scholarly journals The influence of cloud chemistry on HO<sub>x</sub> and NO<sub>x</sub> in the Marine Boundary Layer: a 1-D modelling study

2001 ◽  
Vol 1 (2) ◽  
pp. 277-335
Author(s):  
J. E. Williams ◽  
F. J. Dentener ◽  
A. R. van den Berg
Keyword(s):  
Boundary Layer ◽  
Gas Phase ◽  
Marine Boundary Layer ◽  
Phase Transfer ◽  
Cloud Model ◽  
Chemical Mechanism ◽  
Marine Stratocumulus ◽  
Modelling Studies ◽  
A Minor ◽  
The Impact

Abstract. A 1-D marine stratocumulus cloud model has been supplemented with a comprehensive and up-to-date aqueous phase chemical mechanism for the purpose of assessing the impact that the presence of clouds and aerosols has on gas phase HOx, NOx and O3 budgets in the marine boundary layer. The simulations presented here indicate that cloud may act as a heterogeneous source of HONOg via the conversion of HNO4(g) at moderate pH (~4.5). The photolysis of nitrate (NO3-) has also been found to contribute to this simulated increase in HONOg by ~5% and also acts as a minor source of NO2(g). The effect of introducing deliquescent aerosol on the simulated increase of HONOg is negligible. The most important consequences of this elevation in HONOg are that, in the presence of cloud, gas phase concentrations of NOx species increase by a factor of 2, which minimises the simulated decrease in O3(g), and results in a regeneration of OHg. This partly compensates for the removal of OHg by direct phase transfer into the cloud and has important implications regarding the oxidising capacity of the marine boundary layer. The findings presented here also suggest that previous modelling studies, which neglect the heterogeneous HNO4(g) reaction cycle, may have over-estimated the role of clouds as a sink for OHg and O3(g)in unpolluted oceanic regions, by ~10% and ~2%, respectively.

scholarly journals The influence of cloud chemistry on HO<sub>x</sub> and NO<sub>x</sub> in the moderately polluted marine boundary layer: a 1-D modelling study

2002 ◽  
Vol 2 (1) ◽  
pp. 39-54 ◽  
Author(s):  
J. E. Williams ◽  
F. J. Dentener ◽  
A. R. van den Berg
Keyword(s):  
Boundary Layer ◽  
Gas Phase ◽  
Marine Boundary Layer ◽  
Phase Transfer ◽  
Cloud Model ◽  
Chemical Mechanism ◽  
Cloud Chemistry ◽  
Marine Stratocumulus ◽  
The Impact ◽  
Heterogeneous Source

Abstract. A 1-D marine stratocumulus cloud model has been supplemented with a comprehensive and up-to-date aqueous phase chemical mechanism for the purpose of assessing the impact that the presence of clouds has on gas phaseHOx, NOx and O3 budgets in the marine boundary layer. The simulations presented here indicate that cloud may act as a heterogeneous source of HONOg. The conversion of HNO4(g) at moderate pH (~ 4.5) is responsible for this, and, to a lesser extent, the photolysis of nitrate (NO3-). The effect of introducing deliquescent aerosol on the simulated increase of HONOg is negligible. The most important consequences of this elevation in HONOg are that, in the presence of cloud, gas phase concentrations of NOx species increase by a factor of 2, which minimises the simulated decrease in O3(g), and results in a regeneration of OHg. This partly compensates for the removal of OHg by direct phase transfer into the cloud and may have important implications regarding the oxidising capacity of the marine boundary layer.

scholarly journals Radicals in the marine boundary layer during NEAQS 2004: a model study of day-time and night-time sources and sinks

2009 ◽  
Vol 9 (9) ◽  
pp. 3075-3093 ◽  
Author(s):  
R. Sommariva ◽  
H. D. Osthoff ◽  
S. S. Brown ◽  
T. S. Bates ◽  
T. Baynard ◽  
...  
Keyword(s):  
Boundary Layer ◽  
New England ◽  
Gas Phase ◽  
Marine Boundary Layer ◽  
Peroxy Radical ◽  
Chemical Mechanism ◽  
Physical Parameters ◽  
Peroxy Radicals ◽  
Night Time ◽  
Aerosol Composition

