Wide-spread Occurrence and Increasing Trend of Biogenic Aerosol
Precursors in the Arctic Ocean Simulated by an Ocean Biogeochemical
Model
Abstract
Biogenic aerosol precursors from phytoplankton production can affect
cloud properties, especially in remote regions such as the Arctic Ocean.
Reliable estimates on variability and trend of these precursors are
required as extensive measurements in the Arctic are still scarce. We
present a setup of the coupled ocean biogeochemical model
FESOM2.1-REcoM3 where we integrated dissolved carboxylic acid containing
polysaccharides (PCHO) and Transparent Exopolymer Particles (TEP) to
describe these precursors in the upper ocean. We define PCHO as one part
of the excreted organic carbon, which can then aggregate to form larger
particles, TEP. Compared to observations, the simulation provides a
valid TEP estimate with mean concentrations of 200-400 µg C L-1 on the
continental shelves and 10-50 µg C L-1 in the central basins (0-30 m
depth range). Further, the simulation for 1990-2019 reveals a
significant positive trend of TEP of 0.5-3 µg C L-1 yr-1 during
July-September in the Amerasian Basin (+3.5% yr-1), the Canadian
Archipelago (+1.2% yr-1) and the Kara Sea (+0.8% yr-1), in contrast to
the eastern Fram Strait (-0.4% yr-1), the Barents Sea (-0.3% yr-1),
and parts of the Eurasian Basin with a significant decrease of -0.5-2 µg
C L-1 yr-1. Our study provides for the first time an integration of TEP
formation, aggregation and remineralization processes into a global
ocean biogeochemical model. This simulation assembles valuable data on
biogenic aerosol precursors, and as such, fills a gap on which Earth
System Models can greatly benefit to improve the understanding of
aerosol feedbacks within the Arctic climate.