scholarly journals Analysis of multi-year near-surface ozone observations at the WMO/GAW “Concordia” station, Antarctica

2020 ◽  
Author(s):  
Davide Putero ◽  
Rita Traversi ◽  
Angelo Lupi ◽  
Francescopiero Calzolari ◽  
Maurizio Busetto ◽  
...  
Keyword(s):  
Surface Ozone ◽  
Atmospheric Composition ◽  
Near Surface ◽  
Air Masses ◽  
Antarctic Plateau ◽  
Stratospheric Intrusion ◽  
Statistical Selection ◽  
Annual Frequency ◽  
Selection Methodology ◽  
The Antarctic

<p>In this work, eight years (2006–2013) of continuous measurements of near-surface ozone (O<sub>3</sub>) at the WMO/GAW contributing station “Concordia” (DMC, 75°06’S, 123°20’E, 3280 m a.s.l.) are presented, and the role of specific atmospheric processes in affecting O<sub>3</sub> variability is investigated. In particular, during the period of highest data coverage (i.e., 2008–2013), O<sub>3</sub> enhancement events (OEEs) were systematically observed at DMC, affecting 11.6% of the dataset. As deduced by a statistical selection methodology, the OEEs are affected by a significant interannual variability, both in the average and in the frequency of O<sub>3</sub> values. To explain part of this variability, OEEs were analyzed as a function of: (i) total column of O<sub>3</sub> and UV-A irradiance variability, (ii) long-range transport of air masses over the Antarctic plateau (by using LAGRANTO), and (iii) occurrence of “deep” stratospheric intrusion events (by using STEFLUX). The overall O<sub>3</sub> concentrations are controlled by a day-to-day variability, which indicates the dominating influence of processes occurring at “synoptic” scales rather than “local” processes. Despite previous studies indicated an inverse relationship between OEEs and TCO, we found that the annual frequency of OEEs was higher when TCO values at DMC were higher than usual. The annual occurrence of OEEs at DMC was also related to the total time spent by air masses over the Antarctic plateau before their arrival at DMC, suggesting that the accumulation of photochemically-produced O<sub>3</sub> during the transport dominated the local O<sub>3</sub> production. Lastly, the influence of “deep” stratospheric intrusion events at DMC was analyzed, and it was observed that this contribution played only a marginal role (the highest frequency observed was 3% of the period, in November).</p><p>This latter point, i.e., the frequency and seasonality of stratosphere-to-troposphere (STE) events, and the relative influence of specific transport mechanisms, as well as snow chemistry, are still under debate. These topics will be investigated in the STEAR (Stratosphere-to-Troposphere Exchange in the Antarctic Region) project, starting in 2020 and funded by the Italian Antarctic Research Program (PNRA). In particular, STEAR will provide an assessment of STE events in Antarctica, by using both continuous observations (e.g., O<sub>3</sub> and Beryllium-7) at DMC, and modeling outputs. In addition to DMC measurements, simultaneous atmospheric composition datasets will be analyzed at Antarctic coastal observatories, i.e., the Mario Zucchelli (MZS) and Jang Bogo (JBS) stations.   </p>

scholarly journals The role of open lead interactions in atmospheric ozone variability between Arctic coastal and inland sites

Elem Sci Anth ◽  
2016 ◽  
Vol 4 ◽  
Author(s):  
Peter K. Peterson ◽  
Kerri A. Pratt ◽  
William R. Simpson ◽  
Son V. Nghiem ◽  
Lemuel X. Pérez Pérez ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Sea Ice ◽  
Ozone Depletion ◽  
Surface Ozone ◽  
Optical Absorption Spectroscopy ◽  
Atmospheric Ozone ◽  
Vertical Profiles ◽  
Large Spatial Scale ◽  
Near Surface ◽  
Air Masses

