scholarly journals Tropospheric ozone climatology at two southern subtropical sites, (Reunion Island and Irene, South Africa) from ozone sondes, LIDAR, aircraft and in situ measurements

2008 ◽  
Vol 8 (3) ◽  
pp. 11063-11101
Author(s):  
G. Clain ◽  
J. L. Baray ◽  
R. Delmas ◽  
R. Diab ◽  
J. Leclair de Bellevue ◽  
...  
Keyword(s):  
South Africa ◽  
Tropospheric Ozone ◽  
Seasonal Cycle ◽  
Lower Troposphere ◽  
Ground Level ◽  
Positive Trend ◽  
Reunion Island ◽  
Free Troposphere ◽  
Upper Troposphere ◽  
Réunion Island

Abstract. This paper presents a climatology and trends of tropospheric ozone in the southwestern part of Indian Ocean (Reunion Island) and South Africa (Irene and Johannesburg). This study is based on a multi-instrumental dataset: PTU-O3 radiosoundings, DIAL LIDAR, MOZAIC airborne instrumentation and Dasibi UV ground based measurements. The seasonal profiles of tropospheric ozone at Reunion Island have been calculated from two different data sets: radiosondes and LIDAR. The two climatological profiles are similar, except in austral summer when smaller values for the LIDAR profiles in the free troposphere, and in the upper troposphere for all seasons occur. These results show that the LIDAR profiles are at times not representative of the true ozone climatological value as measurements can be taken only under clear sky conditions, and the upper limit reached depends on the signal. In the lower troposphere, climatological ozone values from radiosondes have been compared to a one year campaign of ground based measurements from a Dasibi instrument located at high altitude site (2150 m) at Reunion Island. The seasonal cycle is comparable for the two datasets, with Dasibi UV values displaying slightly higher values. This suggests that if local dynamical and possibly physico-chemical effects may influence the ozone level, the seasonal cycle can be followed with ground level measurements. Average ground level concentrations measured on the summits of the island seem to be representative of the lower free troposphere ozone concentration at the same altitude (~2000 m) whereas night time data would be representative of tropospheric concentration at a higher altitude (~3000 m) due to the subsidence effect. Finally, linear trends have been calculated from radiosondes data at Reunion and Irene. Considering the whole tropospheric column, the trend is slightly positive for Reunion, and more clearly positive for Irene. Trend calculations have also been made separating the troposphere into three layers, and separating the dataset into seasons. Results shows that the positive trend for Irene is governed by the lower layer most probably by industrial pollution and biomass burning. On the contrary, for Reunion Island, the strongest trends are observed in the upper troposphere, and in winter when stratospheric-tropospheric exchange is more frequently expected.

scholarly journals Tropospheric ozone climatology at two Southern Hemisphere tropical/subtropical sites, (Reunion Island and Irene, South Africa) from ozonesondes, LIDAR, and in situ aircraft measurements

2009 ◽  
Vol 9 (5) ◽  
pp. 1723-1734 ◽  
Author(s):  
G. Clain ◽  
J. L. Baray ◽  
R. Delmas ◽  
R. Diab ◽  
J. Leclair de Bellevue ◽  
...  
Keyword(s):  
South Africa ◽  
Tropospheric Ozone ◽  
Lower Layer ◽  
Austral Summer ◽  
Data Sets ◽  
Positive Trend ◽  
Reunion Island ◽  
Upper Troposphere ◽  
Réunion Island ◽  
Sky Conditions

