Troposphere coefficient

Dievart, P., Allou, L., Louis, F., and Le Calve, S. Tropospheric multiphase chenristry of 2,5- and 2,6-dimethylphenols determination of the mass acconrmodation coefficients and the Herrry s law constants, Phys. Chem. Chem. Phys., 8(14) 1714-1723, 2006. 

Table 8.5 shows the mass accommodation coefficients for S02, as well as for some other gases of tropospheric interest, on liquid water. It is seen that the uptake of most gases into liquid water is quite efficient. Interactions of gas molecules at the air-liquid interface may have additional implications other than the rate at which it is transferred into the aqueous... 

TABLE 8.5 Some Mass Accommodation Coefficients (a) for Gases of Tropospheric Interest on a Liquid Water Surface"... 

Mechanisms and rates of transport of nuclear test debris in the upper and lower atmosphere are considered. For the lower thermosphere vertical eddy diffusion coefficients of 3-6 X 106 cm.2 sec. 1 are estimated from twilight lithium enhancement observations. Radiochemical evidence for samples from 23 to 37 km. altitude at 31° N indicate pole-ward mean motion in this layer. Large increases in stratospheric debris in the southern hemisphere in 1963 and 1964 are attributed to debris from Soviet tests, transported via the mesosphere and the Antarctic stratosphere. Most of the carbon-14 remains behind in the Arctic stratosphere. 210Bi/ 210Pb ratios indicate aerosol residence times of only a few days at tropospheric levels and only several weeks in the lower stratosphere. Implications for the inventory and distribution of radioactive fallout are discussed. 

Fluorescence measurements of HO have been a common feature of laboratory kinetics studies of the reaction-rate coefficients of HO with various molecules and of studies of this free radical in combustion systems (24). In fact, although direct tropospheric fluorescence HO measurements were first... 

Tables on the "reaction probalility or "uptake coefficient" have been summarized for various heterogeneous reactions in a recent review article [87], and by the IUPAC [88] and NASA-JPL [86] evaluation teams. For the purpose of this article, a rough comparison is made of the uptake rates for the reactions (1) to (5) on the different type surfaces. Three major type of surfaces have been considered a) NAT, or Type I PSC, b) Water ice, or Type II PSC and c) sulfuric acid aerosol, which is normally a liquid surface generally composed of 60-80 wt % H,S04 and 40-20 wt % H,0 also considered is the solid form SAT (sulfuric acid tetrahydrate) with a composition of 57.5 wt % H,S04. The importance of chlorine activation on sulfuric acid solutions has been demonstrated in a recent article [89]. Halogen activation on seasalt material will shortly be reviewed as part of the tropospheric processes.

Thus N20, may react with Nad (and NaBr) on seasalt particles in polluted marine areas as well as in the arctic regions. The observed uptake coefficients, with 3xl0"J, imply that the reaction is sufficient fast and may lead to the formation of CINO, overnight C1N02 will photolyze at dawn to give d-atoms which will initiate the oxidation of organic compounds in a manner analoguous to OH radicals. Also the uptake of HNO, on salt powders (NaCl, NaBr) was measured and the release of Hd and HBr observed [108,109]. The latter compounds may release d or Br in the troposphere upon reaction with OH radicals. 

Dimethyl Sulfoxide. The first reported direct measurements on the kinetics of DMSO with atmospheric oxidants are reported by Barnes et al. (this volume). This study was undertaken after the recent laboratory measurements on the reaction between IO and DMS (reaction (8)) showed that this reaction could be an efficient source of DMSO in the marine troposphere (31.32). The rate coefficients for the reactions between DMSO and OH, Cl, and NO3 are listed in Table VII. With the exception of the NO3 reaction, they are faster than the rate coefficients for the DMS analogues (cf. Table I). 

The upper limit for the CH3S + 02 reaction rate coefficient determined here is an order of magnitude lower than previous estimates. Even with this lower value we still can not rule out this reaction in the atmosphere. O has a mixing ratio of 0.21 which implies a loss rate for CH3S < 12 s 1. Even though the NO reaction rate coefficient is 6 x 10 11 cm3 molec 1 s 1, the reaction with O2 could be dominant for NO2 concentrations less than 2 x 1011 molec cm 3, or a mixing ratio of 8 ppb. Since most CH S is produced in the marine troposphere, where NO2 is typically < < lppb, the O reaction can not be ruled out. Since the CH O ) adduct, if it is formed at all, does not appear to react with O2, our upper limit is the real upper limit for CH3S loss in air. 