Abstract Boundary layer atmospheric ozone depletion events (ODEs) are commonly observed across polar sea ice regions following polar sunrise. During March-April 2005 in Alaska, the coastal site of Barrow and inland site of Atqasuk experienced ODEs (O3< 10 nmol mol-1) concurrently for 31% of the observations, consistent with large spatial scale ozone depletion. However, 7% of the time ODEs were exclusively observed inland at Atqasuk. This phenomenon also occurred during one of nine flights during the BRomine, Ozone, and Mercury EXperiment (BROMEX), when atmospheric vertical profiles at both sites showed near-surface ozone depletion only at Atqasuk on 28 March 2012. Concurrent in-flight BrO measurements made using nadir scanning differential optical absorption spectroscopy (DOAS) showed the differences in ozone vertical profiles at these two sites could not be attributed to differences in locally occurring halogen chemistry. During both studies, backward air mass trajectories showed that the Barrow air masses observed had interacted with open sea ice leads, causing increased vertical mixing and recovery of ozone at Barrow and not Atqasuk, where the air masses only interacted with tundra and consolidated sea ice. These observations suggest that, while it is typical for coastal and inland sites to have similar ozone conditions, open leads may cause heterogeneity in the chemical composition of the springtime Arctic boundary layer over coastal and inland areas adjacent to sea ice regions.

scholarly journals Regional responses of surface ozone in Europe to the location of high-latitude blocks and subtropical ridges

2016 ◽  
Author(s):  
Carlos Ordóñez ◽  
David Barriopedro ◽  
Ricardo García-Herrera ◽  
Pedro M. Sousa ◽  
Jordan L. Schnell
Keyword(s):  
High Latitude ◽  
Climate Models ◽  
Surface Ozone ◽  
Zonal Flow ◽  
Near Surface ◽  
Air Masses ◽  
Anticyclonic Circulation ◽  
The Uk ◽  
The Impact ◽  
First Time

Abstract. This paper analyses for the first time the impact of high-latitude blocks and subtropical ridges on near-surface ozone in Europe during a 15-year period. For this purpose, a catalogue of blocks and ridges over the Euro-Atlantic region is used together with a gridded dataset of maximum daily 8-hour running average ozone (MDA8 O3) covering the period 1998–2012. The response of ozone to the location of blocks and ridges with centres in three longitudinal sectors (Atlantic, ATL, 30º–0º W; European, EUR, 0º–30º E; Russian, RUS, 30º–60º E) is examined. The impact of blocks on ozone is regionally and seasonally dependent. In particular, blocks within the EUR sector yield positive ozone anomalies of ~ 5–10 ppb over large parts of central Europe in spring and northern Europe in summer. Over 20 % and 30 % of the days with blocks in that sector register exceedances of the 90th percentile of the seasonal ozone distribution at many European locations during spring and summer, respectively. The impacts of ridges during those seasons are subtle and more sensitive to their specific location, although they can trigger ozone anomalies of ~ 5–10 ppb in Italy and the surrounding countries in summer, eventually exceeding European air quality targets. During winter, surface ozone in the northwest of Europe presents completely opposite responses to blocks and ridges. The anticyclonic circulation associated with winter EUR blocking, and to a lesser extent with ATL blocking, yields negative ozone anomalies between −5 ppb and −10 ppb over the UK, Northern France and the Benelux. Conversely, the enhanced zonal flow around 50˚–60˚ N during the occurrence of ATL ridges favours the arrival of background air masses from the Atlantic and the ventilation of the boundary layer, producing positive ozone anomalies above 5 ppb in an area spanning from the British Isles to Germany. This work provides the first quantitative assessments of the remarkable but distinct impacts that the anticyclonic circulation and the diversion of the zonal flow associated with blocks and ridges exert on surface ozone in Europe. The findings reported here can be exploited in the future to evaluate the modelled responses of ozone to circulation changes within chemical transport models (CTMs) and chemistry-climate models (CCMs).

scholarly journals The Weddell Sea region: an important precipitation channel to the interior of the Antarctic ice sheet as revealed by glaciochemical investigation of surface snow along the longest trans-Antarctic route

1999 ◽  
Vol 29 ◽  
pp. 55-60 ◽  
Author(s):  
Qin Dahe ◽  
Paul A. Mayewski ◽  
Ren Jiawen ◽  
Xiao Cunde ◽  
Sun Junying
Keyword(s):  
Ice Sheet ◽  
Weddell Sea ◽  
Sea Salt ◽  
East Antarctica ◽  
Antarctic Ice Sheet ◽  
Air Masses ◽  
Antarctic Plateau ◽  
Salt Ions ◽  
Surface Snow ◽  
The Antarctic

