全球变化条件下的平流层大气长期变化趋势

两个因素将对21世纪平流层气候变化产生重要作用。一个是温室气体增加,另一个是平流层臭氧的可能恢复。温室气体增加的辐射效应一方面造成地面和对流层变暖,另一方面却导致平流层变冷,而臭氧层恢复的辐射效应则导致平流层变暖。在温室气体增加和臭氧恢复这两种相反因素作用下的平流层温度如何变化是所关心的主要问题。为了预估平流层温度在21世纪的变化,使用了辐射—对流模式进行了敏感性实验,另外,也对他人进行的化学—气候耦合模式（CCM）模拟结果进行了分析。这些模拟结果表明,在21世纪平流层中上层（60～1 hPa）将变冷,而下层（150～60 hPa）变暖。这说明在平流层中上层温室气体的冷却效应将起主导作用,而臭氧恢复的加热效应在平流层下层相对更为重要。CCM的模拟结果表明,臭氧恢复最显著的区域在平流层上层（3 hPa附近）,与最大降温区一致,说明温室气体增加将有利于平流层上层臭氧恢复。CCM的模拟结果还表明,平流层两极地区在冬半年存在变暖的现象。根据已有的研究结果,极区变暖与平流层行星波活动增强有关,动力、热力和化学之间的正反馈作用也有可能对极区变暖有重要的贡献。     

北京上空大气臭氧垂直分布的特征

利用我国自行研制的探空仪和地面接收设备首次较系统地获得了北京地区连续一年（2001年 3月至2002年 2月）的大气臭氧垂直分布资料。结果分析表明：①北京地区上空臭氧浓度极大值的季节均值的变化范围为15．1～16．7 mPa,其高度位于20．7～25．1km之间,极小值的季节均值的变化范围为 2．0～2．8 mPa,其高度在对流层顶附近。②边界层和平流层下部是臭氧浓度变化的活跃区域,并具有明显的季节变化,在边界层内夏季臭氧积分浓度高于冬季相应值的 1．7倍之多,而在平流层下部,冬季臭氧积分浓度则高于夏季的相应值。夏季边界层中臭氧浓度偏高,表明臭氧是北京地区夏季重要的污染气体之一。③北京上空臭氧垂直廓线的形态呈多样性,夏秋季节以单峰为主,冬春季节经常出现双峰和多峰结构;次峰出现的区域一般在10～18km高度范围内。     

拉萨上空大气臭氧垂直分布的高空气球探测

用臭氧探空仪于1998年8月和10月测量了在拉萨上空的臭氧垂直分布,并与河北香河的观测资料进行了对比。结果表明,拉萨上空对流层臭氧浓度较低,在25～26 km之间臭氧分压最大,在30～34 km之间混合比最大。从典型的臭氧垂直分布廓线推算出大气臭氧总含量为261.6DU。     

中层大气模式的应用及发展前景

随着空间探测技术和计算机能力的不断提高,近年来中层大气模式得到了快速的发展。简要概述了中层大气模式的现状及其发展中存在的问题和挑战,同时也阐述了中层大气模式在近年来研究中的一些主要应用和未来的发展前景。目前,完备的基于大气环流模式的中层大气模式大多只包括了对流层和平流层大气,少量的模式可达到中间层和热层大气。这些现有的中层大气模式对平流层的化学过程和一些动力过程都具有了一定的模拟能力,如能较好地模拟出南极臭氧空洞及其时间演变以及热带平流层大气中的准两年和准半年振荡信号。但是不同模式模拟结果之间的差异仍然是显著的,现有的中层大气模式还需要进一步的发展和完善。改进模式的辐射传输方案和重力波参数化方案,实现大气化学过程、动力过程和微物理过程的充分耦合,改善平流层以上的大气化学过程和物理过程在模式中的描述是目前正在进行的工作。中层大气模式目前已开始被广泛应用于大气科学研究的各个方面,进一步发展和完善中层大气模式不仅对天气、气候预报具有重要的意义,对空间科学的研究来讲也是需要的。     

