fasullo et al. (2023) demonstrated that the increase in biomass aerosol resulting from the 2019–20 Australian wildfire season could have triggered this multi-year La Niña. Here, we present compelling evidence from paleo-proxies, utilizing a substantial sample size of 26 volcanic eruptions in the Southern Hemisphere (SH), to support the hypothesis that ocean cooling in the SH can lead to a multi-year La Niña event. This research highlights the importance of focusing on the Southern Ocean, as current climate models struggle to accurately simulate the Pacific response driven by the Southern Ocean.

Original Paper

The 2022 Extreme Heatwave in Shanghai, Lower Reaches of the Yangtze River Valley: Combined Influences of Multiscale Variabilities

Ping LIANG,

Zhiqi ZHANG,

Yihui DING,

Zeng-Zhen HU,

Qi CHEN

2024,

41(4):

593-607.

doi: 10.1007/s00376-023-3007-8

[Abstract](1662)

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(941)

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Abstract:

In the summer of 2022, China (especially the Yangtze River Valley, YRV) suffered its strongest heatwave (HW) event since 1961. In this study, we examined the influences of multiscale variabilities on the 2022 extreme HW in the lower reaches of the YRV, focusing on the city of Shanghai. We found that about 1/3 of the 2022 HW days in Shanghai can be attributed to the long-term warming trend of global warming. During mid-summer of 2022, an enhanced western Pacific subtropical high (WPSH) and anomalous double blockings over the Ural Mountains and Sea of Okhotsk, respectively, were associated with the persistently anomalous high pressure over the YRV, leading to the extreme HW. The Pacific Decadal Oscillation played a major role in the anomalous blocking pattern associated with the HW at the decadal time scale. Also, the positive phase of the Atlantic Multidecadal Oscillation may have contributed to regulating the formation of the double-blocking pattern. Anomalous warming of both the warm pool of the western Pacific and tropical North Atlantic at the interannual time scale may also have favored the persistency of the double blocking and the anomalously strong WPSH. At the subseasonal time scale, the anomalously frequent phases 2–5 of the canonical northward propagating variability of boreal summer intraseasonal oscillation associated with the anomalous propagation of a weak Madden–Julian Oscillation suppressed the convection over the YRV and also contributed to the HW. Therefore, the 2022 extreme HW originated from multiscale forcing including both the climate warming trend and air–sea interaction at multiple time scales.

The Unprecedented Extreme Anticyclonic Anomaly over Northeast Asia in July 2021 and Its Climatic Impacts

Xingyan ZHOU,

Riyu LU

2024,

41(4):

608-618.

doi: 10.1007/s00376-023-3026-5

[Abstract](422)

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(130)

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Abstract:

This study investigates the evolution of an extreme anomalous anticyclone (AA) event over Northeast Asia, which was one of the dominant circulation systems responsible for the catastrophic extreme precipitation event in July 2021 in Henan, and further explores the significant impact of this AA on surface temperatures beneath it. The results indicate that this AA event over Northeast Asia was unprecedented in terms of intensity and duration. The AA was very persistent and extremely strong for 10 consecutive days from 13 to 22 July 2021. This long-lived and unprecedented AA led to the persistence of warmer surface temperatures beyond the temporal span of the pronounced 500-hPa anticyclonic signature as the surface air temperatures over land in Northeast Asia remained extremely warm through 29 July 2021. Moreover, the sea surface temperatures in the Sea of Japan/East Sea were extremely high for 30 consecutive days from 13 July to 11 August 2021, persisting well after the weakening or departure of this AA. These results emphasize the extreme nature of this AA over Northeast Asia in July 2021 and its role in multiple extreme climate events, even over remote regions. Furthermore, possible reasons for this long-lasting AA are explored, and it is suggested to be a byproduct of a teleconnection pattern over extratropical Eurasia during the first half of its life cycle, and of the Pacific–Japan teleconnection pattern during the latter half.

