Estimate of carbonyl sulfide tropical oceanic surface fluxes using Aura Tropospheric Emission Spectrometer observations

Abstract

Quantifying the carbonyl sulfide (OCS) land/ocean fluxes contributes to the understanding of both the sulfur and carbon cycles. The primary sources and sinks of OCS are very likely in a steady state because there is no significant observed trend or interannual variability in atmospheric OCS measurements. However, the magnitude and spatial distribution of the dominant ocean source are highly uncertain due to the lack of observations. In particular, estimates of the oceanic fluxes range from approximately 280 Gg S yr À1 to greater than 800 Gg S yr À1 , with the larger flux needed to balance a similarly sized terrestrial sink that is inferred from NOAA continental sites. Here we estimate summer tropical oceanic fluxes of OCS in 2006 using a linear flux inversion algorithm and new OCS data acquired by the Aura Tropospheric Emissions Spectrometer (TES). Modeled OCS concentrations based on these updated fluxes are consistent with HIAPER Pole-to-Pole Observations during 4th airborne campaign and improve significantly over the a priori model concentrations. The TES tropical ocean estimate of 70 ± 16 Gg S in June, when extrapolated over the whole year (about 840 ± 192 Gg S yr À1 ), supports the hypothesis proposed by Berry et al. (2013) that the ocean flux is in the higher range of approximately 800 Gg S yr À1 .

Reviews and Syntheses: Carbonyl Sulfide as a Multi-scale Tracer for Carbon and Water Cycles

“…Satellite data have shown that tropospheric OCS is elevated above the North Indian and northwest tropical Pacific oceans, and inverse models using enhanced oceanic emissions reproduced a similar pattern (Kuai et al, 2015). Global oceanic emissions would need to amount to 800-1000 Gg S yr -1 to fully account for this missing source.…”

“…A missing source of about 600-800 Gg S yr -1 in the atmospheric budget of OCS has recently been 15 identified by several top-down approaches (Berry et al, 2013;Glatthor et al, 2015;Kuai et al, 2015;Wang et al, 2016). Satellite data have shown that tropospheric OCS is elevated above the North Indian and northwest tropical Pacific oceans, and inverse models using enhanced oceanic emissions reproduced a similar pattern (Kuai et al, 2015).…”

“…Only a few attempts have been made with the Recent satellite-based OCS measurements can be used to derive top-down estimates at continental to regional scales. Kuai et al (2015) proposed to estimate the OCS surface flux from NASA's Tropospheric Emission Spectrometer (TES) ocean-only observations using a Bayesian inversion 10 technique, which can be thought of as a time-independent version of the 4D-VAR assimilation (Liu et al, 2016). Their results implied a large ocean OCS source over the Indo-Pacific region, and the total ocean source budget was consistent with the global budget proposed by Berry et al (2013).…”

Fast retrievals of tropospheric carbonyl sulfide with IASI

“…A monthly mean of TES OCS results from June 2006 was published in Kuai et al (2015), which further validated the concept that direct ocean emissions of OCS are much greater than previously thought (Berry et al, 2013). The published data included retrievals over the ocean around ±40…”

Towards understanding the variability in biospheric CO<sub>2</sub> fluxes: using FTIR spectrometry and a chemical transport model to investigate the sources and sinks of carbonyl sulfide and its link to CO<sub>2</sub>

“…These groundbased in situ measurements are only at limited sites and aircraft measurements cover relatively short time periods. The emerging of the remote sensing data, including ground-based (Notholt et al, 2003) and satellite (Barkley et al, 2008;Kuai et al, 2014Kuai et al, , 2015Glatthor et al, 2015) measurements, will potentially increase the number of OCS measurements largely. The satellite data provide a wide distribution of OCS; however, they are mainly sensitive in the upper troposphere and stratosphere (Barkley et al, 2008;Glatthor et al, 2015) or mid-troposphere (Kuai et al, 2014), and therefore have little help in constraining the land fluxes.…”