2008年1月乌拉尔阻塞高压异常活动的分析研究

不少研究已经表明, 乌拉尔阻塞高压的持续活动对2008年1月中国南方雨雪冰冻灾害的发生有重要作用。本文针对2008年1月乌拉尔阻塞高压的异常, 利用NCEP再分析逐日环流资料、 哈德莱中心的海温资料等, 从对流层北极涛动(AO)、 平流层极涡(PV) 以及海温异常等几方面, 对2008年1月乌拉尔阻塞高压异常产生的原因进行了分析研究。结果显示, 虽然从以往多年情况来看, 前期AO及平流层极涡的异常很可能会导致其后乌拉尔阻塞高压发生异常, 然而就2008年1月的情况而言, 2007～2008年冬季对流层AO和平流层极涡的异常都不能成为异常乌拉尔阻塞高压产生和偏强的原因, 因为它们的关系与多年存在的长期关系相反。进一步的分析研究则显示, 2007年12月和2008年1月赤道太平洋的La Niña事件也对乌拉尔阻塞高压的活动没有明显影响; 而北大西洋海温正异常, 尤其是北大西洋副热带海温正异常的存在, 是2008年1月乌拉尔阻塞高压持续的重要外强迫因素。     

Reduction of a Model Describing Ozone Oscillations in the Troposphere: Example of an Algorithmic Approach to Model Reduction in Atmospheric Chemistry

We consider a simplified reaction mechanism from tropospheric chemistryconsisting ofsix chemical species involved in ten dynamic processes. The concentrations of all six speciesundergo temporal oscillation for some parameter values. An asymptoticapproach to reduction of the original six-variable model to a four-variable version is considered together with detailed explanation of the procedure as well as discussion of conditions under whichthe reduction is possible. The reduced system nearly quantitatively represents the oscillating behavior of thefull model and allows elucidation of its basic dynamical features. This approach also can be used to compare various small models of atmospheric chemistry, and to determine their underlying dynamic structure. The method can be systematically appliedto larger atmospheric models.     

Air Quality,Climate, and Policy: A Case Study of Ozone Pollution in Tucson,Arizona

This article addresses the need to better understand the complex interactions between climate, human activities, vegetation responses, and surface ozone so that more informed air‐quality policy recommendations can be made. The impacts of intraseasonal climate variations on ozone levels in Tucson, Arizona from April through September of 1995 to 1998 are determined by relating variations in ozone levels to variations in atmospheric conditions and emissions of ozone's precursor chemicals, volatile organic compounds (VOCs) and nitrogen oxides (NO_x), and by determining month‐specific atmospheric conditions that are conducive to elevated ozone levels. Results show that the transport of ozone and its precursor chemicals within the Tucson area causes the highest ozone levels to be measured at a downwind monitor. The highest ozone levels occur in August, due in part to the presence of the North American monsoon. Atmospheric conditions conducive to elevated ozone concentrations differ substantially between the arid foresummer (May and June) and the core monsoon months ( July and August). Transport of pollution from Phoenix may have a substantial impact on elevated ozone concentrations during April, May, and June, while El Paso/Ciudad Juarez –derived pollution may contribute significantly to elevated ozone concentrations in August and September. Two broad policy implications derive from this work. Regional pollutant transport, both within the U.S. and between the U.S. and Mexico, is a potential issue that needs to be examined more intensively in future studies. In addition, spatiotemporal variations in sensitivities of ozone production require the adoption of both NO_x and VOC control measures to reduce ozone levels in the Tucson area.     

Methyl halide hydrolysis rates in natural waters

International regulations are under consideration for methyl bromide because of its high time dependent ozone depletion potential. Geocycling of the species is not well understood, and removal may occur in several types of natural water incuding the oceanic and those in soils. The hydrolysis reaction is a dominant loss pathway in environmental aqueous systems, but rate constants have generally been reported only in distilled water and at greater than room temperature. Here we present measurements in sodium chloride solutions and in seawater in addition to pure water, and at temperatures across the oceanographic range. The reaction could be followed even in solutions near the freezing point because product methanol was monitored in the method of initial rates. Time constants for methyl bromide hydrolysis fall between 10 and 1000 days over the temperatures of the sea, and are always within an order of magnitude of the fastest abiotic destruction mode, chlorination. Activation energies for the two processes are similar so that the ratio of their time scales does not vary with oceanic location. Hydrolysis rate constants are also listed for the closely related compounds methyls iodide and chloride. Solvolysis of the methyl halides in natural waters acts as a source of methanol to the ocean and atmosphere.     

用太阳及天光光度计进行大气臭氧探测

在紫外光谱区，大气臭氧有较丰富的吸收带结构。作者用自制的太阳及天光光度计测量直射阳光、直射月光和曙暮光的紫外吸收光谱，并用带吸收法计算臭氧垂直柱总量及斜程含量。文中介绍了观测和计算方法，并给出北京地区晴朗天气条件下观测的初步结果。     

The dependence of the concentration of OH on its precursors under moderately polluted conditions: A model study

Oxidation of trace gases emitted into the atmosphere is frequently promoted by free radicals. During daytime, the most important radical is the hydroxyl radical, since it reacts with almost all pollutants thereby initializing their ultimate removal from the atmosphere. Since the reaction with OH is in many cases the rate-determining step, the ambient OH concentration is a measure for the atmosphere's oxidation capacity. This paper investigates the influence of the chemical precursors and the photolysis frequencies on the atmospheric OH abundance under moderately polluted and rural conditions. The dominant controlling parameter are the photolysis of ozone and the concentrations of the nitrogen oxides.     

