scholarly journals Atmospheric deposition of nutrients and excess N formation in the North Atlantic

2010 ◽  
Vol 7 (2) ◽  
pp. 777-793 ◽  
Author(s):  
L. M. Zamora ◽  
A. Landolfi ◽  
A. Oschlies ◽  
D. A. Hansell ◽  
H. Dietze ◽  
...  
Keyword(s):  
Atmospheric Deposition ◽  
North Atlantic ◽  
N2 Fixation ◽  
Transport Model ◽  
N Deposition ◽  
Atmospheric N Deposition ◽  
N Accumulation ◽  
The North ◽  
The North Atlantic ◽  
Main Thermocline

Abstract. Anthropogenic emissions of nitrogen (N) to the atmosphere have been strongly increasing during the last century, leading to greater atmospheric N deposition to the oceans. The North Atlantic subtropical gyre (NASTG) is particularly impacted. Here, upwind sources of anthropogenic N from North American and European sources have raised atmospheric N deposition to rates comparable with N2 fixation in the gyre. However, the biogeochemical fate of the deposited N is unclear because there is no detectable accumulation in the surface waters. Most likely, deposited N accumulates in the main thermocline instead, where there is a globally unique pool of N in excess of the canonical Redfield ratio of 16N:1 phosphorus (P). To investigate this depth zone as a sink for atmospheric N, we used a biogeochemical ocean transport model and year 2000 nutrient deposition data. We examined the maximum effects of three mechanisms that may transport excess N from the ocean surface to the main thermocline: physical transport, preferential P remineralization of sinking particles, and nutrient uptake and export by phytoplankton at higher than Redfield N:P ratios. Our results indicate that atmospheric deposition may contribute 13–19% of the annual excess N input to the main thermocline. Modeled nutrient distributions in the NASTG were comparable to observations only when non-Redfield dynamics were invoked. Preferential P remineralization could not produce realistic results on its own; if it is an important contributor to ocean biogeochemistry, it must co-occur with N2 fixation. The results suggest that: 1) the main thermocline is an important sink for anthropogenic N deposition, 2) non-Redfield surface dynamics determine the biogeochemical fate of atmospherically deposited nutrients, and 3) atmospheric N accumulation in the main thermocline has long term impacts on surface ocean biology.

scholarly journals Atmospheric deposition of nutrients and excess N formation in the North Atlantic

2009 ◽  
Vol 6 (5) ◽  
pp. 9849-9889 ◽  
Author(s):  
L. M. Zamora ◽  
A. Landolfi ◽  
A. Oschlies ◽  
D. Hansell ◽  
H. Dietze ◽  
...  
Keyword(s):  
Atmospheric Deposition ◽  
North Atlantic ◽  
N2 Fixation ◽  
Transport Model ◽  
N Deposition ◽  
Atmospheric N Deposition ◽  
N Accumulation ◽  
The North ◽  
The North Atlantic ◽  
Main Thermocline

Abstract. Anthropogenic emissions of nitrogen (N) to the atmosphere have been strongly increasing during the last century, leading to greater atmospheric N deposition to the oceans. The North Atlantic subtropical gyre (NASTG) is particularly impacted. Here, upwind sources of anthropogenic N from North American and European sources have raised atmospheric N deposition to rates comparable with N2 fixation in the gyre. However, the biogeochemical fate of the deposited N is unclear because there is no detectable accumulation in the surface waters. Most likely, deposited N accumulates in the main thermocline instead, where there is a globally unique pool of N in excess of the canonical Redfield ratio of 16 N:1 phosphorus (P). To investigate this depth zone as a sink for atmospheric N, we used a biogeochemical ocean transport model and year 2000 nutrient deposition data. We examined the maximum effects of three mechanisms that may transport excess N from the ocean surface to the main thermocline: physical transport, preferential P remineralization of sinking particles, and nutrient uptake and export by phytoplankton at higher than Redfield N:P ratios. Our results indicate that atmospheric deposition may contribute 13–19% of the annual excess N input to the main thermocline. Modeled nutrient distributions in the NASTG were comparable to observations only when non-Redfield dynamics were invoked. Preferential P remineralization could not produce realistic results on its own; if it is an important contributor to ocean biogeochemistry, it must co-occur with N2 fixation. The results suggest that: 1) the main thermocline is an important sink for anthropogenic N deposition, 2) non-Redfield surface dynamics determine the biogeochemical fate of atmospherically deposited nutrients, and 3) atmospheric N accumulation in the main thermocline has long term impacts on surface ocean biology.

