A global model of the coupled sulfur/oxidant chemistry in the troposphere: The sulfur cycle

Abstract

[1] A sulfur cycle chemistry scheme with dimethyl sulfide (DMS), SO 2 , sulfate, H 2 S, and methanesulfonic acid (MSA) is included in the OsloCTM2 model, and concentrations of sulfur are calculated interactively with the oxidant chemistry. This allows more consistent estimates of aqueous phase oxidation of SO 2 to sulfate by O 3 , H 2 O 2 , and HO 2 NO 2 . The year 1996 is chosen as the standard, and a model run with 1996 meteorology and emissions is compared with 1996 observations. The results agree well with observations overall, although the model tends to overestimate SO 2 and underestimate sulfate in Northern Hemisphere winter owing to an oxidation limitation. A global budget for 1996 quantifying the various processes is investigated. Our model results give a global lifetime (global burden) of 1 day (0.25 Tg(S)) and 3.8 days (0.5 3 Tg(S)) for SO 2 and sulfate. Differences between the Southern Hemisphere, characterized by natural emissions and by loss of SO 2 by O 3 and H 2 O 2 oxidation, and the Northern Hemisphere, characterized by anthropogenic emissions and by large loss by dry deposition, are revealed. Significant changes in sulfur emissions have occurred over the last decades with decrease in the Unites States and Europe and increase in Southeast Asia. U.S., European, and Chinese SO 2 emissions have changed by À17.6%, À47.5%, and +93%, respectively. To study the impact of emission changes on the atmospheric composition, we have calculated distributions using the Global Emissions Inventory Activity (GEIA) 1985 inventory. The changes in sulfur emissions have significant changes on the sulfur concentrations and also some effect upon the oxidants. Increased emissions of NO x and hydrocarbons in China enhance O 3 , but increased sulfur inhibit the increase. The SO 2 oxidation by OH, which can lead to formation of new sulfate particles, is given special attention. The model run using GEIA 1985 anthropogenic emission inventory is compared with other model studies.

A tropical West Pacific OH minimum and implications for stratospheric composition

“…This compares very well with the OH measurements of Tan et al (2001) when considering the uncertainty of the measurements and the different time period. Figure 4 of Berglen et al (2004) and Figure 1 of Lelieveld et al (2004) also show low OH values in the boundary layer in the West Pacific for the TM3 and OsloCTM2 tropospheric CTMs, respectively. However, these boundary layer values are not directly comparable to the OH columns shown in Fig.…”

“…Unfortunately, the flights just missed the region where our model runs simulate the lowest OH values, but the results agree well with the model results in that region (see Section 3). Note that there is some seasonal variation in OH abundances (e.g., Berglen et al, 2004).…”

“…chapter 1.3.3). But the degree of temporal and spatial variability of tropospheric OH is the subject of ongoing debate (Hanisco et al, 2001;Lelieveld et al, 2004;Berglen et al, 2004;Manning et al, 2005;Rohrer and Berresheim, 2006;Montzka et al, 2011). There are still systematic discrepancies between models and observations for the spatial distribution of OH (Naik et al, 2013).…”

Changes in Nitrogen Dioxide and Ozone over Southeast and East Asia between Year 2000 and 2030 with Fixed Meteorology

“…The model has been tested and evaluated recently by Berglen et al (2004), Brunner et al (2005), and Isaksen et al (2005). Results from the CTM2 calculations used in this paper have been evaluated against ozone sondes in , see the "Auxiliary Material" of that paper) and in .…”

“…Lightning emissions of NO x are parameterized based on formulas by Price et al (1997a, b), distributing the emissions according to convective activity in the model and choosing 5 Tg(N) yr -1 as total annual output. The model calculates the distribution of 58 chemical compounds through a comprehensive tropospheric chemistry module Isaksen 1997, 1999) using the QSSA numerical solver (Hesstvedt et al 1978) and including a recently developed sulfur module (Berglen et al 2004). Stratospheric boundary conditions are pre-calculated by another version of the model that includes a comprehensive stratospheric chemistry module (Gauss et al 2006b).…”