2021 Download Ozone Africa
Goldie Ringgold
Tropospheric ozone can have a detrimental effect on vegetation, including reducing the quantity of crop yield. This study uses modelled ozone flux values (POD3IAM; phytotoxic ozone dose above 3 nmol m-2 s-1, parameterised for integrated assessment modelling) for 2015, together with species-specific flux-effect relationships, spatial data on production and growing season dates to quantify the impact of ozone on the production of common wheat (Triticum aestivum) and common beans (Phaseolus vulgaris) across Sub-Saharan Africa (SSA). A case study for South Africa was also done using detailed data per province. Results suggest that ozone pollution could decrease wheat yield by between 2 and 13%, with a total annual loss of 453,000 t across SSA. The impact on bean production depended on the season; however, estimated yield losses were up to 21% in some areas of SSA, with an annual loss of 300,000 t for each of the two main growing seasons. Production losses tended to be greater in countries with the highest production, for example, Ethiopia (wheat) and Tanzania (beans). This study provides an indication of the location of areas at high risk of crop losses due to ozone. Results emphasise that efforts to reduce ozone precursors could contribute to reducing the yield gap in SSA. More stringent air pollution abatement policies are required to reduce crop losses to ozone in the future.
This work is supported by the French-South African Cooperative Programme and the French Centre National de la Recherche Scientifique (CNRS), the Regional Council, Conseil Regional de La Réunion and the South Africa National Research Foundation (NRF) (UID: 78682). Data used in this paper were obtained from the SHADOZ website ( ). The authors especially thank Mr. Gerrie Coetzee (South Africa Weather Service) for his valuable time to maintain and perform the ozonesonde measurements over Irene. We also thank NASA-JPL for providing us access to the MLS data through their website.
By means of a meridional chain of 19 stations between Tromso, Norway, and Hermanus, South Africa, a permanent registration of ozone near the ground has been obtained since 1970. From the first year of operation surprisingly systematic annual variations come out, which agree with theoretical calculations on stratospheric-tropospheric exchange.
The suggested paper by Bencherif et al. has contributed to one of the most important issues of the modern atmospheric science: the reliable detection and attribution of the resent ozone changes in the atmosphere. The authors investigated the time evolution of the atmospheric ozone columns and profiles over the Irene station site (25.90S, 28.22E) for 1998-2017 period. The advantages of the presented study are the usage of high quality and thouroghly constructed data sets of ground-based, ozonesonde and satellite measurements (Dobson instrument, SHADOZ, TOMS, OMI,). Also the authors suggested and realized a valuable idea to divide the total ozone column into the stratospheric part and the tropospheric one. After that the ozone changes of these atmospheric parts were evaluated together with the changes of the total ozone column. The evaluation was implemented by state-of-the art statistical tools (the wavelet analysis, trend statistical modeling and tests)
Bremer, H, Kar, J, Drummond, JR, Nichitu, F, Zou, JS, Liu, J, Gille, JC, Deeter, MN, Francis, G, Ziskin, D, Warner, J (2004). Spatial and temporal variation of MOPITT CO in Africa and South America: A comparison with SHADOZ ozone and MODIS aerosol. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 109(D12), D12304.
Abstract
Carbon monoxide (CO) measurements from the Measurements of Pollution in the Troposphere (MOPITT) experiment are used to explore the correlation between biomass burning and ozone profiles at six tropical stations namely Reunion, Irene, Natal, Ascension, San Cristobal, and Paramaribo. Distinct seasonal patterns of CO at each station indicate the strong influence of African and South American biomass burning. All stations show enhanced CO columns during September-November ( SON) corresponding to austral burning. Furthermore, the effects of Sahelian burning can be seen at Natal and Ascension. Similarly, the signature of northern Amazonian fires can be observed at San Cristobal. The CO variations are generally similar to the variations of aerosol optical depth (AOD) retrieved contemporaneously from Moderate Resolution Imaging Spectroradiometer (MODIS) at most stations, with notable differences at Irene, San Cristobal, and Paramaribo. Tropospheric ozone from Southern Hemisphere Additional Ozonesonde (SHADOZ) ozonesonde measurements at all stations show elevated levels, corresponding to the CO enhancements in SON months. However, there are several instances of ozone enhancements unaccompanied by any CO increase. This might indicate that sources other than biomass burning such as stratospheric tropospheric exchange (STE) or lightning related NOx may be operative. At San Cristobal, strong CO enhancements during March April are not accompanied by any significant change in ozone.
The NASA TRACE-A (Transport and Atmospheric Chemistry near the Equator-Atlantic) field study was deployed in August 1992 to determine the cause and source of high concentrations of ozone that accumulate over the Atlantic ocean between southern Africa and South America during the months of August through October. The enhanced levels of ozone were observed to be the highest during the southern hemisphere's springtime, a period of intense burning of vegetation in both southern Africa and South America. The TRACE-A results showed the link between the biomass burning and the ozone pollution. The TRACE-A mission brought together a multi-year series of ground based and balloon measurements, aircraft measurements over Brazil, southern Africa, and the Atlantic ocean, and powerful computer models of the tropical atmosphere. TRACE-A was a cooperative project between NASA and the Brazilian Space Agency (INPE), involving over 200 scientists from US, Brazil and South Africa. The centerpiece of TRACE-A was the NASA DC-8 flying laboratory based at the NASA Ames Research Center. The DC-8 was instrumented with state-of-the-art instruments for measurements of ozone and other gases that are associated with the production of ozone in the atmosphere.
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