某些稀有、有色金属矿床及花岗岩中包裹体微量气体色谱分析研究

研究表明:不同成岩成矿作用不但与温度、压力有关,而且微量气体成分及其含量也有明显的规律变化.例如某爆发岩筒中,酸性气体(HCl、HF、H_2S)含量一般高于不活泼气体(N_2等);随着温度的下降,酸性气体含量减少,而后者增加.在某些地区远离花岗岩体矿物包裹体中CO_2含量有规律地增加,对矿物包裹体中微量气体成分及其含量的研究,有助于解决成岩作用机制,成矿阶段划分及矿床成因.同时,对地球化学找矿,隐伏矿体的揭露也有指导意义.包裹体中微量气体的变化可以作为一个地球化学指示剂.我们在自行研制真空爆裂微量气体测量分析仪的基础上,1979年春,首次成功地使用带热解炉的色谱仪测定了矿物包裹体中H_2O和CO_2等微量气体组分.同时对该色谱仪进行了改装,使该仪器更适合于矿物包裹体微量组分的测定及研究.通过近400多个     

新的臭氧洞现象

南极洲上空的臭氧耗减现象,似乎不仅仅局限于平流层。Schnell等人新近报道,在南极洲的春季里,当上部大气层中出现臭氧洞时,下部大气层即对流层中也出现臭氧损耗现象。这些作者认为,光化学扰动(紫外线辐射增强是由于平流层出现臭氧洞)和对流层环流的变化都与臭氧耗减现象有关。 在1985年首次发现的臭氧洞,出现于平流层中14—22km以上的高度内,每到南极洲的春季,当清新阳光、人为排放的卤化烃及极冷温度引起南极涡流内的冰晶云粒子发生释氯化学反应时,就出现臭氧洞现象。虽然     

臭氧变化及其气候效应的研究进展

综述了近２０年来臭氧变化的规律和机制及其气候效应等领域的研究进展,指出对流层臭氧（主要在北半球）增加、平流层臭氧减少和臭氧总量减少是全球臭氧的变化趋势,原因主要是人类活动导致的ＮＯｘ、ＮＭＨＣ、ＣＯ、ＣＨ４等对流层臭氧前体物的增加和ＮＯｘ、Ｈ２Ｏ、Ｎ２Ｏ、ＣＦＣｓ等平流层臭氧损耗物质的增加。臭氧变化引起的气候效应表现在对流层臭氧的增加将带来地表和低层大气的升温,平流层臭氧的减少则可能导致地表和低层大气的升温或降温。将全球或区域气候模式和大气化学模式进行完全耦合来研究臭氧变化的气候效应是一种十分有效的手段,具有广阔的应用前景。     

平流层爆发性增温中平流层环流及化学成分变化过程研究

利用欧洲中期天气预报中心（ECMWF）气象分析场、欧洲空间局ENVISAT/MIPAS卫星观测资料以及平/对流层大气化学输送模式MOZART 3综合分析了2003—2004年冬季北半球爆发性增温事件对于平流层大气环流、物质输送以及对流层顶附近臭氧通量等多方面的影响。结果表明：①本次增温过程持续时间长、强度大,平流层极涡从高层向下逐层分裂,增温效应作用到大气较低层,当纬向东风形成并维持后极涡又自上向下逐层恢复;②SSW过程前后行星波活动频繁,有长时间多次的上传,且以1波作用为主,2波对其进行补充;③在θ PVLAT坐标中分析发现SSW扰动过程中平流层中存在一对向极、向下的传播模态,相应的对流层中有一向赤道的传播模态,不同符号的纬向风、温度异常信号沿这两个模态传播,且上、下层传播模态在时间上存在着一定的联系;④增温过程中行星波活动引起的向极输送以及极区垂直运动的变化,共同影响了平流层的物质输送过程,从而导致北半球平流层N2O、O3、CH4、H2O等微量气体成分的垂直、水平分布发生显著变化;⑤增温过程中活跃的行星波可以造成平流层Brewer Dobson环流增强,同时导致高纬度地区（60~90°N）穿越对流层顶的臭氧通量（Cross Tropopause Ozone Flux, CTOF）显著增强,与行星波相联系的等熵物质运动引起“middleworld”区域内向赤道的臭氧通量也有所增强。     