Assessment of Wet Season Precipitation in the Central United States by the Regional Climate Simulation of the WRFG Member in NARCCAP and Its Relationship with Large-Scale Circulation Biases

Yating ZHAO,

Ming XUE,

Jing JIANG,

Xiao-Ming HU,

Anning HUANG

2024,

41(4):

619-638.

doi: 10.1007/s00376-023-2353-x

[Abstract](806)

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(183)

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Abstract:

Assessment of past-climate simulations of regional climate models (RCMs) is important for understanding the reliability of RCMs when used to project future regional climate. Here, we assess the performance and discuss possible causes of biases in a WRF-based RCM with a grid spacing of 50 km, named WRFG, from the North American Regional Climate Change Assessment Program (NARCCAP) in simulating wet season precipitation over the Central United States for a period when observational data are available. The RCM reproduces key features of the precipitation distribution characteristics during late spring to early summer, although it tends to underestimate the magnitude of precipitation. This dry bias is partially due to the model’s lack of skill in simulating nocturnal precipitation related to the lack of eastward propagating convective systems in the simulation. Inaccuracy in reproducing large-scale circulation and environmental conditions is another contributing factor. The too weak simulated pressure gradient between the Rocky Mountains and the Gulf of Mexico results in weaker southerly winds in between, leading to a reduction of warm moist air transport from the Gulf to the Central Great Plains. The simulated low-level horizontal convergence fields are less favorable for upward motion than in the NARR and hence, for the development of moist convection as well. Therefore, a careful examination of an RCM’s deficiencies and the identification of the source of errors are important when using the RCM to project precipitation changes in future climate scenarios.

The Contribution of United States Aircraft Reconnaissance Data to the China Meteorological Administration Tropical Cyclone Intensity Data: An Evaluation of Homogeneity

Ming YING,

Xiaoqin LU

2024,

41(4):

639-654.

doi: 10.1007/s00376-023-3040-7

[Abstract](312)

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(95)

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Abstract:

This paper investigates the homogeneity of United States aircraft reconnaissance data and the impact of these data on the homogeneity of the tropical cyclone (TC) best track data for the seasons 1949–1987 generated by the China Meteorological Administration (CMA). The evaluation of the reconnaissance data shows that the minimum central sea level pressure (MCP) data are relatively homogeneous, whereas the maximum sustained wind (MSW) data show both overestimations and spurious abrupt changes. Statistical comparisons suggest that both the reconnaissance MCP and MSW were well incorporated into the CMA TC best track dataset. Although no spurious abrupt changes were evident in the reconnaissance-related best track MCP data, two spurious changepoints were identified in the remainder of the best-track MCP data. Furthermore, the influence of the reconnaissance MSWs seems to extend to the best track MSWs unrelated to reconnaissance, which might reflect the optimistic confidence in making higher estimates due to the overestimated extreme wind “observations”. In addition, the overestimation of either the reconnaissance MSWs or the best track MSWs was greater during the early decades compared to later decades, which reflects the important influence of reconnaissance data on the CMA TC best track dataset. The wind–pressure relationship (WPR) used in the CMA TC best track dataset is also evaluated and is found to overestimate the MSW, which may lead to inhomogeneity within the dataset between the aircraft reconnaissance era and the satellite era.

Alignment of Track Oscillations during Tropical Cyclone Rapid Intensification

Tong XIE,

Liguang WU,

Yecheng FENG,

Jinghua YU

2024,

41(4):

655-670.

doi: 10.1007/s00376-023-3073-y

[Abstract](685)

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(176)

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Abstract:

Recent studies on tropical cyclone (TC) intensity change indicate that the development of a vertically aligned TC circulation is a key feature of its rapid intensification (RI), however, understanding how vortex alignment occurs remains a challenging topic in TC intensity change research. Based on the simulation outputs of North Atlantic Hurricane Wilma (2005) and western North Pacific Typhoon Rammasun (2014), vortex track oscillations at different vertical levels and their associated role in vortex alignment are examined to improve our understanding of the vortex alignment during RI of TCs with initial hurricane intensity. It is found that vortex tracks at different vertical levels oscillate consistently in speed and direction during the RI of the two simulated TCs. While the consistent track oscillation reduces the oscillation tilt during RI, the reduction of vortex tilt results mainly from the mean track before RI. It is also found that the vortex tilt is primarily due to the mean vortex track before and after RI. The track oscillations are closely associated with wavenumber-1 vortex Rossby waves that are dominant wavenumber-1 circulations in the TC inner-core region. This study suggests that the dynamics of the wavenumber-1 vortex Rossby waves play an important role in the regulation of the physical processes associated with the track oscillation and vertical alignment of TCs.

