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Author |
Kukui A, Legrand M, Preunkert S, Frey M M, Loisil R, Gil Roca J, Jourdain B, King M D, France J L, Ancellet G, |
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Title |
Measurements of OH and RO2 radicals at Dome C, East Antarctica
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Journal Article |
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Year |
2014 |
Publication |
Atmos. Chem. Phys. Discuss. |
Abbreviated Journal |
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Volume |
14 |
Issue |
10 |
Pages |
14999-15044 |
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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. |
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903 |
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Copernicus Publications |
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1680-7375 |
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5184 |
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Author |
Legrand M, Preunkert S, Frey M, Bartels-Rausch T, Kukui A, King M D, Savarino J, Kerbrat M, Jourdain B, |
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Title |
Large mixing ratios of atmospheric nitrous acid (HONO) at Concordia (East Antarctic plateau) in summer: a strong source from surface snow?
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Type |
Journal Article |
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Year |
2014 |
Publication |
Atmos. Chem. Phys. Discuss. |
Abbreviated Journal |
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Volume |
14 |
Issue |
8 |
Pages |
11749-11785 |
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Abstract |
During the austral summer 2011/2012 atmospheric nitrous acid was investigated for the second time at the Concordia site (75060 S, 123330 E) located on the East Antarctic plateau by deploying a long path absorption photometer (LOPAP). Hourly mixing ratios of HONO measured in December 2011/January 2012 (35±5.0 pptv) were similar to those measured in December 2010/January 2011 (30.4±3.5 pptv). The large value of the HONO mixing ratio at the remote Concordia site suggests a local source of HONO in addition to weak production from oxidation of NO by the OH radical. Laboratory experiments demonstrate that surface snow removed from Concordia can produce gas phase HONO at mixing ratios half that of NOx mixing ratio produced in the same experiment at typical temperatures encountered at Concordia in summer. Using these lab data and the emission flux of NOx from snow estimated from the vertical gradient of atmospheric concentrations measured during the campaign, a mean diurnal HONO snow emission ranging between 0.5 and 0.8×109 moleculescm-2 s-1 is calculated. Model calculations indicate that, in addition to around 1.2 pptv of HONO produced by the NO oxidation, these HONO snow emissions can only explain 6.5 to 10.5 pptv of HONO in the atmosphere at Concordia. To explain the difference between observed and simulated HONO mixing ratios, tests were done both in the field and at lab to explore the possibility that the presence of HNO4 had biased the measurements of HONO. |
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903 |
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Copernicus Publications |
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1680-7375 |
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5195 |
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Cressot C, Chevallier F, Bousquet P, Crevoisier C, Dlugokencky E J, Fortems-Cheiney A, Frankenberg C, Parker R, Pison I, Scheepmaker R A, Montzka S A, Krummel P B, Steele L P, Langenfelds R L, |
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Title |
On the consistency between global and regional methane emissions inferred from SCIAMACHY, TANSO-FTS, IASI and surface measurements
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Journal Article |
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Year |
2013 |
Publication |
ATMOSPHERIC CHEMISTRY AND PHYSICS |
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Volume |
13 |
Issue |
3 |
Pages |
8023-8064 |
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416 |
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1680-7375 |
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yes |
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Serial |
4451 |
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Author |
Bonne J-L, Masson-Delmotte V, Cattani O, Delmotte M, Risi C, Sodemann H, Steen-Larsen H C, |
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Title |
The isotopic composition of water vapour and precipitation in Ivittuut, Southern Greenland
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Type |
Journal Article |
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Year |
2013 |
Publication |
Atmos. Chem. Phys. Discuss. |
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Volume |
13 |
Issue |
11 |
Pages |
30521-30574 |
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439 |
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1680-7375 |
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yes |
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Serial |
4361 |
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Author |
Erbland, J., W. Vicars, J. Savarino, S. Morin, M. M. Frey, D. Frosini, E. Vince, and J. Martins |
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Title |
Air-snow transfer of nitrate on the East Antarctic Plateau – Part 1: Isotopic evidence for a photolytically driven dynamic equilibrium |
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Journal Article |
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Year |
2012 |
Publication |
ATMOSPHERIC CHEMISTRY AND PHYSICS |
Abbreviated Journal |
1680-7316 |
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Volume |
12 |
Issue |
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Pages |
28559-28564 |
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1011 |
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1680-7316 |
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4272 |
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Author |
France J L, King M D, Frey M M, Erbland J, Picard G, MacArthur A, Savarino J, |
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Title |
Snow optical properties at Dome C, Antarctica implications for snow emissions and snow chemistry of reactive nitrogen
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Journal Article |
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Year |
2011 |
Publication |
Atmos. Chem. Phys. Discuss. |
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Volume |
11 |
Issue |
4 |
Pages |
11959-11993 |
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1013 |
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Copernicus Publications |
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1680-7375 |
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yes |
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3590 |
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Author |
Yver C, Pison I, Fortems-Cheiney A, Schmidt M, Bousquet P, Ramonet M, Jordan A, Søvde A, Engel A, Fisher R, Lowry D, Nisbet E, Levin I, Hammer S, Necki J, Bartyzel J, Reimann S, Vollmer M K, Steinbacher M, Aalto T, Maione M, Arduini I, O'Doherty S, Grant A, Sturges W, Lunder C R, Privalov V, Paramonova N, |
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Title |
A new estimation of the recent tropospheric molecular hydrogen budget using atmospheric observations and variational inversion
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Journal Article |
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2010 |
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Atmos. Chem. Phys. Discuss. |
Abbreviated Journal |
1680-7316 |
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Volume |
10 |
Issue |
11 |
Pages |
28963-29005 |
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416 |
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Copernicus Publications |
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1680-7375 |
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3800 |
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Author |
Feng W, Chipperfield M P, Dhomse S, Monge-Sanz B M, Yang X, Zhang K, Ramonet M, |
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Title |
Evaluation of cloud convection and tracer transport in a three-dimensional chemical transport model
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Journal Article |
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2010 |
Publication |
Atmos. Chem. Phys. Discuss. |
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Volume |
10 |
Issue |
10 |
Pages |
22953 -22991 |
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Abstract |
We investigate the performance of cloud convection and tracer transport in a global off-line 3-D chemical transport model. Various model simulations are performed using different meteorological (re)analyses (ERA-40, ECMWF operational and ECMWF Interim) to diagnose the updraft mass flux, convective precipitation and cloud top height.