Abstract. This paper presents a climatology and trends of tropospheric ozone in the Southwestern Indian Ocean (Reunion Island) and South Africa (Irene and Johannesburg). This study is based on a multi-instrumental dataset: PTU-O3 ozonesondes, DIAL LIDAR and MOZAIC airborne instrumentation. The seasonal profiles of tropospheric ozone at Reunion Island have been calculated from two different data sets: ozonesondes and LIDAR. The two climatological profiles are similar, except in austral summer when the LIDAR profiles show greater values in the free troposphere, and in the upper troposphere when the LIDAR profiles show lower values during all seasons. These results show that the climatological value of LIDAR profiles must be discussed with care since LIDAR measurements can be performed only under clear sky conditions, and the upper limit of the profile depends on the signal strength. In addition, linear trends have been calculated from ozonesonde data at Reunion and Irene. Considering the whole tropospheric column, the trend is slightly positive for Reunion, and more clearly positive for Irene. Trend calculations have also been made separating the troposphere into three layers, and separating the dataset into seasons. Results show that the positive trend for Irene is governed by the lower layer that is affected by industrial pollution and biomass burning. On the contrary, for Reunion Island, the strongest trends are observed in the upper troposphere, and in winter when stratosphere-troposphere exchange is more frequently expected.

scholarly journals Ozone profiles by DIAL at Maïdo Observatory (Reunion Island) Part 1. Tropospheric ozone lidar: system description, performances evaluation and comparison with ancillary data

2017 ◽  
Author(s):  
Valentin Duflot ◽  
Jean-Luc Baray ◽  
Guillaume Payen ◽  
Nicolas Marquestaut ◽  
Françoise Posny ◽  
...  
Keyword(s):  
Tropospheric Ozone ◽  
Current System ◽  
Integration Time ◽  
Buffer Gas ◽  
Reunion Island ◽  
Lidar System ◽  
Ancillary Data ◽  
Upper Troposphere ◽  
Réunion Island ◽  
Good Agreement

Abstract. Recognizing the importance of ozone in the troposphere and lower stratosphere in the tropics, a DIAL tropospheric ozone lidar system (LIO3TUR) was developped and installed at the Université de la Réunion campus site (close to the sea) in Reunion Island (southern tropics) in 1998. From 1998 to 2010, it acquired 427 ozone profiles from the low to the upper troposphere and has been central to several studies. In 2012, the system was moved up to the new Maïdo Observatory facility (2160 m above mean sea level – amsl) where it started operation in February 2013. The current system (LIO3T) configuration generates a 266 nm beam obtained with the fourth harmonic of a Nd:YAG laser sent into a Raman cell filled up with deuterium (using helium as buffer gas) generating the 289 and 316 nm beams enabling the use of the DIAL method for ozone profile measurements. Optimal range for the actual system is 6–19 km amsl, depending on the instrumental and atmospheric conditions; for a 1-hour integration time, vertical resolution varies from 0.7 km at 6 km amsl to 1.3 km at 19 km amsl, and mean uncertainty within the 6–19 km range is between 6 and 13 %. Comparisons with 8 electrochemical concentration cell (ECC) sondes simultaneously launched from the Maïdo Observatory show a good agreement between datasets with a 7.7 % mean absolute value of the relative differences with respect to the mean (D) between 6 and 17 km amsl (LIO3T low); comparisons with 37 ECC sondes launched from the nearby Gillot site during day time in a ±24-hour window around lidar shooting result in a 10.3 % D between 6 and 19 km amsl (LIO3T low); comparisons with 11 ground-based Network for Detection of Atmosphere Composition Change (NDACC) Fourier Transform Infrared (FTIR) spectrometer measurements acquired during day time in a ±24-hour window around lidar shooting show a good agreement between datasets with a D of 11.8 % for the 8.5–16 km partial column (LIO3T high); and comparisons with 39 simultaneous Infrared Atmospheric Sounding Interferometer (IASI) observations over Reunion Island show a good agreement between datasets with a D of 11.3 % for the 6–16 km partial column (LIO3T high). ECC, LIO3TUR and LIO3T O3 monthly climatologies all exhibit the same range of values and patterns. In particular, the southern hemisphere biomass burning seasonal enhancement, the ozonopause altitude decrease in late austral winter-spring, as well as the signature of deep convection bringing boundary layer-ozone poor air masses up to the mid-upper troposphere in late austral summer, are clearly visible on all datasets.

