Ozone Budget of the Troposphere

At typical boundary-layer conditions, 4 S 3 x 10 4 s, so tN2o5 = 0.9 h. The NO3/N205 ratio is obtained from the equilibrium constant K13  

For a more complete analysis of timescales in the N03/N205 system, we refer the reader to Brown et al. (2003b). 

The tropospheric ozone budget can be calculated by global chemical transport models. Table 6.2 presents the tropospheric O3 budget of Wang et al. (1998). The budget is for the 

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Laboratory measurements (17) next showed that reaction R19 proceeded about 40 times faster than determined earlier, strongly promoting ozone production and increasing HO concentrations with major consequences for tropospheric and stratospheric chemistry. Table I presents an ozone budget calculated with a three-dimensional chemistry transport model of the troposphere which takes into account the afore mentioned reactions. 

We simulated a period of three years (not nudged) to investigate the climatology of the tropospheric ozone budget and the contribution by STE. We focus on the NH where the ozone-PV relation derived from MOZAIC is applied. Figure 4 displays the seasonality of cross-tropopause transports, photochemical production/destruction, dry deposition and the tropospheric content of ozone. 

The importance of photochemical destruction in the 03s tropospheric budget implies that the lifetime of 03s is coupled to the chemical production and destruction of 03. Consequently, the simulated tropospheric budget of 03s may be affected directly by differences in the simulated chemistry. For example, simulations with a pre-industrial and a present-day emission scenario or with and without representation of NMHC chemistry will produce different estimates of the tropospheric oxidation efficiencies [39, 40]. However, our simulations indicate only small effects on the calculated 03s budget [6]. Figure 5 presents the simulated zonal distribution of 03s, the chemical destruction rate, of ozone (day"1) and the chemical loss of 03s (ppbv day 1) for the climatological April. The bulk of the 03s in the troposphere resides immediately below the tropopause, whereas the ozone chemical destruction rate maximizes in the tropical lower troposphere (Figures 5a and 5b). Hence, most 03s is photochemically destroyed between 15-25 °N and below 500 hPa. This region... 

Crutzen P.J. and Gidel L.T., A two-dimensional photochemical model of the atmosphere 2 the tropospheric budgets of the anthropogenic chlorocarbons, CO, CHp CHjCl and the effect of various sources on tropospheric ozone. J. Geophys. Res., 88, 6641-6661 (1983). 

The original objective of the EUROTRAC project LACTOZ was to provide kinetic and mechanistic data to enable a quantitative description of the tropospheric ozone budget in numerical models. Following the review by the EUROTRAC-SSC in 1991 the priorities set for the second phase of LACTOZ were understanding... 

Ozonolysis in the gas phase leads to peroxide products and is especially interesting in that regard, because some of these peroxides can be formed even in the presence of NOx. The studies described here provide information about the yields and identity of hydroperoxide products in gas-phase ozonolysis under two sets of conditions highly relevant to the troposphere. These products must be part of any mechanism that purports to explain atmospheric ozonolysis. Since peroxides are a source of radicals and a reservoir of oxidising power, their concentrations must be considered in quantitative descriptions of the tropospheric ozone budget. 

The aims of this investigation was to provide mechanistic, product and kinetic data for NO3 reactions of atmospheric importance and to contribute to the background knowledge of the NO3 reaction mechanisms. These kind of investigations are needed to be able to perform a quantitative description of the tropospheric ozone budget in numerical models. 

Cmtzen, P.J. Gidel, L.T., 1983 A Two-Dimensional Photochemical Model of the Atmosphere. 2. The Tropospheric Budgets of the Anthropogenic Chlorocarbons, CO, CH4, CH3CI and the Effect of Various NOx Sources on Tropospheric Ozone , in Journal of Geophysical Research, 88 6641-6661. 

These alkyl nitrate compounds have been measured in the troposphere and constituted about 1.5% of the total odd nitrogen budget at a rural eastern U.S. site (19). Reaction 16a competes with the oxidation of NO by ozone in the troposphere. 