Abstract. This paper describes a modelling study of several HOx and NOx species (OH, HO2, organic peroxy radicals, NO3 and N2O5) in the marine boundary layer. A model based upon the Master Chemical Mechanism (MCM) was constrained to observations of chemical and physical parameters made onboard the NOAA ship R/V Brown as part of the New England Air Quality Study (NEAQS) in the summer of 2004. The model was used to calculate [OH] and to determine the composition of the peroxy radical pool. Modelled [NO3] and [N2O5] were compared to in-situ measurements by Cavity Ring-Down Spectroscopy. The comparison showed that the model generally overestimated the measurements by 30–50%, on average. The model results were analyzed with respect to several chemical and physical parameters, including uptake of NO3 and N2O5 on fog droplets and on aerosol, dry deposition of NO3 and N2O5, gas-phase hydrolysis of N2O5 and reactions of NO3 with NMHCs and peroxy radicals. The results suggest that fog, when present, is an important sink for N2O5 via rapid heterogeneous uptake. The comparison between the model and the measurements were consistent with values of the heterogeneous uptake coefficient of N2O5 (γN2O5)>1×10−2, independent of aerosol composition in this marine environment. The analysis of the different loss processes of the nitrate radical showed the important role of the organic peroxy radicals, which accounted for a significant fraction (median: 15%) of NO3 gas-phase removal, particularly in the presence of high concentrations of dimethyl sulphide (DMS).

scholarly journals Importance of the surface reaction OH+Cl<sup>-</sup> on sea salt aerosol for the chemistry of the marine boundary layer – a model study

2006 ◽  
Vol 6 (3) ◽  
pp. 3657-3685 ◽  
Author(s):  
R. von Glasow
Keyword(s):  
Boundary Layer ◽  
Gas Phase ◽  
Marine Boundary Layer ◽  
Sulfur Cycle ◽  
Sea Salt ◽  
Sea Salt Aerosol ◽  
Sulfate Production ◽  
Model Study ◽  
Additional Production ◽  
A Minor

Abstract. The reaction of the hydroxyl radical with chloride on the surface of sea salt aerosol producing gas phase Cl2 and particulate OH- and its implications for the chemistry of the marine boundary layer under coastal, remote, and very remote conditions have been investigated with a numerical model. This reaction had been suggested by Laskin et al. (2003) to play a major role in the sulfur cycle in the marine boundary layer by increasing the sulfate production in sea salt by O3 oxidation due to the additional production of alkalinity in the particle. Based on literature data a new &amp;quotbest estimate'' for the rate coefficient of the reaction was deduced and applied, showing that the additional initial sulfate production by this reaction is less than 1%, therefore having only a minor impact on sulfate production. Even though the gas phase concentration of Cl2 increased strongly in the model the concentration of Cl radicals increased by less than 5% for the &amp;quotbest guess'' case. Additional feedbacks between the cycles of chlorine and sulfur in the marine boundary layer are discussed as well as a two-stage acidification of large fresh sea salt aerosol.

scholarly journals Importance of the surface reaction OH + Cl<sup>−</sup> on sea salt aerosol for the chemistry of the marine boundary layer – a model study

2006 ◽  
Vol 6 (11) ◽  
pp. 3571-3581 ◽  
Author(s):  
R. von Glasow
Keyword(s):  
Boundary Layer ◽  
Gas Phase ◽  
Marine Boundary Layer ◽  
Sulfur Cycle ◽  
Sea Salt ◽  
Sea Salt Aerosol ◽  
Sulfate Production ◽  
Model Study ◽  
Additional Production ◽  
A Minor

Abstract. The reaction of the hydroxyl radical with chloride on the surface of sea salt aerosol producing gas phase Cl2 and particulate OH− and its implications for the chemistry of the marine boundary layer under coastal, remote, and very remote conditions have been investigated with a numerical model. This reaction had been suggested by Laskin et al. (2003) to play a major role in the sulfur cycle in the marine boundary layer by increasing the sulfate production in sea salt by O3 oxidation due to the additional production of alkalinity in the particle. Based on literature data a new "best estimate" for the rate coefficient of the reaction was deduced and applied, showing that the additional initial sulfate production by this reaction is less than 1%, therefore having only a minor impact on sulfate production. Even though the gas phase concentration of Cl2 increased strongly in the model, the concentration of Cl radicals increased by less than 5% for the "best guess" case. Additional feedbacks between the cycles of chlorine and sulfur in the marine boundary layer are discussed as well as a two-stage acidification of large fresh sea salt aerosol.

