Atmospheric aerosols are posing a great threat to the already stressed climate with the effects being felt more on African continent. Their presence and interaction with the clouds contribute to the strongest uncertainty in aerosol characteristics and Earth’s energy budget hence; calling for a long term assessment to be done. The present study analyses long term spatiotemporal microphysical aerosol characteristics (namely: effective radius and surface-area concentration), using AErosolROboticNETwork (AERONET) framework over Kenyan urban atmosphere (Nairobi-1°S, 36°E), rural atmosphere (ICIPE-Mbita-0°S, 34°E) and maritime atmosphere (CRPSM-Malindi-2°S, 40°E). AERONET framework was used due to its availability over the selected sites; it is also located in sites that provided contrasting aerosols type, source and characteristics and due to its syner-gism with other frameworks. The findings indicated a spatial and temporal variability in microphysical properties over CRPSM-Malindi, Nairobi and ICIPE-Mbita. CRPSM-Malindi is dominated with coarse aerosols in all sea-sons while Nairobi with coarse mode in the DJF and MAM seasons. ICIPE-Mbita is on the other hand dominated with fine aerosols in all season. In terms of size distribution, the three AERONET sites displayed a bimodal distribution inflecting at 0.44 μm and fine mode radius of 0.15 μm while CRPSM-Malindi recorded a coarse mode of 3.86 μm and Nairobi and ICIPE-Mbita with 5.06 μm. The coarse aerosols have a higher concentration than the fine aerosols in all AERONET sites because of aerosol coagulation and dominance of certain type of aerosols that are coarse in nature.
Cite this paper
Khamala, G. W. , Odhiambo, J. O. and Makokha, J. W. (2018). Seasonal Variability in Aerosol Microphysical Properties over Selected Rural, Urban and Maritime Sites in Kenya. Open Access Library Journal, 5, e4821. doi: http://dx.doi.org/10.4236/oalib.1104821.
Balarabe, M., Abdullah, K. and Nawawi, M. (2016) Seasonal Variations of Aerosol Op-tical Properties and Identification of Different Aerosol Types Based on AERONET Data over Sub-Sahara West-Africa. Atmospheric and Climate Sciences, 6, 13-28. https://doi.org/10.4236/acs.2016.61002
Seinfeld, J.H. and Pandis, S.N. (2012) Atmospheric Chemistry and Physics: From Air Pollution to Climate Change. John Willey and Sons, Inc., New York, 1326 p.
Mkoma, S.L. and Mjemah, I.C. (2011) Influence of Meteorology on Ambient Air Quality in Morogoro, Tanzania. In-ternational Journal of Environmental Sciences, 1, 1107-1115.
Makokha, J.W., Kimani, J.N. and Angeyo, H.K. (2012) Estimation of Radiative Forcing Due to Aerosols over Selected Sites in Kenya. Journal of Meteorological Research, 6, 3-13.
Lyamani, H., Valenzuela, A., Perez-Ramirez, D., Toledano, C., Granados-Munoz, M.J., Olmo, F.J. and Alados-Arboledas, L. (2015) Aerosol Properties over the Western Mediterranean Basin: Temporal and Spatial Variability. Atmospheric Chemistry and Physics, 15, 2473-2486.
https://doi.org/10.5194/acp-15-2473-2015
Makokha, J.W., Odhiambo, J.O. and Shem, J.G. (2018) Long Term Assessment of Aerosol Radiative Forcing over Selected Sites of East Africa. Journal of Geoscience and Environment Protection, 6, 22-34. https://doi.org/10.4236/gep.2018.64002
Ngaina, J.N., Mutai, B.K., Ininda, J.M. and Muthama, J.N. (2014) Monitoring Spatial-Temporal Variability of Aerosols over Kenya. Ethiopian Journal of Environmental Studies and Management, 7, 244-252. https://doi.org/10.4314/ejesm.v7i3.3
Makokha, J.W., Odhiambo, J.O. and Godfrey, J.S. (2017) Trend Analysis of Aerosol Optical and Angstrom Exponent Anomaly over East Africa. Atmospheric and Climate Sciences, 7, 588-603. https://doi.org/10.4236/acs.2017.74043
Houghton, J.T., Ding, Y., Griggs, D.J., Noguer, M., Van der Linden, P.J., Dac, X., Maskell, K. and Johnson: Intergovernmental Panel on Climate Change (IPCC) (2013) Climate Change 2013; The Specific Basis. Contribution of Working Group 1 for the Fifth Assessment Report.
Holben, B.N., Eck, T.F., Slutsker, I., Tanre, D., Buis, J.P., Setzer, A., Vermote, E., Reagan, J.A., Kaufman, Y.J., Nakajima, T., Lavenu, F., Jankowiak, I. and Smirnov, A. (1998) AERONET-A Federated Instrument Network and Data Archive for Aerosol Characterization. Remote Sensing of Environment, 66, 1-16. https://doi.org/10.1016/S0034-4257(98)00031-5
Dubovik, O., Videen, G., Yatskiv, Y. and Mish-Chenko, M. (2006) Optimization of Numerical Inversion in Photopolarimetric Remote Sensing. In: Videen, G., Yatskiv, Y. and Mishchenko, M., Eds., Photopolarimetry in Remote Sensing, Kluwer Academic Publishers, Dordrecht, 65-106.
Dubovik, O. and King, M.D. (2002) Flexible Inversion Algorithm for Retrieval of Aerosol Optical Properties from Sun and Sky Radiance Measurements. Journal of Geophysical Research, 105, 20673-20696. https://doi.org/10.1029/2000JD900282
Boiyo, R.K., Kumar, R. and Zhao, T. (2018) Optical, Microphysical and Radiative Properties of Aerosols over a Tropical Rural Site in Kenya, East Africa: Source Identification, Modification and Aerosol Type Discrimination. Journal Atmospheric Environment, 177, 234-252. https://doi.org/10.1016/j.atmosenv.2018.01.018
Makokha, J.W., Angeyo, H.K. and Muthama, J.N. (2017b) Aerosol Optical Depth and Precipitation Rate Projections over East Africa Utilizing Self Organizing Map The International Journal of Science & Technoledge, 5, 166-175.
Shupeng, W., Li, F., Xingying, Z. and Weihe, W. (2015) Retrieval of Aerosol Properties for Fine/Coarse Mode Aerosol Mixtures over Beijing from PARASOL Measurements. Remote Sensing, 7, 9311-9324. https://doi.org/10.3390/rs70709311
Juma, S.G., Nzioka, J.M. and Bethwel, K.M. (2015) Simulation of Radiative Forcing Due to Aerosols over Some Counties in Kenya. International Journal of Medicine, and Sciences.