A Tri-mode of Mock-Walker Cells

Han QIN,

Ji NIE,

Zhiyong MENG

2024,

41(4):

671-679.

doi: 10.1007/s00376-023-3032-7

[Abstract](367)

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(90)

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Abstract:

This work uses cloud-resolving simulations to study mock-Walker cells driven by a specified sea surface temperature (SST). The associated precipitation in the mock-Walker cells exhibits three different modes, including a single peak of precipitation over the SST maximum (mode 1), symmetric double peaks of precipitation straddling the SST maximum (mode 2), and a single peak of precipitation on one side of the SST maximum (mode 3). The three modes are caused by three distinct convective activity center migration traits. Analyses indicate that the virtual effect of water vapor plays an important role in differentiating the three modes. When the SST gradient is large, the virtual effect may be strong enough to overcome the temperature effect, generating a low-level low-pressure anomaly below the ascending branch of the Walker cell off the center. The results here highlight the importance of the virtual effect of water vapor and its interaction with convection and large-scale circulation in the Walker circulation.

Cloud Top Pressure Retrieval Using Polarized and Oxygen A-band Measurements from GF5 and PARASOL Satellites

Lesi WEI,

Huazhe SHANG,

Jian XU,

Chong SHI,

Gegen TANA,

Kefu CHAO,

Shanhu BAO,

Liangfu CHEN,

Husi LETU

2024,

41(4):

680-700.

doi: 10.1007/s00376-023-2382-5

[Abstract](461)

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(109)

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Abstract:

Cloud top pressure (CTP) is one of the critical cloud properties that significantly affects the radiative effect of clouds. Multi-angle polarized sensors can employ polarized bands (490 nm) or O2 A-bands (763 and 765 nm) to retrieve the CTP. However, the CTP retrieved by the two methods shows inconsistent results in certain cases, and large uncertainties in low and thin cloud retrievals, which may lead to challenges in subsequent applications. This study proposes a synergistic algorithm that considers both O2 A-bands and polarized bands using a random forest (RF) model. LiDAR CTP data are used as the true values and the polarized and non-polarized measurements are concatenated to train the RF model to determine CTP. Additionally, through analysis, we proposed that the polarized signal becomes saturated as the cloud optical thickness (COT) increases, necessitating a particular treatment for cases where COT < 10 to improve the algorithm's stability. The synergistic method was then applied to the directional polarized camera (DPC) and Polarized and Directionality of the Earth’s Reflectance (POLDER) measurements for evaluation, and the resulting retrieval accuracy of the POLDER-based measurements (RMSEPOLDER = 205.176 hPa, RMSEDPC = 171.141 hPa, R2POLDER = 0.636, R2DPC = 0.663, respectively) were higher than that of the MODIS and POLDER Rayleigh pressure measurements. The synergistic algorithm also showed good performance with the application of DPC data. This algorithm is expected to provide data support for atmosphere-related fields as an atmospheric remote sensing algorithm within the Cloud Application for Remote Sensing, Atmospheric Radiation, and Updating Energy (CARE) platform.

Climate–Vegetation Coverage Interactions in the Hengduan Mountains Area, Southeastern Tibetan Plateau, and Their Downstream Effects

Congxi FANG,

Jinlei CHEN,

Chaojun OUYANG,

Lu WANG,

Changfeng SUN,

Quan ZHANG,

Jun WEN

2024,

41(4):

701-716.

doi: 10.1007/s00376-023-3077-7

[Abstract](501)

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(190)

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Abstract:

Little is known about the mechanism of climate–vegetation coverage coupled changes in the Tibetan Plateau (TP) region, which is the most climatically sensitive and ecologically fragile region with the highest terrain in the world. This study, using multisource datasets (including satellite data and meteorological observations and reanalysis data) revealed the mutual feedback mechanisms between changes in climate (temperature and precipitation) and vegetation coverage in recent decades in the Hengduan Mountains Area (HMA) of the southeastern TP and their influences on climate in the downstream region, the Sichuan Basin (SCB). There is mutual facilitation between rising air temperature and increasing vegetation coverage in the HMA, which is most significant during winter, and then during spring, but insignificant during summer and autumn. Rising temperature significantly enhances local vegetation coverage, and vegetation greening in turn heats the atmosphere via enhancing net heat flux from the surface to the atmosphere. The atmospheric heating anomaly over the HMA thickens the atmospheric column and increases upper air pressure. The high pressure anomaly disperses downstream via the westerly flow, expands across the SCB, and eventually increases the SCB temperature. This effect lasts from winter to the following spring, which may cause the maximum increasing trend of the SCB temperature and vegetation coverage in spring. These results are helpful for estimating future trends in climate and eco-environmental variations in the HMA and SCB under warming scenarios, as well as seasonal forecasting based on the connection between the HMA eco-environment and SCB climate.

