Tropospheric ozone above the southwestern Indian Ocean is strongly linked to dynamical conditions prevailing in the tropics

Taupin, F. G.; Bessafi, Miloud; Baldy, S.; Bremaud, P. J.

doi:10.1029/98jd02456

Cited by 46 publications

(54 citation statements)

References 22 publications

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“…Apart from its limited temporal resolution (8 days) and intrinsic uncertainties, an additional major uncertainty is the emission injection height. At Réunion Island, the dominant transport pathway at low altitudes (below 4 km during most of the fire season) originates from the South-East (Taupin et al, 1999). At these low altitudes, African-Madagascar emissions reach Réunion Island only via a roundabout way.…”

Section: Discussionmentioning

confidence: 99%

“…Given the short lifetime of HCHO and of its pyrogenic precursors that could be emitted by fires (a few hours to a few days) it is unlikely that these pathways contribute significantly to the observed HCHO concentrations. Above 4 km, the air masses generally take a direct eastward pathway (Taupin et al, 1999) and any African-Madagascar emissions that reach this altitude band are transported within a short timeframe towards Réunion Island. To assess the emission injection heights and the timescales at which the transport events take place, we have calculated the CO tracer volume mixing ratio detected at Réunion Island for different backward trajectory runtimes.…”

Section: Discussionmentioning

confidence: 99%

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Ground-based FTIR and MAX-DOAS observations of formaldehyde at Réunion Island and comparisons with satellite and model data

et al. 2009

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The FTIR and MAX-DOAS daily mean total columns agree very well: no significant bias is observed and the standard deviation of the comparisons is only 8%. Both FTIR and MAX-DOAS HCHO total columns are in good agreement with SCIAMACHY values in the 2004-2005 period, with standard deviations of 21% and 31%, respectively. The same seasonal cycle is observed by the different instruments, with a minimum in austral winter and a maximum in FebruaryMarch.The FTIR and MAX-DOAS data are confronted with HCHO columns calculated by a global CTM, the IMAGES model. The model underestimates the HCHO columns by 23-29% in comparison with FTIR, and by 15% in comparison with DOAS. This bias might have multiple causes, including an underestimation of OH concentrations in the model (as indicated by a sensitivity study using prescribedCorrespondence to: C. Vigouroux (corinne.vigouroux@aeronomie.be) OH fields) and/or an underestimated contribution of largescale transport of HCHO precursors from Madagascar. The latter hypothesis is comforted by the large observed day-today variability of HCHO columns, and by the observation that the peak values of FTIR columns can often be associated with free tropospheric transport patterns from source regions over Madagascar to Réunion Island, according to simulations performed with the Lagrangian particle dispersion model FLEXPART.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Ground-based FTIR and MAX-DOAS observations of formaldehyde at Réunion Island and comparisons with satellite and model data

et al. 2009

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“…anthropogenic and biomass burning pollution of the lower layers and stratosphere-troposphere exchange, the troposphere has been separated into three layers: one below 4 km, the altitude where the trade wind inversion occurs (Taupin et al, 1999), and the free troposphere which is separated into two equal parts: the mid-troposphere between 4 and 10 km and the upper troposphere between 10 and 16 km.…”

Section: Ozone Monthly Mean Distributionmentioning

confidence: 99%

“…Meteorological analysis based on trajectory statistics showed that a large part of African emissions might be advected to the Indian Ocean Piketh et al, 2002). Mechanisms responsible for regional dispersion of biomass burning emissions have been documented (Baldy et al, 1996;Taupin et al, 1999Taupin et al, , 2002. A climatology by Randriambelo et al (1999) based on ozonesonde and satellite data focuses on the relative importance of the different mechanisms.…”

Section: Regional Sourcesmentioning

confidence: 99%

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

et al. 2009

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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-O 3 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 Correspondence to: G. Clain (gaelle.clain@univ-reunion.fr) 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.

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“…Analyses of ozonesondes showed the influence of different contamination mechanisms from biomass burning by-products (Baldy et al, 1996;Taupin et al, 1999Taupin et al, , 2001) and stratosphere troposphere exchange (Baray et al, 1998). The climatology using ozonesondes and satellite observations of fire and convective areas pinpoint the impact of different mechanisms (Randriambelo et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

Investigation of the short-time variability of tropical tropospheric ozone

et al. 2003

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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. 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 subtropical 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 troCorrespondence to: T. Randriambelo (randriam@univ-reunion.fr) pospheric ozone at Reunion Island through sporadic events characterized by a large spatial and temporal variability.

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Tropospheric ozone above the southwestern Indian Ocean is strongly linked to dynamical conditions prevailing in the tropics

Cited by 46 publications

References 22 publications

Ground-based FTIR and MAX-DOAS observations of formaldehyde at Réunion Island and comparisons with satellite and model data

Ground-based FTIR and MAX-DOAS observations of formaldehyde at Réunion Island and comparisons with satellite and model data

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

Investigation of the short-time variability of tropical tropospheric ozone

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