The diagnosed upward mass flux distribution from TOMCAT agrees quite well with the ECMWF reanalysis data (ERA-40 and ERA-Interim) below 200 hPa. Inclusion of midlevel convection improves the agreement at mid-high latitudes. However, the reanalyses show strong convective transport up to 100 hPa, well into the tropical tropopause layer (TTL), which is not captured by TOMCAT. Similarly, the model captures the spatial and seasonal variation of convective cloud top height although the mean modelled value is about 2 km lower than observed.
The ERA-Interim reanalyses have smaller archived upward convective mass fluxes than ERA-40, and smaller convective precipitation, which is in better agreement with satellite-based data. TOMCAT captures these relative differences when diagnosing convection from the large-scale fields. The model also shows differences in diagnosed convection with the version of the operational analyses used, which cautions against using results of the model from one specific time period as a general evaluation.
We have tested the effect of resolution on the diagnosed modelled convection with simulations ranging from 5.6° × 5.6° to 1° × 1°. Overall, in the off-line model, the higher model resolution does not make a large change to the diagnosed convective tracer transport. Similarly, the resolution of the forcing winds in the higher resolution CTM does not make a large improvement compared to the archived mass fluxes.
Including a radon tracer in the model confirms the importance of convection for reproducing observed midlatitude profiles. The model run using archived mass fluxes transports significantly more radon to the upper troposphere but the available data does not strongly discriminate between the different model versions. |
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Copernicus Publications |
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1680-7375 |
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Serial |
2680 |
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Author |
Kuttippurath J, Godin-Beekmann S, Lefèvre F, Goutail F, |
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Title |
Spatial, temporal, and vertical variability of polar stratospheric ozone loss in the Arctic winters 2004/052009/10
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Journal Article |
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Year |
2010 |
Publication |
Atmos. Chem. Phys. Discuss. |
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Volume |
10 |
Issue |
6 |
Pages |
14675-14711 |
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209 |
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Copernicus Publications |
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1680-7375 |
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3068 |
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Author |
Frey M M, Savarino J, Morin S, Erbland J, Martins J M F, |
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Title |
Photolysis imprint in the nitrate stable isotope signal in snow and atmosphere of East Antarctica and implications for reactive nitrogen cycling
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Journal Article |
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Year |
2009 |
Publication |
Atmos. Chem. Phys. |
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Volume |
9 |
Issue |
22 |
Pages |
8681 -8696 |
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Abstract |
The nitrogen (δ15N) and triple oxygen (δ17O and δ18O) isotopic composition of nitrate (NO3−) was measured year-round in the atmosphere and snow pits at Dome C, Antarctica (DC, 75.1° S, 123.3° E), and in surface snow on a transect between DC and the coast. Comparison to the isotopic signal in atmospheric NO3− shows that snow NO3− is significantly enriched in δ15N by >200‰ and depleted in δ18O by <40‰. Post-depositional fractionation in Δ17O(NO3−) is small, potentially allowing reconstruction of past shifts in tropospheric oxidation pathways from ice cores. Assuming a Rayleigh-type process we find fractionation constants ε of −60±15‰, 8±2‰ and 1±1‰, for δ15N, δ18O and Δ17O, respectively. A photolysis model yields an upper limit for the photolytic fractionation constant 15ε of δ15N, consistent with lab and field measurements, and demonstrates a high sensitivity of 15ε to the incident actinic flux spectrum. The photolytic 15ε is process-specific and therefore applies to any snow covered location. Previously published 15ε values are not representative for conditions at the Earth surface, but apply only to the UV lamp used in the reported experiment (Blunier et al., 2005; Jacobi et al., 2006). Depletion of oxygen stable isotopes is attributed to photolysis followed by isotopic exchange with water and hydroxyl radicals. Conversely, 15N enrichment of the NO3− fraction in the snow implies 15N depletion of emissions. Indeed, δ15N in atmospheric NO3− shows a strong decrease from background levels (4±7‰) to −35‰ in spring followed by recovery during summer, consistent with significant snowpack emissions of reactive nitrogen. Field and lab evidence therefore suggest that photolysis is an important process driving fractionation and associated NO3− loss from snow. The Δ17O signature confirms previous coastal measurements that the peak of atmospheric NO3− in spring is of stratospheric origin. After sunrise photolysis drives then redistribution of NO3− from the snowpack photic zone to the atmosphere and a snow surface skin layer, thereby concentrating NO3− at the surface. Little NO3− appears to be exported off the EAIS plateau, still snow emissions from as far as 600 km inland can contribute to the coastal NO3− budget. |
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1011 |
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Copernicus Publications |
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1680-7324 |
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1883 |
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