scholarly journals Long-term Variations in Ozone Levels in the Troposphere and Lower Stratosphere over Beijing: Observations and Model Simulations

2020 ◽  
Author(s):  
Yuli Zhang ◽  
Mengchu Tao ◽  
Jinqiang Zhang ◽  
Yi Liu ◽  
Hongbin Chen ◽  
...  
Keyword(s):  
Tropospheric Ozone ◽  
Lower Stratosphere ◽  
Stratospheric Ozone ◽  
Lower Troposphere ◽  
Control Measures ◽  
Tropospheric Chemistry ◽  
Lagrangian Model ◽  
Positive Trend ◽  
Sudden Decrease

Abstract. Tropospheric ozone is both a major pollutant and a short-lived greenhouse gas and has therefore attracted much concern in recent years. The ozone profile in the troposphere and lower stratosphere over Beijing has been observed since 2002 by ozonesondes developed by the Institute of Atmospheric Physics. Increasing concentrations of tropospheric ozone from 2002 to 2010 measured by these balloon-based observations have been reported previously. As more observations are now available, we used these data to analyze the long-term variability of ozone over Beijing during the whole period from 2002 to 2018. The ozonesondes measured increasing concentrations of ozone from 2002 to 2012 in both the troposphere and lower stratosphere. There was a sudden decrease in observed ozone between 2011 and 2012. After this decrease, the increasing trend in ozone concentrations slowed down, especially in the mid-troposphere, where the positive trend became neutral. We used the Chemical Lagrangian Model of the Stratosphere (CLaMS) to determine the influence of the transport of ozone from the stratosphere to the troposphere on the observed ozone profiles. CLaMS showed a weak increase in the contribution of stratospheric ozone before the decrease in 2011–2012 and a much more pronounced decrease after this time. Because there is no tropospheric chemistry in CLaMS, the sudden decrease simulated by CLaMS indicates that a smaller downward transport of ozone from the stratosphere after 2012 may explain a significant part of the observed decrease in ozone in the mid-troposphere and lower stratosphere. However, the influence of stratospheric ozone in the lower troposphere is negligible in CLaMS and the hiatus in the positive trend after 2012 can be attributed to a reduction in ozone precursors as a result of stronger pollution control measures in Beijing.

scholarly journals Investigation of the short-time variability of tropical tropospheric ozone

2003 ◽  
Vol 21 (10) ◽  
pp. 2095-2106 ◽  
Author(s):  
T. Randriambelo ◽  
J.-L. Baray ◽  
S. Baldy ◽  
A. M. Thompson ◽  
S. Oltmans ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Tropospheric Ozone ◽  
Transition Period ◽  
Meteorological Data ◽  
Tropical Meteorology ◽  
Atmospheric Composition ◽  
Time Variability ◽  
Reunion Island ◽  
Ozone Profile ◽  
Réunion Island

Abstract. Since 1998, a ground-based tropospheric ozone lidar has been running at Reunion Island and has been involved with a daily measurement campaign that was performed in the latter part of the biomass burning season, during November–December 1999. The averaged ozone profile obtained during November–December 1999 agrees well with the averaged ozone profile obtained from the ozonesondes launch at Reunion during November–December (1992– 2001). Comparing weekly sonde launches (part of the Southern Hemisphere Additional Ozonesondes: SHADOZ program) with the daily ground-based lidar observations shows that some striking features of the day-to-day variability profiles are not observed in the sonde measurements. Ozone profiles respond to the nature of disturbances which vary from one day to the next. The vertical ozone distribution at Reunion is examined as a function of prevailing atmospheric circulation. Back trajectories show that most of the enhanced ozone crossed over biomass burning and convectively active regions in Madagascar and the southern African continent. The analyses of the meteorological data show that ozone stratification profiles are in agreement with the movement of the synoptic situations in November–December 1999. Three different sequences of transport are explained using wind fields. The first sequence from 23 to 25 November is characterized by northerly transport; during the second sequence from 26 to 30 November, the air masses are influenced by meridional transport. The third sequence from 2 to 6 December is characterized by westerly transport associated with the sub-tropical jet stream. The large, standard deviations of lidar profiles in the middle and upper troposphere are in agreement with the upper wind variabilities which evidence passing ridge and trough disturbances. During the transition period between the dry season and the wet season, multiple ozone sources including stratosphere-troposphere exchanges, convection and biomass burning contribute to tropospheric ozone at Reunion Island through sporadic events characterized by a large spatial and temporal variability.Key words. Atmospheric composition and structure (troposphere-composition and chemistry) – Meteorology and atmospheric dynamics (climatology; tropical meteorology)

