Measurement report: Long-term measurements of surface ozone and trends in semi-natural sub-Saharan African ecosystems
<p>For nearly 30 years, the International Network to study Deposition and Atmospheric chemistry in AFrica (INDAAF) programme has measured surface ozone from 14 sites in Africa representative of the main African ecosystems: dry savannas (Banizoumbou, Niger; Katibougou and Agoufou, Mali; Bambey...
Saved in:
| Main Authors: | , , , , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2024-11-01
|
| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/24/13151/2024/acp-24-13151-2024.pdf |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | <p>For nearly 30 years, the International Network to study Deposition and Atmospheric chemistry in AFrica (INDAAF) programme has measured surface ozone from 14 sites in Africa representative of the main African ecosystems: dry savannas (Banizoumbou, Niger; Katibougou and Agoufou, Mali; Bambey and Dahra, Senegal), wet savannas (Lamto, Côte d'Ivoire; Djougou, Benin), forests (Zoétélé, Cameroon; Bomassa, Republic of the Congo) and agricultural–semi-arid savannas (Mbita, Kenya; Louis Trichardt, Amersfoort, Skukuza and Cape Point, South Africa). The data are collected with passive samplers and archived as monthly averages; quality assurance is maintained by INDAAF's calibration and intercomparison protocols with other programmes employing the same systems. This analysis reports on correlations of INDAAF ozone time series (1995–2020) with local meteorological parameters and with ozone precursors, biogenic volatile organic compounds (BVOCs) and nitrogen oxides (NO<span class="inline-formula"><sub><i>x</i></sub></span>), derived from standard global databases. Mean annual averages of surface ozone range from 3.9 <span class="inline-formula">±</span> 1.1 ppb (Bomassa) to 30.8 <span class="inline-formula">±</span> 8.0 ppb (Louis Trichardt), reflecting a general positive gradient from west central Africa to South Africa. At the decade scale, from 2000 to 2020, the Katibougou and Banizoumbou sites (dry savanna) experienced a significant decrease in ozone of around <span class="inline-formula">−</span>2.4 and <span class="inline-formula">−</span>0.8 ppb per decade, respectively. These decreasing trends are consistent with those observed for nitrogen dioxide (NO<span class="inline-formula"><sub>2</sub></span>) and BVOCs. An increasing trend is observed in Zoétélé (2001–2020), estimated at <span class="inline-formula">+</span>0.7 ppb per decade, and at Skukuza (2000–2015; <span class="inline-formula">+</span>3.4 ppb per decade). The increasing trends are consistent with increasing biogenic emissions at Zoétélé and NO<span class="inline-formula"><sub>2</sub></span> levels at Skukuza. Very few surface O<span class="inline-formula"><sub>3</sub></span> measurements exist in Africa, and the long-term results presented in this study are the most extensive for the ecosystems studied. The importance of maintaining long-term observations like INDAAF cannot be overstated. The data can be used to assess ozone<span id="page13152"/> impacts on African crops. For the Tropospheric Ozone Assessment Report Phase II (TOAR II), they provide invaluable constraints for models of chemical and climate processes in the atmosphere.</p> |
|---|---|
| ISSN: | 1680-7316 1680-7324 |