Volcanic sulfur emissions: Estimates of source strength and its contribution to the global sulfate distribution

Abstract

Abstract. Anthropogenic emission of SO 2 and conversion into SO42-is argued to be the most important factor damping and modulating the global greenhouse effect. Recent estimates of the relative strength of the three important sources of volatile sulfur (SO2 from fossil fuel combustion -78 Tg S/yr, from biomass burning -2 Tg S/yr, and from natural sources ~ 25 Tg S/yr) suggest an overwhelming effect of the anthropogenic emissions for climate forcing. However, the radiatively relevant product SO42-may have different patterns due to the distribution of the sources (some very dense areas near the surface for anthropogenic SO 2, formation of SO 2 from dimethylsulfide in the marine boundary layer, and emission of volcanic SO2 mostly in the free atmosphere in rural areas). In this paper we study the relative contribution of volcanic SO2 emissions to the atmospheric sulfur budget applying an atmospheric general circulation model including a full sulfur cycle and prescribed source distributions. An off-line analysis tool is applied to determine the radiative forcing of sulfate aerosols. The results show that natural S sources are at least as important as the anthropogenic ones, even though their source strength is much smaller. The reasons are different lifetimes due to different production and emission processes. Therefore, we should improve our knowledge about the volcanic volatile sources and their time-space variability.

Size-resolved sulfate and ammonium measurements in marine boundary layer over the North and South Pacific

“…The concentrations of NH 4 + and nss-SO (ngS m -3 ) concentration ratio (=12) of LP_11 was close to the global burden ratio of biomass burning (BC/nss-SO 4 2-= 15), which was calculated from the global model results (Graf et al, 1997;Reddy and Boucher, 2004). We will use this ratio as a concentration ratio of EC/nss-SO 4 2-derived from the biomass burning transported over the ocean for a long time (section 3.7.3).…”

“…Those ratios of EC(or BC)/nss-SO 4 2-found under the anthropogenic influence of the East Asia were close to the global burden ratio of BC to nss-SO 4 2-(0.2 = 0.06 Tg BC/0.29 Tg S) derived from anthropogenic fossil fuel burning, which is calculated by using the global model results of Graf et al (1997) and Reddy and Boucher (2004). We will use this ratio as a concentration ratio of EC/nss-SO 4 2-derived from the anthropogenic fuel burning transported over the ocean for a long time (section 3.7.3).…”

“…In marine air, non-sea-salt-(nss-) SO 4 2-is the major component of accumulation mode range aerosols and accounts for the largest number of aerosol particles (O'Dowd and Smith, 1993), while Novakov et al (1997) suggested that organic matter released from the ocean surface is also an important component of marine aerosol. The global burden of nss-SO 4 2-of 0.78 Tg S is distributed as follows: 37% from anthropogenic fossil fuel burning, 36% from volcanoes, 25% from dimethyl sulfide (DMS) produced by marine phytoplankton, and 1.6% from biomass burning (Graf et al, 1997). In the middle latitude of Cape Grim (41 S, 144 E) in the Southern Ocean, the seasonal variation of nss-SO 4 2-concentration, which is high in summer during high productive season and low in winter, was consistent with the seasonal variations of DMS and methane sulfonic acid (MSA) aerosol as good indicators of marine biogenic sources (Ayers and Gras, 1991;.…”

Halogen emissions from a small volcanic eruption: Modeling the peak concentrations, dispersion, and volcanically induced ozone loss in the stratosphere

“…The eruption plumes from $75% of these eruptions will reach altitudes >12 km [Pyle et al, 1996], and approximately 30% will occur at latitudes higher than 40°, where tropopause altitudes lie at 10 -12 km. Thus, high latitude VEI 3 eruptions may have a marked stratospheric impact, as demonstrated by the dominance of volcanic SO 2 in the lower stratosphere over anthropogenic SO 2 [Graf et al, 1997]. Tropical eruptions need to be larger to show a similar impact; both because of the greater tropopause heights, and the greater water vapor content in the lower troposphere at tropical latitudes, which enhance removal of soluble acid gases.…”

Canadian Aerosol Module: A size‐segregated simulation of atmospheric aerosol processes for climate and air quality models 1. Module development

“…sulphates, nitrate, black carbon, organic particles, biomass burning and soil dust from land-surfacemodification) and natural components. The latter are from biomass burning , sea salt [Gong et al, 1997;Quinn et al, 1999], soil dust [Ginoux et al, 2001;Fung, 1994, 1996], biogenic organic sources and volcanic emissions [Graf et al, 1997]. The absence of natural aerosols in climate models has resulted in a major uncertainty in assessing aerosol forcing to date [O'Dowd et al, 1999].…”