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Journal Article: ID no. (ISBN etc.):  0148-0227 BibTeX citation key:  Johnson2008b
Johnson, B. T., Heese, B., McFarlane, S. A., Chazette, P., Jones, A. E. & Bellouin, N. (2008) Vertical distribution and radiative effects of mineral dust biomass burning aerosol over West Africa during DABEX. IN Journal of Geophysical Research - Atmospheres, 113. D00C12.
Added by: Devic 2008-09-04 10:48:13    Last Edited by: Fanny Lefebvre 2011-01-21 11:27:53
Categories: Aerosol and Chemistry
Keywords: Aerosol, SOP
Creators: Bellouin, Chazette, Heese, Johnson, Jones, McFarlane
Collection: Journal of Geophysical Research - Atmospheres

Peer reviewed
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Maturity index:  published

This paper presents measurements of the vertical distribution of aerosol extinction coefficient over West Africa, during the Dust and Biomass burning aerosol Experiment (DABEX) / African Monsoon Multidisciplinary Analysis dry season Special Observing period zero (AMMA-SOP0). In situ air-craft measurements from the UK FAAM aircraft have been compared with two ground based lidars (POLIS and ARM MPL) and an airborne lidar on an ultra-light aircraft. In general mineral dust was observed at low altitudes (up to 2km) and a mixture of biomass burning aerosol and dust was observed at altitudes of 2-5km. The study exposes difficulties associated with spatial and temporal variability when inter-comparing aircraft and ground measurements. Averaging over many profiles provided a better means of assessing consistent errors and biases associated with in situ sampling instruments and retrievals of lidar ratios. Shortwave radiative transfer calculations and a 3-year simulation with the HadGEM2-A climate model show that the radiative effect of biomass burning aerosol was somewhat sensitive to the vertical distribution of aerosol. In particular, when the observed low-level dust layer was included in the model, the absorption of solar radiation by the biomass burning aerosols increased by 10%. We conclude that this absorption enhancement was caused by the dust reflecting solar radiation up into the biomass burning aerosol layer. This result illustrates that the radiative forcing of anthropogenic absorbing aerosol can be sensitive to the presence of natural aerosol species.
Last Edited by: Fanny Lefebvre