大气化学

大气化学是大气科学的一个新的分支学科。在20世纪40年代以前,大气科学的研究集中在大气中发生的宏观现象和物理过程上,大气被当成化学稳定的物理体系。那时,人们只定量地测量过大气的主要成分,即N_2,O_2,惰性气体、平流层臭氧、二氧化碳和水汽。第二次世界大战以后,随着光学、分子光谱学和光学探测、光谱分析技术的发展,高分辩率太阳光谱的观测分析不断揭示出新的大气成分,如CH_4,N_2O,CO,H_2,NH_3,SO_2等微量气体和气溶胶粒子。此后,     

黑河流域水汽输送及收支的时空结构分析

利用NCEP/NCAR再分析气候资料和气象站地面观测资料,分析了黑河流域水汽输送及收支的时空结构变化.结果表明:在水汽输送的年变化中,6-9月为高输送时段,中层700～500 hPa为强输送层,大气水汽含量的年变化是主要影响因子;在水汽输送的年际变化中,1960年代中期和1970年代后期有两次较明显的转折,总体呈下降的长期变化趋势,水汽输送仍以中层输送为主,风速的年际变化是主要影响因子,大气水汽含量下降则提供了长期变化趋势背景.水汽输送的空间结构主要受气流分布的影响,多年平均6-9月的状况为:在低层为南北辐合状,中层为西风辐合状,高层为平直北西风辐散状.水汽净收入以低层为主,占整层水汽净收入的85%以上.在黑河主流区2°×5°的范围内,大气水汽输入为2 484×108m3,输出为2 196×108m3,水汽净收入为288×108m3.     

Ozone trends in the vertical structure of Upper Troposphere and Lower stratosphere over the Indian monsoon region

Ozone trends in the Upper Troposphere and Lower Stratosphere over the Indian region are investigated using three satellite data sets namely Halogen Occultation Experiment (1993–2005), Stratospheric Aerosol and Gas Experiment (1993–2005) II, and Aura Microwave Limb Sounder (MLS, 2005–2011). Estimated ozone trends using multi-variate regression analysis are compared with trends at two Indian ozonesonde stations (Delhi, 28°N, 77°E and Pune, 18°N, 73°E), and a 3-D Chemical Transport Model (CTM, SLIMCAT) for the 1993–2005 time period. Overall, all the observational data sets and model simulations indicate significant increasing trend in the upper troposphere (0–2.5 %/year). In the lower stratosphere, estimated trends are slightly positive up to 30 mb and are negative between 30 and 10 mb. Increasing trends in the upper troposphere is probably due to increasing trends in the tropospheric ozone precursor gases (e.g. CO, NO _x , NMHCs). Here, we argue that these contrasting ozone-trend profiles might be partially responsible for insignificant long-term trends in the tropical total column ozone. On seasonal scale, positive trends are observed during all the seasons in the upper troposphere while structure of trend profile varies in lower stratosphere. Seasonal variations of ozone trends and its linkages with stratospheric intrusions and increasing trends in lightning flashes in the troposphere are also discussed.     

