Project Details
Projekt
NSFGEO-DFG-BSF: The contribution of coastal systems to the atmospheric carbonyl sulfide budget using tower-based fluxes, isotopic measurements and modeling
Applicant
Professorin Dr. Sinikka Lennartz
Subject Area
Oceanography
Term
since 2025
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 563774325
Carbonyl sulfide (OCS) is the most abundant reduced sulfur-containing gas in the atmosphere and a critical precursor for stratospheric aerosol formation. Its concentration in the atmosphere has been stable over recent decades suggesting the primary sinks (terrestrial) and sources (marine emissions and anthropogenic) are balanced. However, a proliferation of recent measurements of the land sink have revealed larger rates of uptake than previously thought, suggesting there are vast missing sources from the budget that are presumed to originate from the ocean. We hypothesize that coastal systems represent a key missing source in the tropospheric OCS budget as previous measurement campaigns have focused on the open ocean and modeling efforts have lacked the resolution and processes to capture coastal gas exchange dynamics. We propose to deploy an OCS analyzer on the Air Sea Interaction Tower (ASIT) located 3 km offshore from Martha’s Vineyard, where we will measure OCS, CO2, and CO fluxes as well as their near-surface dissolved gas concentrations over a year-long campaign. The effort will be paired with discrete flask and dissolved measurement of OCS isotopes and precursor gasses (CS2 and DMS) to separate sources of OCS contributing to the flux. We will use this data, as well as measurements from a coastal site in the Baltic Sea, to develop a 1d water column model for coastal fluxes that accounts for physical limitations on air-sea exchange using LiDAR/polarimetric measurements of ocean wave properties and atmospheric boundary layer turbulence as well as revised models for light and dark production terms specific to coastal systems over a complete annual cycle. This tower level OCS model will be scaled up to develop a holistic regional OCS model – capturing both land sinks and marine sources – using an atmospheric inversion with sufficient resolution to represent complexities across the coastal transition. We will use these analyses to test three hypotheses: (1) coastal fluxes are a significant global source of OCS that is underrepresented in current global budgets; (2) the gas transfer velocity for OCS follows parameterizations for CO2; and (3) sedimentary sources of OCS from abiotic sulfurization of organic compounds are a key component of the coastal flux.
DFG Programme
Research Grants
International Connection
Israel, USA
Co-Investigator
Privatdozentin Dr. Christa Marandino
