Mixing ratios of biogenic volatile organic compounds in highland and lowland ecosystems in Kenya

African dryland ecosystems and human-modified systems, including savannas, bushland, grassland, and agroforestry are widely distributed and cover 55.2 % of tropical Africa, which have a high potential for native ecosystem changes and face a higher frequency of extreme climate events in future scenarios, resulting in BVOC releasing more changeable from these African climate sensitive ecosystems. The overall objective of our study was to quantify BVOC mixing ratios in the humid highlands and the dry lowlands in Kenya during the rainy and dry season in 2019. We collected samples in an agroforestry in the highland, and bushland and agriculture mosaic landscapes in the lowland. We analyzed the mixing ratios of isoprene (C5H8), 2-methyl-3-buten-2-ol (MBO, C5H10O), monoterpenoids (MTs, C10H16 and C10H18O), sesquiterpenes (SQTs, C15H24), and bornyl acetate (C12H20O). The mixing ratio of isoprene from the highland and lowland ecosystems were 4 times to an order of magnitude lower than that measured in relevant ecosystems in west and central Africa in previous studies. Monoterpenoids were similar to those measured in the relevant ecosystems in west, central and south Africa in previous studies (Table. 1 in Liu et al., 2021). The dominant species within the MT group were limonene, -pinene, and -pinene. Estimating the emission factors (EFs) for BVOCs by a inverse model, the EFs of isoprene and -pinene agreed well with what is currently assumed in the worlds most extensively used biogenic emissions model, the Model of Emissions of Gases and Aerosols from Nature (MEGAN), for warm C4 grass, but the estimated EFs for MBO, -pinene, and especially limonene, were significantly higher than that assumed in MEGAN for the relevant plant functional type. Reference Liu, Y., Schallhart, S., Taipale, D., Tykkä, T., Räsänen, M., Merbold, L., Hellén, H., and Pellikka, P.: Seasonal and diurnal variations of biogenic volatile organic compounds in highland and lowland ecosystems in southern Kenya, Atmos. Chem. Phys. Discuss. [preprint], https://doi.org/10.5194/acp-2021-445, in review, 2021.