北京地区太阳紫外辐射的观测与分析研究

利用北京地区太阳辐射和其它常规气象观测资料，得到了到达地面的太阳紫外辐射的计算公式，并将计算值与观测值进行了比较，两者吻合得比较好。最后给出了北京地区地面太阳紫外总辐射的变化趋势，计算结果表明，地面太阳紫外总辐射对大气浑浊度的变化比对大气臭氧总量的变化敏感得多。     

气象因子对近地面臭氧污染影响的研究

本文通过对１９９３年春季和春夏之交的O3浓度逐日变化、日变化和气象因子关系的分析，提出了影响O3浓度的主导气象因子和不同情况下形成高浓度O3的主要因子，提出了大风速对逐日变化中O3浓度特高及浓度日变化峰值的重要作用，并指出高温、低湿、小风并不是在所有情况都是促成高浓度O3的因子。另外，雾也可以成为近地面O3浓度增值的因素，主要原因是雾内湍流发展将高浓度O3大量输向下方。     

The impact of high altitude aircraft on the ozone layer in the stratosphere

The paper discusses the potential effects on the ozone layer of gases released by the engines of proposed high altitude supersonic aircraft. The major problem arises from the emissions of nitrogen oxides which have the potential to destroy significant quantities of ozone in the stratosphere. The magnitude of the perturbation is highly dependent on the cruise altitude of the aircraft. Furthermore, the depletion of ozone is substantially reduced when heterogeneous conversion of nitrogen oxides into nitric acid on sulfate aerosol particles is taken into account in the calculation. The sensitivity of the aerosol load on stratospheric ozone is investigated. First, the model indicates that the aerosol load induced by the SO₂ released by aircraft is increased by about 10–20% above the background aerosols at mid-high latitude of the Northern Hemisphere at 15 km for the NASA emission scenario A (the NASA emission scenarios are explained in Tables I to III). This increase in aerosol has small effects on stratospheric ozone. Second, when the aerosol load is increased following a volcanic eruption similar to the eruption of El Chichon (Mexico, April 1982), the ozone column in spring increases by as much as 9% in response to the injection of NO _x from the aircraft with the NASA emission scenario A. Finally, the modeled suggests that significant ozone depletion could result from the formation of additional polar stratospheric clouds produced by the injection of H₂O and HNO₃ by the aircraft engines.     

A photoelectric detector for the measurement of photolysis frequencies of ozone and other atmospheric molecules

Photoelectric detectors for the measurement of photolysis frequencies of different trace gases in the atmosphere are described. They exhibit uniform response characteristics over one hemisphere (2 sr) and wavelength characteristics closely matched to those of the photolysis frequencies J _O1D, J _NO2, and J _NO3, respectively. Absolute calibration of the J _O1D detector was performed by chemical actinometry with an accuracy of ±16 percent. Simultaneous measurements of J _NO2 and J _O1D are presented.     

Performance of the electrochemical ozone sonde OSR

Summary The accuracy of the electrochemical ozone sonde, type OSR, has been estimated by analysing tandem ozone soundings of the balloon-borne electrochemical ozone sonde OSR at the Lindenberg Observatory from May to November 1982. A negative bias, though not significant, has been observed above about 28 km for soundings having high single correction factors. Random errors are at their minimum just above the level of the maximum of ozone partial pressure, and reach their maximum in the troposphere. Except at heights above about 28 km the random error of ozone sondes is a factor 2 to 3 times less than the error of the short Umkehr method. Provided that soundings with too high correction factors are neglected, the ozone sonde OSR has an accuracy comparable to that of other Brewer type sondes.The maximum amount of information on the vertical ozone distribution can be drawn from sonde measurements in the lower stratosphere. A study is underway to improve the sensitivity of the sonde OSR and thus to further enhance its reliability.     

Prediction of the abiotic degradability of organic compounds in the troposphere

A statistically relevant correlation between the reaction rate coefficient, k _OH, for the OH radical reaction with 161 organic compounds in the gas phase at 300 K, and the corresponding vertical ionisation energies E _i,v, reveals two classes of compounds: aromatics where –log(k _OH/cm³s^-1)3/2E _i,v(eV)–2 and aliphatics where –log(k _OH/cm³s^-1)4/5E _i,v(eV)+3. The prediction of the rate coefficient, k _OH, for the reaction of OH with organic molecules from the above equations has a probability of about 90%. Assuming a global diurnal mean of the OH radical concentration of 5×10⁵ cm³, the upper limit of the tropospheric half-life of organic compounds and their persistence can be estimated.     

The latitudinal distribution of carbon monoxide across the pacific from California to Antarctica

The results of a research study of the carbon monoxide concentration from California to 90° S, Antarctica are presented. The data both extend and support other research studies of the latitudinal distribution of carbon monoxide in that higher concentrations are evident over the Northern Hemisphere than over the Southern Hemisphere. Carbon monoxide concentrations range between 50 to 60 ppb with a few peaks into the 60s in the latitudinal area south of the ITCZ and values of 80 ppb or higher at latitudes north of Hawaii. A comparison is also made of carbon monoxide and ozone concentrations along the flight tract between California and Antarctica, over the Ellsworth Mountains of Antarctica, and between 78° S and the South Pole. These ozone-carbon monoxide data show statistically significant negative correlations in the upper troposphere and lower stratosphere over Antarctica. It is believed that this is a good indication of mixing across the tropopause.     

Ultraviolet absorption spectra of some Br-containing haloalkanes

The ultraviolet absorption cross sections were measured for CF₃Br, CF₂ClBr, CF₂Br-CF₂Br, CF₂Br₂, CHF₂Br, CHFBr-CF₃, CH₂Br-CF₃, CHClBr-CF₃ in the wavelength range 190–320 nm at 295 K. The photolysis is concluded to be the minor atmospheric sink for CHF₂Br, CHFBr-CF₃, CH₂Br-CF₃, CHClBr-CF₃.     

Total ozone response to major geomagnetic storms and changes in meteorological situations

Summary The total ozone response to strong major geomagnetic storms (A_p≥60) in winter along the 50° N latitudinal circle is studied. The results add to the recent results of Laštovička et al. (1992) obtained for European middle latitudes (∼50°N) and to the results of Mlch (1994). A significant response of total ozone is only observed in winter under high solar activity/E-phase of QBO conditions (E-max) and seems to be caused by geomagnetic storm-induced changes of atmospheric dynamics. There are two sectors along latitude 50°N, which are sensitive to forcing by geomagnetic storms both in total ozone and the troposphere — north-eastern Atlantic-European and eastern Siberia-Aleutian sectors. The total ozone response under E-max conditions manifests itself mainly as a large decrease in the longitudinal variation of ozone after the storm, which means an increase of ozone in Europe. The observed effects in total ozone consist in redistribution, not production or loss of ozone.     

Low-latitude total ozone measurements in the Brazilian sector

Regular measurements of the atmospheric ozone in the Brazilian sector were started at Cachoeira Paulista (22.7°S, 45.0°W), and Natal (5.8°S, 35.2°W) in May 1974 and November 1978, respectively. The results of the total ozone measurements carried out at these two stations up to 1981 are presented in this communication and compared with other low-and mid-latitude stations. Although Natal is an equatorial station, it presents a prominent annual variation, and the average total ozone content is high compared to satellite measurements. During 1977–78, abnormally low values of total ozone were observed at Cachoeira Paulista. Some preliminary results about the QBO 9quasi-biennial oscillation) during 1974–81 are also presented.