Evaluation of climate model aerosol seasonal and spatial variability over Africa using AERONET

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dc.contributor.author Horowitz, Hannah M.
dc.contributor.author Garland, Rebecca M.
dc.contributor.author Thatcher, Marcus
dc.contributor.author Landman, W.A. (Willem Adolf), 1964-
dc.contributor.author Dedekind, Zane
dc.contributor.author Van der Merwe, Jacobus
dc.contributor.author Engelbrecht, Francois A.
dc.date.accessioned 2018-04-23T10:28:08Z
dc.date.available 2018-04-23T10:28:08Z
dc.date.issued 2017-11-24
dc.description.abstract The sensitivity of climate models to the characterization of African aerosol particles is poorly understood. Africa is a major source of dust and biomass burning aerosols and this represents an important research gap in understanding the impact of aerosols on radiative forcing of the climate system. Here we evaluate the current representation of aerosol particles in the Conformal Cubic Atmospheric Model (CCAM) with ground-based remote retrievals across Africa, and additionally provide an analysis of observed aerosol optical depth at 550 nm (AOD550 nm) and Ångström exponent data from 34 Aerosol Robotic Network (AERONET) sites. Analysis of the 34 long-term AERONET sites confirms the importance of dust and biomass burning emissions to the seasonal cycle and magnitude of AOD550 nm across the continent and the transport of these emissions to regions outside of the continent. In general, CCAM captures the seasonality of the AERONET data across the continent. The magnitude of modeled and observed multiyear monthly average AOD550 nm overlap within 1 standard deviation of each other for at least 7 months at all sites except the Réunion St Denis Island site (Réunion St. Denis). The timing of modeled peak AOD550 nm in southern Africa occurs 1 month prior to the observed peak, which does not align with the timing of maximum fire counts in the region. For the western and northern African sites, it is evident that CCAM currently overestimates dust in some regions while others (e.g., the Arabian Peninsula) are better characterized. This may be due to overestimated dust lifetime, or that the characterization of the soil for these areas needs to be updated with local information. The CCAM simulated AOD550 nm for the global domain is within the spread of previously published results from CMIP5 and AeroCom experiments for black carbon, organic carbon, and sulfate aerosols. The model’s performance provides confidence for using the model to estimate largescale regional impacts of African aerosols on radiative forcing, but local feedbacks between dust aerosols and climate over northern Africa and the Mediterranean may be overestimated. en_ZA
dc.description.department Geography, Geoinformatics and Meteorology en_ZA
dc.description.librarian am2018 en_ZA
dc.description.sponsorship This work was supported by NRF CSUR grant number 9157 and a CSIR Parliamentary Grant. Hannah M. Horowitz was funded through the NSF GROW with USAID RI Fellowship. We thank the PIs and their staff for establishing and maintaining the 34 AERONET sites used in this study. en_ZA
dc.description.uri http://www.atmospheric-chemistry-and-physics.net en_ZA
dc.identifier.citation Horowitz, H.M., Garland, R., Thatcher, M. et al. 2017, 'Evaluation of climate model aerosol seasonal and spatial variability over Africa using AERONET', Atmospheric Chemistry and Physics, vol. 17, pp. 13999-14023. en_ZA
dc.identifier.issn 1680-7316 (print)
dc.identifier.issn 1680-7324 (online)
dc.identifier.other 10.5194/acp-17-13999-2017
dc.identifier.uri http://hdl.handle.net/2263/64702
dc.language.iso en en_ZA
dc.publisher Copernicus on behalf of the European Geosciences Union en_ZA
dc.rights © Author(s) 2017. This work is distributed under the Creative Commons Attribution 3.0 License. en_ZA
dc.subject Climate models en_ZA
dc.subject African aerosol particles en_ZA
dc.subject Conformal cubic atmospheric model (CCAM) en_ZA
dc.subject Aerosol robotic network (AERONET) en_ZA
dc.title Evaluation of climate model aerosol seasonal and spatial variability over Africa using AERONET en_ZA
dc.type Article en_ZA


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