Impact of Initial Soil Conditions on Soil Hydrothermal and Surface Energy Fluxes in the Permafrost Region of the Tibetan Plateau

Siqiong LUO,

Zihang CHEN,

Jingyuan WANG,

Tonghua WU,

Yao XIAO,

Yongping QIAO

2024,

41(4):

717-736.

doi: 10.1007/s00376-023-3100-z

[Abstract](336)

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(78)

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Abstract:

Accurate initial soil conditions play a crucial role in simulating soil hydrothermal and surface energy fluxes in land surface process modeling. This study emphasized the influence of the initial soil temperature (ST) and soil moisture (SM) conditions on a land surface energy and water simulation in the permafrost region in the Tibetan Plateau (TP) using the Community Land Model version 5.0 (CLM5.0). The results indicate that the default initial schemes for ST and SM in CLM5.0 were simplistic, and inaccurately represented the soil characteristics of permafrost in the TP which led to underestimating ST during the freezing period while overestimating ST and underestimating SLW during the thawing period at the XDT site. Applying the long-term spin-up method to obtain initial soil conditions has only led to limited improvement in simulating soil hydrothermal and surface energy fluxes. The modified initial soil schemes proposed in this study comprehensively incorporate the characteristics of permafrost, which coexists with soil liquid water (SLW), and soil ice (SI) when the ST is below freezing temperature, effectively enhancing the accuracy of the simulated soil hydrothermal and surface energy fluxes. Consequently, the modified initial soil schemes greatly improved upon the results achieved through the long-term spin-up method. Three modified initial soil schemes experiments resulted in a 64%, 88%, and 77% reduction in the average mean bias error (MBE) of ST, and a 13%, 21%, and 19% reduction in the average root-mean-square error (RMSE) of SLW compared to the default simulation results. Also, the average MBE of net radiation was reduced by 7%, 22%, and 21%.

Persistent Variations in the East Asian Trough from March to April and the Possible Mechanism

Shui YU,

Jianqi SUN

2024,

41(4):

737-753.

doi: 10.1007/s00376-023-3024-7

[Abstract](565)

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(142)

[PDF 11055KB](58)

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Abstract:

The East Asian trough (EAT) profoundly influences the East Asian spring climate. In this study, the relationship of the EATs among the three spring months is investigated. Correlation analysis shows that the variation in March EAT is closely related to that of April EAT. Extended empirical orthogonal function (EEOF) analysis also confirms the co-variation of the March and April EATs. The positive/negative EEOF1 features the persistent strengthened/weakened EAT from March to April. Further investigation indicates that the variations in EEOF1 are related to a dipole sea surface temperature (SST) pattern over the North Atlantic and the SST anomaly over the tropical Indian Ocean. The dipole SST pattern over the North Atlantic, with one center east of Newfoundland Island and another east of Bermuda, could trigger a Rossby wave train to influence the EAT in March−April. The SST anomaly over the tropical Indian Ocean can change the Walker circulation and influence the atmospheric circulation over the tropical western Pacific, subsequently impacting the southern part of the EAT in March−April. Besides the SST factors, the Northeast Asian snow cover could change the regional thermal conditions and lead to persistent EAT anomalies from March to April. These three impact factors are generally independent of each other, jointly explaining large variations in the EAT EEOF1. Moreover, the signals of the three factors could be traced back to February, consequently providing a potential prediction source for the EAT variation in March and April.

Data Description Article

Shallow Convection Dataset Simulated by Three Different Large Eddy Models

Yaxin ZHAO,

Xiaocong WANG,

Yimin LIU,

Guoxiong WU,

Yanjie LIU

2024,

41(4):

754-766.

doi: 10.1007/s00376-023-3106-6

[Abstract](1535)

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(108)

[PDF 3938KB](55)

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Abstract:

Shallow convection plays an important role in transporting heat and moisture from the near-surface to higher altitudes, yet its parameterization in numerical models remains a great challenge, partly due to the lack of high-resolution observations. This study describes a large eddy simulation (LES) dataset for four shallow convection cases that differ primarily in inversion strength, which can be used as a surrogate for real data. To reduce the uncertainty in LES modeling, three different large eddy models were used, including SAM (System for Atmospheric Modeling), WRF (Weather Research and Forecasting model), and UCLA-LES. Results show that the different models generally exhibit similar behavior for each shallow convection case, despite some differences in the details of the convective structure. In addition to grid-averaged fields, conditionally sampled variables, such as in-cloud moisture and vertical velocity, are also provided, which are indispensable for calculation of the entrainment/detrainment rate. Considering the essentiality of the entraining/detraining process in the parameterization of cumulus convection, the dataset presented in this study is potentially useful for validation and improvement of the parameterization of shallow convection.

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