AbstractGlaciochemical analysis of surface snow samples, collected along a profile crossing the Antarctic ice sheet from the Larsen Ice Shelf, Antarctic Peninsula, via the Antarctic Plateau through South Pole, Vostok and Komsomolskaya to Mirny station (at the east margin of East Antarctica), shows that the Weddell Sea region is an important channel for air masses to the high plateau of the Antarctic ice sheet (>2000 m a.s.l.). This opinion is supported by the following. (1) The fluxes of sea-salt ions such as Na+, Mg2 + and CF display a decreasing trend from the west to the east of interior Antarctica. In |eneral, as sea-salt aerosols are injected into the atmosphere over the Antarctic ice sheet from the Weddell Sea, large aerosols tend to decrease. For the inland plateau, few large particles of sea-salt aerosol reach the area, and the sea-salt concentration levels are low (2) The high altitude of the East Antarctic plateau, as well as the polar cold high-pressure system, obstruct the intrusive air masses mainly from the South Indian Ocean sector. (3) For the coastal regions of the East Antarctic ice sheet, the elevation rises to 2000 m over a distance from several to several tens of km. High concentrations of sea salt exist in snow in East Antarctica but are limited to a narrow coastal zone. (4) Fluxes of calcium and non-sea-salt sulfate in snow from the interior plateau do not display an eastward-decreasing trend. Since calcium is mainly derived from crustal sources, and nssSO42- is a secondary aerosol, this again confirms that the eastward-declining tendency of sea-salt ions indicates the transfer direction of precipitation vapor.

scholarly journals Cyclone-induced surface ozone and HDO depletion in the Arctic

2017 ◽  
Vol 17 (24) ◽  
pp. 14955-14974 ◽  
Author(s):  
Xiaoyi Zhao ◽  
Dan Weaver ◽  
Kristof Bognar ◽  
Gloria Manney ◽  
Luis Millán ◽  
...  
Keyword(s):  
Ozone Depletion ◽  
Deuterium Oxide ◽  
Surface Ozone ◽  
Weddell Sea ◽  
Cloud Layer ◽  
The Arctic ◽  
Blowing Snow ◽  
Near Surface ◽  
Air Masses ◽  
Ice Cloud

Abstract. Ground-based, satellite, and reanalysis datasets were used to identify two similar cyclone-induced surface ozone depletion events at Eureka, Canada (80.1° N, 86.4° W), in March 2007 and April 2011. These two events were coincident with observations of hydrogen deuterium oxide (HDO) depletion, indicating that condensation and sublimation occurred during the transport of the ozone-depleted air masses. Ice clouds (vapour and crystals) and aerosols were detected by lidar and radar when the ozone- and HDO-depleted air masses arrived over Eureka. For the 2007 event, an ice cloud layer was coincident with an aloft ozone depletion layer at 870 m altitude on 2–3 March, indicating this ice cloud layer contained bromine-enriched blowing-snow particles. Over the following 3 days, a shallow surface ozone depletion event (ODE) was observed at Eureka after the precipitation of bromine-enriched particles onto the local snowpack. A chemistry–climate model (UKCA) and a chemical transport model (pTOMCAT) were used to simulate the surface ozone depletion events. Incorporating the latest surface snow salinity data obtained for the Weddell Sea into the models resulted in improved agreement between the modelled and measured BrO concentrations above Eureka. MERRA-2 global reanalysis data and the FLEXPART particle dispersion model were used to study the link between the ozone and HDO depletion. In general, the modelled ozone and BrO showed good agreement with the ground-based observations; however, the modelled BrO and ozone in the near-surface layer are quite sensitive to the snow salinity. HDO depletion observed during these two blowing-snow ODEs was found to be weaker than pure Rayleigh fractionation. This work provides evidence of a blowing-snow sublimation process, which is a key step in producing bromine-enriched sea-salt aerosol.

scholarly journals Year-round record of near-surface ozone and O<sub>3</sub> enhancement events (OEEs) at Dome A, East Antarctica

