平流层臭氧的温室效应及其气候影响

本文阐述大气中重要的“痕量气体”之一——臭氧(平流层臭氧)对地球表面和低层大气的温室效应及其全球气候的反馈影响;指出了云的辐射力的概念及其重要性,并讨论了“南极臭氧洞”现象。     

DEVELOPMENT OF THE 2-D COUPLED STRATOSPHERIC-TROPOSPHERIC DYNAMICAL-RADIATIVE-CHEMICAL MODEL—PART Ⅰ:THE DESCRIPTION OF THE MODEL AND ITS PRELIMINARY RESULTS

In this paper,a two-dimensional(2-D)coupled stratospheric-tropospheric dynamical-radiative-chemical model has been developed,and some preliminary results have been given.From theseresults we can see that the latitude-height distribution characteristics and the seasonal variation ofthe dynamical fields such as atmospheric temperature,wind field,etc.can be effectively simulatedby using this model;and the modelled latitude-height distribution of trace gases gives theirdistribution characteristics and seasonal variation rather well.All of these are testimony to thestrong ability of the model.     

The Gas-Phase Chemistry Of Urban Atmospheres

This paper reviews the chemistry of urban atmospheres,using recent measurement data to highlight the key concepts. We briefly summarise historical reports of air pollution and the impact that human activities have had on urban atmospheres since the IndustrialRevolution. Although pollution events in the first half of the 20th century were caused by high concentrations of smoke and sulphur dioxide, photochemical pollution has become the major problem in most of the major citiesaround the world. The chemistry of photochemical pollution episodes is discussed in some detail, particularly the crucial role played by volatile organic carbon and nitrogen oxides. Issues to be considered when modelling the chemistry of urban areas are briefly summarised, such as the uncertainties in chemical mechanisms and emission inventories, as well as the complexities of dynamical processes. Finally, we present some recent issues in urban chemistry, including the discovery that the amount of volatile organic carbon in urban atmospheres may be grossly under-estimated. We also use modelling resultsto show the importance of the reaction of ozone with reactive hydrocarbons as a radical source in urban atmospheres. Finally, the use of NO_X-NO₂ relationships to predict annual mean NO₂ concentrations is discussed.     

Fourier transform measurement of NO2 absorption cross-section in the visible range at room temperature

New laboratory measurements of NO₂ absorption cross-section were performed using a Fourier transform spectrometer at 2 and 16 cm^-1 (0.03 and 0.26 nm at 400 nm) in the visible range (380–830 nm) and at room temperature. The use of a Fourier transform spectrometer leads to a very accurate wavenumber scale (0.005 cm^-1, 8×10^-5 nm at 400 nm). The uncertainty on the new measurements is better than 4%. Absolute and differential cross-sections are compared with published data, giving an agreement ranging from 2 to 5% for the absolute values. The discrepancies in the differential cross-sections can however reach 18%. The influence of the cross-sections on the ground-based measurement of the stratospheric NO₂ total amount is also investigated.     

南极中山站NO_2的观测及平流层NO_2与O_3的关系分析

利用Ｂｒｅｗｅｒ臭氧仪对南极中山站上空的Ｏ３、ＮＯ２柱总量及平流层Ｏ３、ＮＯ２含量进行了长期观测研究，分析了１９９３～１９９５年，尤其是１９９５年南极臭氧洞和非臭氧洞时期ＮＯ２柱总量及平流层ＮＯ２含量的季节变化及与Ｏ３含量的关系，指出平流层ＮＯ２含量的减少是造成南极臭氧洞成因和近年来不断加剧的一个主要原因。     

Measurement of PAN in the Polluted Boundary Layer and Free Troposphere Using a Luminol-NO2 Detector Combined with a Thermal Converter

Peroxyacetyl nitrate (PAN,CH³C(O)O₂NO₂) has been measured inthe polluted boundary layer and free troposphere by thermal conversion tonitrogen dioxide (NO₂) followed by detection of thedecomposition product with a Scintrex LMA-3 NO₂-luminolinstrument. Following laboratory tests of the efficiency of PAN conversionand investigations of possible interferences, the technique was evaluated atthe West Beckham TOR (Tropospheric Ozone Research) Station near the northNorfolk coast in Eastern England between September 1989 and August 1990. PANmeasured by the new technique was reasonably well correlated with PANrecorded using electron capture gas chromatography (EC/GC). PAN was alsowell correlated with ozone (O³) in the summer months. Springand autumn episodes of simultaneously high concentrations of PAN andO³ were examined in conjunction with air parcelback-trajectories and synoptic- and local-scale meteorology in a study ofthe sources of photooxidants on the east coast of England. Spring-timemeasurements of PAN made in the free troposphere in a light aircraft ataltitudes up to 3.1 km showed the presence of 0.54 and 0.26 ppbv PAN inpolar maritime and mid-latitude oceanic air masses, respectively. Thetechnique is particularly suited to airborne applications because potentialinterferences are minimised and the frequency of measurements is higher thangenerally achieved with EC/GC methods.     

