Modelling the impact of oxygenated VOC and meteorology upon the boundary layer photochemistry at the South Pole

2007 ◽  
Vol 8 (1) ◽  
pp. 14-20 ◽  
Author(s):  
P. D. Hamer ◽  
D. E. Shallcross
Keyword(s):  
Boundary Layer ◽  
South Pole ◽  
The South ◽  
The Impact

scholarly journals Modelling the impact of possible snowpack emissions of O(3P) and NO2 on photochemistry in the South Pole boundary layer

2008 ◽  
Vol 5 (4) ◽  
pp. 268 ◽  
Author(s):  
P. D. Hamer ◽  
D. E. Shallcross ◽  
A. Yabushita ◽  
M. Kawasaki
Keyword(s):  
Climate Change ◽  
Boundary Layer ◽  
Physical Phenomenon ◽  
Surface Ozone ◽  
Ozone Production ◽  
South Pole ◽  
The South ◽  
Photochemical Pollution ◽  
Ozone Concentrations ◽  
The Impact

Environmental context. The study of surface photochemical ozone production on the Antarctic continent has direct relevance to climate change and general air quality and is scientifically noteworthy given the otherwise pristine nature of this environmental region. The identification of possible direct ozone emissions from snow surfaces and their contribution to the already active photochemical pollution present there represents a unique physical phenomenon. This process could have wider global significance for other snow-covered regions and therefore for global climate change. Abstract. O(3P) emissions due to photolysis of nitrate were recently identified from ice surfaces doped with nitric acid. O(3P) atoms react directly with molecular oxygen to yield ozone. Therefore, these results may have direct bearing on photochemical activity monitored at the South Pole, a site already noted for elevated summertime surface ozone concentrations. NO2 is also produced via the photolysis of nitrate and the firn air contains elevated levels of NO2, which will lead to direct emission of NO2. A photochemical box model was used to probe what effect O(3P) and NO2 emissions have on ozone concentrations within the South Pole boundary layer. The results suggest that these emissions could account for a portion of the observed ozone production at the South Pole and may explain the observed upward fluxes of ozone identified there.

scholarly journals The effect of the novel HO2 + NO → HNO3 reaction channel at South Pole, Antarctica

2012 ◽  
Vol 24 (4) ◽  
pp. 417-425 ◽  
Author(s):  
C.S. Boxe ◽  
P.D. Hamer ◽  
W. Ford ◽  
M. Hoffmann ◽  
D.E. Shallcross
Keyword(s):  
Boundary Layer ◽  
Atmospheric Chemistry ◽  
Ozone Depletion ◽  
Field Measurements ◽  
Ozone Production ◽  
The Novel ◽  
South Pole ◽  
The South ◽  
The Impact ◽  
Production Channel

AbstractIt is well established that the reaction of HO2 with NO plays a central role in atmospheric chemistry, by way of OH/HO2 recycling and reduction of ozone depletion by HOx cycles in the stratosphere and through ozone production in the troposphere. Utilizing a photochemical box model, we investigate the impact of the recently observed HNO3 production channel (HO2+NO → HNO3) on NOx (NO + NO2), HOx (OH + HO2), HNO3, and O3 concentrations in the boundary layer at the South Pole, Antarctica. Our simulations exemplify decreases in peak O3, NO, NO2, and OH and an increase in HNO3. Also, mean OH is in better agreement with observations, while worsening the agreement with O3, HO2, and HNO3 concentrations observed at the South Pole. The reduced concentrations of NOx are consistent with expected decreases in atmospheric NOx lifetime as a result of increased sequestration of NOx into HNO3. Although we show that the inclusion of the novel HNO3 production channel brings better agreement of OH with field measurements, the modelled ozone and HNO3 are worsened, and the changes in NOx lifetime imply that snowpack NOx emissions and snowpack nitrate recycling must be re-evaluated.

Replacing Chlorofluorocarbons in Industry

1990 ◽  
Vol 33 (6) ◽  
pp. 23-26
Author(s):  
Kurt Weigel
Keyword(s):  
Decision Making ◽  
Ozone Depletion ◽  
Scientific Evidence ◽  
Decision Making Process ◽  
South Pole ◽  
The South ◽  
Blowing Agents ◽  
Research Organizations ◽  
Speed Up ◽  
The Impact

Scientific evidence indicates that ozone depletion over the South Pole is more serious than was suspected a few years ago. As a result, production of the principal ozone-depleting compounds is scheduled to be phased out over the next decade. The impact of the elimination of these chemicals on industries will be immediate and significant, with the aerospace and electronics industries among the most severely affected. Alternative solvents, refrigerants, and foam-blowing agents are being developed, but will not be available in commercial quantities until 1992 at the earliest. Meanwhile, CFC users are working with the chemical manufacturers, EPA, DoD, and various research organizations, to speed up the process of identifying and implementing alternative compounds or processes. Most of the proposed alternatives have some drawbacks when compared with CFCs, but can be implemented safely if the user takes the time to understand the issues thoroughly and involves all affected parties in the decision-making process.