scholarly journals Attributing land transport emissions to ozone and ozone precursors in Europe and Germany

2019 ◽  
Author(s):  
Mariano Mertens ◽  
Astrid Kerkweg ◽  
Volker Grewe ◽  
Patrick Jöckel ◽  
Robert Sausen
Keyword(s):  
Carbon Monoxide ◽  
Nitrogen Oxides ◽  
Tropospheric Ozone ◽  
Seasonal Cycle ◽  
Emission Inventory ◽  
Ground Level ◽  
Global Model ◽  
Ozone Precursors ◽  
Po Valley ◽  
Transport Emissions

Abstract. Land transport is an important emission source of nitrogen oxides, carbon monoxide and volatile organic compounds, which serves as precursors for tropospheric ozone. Besides the direct negative impact of nitrogen oxides, air quality is also affected by these enhanced ozone tropospheric ozone concentrations. As ozone is radiativly active, its increase contributes to climate change. Due to the strong non-linearity of the ozone chemistry, the contribution of land transport emissions to tropospheric ozone cannot be calculated or measured directly, instead atmospheric-chemistry models equipped with specific source apportionment methods (called tagging) are required. In this study we investigate the contributions of land transport emissions to ozone and ozone precursors using the MECO(n) model system, coupling a global and a regional chemistry climate model, which are equipped with a tagging diagnostic. For the first time the effects of long range transport and regional effects of regional emissions are investigated. This is only possible by applying a tagging method simultaneously and consistently on the global and regional scale. We performed two three-year simulations with different anthropogenic emission inventories for Europe by applying our global model with two regional refinements, i.e. a European nest (50 km resolution) in the global model and a German nest (12 km resolution) in the European nest. We find contributions of land transport emissions to reactive nitrogen (NOy) near ground-level in the range of 5 to 10 nmol mol−1, corresponding to 50 to 70 % of the ground level NOy values. The largest contributions are around Paris, Southern England, Moscow, the Po Valley, and Western Germany. Carbon monoxide contributions range from 30 nmol mol−1 to more than 75 nmol mol−1 near emission hot spots such as Paris or Moscow. The contribution of land transport emissions to ozone show a strong seasonal cycle which absolute contributions of 3 nmol mol−1 during winter and 5 to 10 nmol mol−1 during summer. This corresponds to relative contributions of 8 to 10 % during winter and up to 16 % during summer. Those largest values during summer are confined to the Po Valley, while the contribution in Western Europa ranges from 12 to 14 %. The ozone contributions are robust. Only during summer the ozone contributions are slightly influenced by the emission inventory, but these differences are smaller than the range of the seasonal cycle of the contribution. This cycle is caused by a complex interplay of seasonal cycles of other emissions (e.g. biogenic) and seasonal difference of the ozone regimes. This small difference of the ozone contributions due to the emission inventory is remarkable as the precursor concentrations (NOx and CO) are much more affected by the change. In addition, our results suggest that during events with large ozone values the contribution of land transport emissions and biogenic emissions increase strongly. Here, the contribution of land transport emission peak up to 28 %. Hence, land transport is an important contributor to events of large ozone values.

scholarly journals Tropospheric ozone profiles by DIAL at Maïdo Observatory (Reunion Island): system description, instrumental performance and result comparison with ozone external data set