The Potential Influence of ClO·O2 on Stratospheric Ozone Depletion Chemistry

The inability to explain the observedoxygen suppression of chlorine photosensitized ozoneloss remains a gap in our understanding of thephotochemistry responsible for depletion of thestratospheric ozone layer. It has been suggested thatthe presence of a weakly bound ClO·O₂complexcould explain this effect. The existence of thiscomplex would alter the chlorine budget of thestratosphere, perhaps reducing the chlorine availablefor catalytic ozone destruction. On the other hand,the chemistry of ClO·O₂ provides two newpathwaysfor ClO dimer formation, which could increase the rateof catalytic ozone loss. In this paper, we constrainthe kinetic rate system of ClO·O₂ tomatch themeasured Cl_y budget. It is shown thatClO·O₂cannot be both fairly stable and rapidly form the ClOdimer, or the resulting partitioning of chlorinebecomes incompatible with observations of both ClO andtotal available chlorine. These constraints allow thateither: (1) the ClO·O₂ is fairly stable,but doesnot significantly enhance ClO dimer formation andtherefore has a negligible effect on ozone loss rates,or (2) the ClO·O₂ complex is only veryweaklystable, but does rapidly form the ClO dimer, andtherefore can influence stratospheric ozone depletion.Even at the ClO·O₂ mixing ratios allowedunderthe assumption of weak stability, 0.1 to 0.2 ppbv,significant ozone loss rate enhancements werecalculated. Of course, the chlorine budget constraintalso allows for a thirdpossibility; that ClO·O₂ is neither verystablenor forms Cl₂O₂ very rapidly. Measuredlimits on the reaction rates for ClO·O₂to form the ClO dimer would greatly aid the resolution of thisissue. Since the uncertainties aboutClO·O₂chemistry are so large, a potential role forClO·O₂ in stratospheric ozone loss cannotbe ruled out at this time.     

Biological Impact of Elevated Ocean CO<Subscript>2</Subscript> Concentrations: Lessons from Animal Physiology and Earth History

CO₂ currently accumulating in the atmosphere permeates into ocean surface layers, where it may impact on marine animals in addition to effects caused by global warming. At the same time, several countries are developing scenarios for the disposal of anthropogenic CO₂ in the worlds' oceans, especially the deep sea. Elevated CO₂ partial pressures (hypercapnia) will affect the physiology of water breathing animals, a phenomenon also considered in recent discussions of a role for CO₂ in mass extinction events in earth history. Our current knowledge of CO₂ effects ranges from effects of hypercapnia on acid-base regulation, calcification and growth to influences on respiration, energy turnover and mode of metabolism. The present paper attempts to evaluate critical processes and the thresholds beyond which these effects may become detrimental. CO₂ elicits acidosis not only in the water, but also in tissues and body fluids. Despite compensatory accumulation of bicarbonate, acid-base parameters (pH, bicarbonate and CO₂ levels) and ion levels reach new steady-state values, with specific, long-term effects on metabolic functions. Even though such processes may not be detrimental, they are expected to affect long-term growth and reproduction and may thus be harmful at population and species levels. Sensitivity is maximal in ommastrephid squid, which are characterized by a high metabolic rate and extremely pH-sensitive blood oxygen transport. Acute sensitivity is interpreted to be less in fish with intracellular blood pigments and higher capacities to compensate for CO₂ induced acid-base disturbances than invertebrates. Virtually nothing is known about the degree to which deep-sea fishes are affected by short or long term hypercapnia. Sensitivity to CO₂ is hypothesized to be related to the organizational level of an animal, its energy requirements and mode of life. Long-term effects expected at population and species levels are in line with recent considerations of a detrimental role of CO₂ during mass extinctions in the earth's history. Future research is needed in this area to evaluate critical effects of the various CO₂ disposal scenarios. This revised version was published online in July 2006 with corrections to the Cover Date.     

A computational study of the ozone dimer

The dimer of ozone is treatedab initio by the second-order Møller-Plesset perturbation approach with the 6-31G* and 6-1+G* basis sets (with an evaluation of the basis set superposition error and the fourth-order corrections). It is found that the minimum-energy structure exhibitsC _s symmetry (with some patterns resembling the structure of the water dimer). The calculated dimerization energy varies between –13 and –1 kJ/mol. Monomer-dimer shifts in the vibrational frequencies are rather small (about 10 cm^–1 or less) while the inter-molecular frequencies vary between 30 and 120 cm^–1. The ozone dimer could influence some spectral observations under atmospheric conditions.Part III In the series Computational Studies of Atmospheric Chemistry Species; for Part II, see Slaninaet al., 1992.On a leave of absence from the Czechoslovak Academy of Sciences, Prague.