Enhanced dataset of global marine isoprene emission from biogenic and photochemical processes for the period 2001–2020

Abstract

Abstract. Isoprene is a crucial non-methane biogenic volatile organic compound (BVOC) that exhibits the largest emissions globally. It is chemically reactive in the atmosphere and serves as the primary source to generate of secondary organic aerosols (SOA) in terrestrial and remote marine regions. However, a comprehensive estimation of marine isoprene emissions is currently lacking. Here we built a module to present a twenty-year (2001–2020) global hourly dataset for marine isoprene emissions, including phytoplankton-generated biological emissions (BIO emissions) and photochemistry-generated emissions in the sea surface microlayer (SML emissions) based on the latest advancements in biological, physical, and chemical processes, with high spatial and temporal resolutions. The ERA5-hourly meteorological reanalysis (0.25°×0.25° horizontal spatial resolution) from the European Centre for Medium-Range Weather Forecasts (ECMWF) for the period of 2001–2020 were used as input for meteorological factors. Chlorophyll concentration data and the downwelling radiative flux diffuse attenuation coefficient data were collected from the National Aeronautics and Space Administration’s (NASA) Ocean Color Web MODIS Level-3 data, with a resolution of 9 km, covering the same period. Additionally, monthly normalized water-leaving radiance at 410 nm data from the Visible and Infrared Imager/Radiometer Suite (VIIRS) were provided by the National Oceanic and Atmospheric Administration (NOAA). Our dataset suggests the annual global marine isoprene emissions amount to 1.049 ± 0.009 Tg·yr-1. Among these, the BIO emissions are 0.433 ± 0.007 Tg·yr-1 while SML emissions contribute 0.616 ± 0.003 Tg·yr-1. The ability of this module to estimate marine isoprene emissions was evaluated through comparison with a series of observations of marine isoprene concentrations and emission fluxes. Annual total isoprene emission across tropical ocean shows a declining trend from 2001 to 2020. Most ocean regions exhibit a one-year emission period, whereas a significant intraseasonal period is found in the tropical ocean. This dataset can be employed as input for the simulation of marine SOA formation in earth system models. This work provides the foundation for further studies into the impact of the air-sea system on marine SOA formation and its climate effect. The DOI link for the dataset is http://dx.doi.org/10.11888/Atmos.tpdc.300521 (Cui and Zhu., 2023).

Impact of Marine Shipping Emissions on Ozone Pollution During the Warm Seasons in China

“…However, there is some overestimation in central China, YRD, Fujian, Guangxi, Beijing, and some underestimation in Shandong, YRD, and Liaoning (Figure S2 in Supporting Information ). There is an underestimation of marine HCHO VCD by the model, which may be due to the fact that our marine modeling only considers MSEs and ignores isoprene emissions from marine vegetation (Conte et al., 2020; Cui et al., 2023; W. Zhang & Gu, 2022).…”

“…Our marine emissions include only shipping emissions, but there are more sources of marine emissions than just ships. For isoprene, for example, marine phytoplankton, heterotrophic bacteria, and algae can also emit isoprene (Carpenter et al., 2012; Conte et al., 2020; Cui et al., 2023; W. Zhang & Gu, 2022). Although the amount of isoprene emitted by marine vegetation is smaller than that emitted by terrestrial vegetation (Gu et al., 2017; Guenther et al., 2006), these emissions have an influence on atmospheric chemistry.…”