Tropospheric ozone budgets, globally and for the northern (NH) and southern (SH) hemisphere in unit of 1013 mole/year. Only CH4 and CO oxidation cycles were considered. Calculations were made with the global, three-dimensional MOGUNT1A model (IS). 

MODEL ANALYSIS OF STRATOSPHERE-TROPOSPHERE EXCHANGE OF OZONE AND ITS ROLE IN THE TROPOSPHERIC OZONE BUDGET... 

In this study we will present aspects of STE in relation with the budget and concentrations of ozone in the troposphere, specifically in the Northern Hemisphere. Firstly, we present ozone observations in the tropopause region from the measurement campaign MOZAIC, and discuss their correlation with potential vorticity. The results have been used to improve the parameterization of stratospheric ozone in a coupled tropospheric chemistry - general circulation model. We will show examples of the performance of the model regarding the simulation of ozone in the tropopause region, and present the simulated seasonality of cross-tropopause ozone transport in relation to other tropospheric ozone sources and sinks. Finally, we will examine and compare the influence of cross-tropopause transports to surface ozone concentrations for simulations with contemporary, pre-industrial, and future emission scenarios. 

The difference between the concentration of 03 and 03s is a measure of ozone that originates from photochemistry in the troposphere, referred to as 03t. The modeled 03, 03s and 03t fields from the three simulations are used to calculate budgets of chemistry and of transports within the troposphere and between the stratosphere and the troposphere, and to estimate the impact of STE on tropospheric 03 levels. 

Holton, J.R., and Lelieveld, J. (1996) Stratosphere-troposphere exchange and its role in the budget of tropospheric ozone, in P.J. Crutzen and V. Ramanathan (Eds.), Clouds, Chemistry and Climate, NATO ASI Series, Springer-Verlag, Berlin, pp. 173-190. 

Gidel, L.T., and Shapiro, M.A. (1980) General circulation model estimates of the net vertical flux of ozone in the lower stratosphere and the implications for the tropospheric ozone budget, J. Geophys. Res. 85, 4049-... 

C is a term representative of the photochemistry (production or destruction), Ey the entrainment velocity, [03] the concentration of free tropospheric ozone, the dry deposition velocity and H the height of the boundary layer. The ozone budget shown in Table 8 has been calculated both in the summer and winter using the ozone continuity equation for a site in the marine boundary layer. 

We have also studied the behavior of gas-phase radicals, such as the hy-droperoxyl radical (HO2) [62], in water clusters which is important in atmospheric science (Figure 16.4). The hydroperoxyl radical is a major species in the HOx chemical family [2] that affects the budgeting of many chemical systems in the atmosphere. The HOx system plays a central role (along with the OH radical) in oxidative chemistry in the troposphere and ultimately controls the production rate of tropospheric ozone [7,16]. It is hence considered significant in atmospheric [2,5] and combustion chemistry [184]. Recent theoretical studies [16,17] have indicated the HO2 radical to possess stable interactions with water clusters. Such stability provides an important sink for HOx compounds [16,17,61,185] in the troposphere. As a result, the structural and dynamical features of water clusters play a vital role on HO2 related chemistry. 

Jesson J.P., Release of industrial halocarbons and tropospheric budget, in Proceedings of the NATO Advanced Study Institute on Atmospheric Ozone , FAA Report No. FAA-EE-80-20, Nicolet, M. and Aikin, A. C., editors, pp. 373-396 (1980). 

Monod A. and P. Carlier Impact of clouds on the tropospheric ozone budget Direct effect of multiphase photochemistry of soluble organic compounds, Atmos. Environ., 33 (1999) 4431-4446. 

Since the presence (in very small quantities) of O D) in the troposphere results from the photolysis of ozone (see Reaction (5.16)), an assessment of the oxidizing power of the atmosphere requires that the global budget of tropospheric ozone be accurately quantified. 

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