Chlorine in the stratosphere

This paper reviews the various aspects of chlorine compounds in the stratosphere, both their roles as reactants and as tracers of dynamical processes. In the stratosphere, reactive chlorine is released from chlorofluorocarbons and other chlorine-containing organic source gases. To a large extent reactive chlorine is then sequestered in reservoir species ClONO₂ and HCl. Re-activation of chlorine happens predominantly in polar winter vortices by heterogeneous reaction in combination with sunlight. Catalytic cycles involving Cl, ClO, BrO, Cl₂O₂, ClO₂, and others like NO, NO₂, OH, and HO₂ remove odd oxygen (ozone and atomic oxygen) from the atmosphere. Under an ozone hole condition, the ClO dimer cycle is particularly important, while in mid-latitudes the short-lived reservoir HOC1 has some importance. Solar proton events can also affect stratospheric chlorine chemistry, but whether solar protons effectively activate or deactivate chlorine was shown to depend on illumination conditions. The lifetime of chlorofluorocarbons has an impact on the availability of ozone destructing substances in the stratosphere and depends on the Brewer-Dobson circulation which controls at which altitudes and how long an air parcel is exposed to photochemistry. In turn, the chlorine-containing source gases can be used as tracers to constrain the age of stratospheric air and thus to diagnose the Brewer-Dobson circulation. The use of complementary measurement systems was essential to extend our knowledge on chlorine-containing compounds in the stratosphere. ClO is best measured by remote sensing in its rotational bands in the far infrared and microwave region. For HOC1 the far infrared bands are ideal, but some substantial information was also gained with microwave and mid-infrared measurements. ClONO₂ is only measured in the thermal infrared, while HCl has a measurable signal in the microwave, far infrared and mid-infrared regions. The mid-infrared HCl lines, however, are situated at wavelengths where blackbody emission at terrestrial temperatures is so low that infrared measurements of HCl are possible only in solar absorption geometry, but not in thermal emission. Chlorine source gases are most accurately measured by air sampling techniques, while global coverage can only be achieved by satellite-borne thermal infrared measurements. In epistemological terms, research on stratospheric chemistry and particularly the role of chlorine compounds used various scientific concepts from deductive reasoning, falsificationism, abductive reasoning and so-called “puzzle-solving within normal science”. The structuralist theory of science with the concept of non-statement view of theories, however, seems to be best applicable to stratospheric chlorine research of the recent decades.     

过去1 000 a大气中主要温室气体冰芯记录研究概述

对南北两极和中低纬度山地冰芯中开展的温室气体的相关研究进行了回顾.结果显示:在1000aBP到工业革命阶段,大气中CO2,CH4和N2O等温室气体的浓度及气体稳定同位素受各种自然来源影响显著,平均含量较低,浓度波动也较小;工业革命之后,随着人类工农业等活动对环境的影响的加剧,大气中3种温室气体的含量呈现出剧烈的上升趋势.2007年IPCC第四次评估报告显示,目前CO2、CH4和N2O气体浓度的全球大气平均含量分别达到379mL·m-3、1774μL·m-3和319μL·m-3.对影响工业革命前南极、格陵兰及青藏高原冰芯中温室气体的含量的因素总结发现,由于受不同的温度、杂质含量等条件的影响,温室气体含量区域差异较大.1800A.D.以前,格陵兰冰芯中CO2的含量较南极冰芯高出9mL·m-3,青藏高原达索普冰芯CH4平均含量较南极和格陵兰冰盖高出15%～20%,格陵兰冰芯中的N2O含量也明显高于南极冰芯.工业革命以后,冰芯中3种气体浓度表现出强烈的上升趋势,并均达到1000A.D.以来的最高值.     

南极冰盖NO－3浓度记录研究进展

综述了近年来南极冰盖雪冰中NO－ 3浓度的影响因素、NO－ 3的来源、沉积后变化及其浓度的时空变化特征的最新研究进展。尽管质子事件、超新星活动、陨石事件、火山喷发和核试验等各种突发事件都可能对南极雪冰中NO－ 3浓度产生影响,但综述和模拟结果表明中低纬度对流层闪电和极地平流层来源可能是南极雪冰中NO－ 3浓度本底的主要来源。综合研究表明,南极冰盖雪冰中记录的NO－ 3浓度可能是其来源、传输路径、沉积过程以及沉积后变化等的综合反映。     

Is global ozone recovering?