Observations of summertime NO fluxes and boundary-layer height at the South Pole during ISCAT 2000 using scalar similarity

2004 ◽  
Vol 38 (32) ◽  
pp. 5389-5398 ◽  
Author(s):  
S.P. Oncley ◽  
M. Buhr ◽  
D.H. Lenschow ◽  
D. Davis ◽  
S.R. Semmer
Keyword(s):  
Boundary Layer ◽  
South Pole ◽  
The South ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Scalar Similarity ◽  
No Fluxes

scholarly journals Measurements of OH and RO<sub>2</sub> radicals at Dome C, East Antarctica

2014 ◽  
Vol 14 (10) ◽  
pp. 14999-15044 ◽  
Author(s):  
A. Kukui ◽  
M. Legrand ◽  
S. Preunkert ◽  
M. M. Frey ◽  
R. Loisil ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Oxidative Capacity ◽  
Local Times ◽  
Oh Radicals ◽  
Peroxy Radicals ◽  
South Pole ◽  
The South ◽  
Primary Radical ◽  
Antarctic Plateau ◽  
Photochemical Modelling

Abstract. Concentrations of OH radicals and the sum of peroxy radicals, RO2, were measured in the boundary layer for the first time on the East Antarctic Plateau at the Concordia Station (Dome C, 75.10° S, 123.31° E) during the austral summer 2011/2012. The median concentrations of OH and RO2 radicals were 3.1 × 106 molecule cm−3 and 9.9 × 107 molecule cm−3, respectively. These values are comparable to those observed at the South Pole, confirming that the elevated oxidative capacity of the Antarctic atmospheric boundary layer found at the South Pole is not restricted to the South Pole but common over the high Antarctic plateau. At Concordia, the concentration of radicals showed distinct diurnal profiles with the median maximum of 5.2 × 106 molecule cm−3 at 11:00 and the median minimum of 1.1 × 106 molecule cm−3 at 01:00 for OH radicals and 1.7 × 108 molecule cm−3 and 2.5 × 107 molecule cm−3 for RO2 radicals at 13:00 and 23:00, respectively (all times are local times). Concurrent measurements of O3, HONO, NO, NO2, HCHO and H2O2 demonstrated that the major primary source of OH and RO2 radicals at Dome C was the photolysis of HONO, HCHO and H2O2, with the photolysis of HONO contributing ∼75% of total primary radical production. However, photochemical modelling with accounting for all these radical sources overestimates the concentrations of OH and RO2 radicals by a factor of 2 compared to field observations. Neglecting the OH production from HONO in the photochemical modelling results in an underestimation of the concentrations of OH and RO2 radicals by a factor of 2. To explain the observations of radicals in this case an additional source of OH equivalent to about 25% of measured photolysis of HONO is required. Even with a factor of 4 reduction in the concentrations of HONO, the photolysis of HONO represents the major primary radical source at Dome C. Another major factor leading to the large concentration of OH radicals measured at Dome C was large concentrations of NO molecules and fast recycling of peroxy radicals to OH radicals.

scholarly journals Inter-annual variability of surface ozone at coastal (Dumont d’Urville, 2004–2014) and inland (Concordia, 2007–2014) sites in East Antarctica

2016 ◽  
Author(s):  
M. Legrand ◽  
S. Preunkert ◽  
J. Savarino ◽  
M. M. Frey ◽  
A. Kukui ◽  
...  
Keyword(s):  
Surface Ozone ◽  
Ozone Layer ◽  
Weddell Sea ◽  
East Antarctica ◽  
Late Winter ◽  
South Pole ◽  
The South ◽  
Coastal Site ◽  
Antarctic Plateau ◽  
The Impact