Cooper, D.L., Cunningham, T.P., Allan, N.L., McCulloch, A. (1992) Tropospheric lifetimes of potential CFC replacements Rate coefficients for reaction with the hydroxyl radical. Atmos. Enrivon. 26A, 133-1334. 

At lower altitudes where significant concentrations of ozone exist, O- ions are generated by dissociative attachment [reaction (10b)]. These electron attachment processes and the laboratory techniques used to determine their rate coefficients were reviewed some time ago by Phelps1 S4 In the stratosphere and troposphere, negative ions can also be generated by dissociative attachment reactions of thermalised electrons with pollutants1 s5,1561 such as the freons e.g. 

The temperature profile strongly influences those reactions whose rate coefficients have large activation energies. As will be shown in Sections IV, V, and VI, a number of reaction paths, while dominant in the lower troposphere, lose their importance with increasing altitude as the temperature drops sharply. Particularly affected are the altitude profiles of the hydroxyl radical, formaldehyde, and nitric oxide number densities. 

The large fluctuations with altitude that are frequently observed in tropospheric measurements of ozone and water number densities suggest that vertical eddy diffusion with a constant diffusion coefficient is not adequate. 

Noon values are J43a = 4 x 10 and J43b = 1 x 10. The value of the rate coefficient for R48, K48 = 1.5 x 10 [Morris and Niki (177)], has already been discussed (see Section IV.D.2). In the lower troposphere, the two loss paths—photolysis and OH reaction—are comparable, while in the middle and upper troposphere, where n(OH) drops off, photolysis is dominant. At the same time, the destruction of CH by OH, which has a large activation energy, slows greatly, resulting in a significant reduction in the production of H2C=0 and therefore in n(H2C=0) itself. 

Lack of measurements of a number of activation energies—in particular, R22 and R20—in the tropospheric temperature range. Many of the rate coefficients—R6,... 

There is a great need for determination of activation energies in the tropospheric temperature range absorption cross sections for N03 and HNC>2 reaction rates and mechanisms for CH302 and CH302H more accurate rate coefficients for many reactions, such as R6, R28, and R20 ... 

Mircea M, D Isidoro M, Maurizi A, Vitali L, Monforti F, Zanini G, Tampieri F (2008) A comprehensive performance evaluation of the air quality model BOLCHEM to reproduce the ozone concentrations over Italy. Atmos Environ 42(6) 1169-1185 Tampieri E, Maurizi A (2007) Evaluation of the dispersion coefficient for numerical simulations of tropospheric transport Nuovo Cimento C 30 395 06 Tegen I, Harrison SP, Kohfeld K, Colin Prentice I, Coe M, Heinmann M (2002) J Geophys Res 107 D21. doi 10.1029/2001JD000963... 

Tiesi A, Villani MG, D Isidoro M, Praia AJ, Maurizi A, Tampieri E (2006) Estimation of dispersion coefficient in the troposphere from satellite images of volcanic plumes. Atmos Environ 40 628-638. doi 10.1016/j.atmosenv.2005.09.079 Villani MG, Mona L, Maurizi A, Pappalardo G, Tiesi A, Pandolfi M, D Isidoro M, Cuomo V, Tampieri F (2006) Transport of volcanic aerosol in the troposphere the case study of the 2002 Etna plume. JGeophys Res 111 D21102. doi 10.1029/2006JD00712... 

Removal of free ions occurs by two mechanisms ion-ion recombination (essentially saturated ternary ion-ion recombination effective binary coefficient a = 2 10 cm s ) and ion-attachment to aerosol particles. The latter process leads to so-called large ions which are, in fact, electrically-charged aerosols rather than ions in a strictly physical sense [60]. Usually, ion-attachment is the most important sink for free ions throughout the troposphere as the tropospheric aerosol content is relatively large (Fig. 2). In this respect, the tropospheric ionization-deionization balance differs greatly from the stratospheric one. 

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