Global Atmospheric Composition Effects from Marine Isoprene Emissions.

Isoprene emissions, primarily of biogenic origin, play an important role in atmospheric chemistry and climate. However, the atmospheric implications of marine isoprene emissions remain underexplored due to sparse in situ measurements and the intricate mechanisms governing isoprene in the upper ocean. This study uses 20 years of MODIS satellite observations to upscale isoprene production and loss rates derived from laboratory experiments, enabling global modeling of aqueous isoprene concentrations and emissions. Earth system model simulations with integrated marine isoprene emissions demonstrate substantial alterations in atmospheric composition over global oceanic regions. Our investigation uncovers diurnal variations in the vertical profiles of atmospheric isoprene, indicating that surface isoprene can ascend to the mid-to-upper troposphere, where nitrogen monoxide (NO) influences isoprene epoxydiol (IEPOX) production differently over selected oceanic and terrestrial regions. These findings pave the way for future studies on the role of marine isoprene in climate models and advance our understanding of its broader implications for atmospheric chemistry under a changing climate.