Abstract. Surface ozone has been measured since 2004 at the coastal East Antarctic site of Dumont d'Urville (DDU) and since 2007 at the Concordia station located on the high East Antarctic plateau. This paper discusses long-term trends, seasonal and diurnal cycles, as well as inter-annual summer variability observed at these two East Antarctic sites. At Concordia, near surface ozone data were complemented by balloon soundings and compared to similar measurements done at the South Pole. The DDU record is compared to those obtained at the coastal site of Syowa also located in East Antarctica, as well as the coastal sites of Neumayer and Halley, both located at the coast of the Weddell Sea in West Antarctica. Surface ozone mixing ratios exhibit very similar seasonal cycle at Concordia and the South Pole. However, in summer the diurnal cycle and the vertical distribution of ozone above the snow surface are different at the two sites with a drop of ozone in the afternoon at Concordia and not at the South Pole, and a far well-mixed rich ozone layer within the lower 250 m at Concordia than at the South Pole during sunlight hours. These differences are related to different solar radiation and wind regimes encountered at these two inland sites. DDU appears to be the coastal site where the impact of the late winter/spring bromine chemistry is the weakest, but where the impact of NOx snow emissions from the high Antarctic plateau is the highest. The highest impact of the bromine chemistry is seen at Halley and Neumayer, and to a lesser extent at Syowa. These three sites are only weakly impacted by the NOx chemistry and the net ozone production occurring on the high Antarctic plateau. The differences in late winter/spring are attributed to the abundance of sea-ice offshore the sites whereas those in summer are related to the topography of East Antarctica that promotes the katabatic flow bringing oxidant-rich inland air masses to the site. There appears to be a decreasing trend in summer at the two East Antarctic sites of Concordia and DDU over the most recent period (2004/2007–2014). Further researches including continuing monitoring are needed at these two sites to better separate effect of synoptic transport from possible change of NOx snow emissions in response to change of the stratospheric ozone layer.

scholarly journals The Meteorology and Chemistry of High Nitrogen Oxide Concentrations in the Stable Boundary Layer at the South Pole

2017 ◽  
Author(s):  
William Neff ◽  
Jim Crawford ◽  
Marty Buhr ◽  
John Nicovich ◽  
Gao Chen ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Stable Boundary Layer ◽  
Early Summer ◽  
Late Spring ◽  
Small Scale ◽  
South Pole ◽  
The South ◽  
Stable Boundary ◽  
Direct Measurements ◽  
The Antarctic

Abstract. Four summer seasons of nitrogen oxide (NO) concentrations were obtained at the South Pole during the Sulfur Chemistry in the Antarctic Troposphere (ISCAT) program (1998 and 2000) and the Antarctic Tropospheric Chemistry Investigation (ANTCI) in (2003, 2006–7). Together, analyses of their data here provide insight into the large-to-small scale meteorology that sets the stage for high NO and the significant variability that occurs day-to-day, within seasons and year-to-year. In addition, these observations reveal the interplay between physical and chemical processes at work in the stable boundary layer of the high Antarctic plateau. We found a systematic evolution of the large-scale wind system over the ice sheet from winter to summer that controls the surface boundary layer and its effect on NO: Initially in early spring (Days 280–310) the transport of warm air and clouds over West Antarctica dominates the environment over the South Pole; In late spring (Days 310–340), of significance to NO, the winds at 300-hPa exhibit a bimodal behavior alternating between NW and SE; In early summer (Days 340–375), the flow aloft is dominated by winds from the Weddell Sea. During late spring, winds aloft from the SE are strongly associated with clear skies, shallow stable boundary layers, and light surface winds from the east: it is under these conditions that the highest NO occurs. Examination of the winds at 300 hPa from 1961 to 2013 shows that this seasonal pattern has not changed significantly although the last twenty years have seen an increasing trend in easterly surface winds at the South Pole. What has also changed is the persistence of the ozone hole, often into early summer. With lower total ozone column density and higher sun elevation, the highest actinic flux responsible for the photolysis of snow nitrate now occurs in late spring under the shallow boundary layer conditions optimum for high accumulation of NO. This may occur via the non-linear HOX-NOX chemistry proposed after the first ISCAT field programs and NOX recycling to the surface where quantum yields may be large under the low-snow-accumulation regime of the Antarctic plateau. During the 2003 field program a sodar made direct measurements of the stable boundary layer depth (BLD), a key factor in explaining the chemistry of the high NO concentrations. Because direct measurements were not available in the other years, we developed an estimator for BLD using direct observations obtained in 2003 and step-wise linear regression with meteorological data from a 22-m tower (that was tested against independent data obtained in 1993). These data were then used with assumptions about the column abundance of NO to estimate surface fluxes of NOX. These results agreed in magnitude with results at Concordia Station and confirmed significant daily, intraseasonal and interannual variability in NO and its flux from the snow surface. Finally, we found that synoptic to mesoscale eddies governed the boundary layer circulation and accumulation pathways for NO at the South Pole rather than katabatic forcing. It was the small scale features of the circulation including the transition from cloudy to clear conditions that set the stage for short-term extremes in NO whereas larger-scale features were associated with more moderate concentrations.

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