EGU25-19104, updated on 15 Mar 2025
https://doi.org/10.5194/egusphere-egu25-19104
EGU General Assembly 2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
A new measurement site in northern Botswana to observe savanna fire plumes
Ville Vakkari1,2, Baagi T. Mmereki3, Daniel Koolebogile4, Christiaan P. E. van Niekerk2, Viet Le1, Mabala Letsatle4, Kerneels Jaars2, and Pieter G. van Zyl2
Ville Vakkari et al.
  • 1Finnish Meteorological Institute, Helsinki, Finland (ville.vakkari@fmi.fi)
  • 2Atmospheric Chemistry Research Group, Chemical Resource Beneficiation, North-West University, Potchefstroom, South Africa
  • 3Department of Chemistry, University of Botswana, Gaborone, Botswana
  • 4Department of Waste Management and Pollution Control, Maun, Botswana

Globally, approximately half of landscape fire emissions originate from savannas and grasslands. Furthermore, our observations in South Africa indicated major secondary aerosol formation in near-fire plume ageing. However, the measurements in South Africa are affected by anthropogenic emissions from the Highveld region, except for a clean sector towards the semi-arid Karoo region. Aiming for a savanna environment with minimal anthropogenic influence we set up a new measurement site in the Okavango delta area in northern Botswana in August 2024.

For the active savanna fire season in 2024, we operated online measurements of aerosol chemical composition with an aerosol chemical speciation monitor (ACSM), an online gas chromatograph coupled to an MS detector (GC-MS) for volatile organic compounds and a single particle soot photometer (SP2) for refractive BC. Measurements of aerosol particle size distribution with a differential mobility particle sizer (DMPS), aerosol absorption with a multi angle absorption photometer (MAAP), as well as CO and CO2 concentrations will continue for the next couple of years at least.

For fresh plumes, initial analysis shows a strong decrease in submicron aerosol emission factor (EFPM1) with increasing modified combustion efficiency, i.e. with increasing flaming fraction. The EFPM1 values are in good agreement with previous observations in southern African savanna and with recent laboratory experiments that we carried out in collaboration with University of Eastern Finland. Analysis of ageing effects on the fire plumes in a clean savanna environment is ongoing.

How to cite: Vakkari, V., Mmereki, B. T., Koolebogile, D., van Niekerk, C. P. E., Le, V., Letsatle, M., Jaars, K., and van Zyl, P. G.: A new measurement site in northern Botswana to observe savanna fire plumes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19104, https://doi.org/10.5194/egusphere-egu25-19104, 2025.