Thanks to the Montreal Protocol, the stratospheric concentrations of ozone-depleting chlorine and bromine have been declining since their peak in the late 1990s. Global ozone has responded: The substantial ozone decline observed since the 1960s ended in the late 1990s. Since then, ozone levels have remained low, but have not declined further. Now general ozone increases and a slow recovery of the ozone layer is expected. The clearest signs of increasing ozone, so far, are seen in the upper stratosphere and for total ozone columns above Antarctica in spring. These two regions had also seen the largest ozone depletions in the past. Total column ozone at most latitudes, however, does not show clear increases yet. This is not unexpected, because the removal of chlorine and bromine from the stratosphere is three to four times slower than their previous increase. Detecting significant increases in total column ozone, therefore, will require much more time than the detection of its previous decline. The search is complicated by variations in ozone that are not caused by declining chlorine or bromine, but are due, e.g., to transport changes in the global Brewer–Dobson circulation. Also, very accurate observations are necessary to detect the expected small increases. Nevertheless, observations and model simulations indicate that the stratosphere is on the path to ozone recovery. This recovery process will take many decades. As chlorine and bromine decline, other factors will become more important. These include climate change and its effects on stratospheric temperatures, changes in the Brewer–Dobson circulation (both due to increasing CO₂), increasing emissions of trace gases like N₂O, CH₄, possibly large future increases of short-lived substances (like CCl₂H₂) from both natural and anthropogenic sources, and changes in tropospheric ozone.     

大气硝酸盐中氮氧稳定同位素研究进展

受人类活动和工农业快速发展的影响,大气硝酸盐(NO_3^-)污染越来越严重且已成为世界范围内的环境问题之一。探究大气NO_3^-的稳定同位素组成(δ15N,δ18O和Δ17O),可以为深入理解大气氮循环、有效控制大气NO_3^-污染提供有力依据。综述了目前大气NO_3^-不同来源NOx的δ15N值、NO_3^-的δ15N季节变化特征及主要影响因素,总结了大气中不同氧化剂的δ18O值和Δ17O值,归纳了全球范围内部分大气NO_3^-中δ18O值和Δ17O值的时空分布特征及可能影响因素,回顾了NO_3^-同位素分析测试技术的主要进展,在前期工作基础上提出未来大气NO_3^-稳定同位素研究应更多关注NO_3^-的氧化生成机制(不同类型氧化剂同位素组成时空差异)、不同NOx来源的δ15N组成、借助化学模型开展大气NO_3^-循环过程等方面的研究。     

Cosmogenic and bomb-produced7Be in stratospheric air

Concentration of⁷Be has been measured in 15 air filters flown at 18·3 km in the latitudes 10 to 25°N and longitudes 80 to 96°W. Testing of nuclear weapons in atmosphere increased⁷Be considerably, on two occasions, above the expected cosmic-ray production level in the stratosphere. This provides evidence for the existence of interhemispheric mixing,via stratosphere.     

Relation between temperature changes of the mid-upper troposphere over Eurasian mid-high latitudes and solar irradiance in the twentieth century