scholarly journals Influence of the North Atlantic oscillation on the atmospheric levels of benzo[a]pyrene over Europe

2021 ◽  
Author(s):  
Pedro Jiménez-Guerrero ◽  
Nuno Ratola
Keyword(s):  
Spatial Pattern ◽  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Transport Model ◽  
Regional Scale ◽  
The South ◽  
Climatic Fluctuations ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

AbstractThe atmospheric concentration of persistent organic pollutants (and of polycyclic aromatic hydrocarbons, PAHs, in particular) is closely related to climate change and climatic fluctuations, which are likely to influence contaminant’s transport pathways and transfer processes. Predicting how climate variability alters PAHs concentrations in the atmosphere still poses an exceptional challenge. In this sense, the main objective of this contribution is to assess the relationship between the North Atlantic Oscillation (NAO) index and the mean concentration of benzo[a]pyrene (BaP, the most studied PAH congener) in a domain covering Europe, with an emphasis on the effect of regional-scale processes. A numerical simulation for a present climate period of 30 years was performed using a regional chemistry transport model with a 25 km spatial resolution (horizontal), higher than those commonly applied. The results show an important seasonal behaviour, with a remarkable spatial pattern of difference between the north and the south of the domain. In winter, higher BaP ground levels are found during the NAO+ phase for the Mediterranean basin, while the spatial pattern of this feature (higher BaP levels during NAO+ phases) moves northwards in summer. These results show deviations up to and sometimes over 100% in the BaP mean concentrations, but statistically significant signals (p<0.1) of lower changes (20–40% variations in the signal) are found for the north of the domain in winter and for the south in summer.

scholarly journals Ozone variability and halogen oxidation within the Arctic and sub-Arctic springtime boundary layer

2010 ◽  
Vol 10 (21) ◽  
pp. 10223-10236 ◽  
Author(s):  
J. B. Gilman ◽  
J. F. Burkhart ◽  
B. M. Lerner ◽  
E. J. Williams ◽  
W. C. Kuster ◽  
...  
Keyword(s):  
Boundary Layer ◽  
North Atlantic ◽  
Marine Boundary Layer ◽  
Transport Model ◽  
Arctic Basin ◽  
The Arctic ◽  
Arctic Boundary Layer ◽  
Air Masses ◽  
The North ◽  
The North Atlantic

Abstract. The influence of halogen oxidation on the variabilities of ozone (O3) and volatile organic compounds (VOCs) within the Arctic and sub-Arctic atmospheric boundary layer was investigated using field measurements from multiple campaigns conducted in March and April 2008 as part of the POLARCAT project. For the ship-based measurements, a high degree of correlation (r = 0.98 for 544 data points collected north of 68° N) was observed between the acetylene to benzene ratio, used as a marker for chlorine and bromine oxidation, and O3 signifying the vast influence of halogen oxidation throughout the ice-free regions of the North Atlantic. Concurrent airborne and ground-based measurements in the Alaskan Arctic substantiated this correlation and were used to demonstrate that halogen oxidation influenced O3 variability throughout the Arctic boundary layer during these springtime studies. Measurements aboard the R/V Knorr in the North Atlantic and Arctic Oceans provided a unique view of the transport of O3-poor air masses from the Arctic Basin to latitudes as far south as 52° N. FLEXPART, a Lagrangian transport model, was used to quantitatively determine the exposure of air masses encountered by the ship to first-year ice (FYI), multi-year ice (MYI), and total ICE (FYI+MYI). O3 anti-correlated with the modeled total ICE tracer (r = −0.86) indicating that up to 73% of the O3 variability measured in the Arctic marine boundary layer could be related to sea ice exposure.

