In:
Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 21, No. 2 ( 2021-01-20), p. 831-851
Abstract:
Abstract. Marine biogenic particle contributions to atmospheric
aerosol concentrations are not well understood though they are important for
determining cloud optical and cloud-nucleating properties. Here we examine
the relationship between marine aerosol measurements (with satellites and
model fields of ocean biology) and meteorological variables during the North
Atlantic Aerosols and Marine Ecosystems Study (NAAMES). NAAMES consisted of
four field campaigns between November 2015 and April 2018 that aligned with
the four major phases of the annual phytoplankton bloom cycle. The FLEXible PARTicle (FLEXPART)
Lagrangian particle dispersion model is used to spatiotemporally connect these variables
to ship-based aerosol and dimethyl sulfide (DMS)
observations. We find that correlations between some aerosol measurements
with satellite-measured and modeled variables increase with increasing
trajectory length, indicating that biological and meteorological processes over
the air mass history are influential for measured particle properties and
that using only spatially coincident data would miss correlative connections
that are lagged in time. In particular, the marine non-refractory organic
aerosol mass correlates with modeled marine net primary production when
weighted by 5 d air mass trajectory residence time (r=0.62). This
result indicates that non-refractory organic aerosol mass is influenced by
biogenic volatile organic compound (VOC) emissions that are typically
produced through bacterial degradation of dissolved organic matter,
zooplankton grazing on marine phytoplankton, and as a by-product of
photosynthesis by phytoplankton stocks during advection into the region.
This is further supported by the correlation of non-refractory organic mass
with 2 d residence-time-weighted chlorophyll a (r=0.39), a proxy for
phytoplankton abundance, and 5 d residence-time-weighted downward
shortwave forcing (r=0.58), a requirement for photosynthesis. In
contrast, DMS (formed through biological processes in the seawater) and
primary marine aerosol (PMA) concentrations showed better correlations with
explanatory biological and meteorological variables weighted with shorter
air mass residence times, which reflects their localized origin as primary
emissions. Aerosol submicron number and mass negatively correlate with sea
surface wind speed. The negative correlation is attributed to enhanced PMA
concentrations under higher wind speed conditions. We hypothesized that the
elevated total particle surface area associated with high PMA concentrations
leads to enhanced rates of condensation of VOC oxidation products onto PMA.
Given the high deposition velocity of PMA relative to submicron aerosol,
PMA can limit the accumulation of secondary aerosol mass. This study
provides observational evidence for connections between marine aerosols and
underlying ocean biology through complex secondary formation processes,
emphasizing the need to consider air mass history in future analyses.
Type of Medium:
Online Resource
ISSN:
1680-7324
DOI:
10.5194/acp-21-831-2021
DOI:
10.5194/acp-21-831-2021-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2021
detail.hit.zdb_id:
2092549-9
detail.hit.zdb_id:
2069847-1
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