2020 ◽  
Author(s):  
Minghu Ding ◽  
Biao Tian ◽  
Michael Ashley ◽  
Zhenxi Zhu ◽  
Lifan Wang ◽  
...  
Keyword(s):  
Surface Ozone ◽  
Dominant Factor ◽  
Back Trajectory ◽  
Dome A ◽  
Polar Night ◽  
Near Surface ◽  
Mean Values ◽  
Back Trajectory Analysis ◽  
Stratospheric Intrusion ◽  
Surface O3

Abstract. To evaluate the characteristics of near-surface O3 over Dome A (Kunlun Station), which is located at the summit of the east Antarctic Ice Sheet, continuous observations were carried out in 2016. Together with observations from the Amundsen–Scott Station (South Pole) and Zhongshan Station, the seasonal and diurnal O3 variabilities were investigated. The results showed different patterns between coastal and inland Antarctic areas that were characterized by high concentrations in cold seasons and at night. The annual mean values at the three stations were 29.19 ± 7.52 ppb, 29.94 ± 4.97 ppb and 24.06 ± 5.79 ppb. Then, specific atmospheric processes, including synoptic-scale air mass transport, were analysed by Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) back-trajectory analysis and the potential source contribution function (PSCF) model. Long-range transport was found to account for the O3 enhancement events (OEEs) during summer at Dome A, rather than efficient local production (consistent with previous studies in inland Antarctica). In addition, we observed OEEs during the polar night in the Dome A region, which was not previously found in Antarctica. To explain this unique finding, the occurrence of stratospheric intrusion (stratosphere-to-troposphere, STT) events was studied with the Stratosphere-to-Troposphere Exchange Flux (STEFLUX) tool. This finding suggested that STT events occurred frequently over Dome A and could account for 55 % of the total polar night period. The occurrence probability of OEEs agreed well with STT events, indicating that the STT process was the dominant factor affecting the near-surface O3 over Dome A in the absence of photochemical reaction sources during polar night. This work provides unique information on ozone variation at Dome A and expands our knowledge regarding such events in Antarctica.

scholarly journals Evaluation of near-surface ozone over Europe from the MACC reanalysis

2015 ◽  
Vol 8 (7) ◽  
pp. 2299-2314 ◽  
Author(s):  
E. Katragkou ◽  
P. Zanis ◽  
A. Tsikerdekis ◽  
J. Kapsomenakis ◽  
D. Melas ◽  
...  
Keyword(s):  
Surface Ozone ◽  
Monitoring And Evaluation ◽  
Early Spring ◽  
Atmospheric Composition ◽  
Near Surface ◽  
Gross Error ◽  
Diurnal Range ◽  
North Eastern ◽  
Funded Project ◽  
Summer Maximum

Abstract. This work is an extended evaluation of near-surface ozone as part of the global reanalysis of atmospheric composition, produced within the European-funded project MACC (Monitoring Atmospheric Composition and Climate). It includes an evaluation over the period 2003–2012 and provides an overall assessment of the modeling system performance with respect to near-surface ozone for specific European subregions. Measurements at rural locations from the European Monitoring and Evaluation Program (EMEP) and the European Air Quality Database (AirBase) were used for the evaluation assessment. The fractional gross error of near-surface ozone reanalysis is on average 24 % over Europe, the highest found over Scandinavia (27 %) and the lowest over the Mediterranean marine stations (21 %). Near-surface ozone shows mostly a negative bias in winter and a positive bias during warm months. Assimilation reduces the bias in near-surface ozone in most of the European subregions – with the exception of Britain and Ireland and the Iberian Peninsula and its impact is mostly notable in winter. With respect to the seasonal cycle, the MACC reanalysis reproduces the photochemically driven broad spring-summer maximum of surface ozone of central and south Europe. However, it does not capture adequately the early spring peak and the shape of the seasonality at northern and north-eastern Europe. The diurnal range of surface ozone, which is as an indication of the local photochemical production processes, is reproduced fairly well, with a tendency for a small overestimation during the warm months for most subregions (especially in central and southern Europe). Possible reasons leading to discrepancies between the MACC reanalysis and observations are discussed.

scholarly journals How to most effectively expand the global surface ozone observing network

