Distribution and Drivers of Marine Isoprene Concentration across the Southern Ocean

• Published in: Atmosphere
• Main Authors: Pablo Rodríguez-Ros, Pau Cortés, Charlotte Mary Robinson, Sdena Nunes, Christel Hassler, Sarah-Jeanne Royer, Marta Estrada, M. Montserrat Sala, Rafel Simó
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2020
• Subjects: isoprene; Southern Ocean; drivers; phytoplankton; blooms; Lagrangian; Meteorology. Climatology; QC851-999; Near Islands
• Online Access: https://doi.org/10.3390/atmos11060556; https://doaj.org/article/128fd10ee5ff424cae938da23957ebca

Isoprene is a biogenic trace gas produced by terrestrial vegetation and marine phytoplankton. In the remote oceans, where secondary aerosols are mostly biogenic, marine isoprene emissions affect atmospheric chemistry and influence cloud formation and brightness. Here, we present the first compilation of new and published measurements of isoprene concentrations in the Southern Ocean and explore their distribution patterns. Surface ocean isoprene concentrations in November through April span 1 to 94 pM. A band of higher concentrations is observed around a latitude of ≈40 <math display="inline"> <semantics> <msup> <mrow></mrow> <mo>∘</mo> </msup> </semantics> </math> S and a surface sea temperature of 15 <math display="inline"> <semantics> <msup> <mrow></mrow> <mo>∘</mo> </msup> </semantics> </math> C. High isoprene also occurs in high productivity waters near islands and continental coasts. We use concurrent measurements of physical, chemical, and biological variables to explore the main potential drivers of isoprene concentration by means of paired regressions and multivariate analysis. Isoprene is best explained by phytoplankton-related variables like the concentrations of chlorophyll-a, photoprotective pigments and particulate organic matter, photosynthetic efficiency (influenced by iron availability), and the chlorophyll-a shares of most phytoplankton groups, and not by macronutrients or bacterial abundance. A simple statistical model based on chlorophyll-a concentration and a sea surface temperature discontinuity accounts for half of the variance of isoprene concentrations in surface waters of the Southern Ocean.