2017 ◽  
Vol 10 (9) ◽  
pp. 3359-3373 ◽  
Author(s):  
Valentin Duflot ◽  
Jean-Luc Baray ◽  
Guillaume Payen ◽  
Nicolas Marquestaut ◽  
Francoise Posny ◽  
...  
Keyword(s):  
Current System ◽  
Atmospheric Composition ◽  
Integration Time ◽  
Data Sets ◽  
Buffer Gas ◽  
Reunion Island ◽  
Data Set ◽  
Upper Troposphere ◽  
Réunion Island ◽  
Good Agreement

Abstract. In order to recognize the importance of ozone (O3) in the troposphere and lower stratosphere in the tropics, a DIAL (differential absorption lidar) tropospheric O3 lidar system (LIO3TUR) was developed and installed at the Université de la Réunion campus site (close to the sea) on Reunion Island (southern tropics) in 1998. From 1998 to 2010, it acquired 427 O3 profiles from the low to the upper troposphere and has been central to several studies. In 2012, the system was moved up to the new Maïdo Observatory facility (2160 m a.m.s.l. – metres above mean sea level) where it started operation in February 2013. The current system (LIO3T) configuration generates a 266 nm beam obtained with the fourth harmonic of a Nd:YAG laser sent into a Raman cell filled up with deuterium (using helium as buffer gas), generating the 289 and 316 nm beams to enable the use of the DIAL method for O3 profile measurements. The optimal range for the actual system is 6–19 km a.m.s.l., depending on the instrumental and atmospheric conditions. For a 1 h integration time, vertical resolution varies from 0.7 km at 6 km a.m.s.l. to 1.3 km at 19 km a.m.s.l., and mean uncertainty within the 6–19 km range is between 6 and 13 %. Comparisons with eight electrochemical concentration cell (ECC) sondes simultaneously launched from the Maïdo Observatory show good agreement between data sets with a 6.8 % mean absolute relative difference (D) between 6 and 17 km a.m.s.l. (LIO3T lower than ECC). Comparisons with 37 ECC sondes launched from the nearby Gillot site during the daytime in a ±24 h window around lidar shooting result in a 9.4 % D between 6 and 19 km a.m.s.l. (LIO3T lower than ECC). Comparisons with 11 ground-based Network for Detection of Atmospheric Composition Change (NDACC) Fourier transform infrared (FTIR) spectrometer measurements acquired during the daytime in a ±24 h window around lidar shooting show good agreement between data sets with a D of 11.8 % for the 8.5–16 km partial column (LIO3T higher than FTIR), and comparisons with 39 simultaneous Infrared Atmospheric Sounding Interferometer (IASI) observations over Reunion Island show good agreement between data sets with a D of 11.3 % for the 6–16 km partial column (LIO3T higher than IASI). ECC, LIO3TUR and LIO3T O3 monthly climatologies all exhibit the same range of values and patterns. In particular, the Southern Hemisphere biomass burning seasonal enhancement and the ozonopause altitude decrease in late austral winter–spring, as well as the sign of deep convection bringing boundary layer O3-poor air masses up to the middle–upper troposphere in late austral summer, are clearly visible in all data sets.

scholarly journals Remote sensed and in situ constraints on processes affecting tropical tropospheric ozone

2006 ◽  
Vol 6 (6) ◽  
pp. 11465-11520 ◽  
Author(s):  
B. Sauvage ◽  
R. V. Martin ◽  
A. van Donkelaar ◽  
X. Liu ◽  
K. Chance ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Tropospheric Ozone ◽  
Transport Model ◽  
Lower Troposphere ◽  
In Situ Measurements ◽  
Top Down ◽  
Upper Troposphere ◽  
In Situ Observations ◽  
Tropospheric O3