2015 ◽  
Vol 15 (15) ◽  
pp. 21025-21061
Author(s):  
E. D. Sofen ◽  
D. Bowdalo ◽  
M. J. Evans
Keyword(s):  
Atmospheric Chemistry ◽  
Surface Ozone ◽  
Tropospheric Chemistry ◽  
Atmospheric Composition ◽  
Model Assessment ◽  
Air Masses ◽  
The Cost ◽  
The Tropics ◽  
The Impact ◽  
Global Surface

Abstract. Surface ozone observations with modern instrumentation have been made around the world for almost 50 years. Some of these observations have been made as one-off activities with short term, specific science objectives and some have been made as part of wider networks which have provided a foundational infrastructure of data collection, calibration, quality control and dissemination. These observations provide a fundamental underpinning to our understanding of tropospheric chemistry, air quality policy, atmosphere-biosphere interactions, etc. Sofen et al. (2015) brought together 8 of these networks to provide a single dataset of surface ozone observations. We investigate how representative this combined dataset is of global surface ozone using the output from a global atmospheric chemistry model. We estimate that on an area basis, 25 % of the globe is observed (34 % land, 21 % ocean). Whereas Europe and North America have almost complete coverage, other continents such as Africa, South America and Asia (12–17 %) show significant gaps. Antarctica is surprisingly well observed (78 %). Little monitoring occurs over the oceans with the tropical and southern oceans particularly poorly represented. The surface ozone over key biomes such as tropical forests and savanna is almost completely unmonitored. A chemical cluster analysis suggests that a significant number of observations are made of polluted air masses, but cleaner air masses whether over the land or ocean (especially again in the tropics) are significantly under observed. The current network is unlikely to see the impact of ENSO but may be capable of detecting other planetary scale signals. Model assessment and validation activities are hampered by a lack of observations in regions where they models differ substantially, as is the ability to monitor likely changes in surface ozone over the next century. Using our methodology we are able to suggest new sites which would help to close the gap in our ability to measure global surface ozone. An additional 20 surface ozone monitoring sites (a 20 % increase in the WMO GAW ozone sites or a 1 % increase in the total background network) located on 10 islands and in 10 continental regions would almost double the area observed. The cost of this addition to the network is small compared to other expenditure on atmospheric composition research infrastructure and would provide a significant long term benefit to our understanding of the composition of the atmosphere and in the development of policy.

The semi-annual oscillation and Antarctic climate. Part 1: influence on near surface temperatures (1957–79)

1998 ◽  
Vol 10 (2) ◽  
pp. 175-183 ◽  
Author(s):  
Michiel R. Van Den Broeke
Keyword(s):  
Surface Pressure ◽  
Meridional Circulation ◽  
Second Harmonic ◽  
Temperature Inversion ◽  
East Antarctica ◽  
Temperature Cycle ◽  
Near Surface ◽  
Antarctic Plateau ◽  
Surface Temperatures ◽  
The Antarctic

We studied the influence of the semi-annual oscillation (SAO) on near-surface temperatures in Antarctica, using observations of 27 stations that were operational during (part of) the period 1957–79. For the annual cycle of surface pressure, the second harmonic explains 17–36% of the total variance on the Antarctic Plateau, 36–68% along the East Antarctic coast and almost 80% on the west coast of the Peninsula, and decreases further to the north. As a result of the amplification of the wave-3 structure of the circulation around Antarctica, a significant modification of the seasonal cooling is observed at many stations. The magnitude of this modification is largely determined by the strength of the temperature inversion at the surface: the percentage of the variance explained by the second harmonic of the annual temperature cycle is then largest on the Antarctic Plateau (11–18%), followed by the large ice shelves and coastal East Antarctica (6–12%) and stations at or close to the Peninsula (0–5%). A significant coupling between the half-yearly wave in surface pressure and that in surface temperature is found for coastal East Antarctica, which can be directly explained by the changes in meridional circulation brought about by the SAO. We show that the coupling of Antarctic temperatures to the meridional circulation is not only valid on the seasonal time scale of the SAO, but probably also on daily and interannual time scales. This has important implications for the interpretation of time series of Antarctic temperatures, a problem that will be addressed in part 2 of this paper.

scholarly journals Transport of Antarctic stratospheric strongly dehydrated air into the troposphere observed during the HALO-ESMVal campaign 2012