A REGIONAL MODEL STUDY OF THE VARIATIONS AND DISTRIBUTIONS OF OZONE AND ITS PRECURSORS ON EASTERN ASIA AND WEST PACIFIC OCEAN REGIONS

A simulated study of mechanism for variations and distributions of ozone and its precursors was made by using thethree-dimensional regional Eulerian model.The results showed that the ozone production was controlled by NO,butthere is a complicated nonlinear relation between them.The photochemical reactions controlled by solar radiation arethe determinative factors affecting the variations of the surface ozone and its precursors.The relations of ozone and CO,PAN were studied.We compared the simulated and observed results during the PEM-WEST A in order to better under-stand the photochemical processes of ozone and its precursors.     

Hydroperoxides in the marine troposphere over the Atlantic Ocean

Hydrogen peroxide (H₂O₂) and organic hydroperoxides (ROOH) were measured on board of theRV Polarstern during its cruise across the Atlantic Ocean from 20 October to 12 November 1990 (54° N to 51° S latitude) by the enzyme fluorometric method. The H₂O₂ mixing ratio varied from below the detection limit of about 0.12 ppbv up to 3.89 ppbv, showing a latitudinal dependence with generally higher values around the equator and decreasing values poleward. The shape of the latitudinal H₂O₂ distribution agrees well with an analytical steady state expression for H₂O₂ using the measured H₂O and O₃ distribution and a wind dependent H₂O₂ deposition rate. The ROOH mixing ratio varied from below the detection limit of about 0.08 ppbv up to 1.25 ppbv with qualitatively the same latitudinal dependence as H₂O₂. The observed ratio ROOH/(ROOH + H₂O₂) varied between 0.17 and 0.98 showing higher values at the lowest H₂O₂ mixing ratios at high latitudes. The measured H₂O₂ mixing ratio shows a significant diurnal variation with a maximum around 14:00 local time, explicable by a superposition of the photochemical H₂O₂ production with a constant H₂O₂ deposition rate. Four independent estimations of the average effective H₂O₂ deposition rate inferred from the H₂O₂ decrease in the night, from the midday H₂O₂ production deficit (as derived from comparison with a photochemical model and from the daily ozone loss), and from the offset in the latitudinal H₂O₂ distribution, were consistent. An episode of maximum H₂O₂ concentration suggests the possibility of its formation in clouds.     

Intercomparison campaign of vertical ozone profiles including electrochemical sondes of ECC and Brewer-Mast type and a ground based UV-differential absorption lidar

An intercomparison campaign was conducted at the Observatoire de Haute Provence (OHP) in Southern France in September 1989 in order to compare the three instruments used for vertical tropospheric ozone profiling in the European TOR (Tropospheric Ozone Research Project) network: balloon borne ECC and Brewer-Mast sondes and a ground based UV-DIAL (DifferentialAbsorptionLidar). Additionally, a stratospheric lidar system and the Dobson spectrophotometer of the OHP were operated. Seven simultaneously measured vertical ozone profiles gave evidence for systematic differences of 15% between both types of electrochemical sondes in the troposphere, the Brewer-Mast sondes reading the smaller ozone values. These differences might be explained on the one hand by a possible contamination of the ozone sensor with reducing substances, causing a negative bias mainly for Brewer-Mast sondes and, on the other hand, by the evolution of the sonde background current during the flight, causing a positive bias for ECC sondes and a negative bias for Brewer-Mast sondes. The tropospheric lidar system, measuring the vertical ozone distribution between 6 and 12–15 km, showed ozone concentrations intermediate between the sonde results. This is in good agreement with its estimated systematic error of better than 7% in the upper troposphere. In the stratosphere, the differences between electrochemical sondes and the lidar are between 5 and 10% before the normalisation with the total ozone values measured by the Dobson spectrophotometer, and always below 5% after. While the Dobson normalisation thus corrects rather well the stratospheric part of the sonde profile, it only partially reduces errors occurring in the troposphere.     

On the variability and correlation of surface ozone and carbon monoxide observed in Hong Kong using trajectory and regression analyses

This paper investigates, the variability and correlation of surface ozone (Os) and carbon monoxide (CO) observed at Cape D'Aguilar in Hong Kong from 1 January 1994 to 31 December 1995. Statistical analysis shows that the average O3 and CO mixing ratios during the two years are 32±17ppbv and 305±191 ppbv, respectively. The O3/CO ratio ranges from 0.05 to 0.6 ppbv/ppbv with its frequency peaking at 0.15. The raw dataset is divided into six groups using backward trajectory and cluster analyses. For data assigned to the same trajectory type, three groups are further sorted out based on CO and NOX mixing ratios. The correlation coefficients and slopes of O3/CO for the 18 groups are calculated using linear regression analysis. Finally, five kinds of air masses with different chemical features are identified: continental background (CB), marine background (MB), regional polluted continental (RPC), perturbed marine (P*M), and local polluted (LP) air masses. Further studies indicate that O3 and CO in the conti