Abstract. We use a global chemical transport model (GEOS-Chem) to evaluate the consistency of satellite measurements of lightning flashes and ozone precursors with in situ measurements of tropical tropospheric ozone. The measurements are tropospheric O3, NO2, and HCHO columns from the GOME satellite instrument, lightning flashes from the OTD and LIS instruments, profiles of O3, CO, and relative humidity from the MOZAIC aircraft program, and profiles of O3 from the SHADOZ ozonesonde network. We interpret these multiple data sources with our model to better understand what controls tropical tropospheric ozone. Tropical tropospheric ozone is mainly affected by lightning and convection in the upper troposphere and by surface emissions in the lower troposphere. Scaling the spatial distribution of lightning in the model to the observed flash counts improves the simulation of O3 in the upper troposphere by 5–20 ppbv versus in situ observations and by 1–4 Dobson Units versus GOME retrievals of tropospheric O3 columns. A lightning source strength of 5±2 Tg N/yr best represents in situ observations from aircraft and ozonesonde. Tropospheric NO2 and HCHO columns from GOME are applied to provide top-down constraints on emission inventories of NOx (biomass burning and soils) and VOCs (biomass burning). The top-down biomass burning inventory is larger by a factor of 2 for HCHO and alkenes, and by 2.6 for NOx over northern equatorial Africa. These emissions increase lower tropospheric O3 by 5–20 ppbv, improving the simulation versus aircraft observations, and by 4 Dobson Units versus GOME observations of tropospheric O3 columns. Emission factors in the a posteriori inventory are more consistent with a recent compilation from in situ measurements. The ozone simulation using two different dynamical schemes (GEOS-3 and GEOS-4) is evaluated versus observations; GEOS-4 better represents O3 observations by 5–15 ppbv due to enhanced convective detrainment in the upper troposphere. Heterogeneous uptake of HNO3 on aerosols reduces simulated O3 by 5–7 ppbv, reducing a model bias versus in situ observations over and downwind of deserts. Exclusion of HO2 uptake on aerosols improves O3 by 5 ppbv in biomass burning regions.

scholarly journals 3-D evaluation of tropospheric ozone simulations by an ensemble of regional Chemistry Transport Model

2011 ◽  
Vol 11 (10) ◽  
pp. 28797-28849 ◽  
Author(s):  
D. Zyryanov ◽  
G. Foret ◽  
M. Eremenko ◽  
M. Beekmann ◽  
J.-P. Cammas ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Tropospheric Ozone ◽  
Transport Model ◽  
Lower Troposphere ◽  
Systematic Bias ◽  
Free Troposphere ◽  
Commercial Aircraft ◽  
Data Set ◽  
Vertical Ozone

Abstract. A detailed 3-D evaluation of an ensemble of five regional CTM's and one global CTM with focus on free tropospheric ozone over Europe is presented. It is performed over a summer period (June to August 2008) in the context of the GEMS-RAQ project. A data set of about 400 vertical ozone profiles from balloon soundings and commercial aircraft at 11 different locations is used for model evaluation, in addition to satellite measurements with the infrared nadir IASI sounder showing largest sensitivity to free tropospheric ozone. In the free troposphere, models using the same top and boundary conditions from MOZART-IFS exhibit a systematic negative bias with respect to observed profiles of about −20%. RMSE values are constantly growing with altitude, from 22% to 32% to 53%, respectively for 0–2 km, 2–8 km and 8–10 km height ranges. Lowest correlation is found in the free troposphere, with minimum coefficients (R) between 0.2 to 0.45 near 8 km, as compared to 0.7 near the surface and similar values around 10 km. Use of hourly instead of monthly chemical boundary conditions generally improves the model skill. Lower tropospheric 0–6 km partial ozone columns derived from IASI show a clear North-South gradient over Europe, which is qualitatively reproduced by the models. Also the temporal variability showing decreasing ozone concentrations in the lower troposphere (0–6 km columns) during summer is well catched by models even if systematic bias remains (the value of the bias being also controlled by the type of BC used). A multi-day case study of a through with low tropopause was conducted and showed that both IASI and models were able to resolve strong horizontal gradients of middle and upper tropospheric ozone occurring in the vicinity of an upper tropospheric frontal zone.

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