2015 ◽  
Vol 15 (6) ◽  
pp. 7895-7932 ◽  
Author(s):  
C. Rolf ◽  
A. Afchine ◽  
H. Bozem ◽  
B. Buchholz ◽  
V. Ebert ◽  
...  
Keyword(s):  
Water Vapor ◽  
Exchange Process ◽  
Satellite Measurements ◽  
Transport Barrier ◽  
Transport Pathways ◽  
Near Surface ◽  
Air Masses ◽  
The Antarctic

Abstract. Dehydration in the Antarctic winter stratosphere is a well-known phenomenon that is occasionally observed by balloon-borne and satellite measurements. However, in-situ measurements of dehydration in the Antarctic vortex are very rare. Here, we present detailed observations with the in-situ and GLORIA remote sensing instrument payload aboard the new German aircraft HALO. Strongly dehydrated air masses down to 1.6 ppmv of water vapor were observed as far north as 47° S and between 12 and 13 km in altitude, which has never been observed by satellites. The dehydration can be traced back to individual ice formation events, where ice crystals sedimented out and water vapor was irreversibly removed. Within these dehydrated stratospheric air masses, filaments of moister air reaching down to the tropopause are detected with the high resolution limb sounder, GLORIA. Furthermore, dehydrated air masses are observed with GLORIA in the Antarctic troposphere down to 7 km. With the help of a backward trajectory analysis, a tropospheric origin of the moist filaments in the vortex can be identified, while the dry air masses in the troposphere have stratospheric origins. The transport pathways of Antarctic stratosphere/troposphere exchange are investigated and the irrelevant role of the Antarctic thermal tropopause as a transport barrier is confirmed. Further, it is shown that the exchange process can be attributed to several successive Rossby wave events in combination with an isentropic interchange of air masses across the weak tropopause and subsequent subsidence due to radiative cooling. Once transported to the troposphere, air masses with stratospheric origin are able to reach near-surface levels within 1–2 months.

scholarly journals Summertime evolution of snow specific surface area close to the surface on the Antarctic Plateau

2015 ◽  
Vol 9 (4) ◽  
pp. 4499-4538
Author(s):  
Q. Libois ◽  
G. Picard ◽  
L. Arnaud ◽  
M. Dumont ◽  
M. Lafaysse ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Summer Precipitation ◽  
Strong Wind ◽  
Near Surface ◽  
Antarctic Plateau ◽  
Annual Variability ◽  
Wind Events ◽  
The Antarctic

Abstract. On the Antarctic Plateau, snow specific surface area (SSA) close to the surface shows complex variations at daily to seasonal scales which affect the surface albedo and in turn the surface energy budget of the ice sheet. While snow metamorphism, precipitation and strong wind events are known to drive SSA variations, usually in opposite ways, their relative contributions remain unclear. Here, a comprehensive set of SSA observations at Dome C is analysed with respect to meteorological conditions to assess the respective roles of these factors. The results show an average two-to-three-fold SSA decrease from October to February in the topmost 10 cm, in response to the increase of air temperature and absorption of solar radiation in the snowpack during spring and summer. Surface SSA is also characterised by significant daily to weekly variations, due to the deposition of small crystals with SSA up to 100 m2 kg−1 onto the surface during snowfall and blowing snow events. To complement these field observations, the detailed snowpack model Crocus is used to simulate SSA, with the intent to further investigate the previously found correlation between inter-annual variability of summer SSA decrease and summer precipitation amount. To this end, Crocus parameterizations have been adapted to Dome C conditions, and the model was forced by ERA-Interim reanalysis. It successfully matches the observations at daily to seasonal time scales, except for few cases when snowfalls are not captured by the reanalysis. On the contrary, the inter-annual variability of summer SSA decrease is poorly simulated when compared to 14 years of microwave satellite data sensititve to the near surface SSA. A simulation with disabled summer precipitation confirms the weak influence in the model of the precipitation on metamorphism, with only 6 % enhancement. However we found that disabling strong wind events in the model is sufficient to reconciliate the simulations with the observations. This suggests that Crocus reproduces well the contributions of metamorphism and precipitation on surface SSA, but that snow compaction by the wind might be overestimated in the model.

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