Abstract
AbstractBiogenic emissions of dimethylsulfide (DMS) are an important source of sulfur to the atmosphere, with implications for aerosol formation and cloud albedo over the ocean. Natural aerosol sources constitute the largest uncertainty in estimates of aerosol radiative forcing and climate and thus, an improved understanding of DMS sources is needed. Coral reefs are strong point sources of DMS; however, this coral source of biogenic sulfur is not explicitly included in climatologies or in model simulations. Consequently, the role of coral reefs in local and regional climate remains uncertain. We aim to improve the representation of tropical coral reefs in DMS databases by calculating a climatology of seawater DMS concentration (DMSw) and sea‐air flux in the Great Barrier Reef (GBR), Australia. DMSw is calculated from remotely sensed observations of sea surface temperature and photosynthetically active radiation using a multiple linear regression model derived from field observations of DMSw in the GBR. We estimate that coral reefs and lagoon waters in the GBR (∼347,000 km2) release 0.03–0.05 Tg yr−1 of DMS (0.02 Tg yr−1 of sulfur). Based on this estimate, global tropical coral reefs (∼600,000 km2) could emit 0.08 Tg yr−1 of DMS (0.04 Tg yr−1 of sulfur), with the potential to influence the local radiative balance.
Highlights
Aerosols and clouds play a key role in the Earth's radiative budget and climate
To reduce the variability in this limited data set, we calculated correlation coefficients for a 3-day moving average of each variable (n = 24). This resulted in similar correlations as the hourly mean data set, which increased in strength due to reduced variability (Table 1)
Three-day moving mean wind speed (WS) did not correlate with DMSw, yet DMSPt strongly positively correlated with DMSw (Table 1)
Summary
Aerosols and clouds play a key role in the Earth's radiative budget and climate. The influence of anthropogenic greenhouse gas (GHG) emissions on the radiative balance is relatively well understood and is estimated to have exerted an average global warming effect of 2.3 W m−2 over the industrial period (IPCC, 2014). Anthropogenic and natural aerosols offset this warming effect by −0.9 W m−2 (−1.9 to −0.1 W m−2) through scattering of short-wave radiation and increasing the albedo, lifetime, and cover of clouds (Andreae, 1995; IPCC, 2014; Twomey, 1974). The radiative effects of natural aerosols and their role in climate is complex and less well understood. 45% of the variance in aerosol radiative forcing is derived JACKSON ET AL. Journal of Geophysical Research: Oceans from uncertainties in the role of natural aerosol sources, including marine dimethylsulfide (DMS) (Carslaw et al, 2013)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
