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The potentially significant role of the biogenic trace gas dimethylsulfide (DMS) in determining the Earth's radiation budget makes it necessary to accurately reproduce seawater DMS distribution and quantify its global flux across the sea/air interface. Following a threefold increase of data (from 15,000 to over 47,000) in the global surface ocean DMS database over the last decade, new global monthly climatologies of surface ocean DMS concentration and sea-to-air emission flux are presented as updates of those constructed 10 years ago. Interpolation/extrapolation techniques were applied to project the discrete concentration data onto a first guess field based on Longhurst's biogeographic provinces. Further objective analysis allowed us to obtain the final monthly maps. The new climatology projects DMS concentrations typically in the range of 1-7 nM, with higher levels occurring in the high latitudes, and with a general trend toward increasing concentration in summer. The increased size and distribution of the observations in the DMS database have produced in the new climatology substantially lower DMS concentrations in the polar latitudes and generally higher DMS concentrations in regions that were severely undersampled 10 years ago, such as the southern Indian Ocean. Using the new DMS concentration climatology in conjunction with state-of-the-art parameterizations for the sea/air gas transfer velocity and climatological wind fields, we estimate that 28.1 (17.6-34.4) Tg of sulfur are transferred from the oceans into the atmosphere annually in the form of DMS. This represents a global emission increase of 17% with respect to the equivalent calculation using the previous climatology. This new DMS climatology represents a valuable tool for atmospheric chemistry, climate, and Earth System models. Copyright © 2011 by the American Geophysical Union.

The relative role of extraequatorial mechanisms modulating decadal sea surface temperature anomalies (SSTA) in the equatorial Atlantic is investigated using a suite of sensitivity experiments based on an ocean general circulation model. The model is forced by observed wind stress and/or computed heat flux from an associated advective atmospheric mixed layer model. In addition, the surface forcing is optionally applied on the equator or in off-equatorial regions. The long-term response of equatorial SST is dominated by local forcing. However, a weak but significant part of the response that is not in phase with the locally induced SST variability is caused by remote forcing. Subtropical cells (STCs) provide the oceanic bridging of the climate signals. The dynamical forcing leads to a spin-up and spin-down of the shallow cells, which, in the case of local forcing included, coincides with cold and warm SSTA. The local heat flux forcing reveals an overall damping tendency on the dynamical SST response. When excluding the local forcing, the isolation of the effect of the northern remote forcing from the one in the south appears to be essential in understanding the respective mechanisms at work. In the Northern Hemisphere, the spin-up and spin-down of the STC is highly correlated with the (lagging) SSTA, and the effect of off-equatorial heat flux forcing on SSTA is negligible. In the Southern Hemisphere, both momentum and heat fluxes in the subtropics lead to a significant SST response on the equator.