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Modeling the Seasonality and Controls of Nitrous Oxide Emissions on the Northwest European Continental Shelf
Author(s) -
Lessin Gennadi,
Polimene Luca,
Artioli Yuri,
Butenschön Momme,
Clark Darren R.,
Brown Ian,
Rees Andrew P.
Publication year - 2020
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1029/2019jg005613
Subject(s) - continental shelf , oceanography , environmental science , biogeochemical cycle , nitrous oxide , pycnocline , stratification (seeds) , climatology , seasonality , atmospheric sciences , geology , chemistry , ecology , seed dormancy , germination , botany , dormancy , biology , organic chemistry , environmental chemistry
Estimates of oceanic emissions of nitrous oxide (N 2 O) are surrounded by a considerable degree of uncertainty, particularly regarding the contribution of productive shelf regions, where assessments are based on limited observations. In this paper, we have applied a coupled hydrodynamic‐biogeochemical model resolving N 2 O dynamics to estimate N 2 O emissions within the northwest European continental shelf. Based on 10‐year average distributions (2006–2015), dominant seasonal patterns of N 2 O air‐sea exchange were identified. Within the southwest region of the shelf and deep parts of the North Sea, emissions are highest during winter. Peak emissions during late autumn are typical for the northwest part of the shelf and central North Sea, while in the western English Channel, Irish Sea and western North Sea peak outflux shifts toward early autumn. Within these regions, most N 2 O production occurs below the seasonal pycnocline, and duration and intensity of stratification defines the timing and rate of its subsequent release to the atmosphere. In contrast, within the southeast North Sea and most of the coastal areas, lack of stratification allows the excess N 2 O to outgas as soon as it is produced, driven by ammonium availability, resulting in peak emissions in summer. We estimate that N 2 O emissions from the northwest European shelf contribute 0.02224 Tg N to the atmosphere annually, that is, between 3.3–6.8% of total emissions from European shelves and estuaries.