scholarly journals Radicals in the marine boundary layer during NEAQS 2004: a model study of day-time and night-time sources and sinks

2008 ◽  
Vol 8 (4) ◽  
pp. 16643-16692 ◽  
Author(s):  
R. Sommariva ◽  
H. D. Osthoff ◽  
S. S. Brown ◽  
T. S. Bates ◽  
T. Baynard ◽  
...  
Keyword(s):  
Boundary Layer ◽  
New England ◽  
Gas Phase ◽  
Marine Boundary Layer ◽  
Peroxy Radical ◽  
Chemical Mechanism ◽  
Physical Parameters ◽  
Peroxy Radicals ◽  
Night Time ◽  
Aerosol Composition

Abstract. This paper describes a modelling study of several HOx and NOx species (OH, HO2, organic peroxy radicals, NO3 and N2O5) in the marine boundary layer. A model based upon the Master Chemical Mechanism (MCM) was constrained to observations of chemical and physical parameters made onboard the NOAA ship R/V Brown as part of the New England Air Quality Study (NEAQS) in the summer of 2004. The model was used to calculate [OH] and to determine the composition of the peroxy radical pool. Modelled [NO3] and [N2O5] were compared to in-situ measurements by Cavity Ring-Down Spectroscopy. The comparison showed that the model generally overestimated the measurements by 30–50%, on average. The model results were analyzed with respect to several chemical and physical parameters, including uptake of NO3 and N2O5 on fog droplets and on aerosol, dry deposition of NO3 and N2O5, gas-phase hydrolysis of N2O5 and reactions of NO3 with NMHCs and peroxy radicals. The results suggest that fog, when present, is an important sink for N2O5 via rapid heterogeneous uptake. The comparison between the model and the measurements were consistent with values of the heterogeneous uptake coefficient of N2O5 (γN2O5)>1×10−2, independent of aerosol composition in this marine environment. The analysis of the different loss processes of the nitrate radical showed the important role of the organic peroxy radicals, which accounted for a significant fraction (median: 15%) of NO3 gas-phase removal, particularly in the presence of high concentrations of dimethyl sulphide (DMS).

scholarly journals An investigation of the origins of reactive gaseous mercury in the Mediterranean marine boundary layer

2009 ◽  
Vol 9 (6) ◽  
pp. 24815-24846 ◽  
Author(s):  
F. Sprovieri ◽  
I. M. Hedgecock ◽  
N. Pirrone
Keyword(s):  
Gas Phase ◽  
Marine Boundary Layer ◽  
Atmospheric Mercury ◽  
Chemical Mechanism ◽  
Back Trajectory ◽  
Emission Sources ◽  
Anthropogenic Emission ◽  
Modelling Studies ◽  
In Situ Production

Abstract. Atmospheric mercury concentrations were measured during two oceanographic cruise campaigns covering the Adriatic Sea, the first during the autumn in 2004 and the second in the summer of 2005. The inclement weather during the autumn campaign meant that no clear in-situ production of oxidised gas phase mercury was seen, and that events where high values of HgII(g) and/or Hg associated with particulates (HgP) were observed, were the result of plumes from anthropogenic emission sources. During the summer campaign however, the by now rather familiar diurnal variation of HgII(g) concentration, with maxima around midday, was observed. Again there were events when high HgII(g) and particulates (HgP) concentrations were seen which did not fit with the pattern of daily in-situ HgII(g) production, which were traceable, with the help of back trajectory calculations, to anthropogenic emission sources. All the emission plumes encountered could be traced back to ports, not all of which are associated with major industrial installations. It therefore seems likely in theses cases that the emissions are either due to shipping or to port activities. Box modelling studies of the summer 2005 campaign show that although the in-situ production of HgII(g) occurs in the MBL, the exact chemical mechanism responsible is difficult to determine. However given the high O3 concentrations encountered during this campaign it seems clear that if Hg0 does react with O3, it does not produce gas phase HgII, and the reaction between Hg0 and OH if it occurs, does not contribute appreciably to HgII(g) production.

scholarly journals Influence of Water on the Gas-Phase Reaction of Dimethyl Sulfide with BrO in the Marine Boundary Layer