The δ¹⁸O data obtained from an 18.7 m ice core drilled in Chongce Ice Cap at an elevation of 6,530 m a.s.l. in the West Kunlun Mountains on the northern Tibetan Plateau show a strong correlation with the summer temperature of the middle to upper troposphere over the mid-high latitudes of Eurasia. Based on this, the δ¹⁸O record can be used as a proxy of the June–September mean temperature of the mid-upper troposphere (MUT) from 1903 to 1992. The time span of the ice core record is much longer than the meteorological data available only after 1948. Using the empirical mode decomposition method (EMD), the δ¹⁸O record is decomposed into various frequency components and compared with the solar irradiance variations of the same period. The results show that (1) The June–September mean temperature of the MUT over Eurasian mid-high latitudes is completely decomposed into four IMF (intrinsic mode function) components and an increasing trend. (2) Solar irradiance is decomposed into the Schwabe cycle, the Hale cycle, the Gleissberg cycle, and an increasing trend. (3) The correlation coefficients between the June and September mean temperatures of the MUT over Eurasian mid-high latitudes and solar irradiance on the longer timescales (at least more than 11-year) show the significant correlations; their phase changes are basically identical in general, and (4) the 11-year Schwabe cycle exists in the June–September mean temperature of the MUT over Eurasian mid-high latitudes during most of the time from 1903 to 1992, and only in the two high-temperature phases (1929–1944 and from 1975 to the present) may global warming disturb this relation. A full understanding of this phenomenon would shed insight into the potential consequence of global warming on the MUT.     

Carbon dioxide and nitrogenous gases in the soil atmosphere

Carbon dioxide and nitrogenous trace gases (N₂O, NO) in the soil atmosphere are mainly the products of microbially mediated processes. Once produced, these gases pass to the overlying atmosphere primarily via molecular diffusion, a process which is described by Fick's law of diffusion.In a diffusion-dominated soil, the partial pressure, or concentration, of CO₂ in the soil atmosphere varies as a function of soil depth and is dependent on the production rate and diffusivities. Since these parameters are highly variable, CO₂ concentrations vary widely both between, and within, differing ecosystems. In a compilation of data from around the world, arranged according to an ecosystem classification, soil CO₂ concentrations varied from 0.04 to 13.0% by volume in the upper several meters of soil. These data also highlight the importance of organic substrate (soil organic matter, roots, root exudates), temperature, and (to some extent) moisture on CO₂ production and the resulting concentration in soil profiles. The δ¹³C of the soil CO₂ also varies as a function of depth due to differences in the δ¹³C of the organic substrate undergoing decomposition and the mixing with CO₂ of the overlying atmosphere. Recent work suggests that the δ¹⁸O of the soil CO₂ may hold some promise in estimating the δ¹⁸O of soil water.Biological production and consumption of N₂O and NO results primarily from activity of nitrifying and denitrifying bacteria. Ammonium limitation of nitrification and organic carbon limitation of denitrification usually restricts these processes to surface soil horizons, although denitrification may be an important process for reducing NO₃⁻ in groundwater. These microbial processes and the relative proportions of their gaseous end products are strongly influenced by redox conditions. Microsite variation in sources of electron donors and acceptors is critical to understanding rates and distributions of N trace gas production. Several abiological oxidation and reduction reactions are also important, and interaction of biological and abiological processes deserves more research attention.     

Molar gas ratios of air entrapped in ice: A new tool to determine the origin of relict massive ground ice bodies in permafrost

The molar ratios of atmospheric gases change during dissolution in water due to differences in their relative solubilities. We exploited this characteristic to develop a tool to clarify the origin of ice formations in permafrost regions. Extracted from ice, molar gas ratios can distinguish buried glacier ice from intrasedimental ground ice formed by freezing groundwaters. An extraction line was built to isolate gases from ice by melting and trapping with liquid He, followed by analysis of N₂, O_2,, Ar, ¹⁸O_O2 and ¹⁵N_N2, by continuous flow mass spectrometry. The method was tested using glacier ice, aufeis ice (river icing) and intrasedimental ground ice from sites in the Canadian Arctic. O₂/Ar and N₂/Ar ratios clearly distinguish between atmospheric gas in glacial ice and gases from intrasedimental ground ice, which are exsolved from freezing water. δ¹⁵N_N2 and δ¹⁸O_O2 in glacier ice, aufeis ice and intrasedimental ground ice do not show clear distinguishing trends as they are affected by various physical processes during formation such as gravitational settling, excess air addition, mixing with snow pack, and respiration.