Tropical Dominance of N2 Fixation in the North Atlantic Ocean

2017 ◽  
Vol 31 (10) ◽  
pp. 1608-1623 ◽  
Author(s):  
Dario Marconi ◽  
Daniel M. Sigman ◽  
Karen L. Casciotti ◽  
Ethan C. Campbell ◽  
M. Alexandra Weigand ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
N2 Fixation ◽  
North Atlantic Ocean ◽  
The North ◽  
The North Atlantic

Atmospheric deposition of nutrients to the North Atlantic Basin

1996 ◽  
pp. 27-73 ◽  
Author(s):  
J. M. Prospero ◽  
K. Barrett ◽  
T. Church ◽  
F. Dentener ◽  
R. A. Duce ◽  
...  
Keyword(s):  
Atmospheric Deposition ◽  
North Atlantic ◽  
Atlantic Basin ◽  
North Atlantic Basin ◽  
The North ◽  
The North Atlantic

scholarly journals Free-troposphere ozone and carbon monoxide over the North Atlantic for 2001–2011

2013 ◽  
Vol 13 (24) ◽  
pp. 12537-12547 ◽  
Author(s):  
A. Kumar ◽  
S. Wu ◽  
M. F. Weise ◽  
R. Honrath ◽  
R. C. Owen ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
North Atlantic ◽  
Transport Model ◽  
Measurement Data ◽  
Free Troposphere ◽  
Chemical Transport Model ◽  
Significance Level ◽  
The Past ◽  
The North ◽  
The North Atlantic

Abstract. In situ measurements of carbon monoxide (CO) and ozone (O3) at the Pico Mountain Observatory (PMO) located in the Azores, Portugal, are analyzed together with results from an atmospheric chemical transport model (GEOS-Chem) and satellite remote sensing data (AIRS (Atmospheric Infrared Sounder) for CO, and TES (Tropospheric Emission Spectrometer) for O3) to examine the evolution of free-troposphere CO and O3 over the North Atlantic for 2001–2011. GEOS-Chem captured the seasonal cycles for CO and O3 well but significantly underestimated the mixing ratios of CO, particularly in spring. Statistically significant (using a significance level of 0.05) decreasing trends were found for both CO and O3 based on harmonic regression analysis of the measurement data. The best estimates of the possible trends for CO and O3 measurements are −0.31 ± 0.30 (2-σ) ppbv yr−1 and −0.21 ± 0.11 (2-σ) ppbv yr−1, respectively. Similar decreasing trends for both species were obtained with GEOS-Chem simulation results. The most important factor contributing to the decreases in CO and O3 at PMO over the past decade is the decline in anthropogenic emissions from North America, which more than compensate for the impacts from increasing Asian emissions. It is likely that climate change in the past decade has also affected the intercontinental transport of O3.

scholarly journals Long-Term Wintertime Trend of Zonally Asymmetric Ozone in Boreal Extratropics During 1979–2016

Atmosphere ◽  
2018 ◽  
Vol 9 (12) ◽  
pp. 468
Author(s):  
Andrea Schneidereit ◽  
Dieter Peters
Keyword(s):  
North Atlantic ◽  
Total Ozone ◽  
Transport Model ◽  
Wave Train ◽  
The Arctic ◽  
European Region ◽  
The North ◽  
Wave Transport ◽  
Ozone Transport ◽  
The North Atlantic

Strong zonally asymmetric ozone (ZAO) changes are observed in the boreal extratropics for winter. During the TOMS (Total Ozone Mapping Spectrometer) period (1979–1992) the decrease of zonally asymmetric total ozone (ZATO) was twice as large as the observed zonal mean total ozone trend over Europe in January mainly caused by ultra-long wave transport. Recent studies have demonstrated that the ozone evolution reveals three different quasi-bidecadal trend stages: (i) Decline, (ii) leveling, and (ii) healing. This study focuses on the ZAO structure in boreal extratropics and on ozone transport changes by ultra-long waves during winter months. ERA-Interim data together with a linearized transport model are used. During the healing stage ZATO increases significantly over the North Atlantic/European region for January. The ZATO increase (healing stage) and ZATO decrease (decline stage) are caused by different monthly mean ozone transport characteristics of ultra-long planetary waves over the North Atlantic/European region. Furthermore, the vertical advection (ageostrophic transport) of ozone versus its horizontal component dominates in the lower and middle stratosphere during the healing stage. It is hypothesized that these ageostrophic wind changes are mainly caused by a wave train directed northeastwards which seems to be directly linked to the Arctic warming.

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