ACS Omega ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 2410-2419
Author(s):  
Junyao Li ◽  
Narcisse T. Tsona ◽  
Shanshan Tang ◽  
Xiuhui Zhang ◽  
Lin Du
Keyword(s):  
Boundary Layer ◽  
Gas Phase ◽  
Dimethyl Sulfide ◽  
Marine Boundary Layer ◽  
Phase Reaction ◽  
Gas Phase Reaction ◽  
Influence Of Water

scholarly journals Gaseous chemistry and aerosol mechanism developments for version 3.5.1 of the online regional model, WRF-Chem

2014 ◽  
Vol 7 (6) ◽  
pp. 2557-2579 ◽  
Author(s):  
S. Archer-Nicholls ◽  
D. Lowe ◽  
S. Utembe ◽  
J. Allan ◽  
R. A. Zaveri ◽  
...  
Keyword(s):  
Gas Phase ◽  
Chemical Mechanism ◽  
Reduced Form ◽  
Sea Spray ◽  
Wind Fields ◽  
Aerosol Composition ◽  
Aerosol Emission ◽  
Sea Spray Aerosol ◽  
The Impact ◽  
Phase Chemical

Abstract. We have made a number of developments to the Weather, Research and Forecasting model coupled with Chemistry (WRF-Chem), with the aim of improving model prediction of trace atmospheric gas-phase chemical and aerosol composition, and of interactions between air quality and weather. A reduced form of the Common Reactive Intermediates gas-phase chemical mechanism (CRIv2-R5) has been added, using the Kinetic Pre-Processor (KPP) interface, to enable more explicit simulation of VOC degradation. N2O5 heterogeneous chemistry has been added to the existing sectional MOSAIC aerosol module, and coupled to both the CRIv2-R5 and existing CBM-Z gas-phase schemes. Modifications have also been made to the sea-spray aerosol emission representation, allowing the inclusion of primary organic material in sea-spray aerosol. We have worked on the European domain, with a particular focus on making the model suitable for the study of nighttime chemistry and oxidation by the nitrate radical in the UK atmosphere. Driven by appropriate emissions, wind fields and chemical boundary conditions, implementation of the different developments are illustrated, using a modified version of WRF-Chem 3.4.1, in order to demonstrate the impact that these changes have in the Northwest European domain. These developments are publicly available in WRF-Chem from version 3.5.1 onwards.

Can Marine Cloud Brightening Reduce Sea-Surface Temperatures to Moderate Extreme Hurricanes and Typhoons?

2021 ◽  
Vol 6 (3) ◽  
Author(s):  
Salter SH ◽  
Keyword(s):  
Boundary Layer ◽  
Marine Boundary Layer ◽  
Sea Water ◽  
Cloud Condensation Nuclei ◽  
Sea Surface ◽  
Sea Surface Temperatures ◽  
Marine Stratocumulus ◽  
Surface Temperatures ◽  
Stratocumulus Clouds ◽  
Cloud Tops

Elevated sea-surface temperatures are a necessary but not sufficient requirement for the formation of hurricanes and typhoons. This paper suggests a way to exploit this. Twomey [1] showed that cloud reflectivity depends on the size-distribution of cloud drops, with a large number of small drops reflecting more than a smaller number of larger ones. Mid-ocean air is cleaner than over land. Latham [2-4] suggested that reflectivity of marine stratocumulus clouds could be increased by releasing a submicron spray of filtered sea water into the bottom of the marine boundary layer. The salt residues left after evaporation would be mixed by turbulence through the full depth of the marine boundary layer and would be ideal cloud condensation nuclei. Those that reached a height where the air had a super-saturation above 100% by enough to get over the peak of the Köhler curve would produce an increased number of cloud drops and so trigger the Twomey effect. The increase in reflection from cloud tops back out to space would cool sea-surface water. We are not trying to increase cloud cover; we just want to make existing cloud tops whiter. The spray could be produced by wind-driven vessels cruising chosen ocean regions. The engineering design of sea-going hardware is well advanced. This paper suggests a way to calculate spray quantities and the number and cost of spray vessels to achieve a hurricane reduction to a more acceptable intensity. It is intended to show the shape of a possible calculation with credible if not exact assumptions. Anyone with better assumptions should be able to follow the process.

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