final_program_abstracts[1]

11 IMSC Session Program
Towards an improved understanding of aerosol effects on the
climate
Thursday - Poster Session 2
Lindsay Collins, Ken Carslaw, Graham Mann and Dominick Spracklen
University of Leeds, UK
The AErosol model RObustness and Sensitivity study (AEROS) aims to provide
improved climate and air quality prediction through an improved understanding of the
uncertainties in aerosol effects on the climate. Aerosol has persistently been assessed
as the largest radiative forcing uncertainty (IPCC, 2007) with its effects being of
comparable magnitude but with opposite sign to the greenhouse gases (a cooling
effect on the atmosphere). The best current knowledge of aerosol processes is
encapsulated in the GLObal Model of Aerosol Processes (GLOMAP), Spracklen
(2005). GLOMAP is the aerosol module of the UK climate model and the aerosol
scheme for the UK’s Earth System model. Complex aerosol microphysics have
enhanced model realism and improved reliability of predictions but model
uncertainties remain high. The computational demands of GLOMAP mean that
uncertainty at the process level has not yet been quantified. GLOMAP has
participated in model-intercomparison studies in which a large diversity between
models is seen. This has shown that more complex models do not necessarily perform
best in comparison to observations and it is not yet known whether they have greater
explanatory power or whether parameter uncertainty dominates.
The aim of AEROS is to establish comparable process-level diagnostics across a
diverse range of models, developed using the GLOMAP model. Uncertainty and
sensitivity analysis offers great potential in aerosol modelling due to the wide range of
uncertain parameters and model structures. The process-level model uncertainty is to
be quantified and the major sources with respect to model parameters and model
structure to be identified. Initially, Gaussian Process emulation is employed with
respect to GLOMAP’s uncertain parameters working closely with the model
developers. Early results and intentions for future research are presented here.
Spracklen, D.V, Pringle, K.J, Carslaw, K.S, Chipperfield, M.P, Mann, G.W. A global
off-line model of size-resolved aerosol microphysics: I. Model development and
prediction of aerosol properties. Atmos. Chem. Phys., 5, 2227–2252, 2005
IPCC, 2007: Climate Change 2007: The Physical Science Basis. Contribution of
Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on
Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B.
Averyt, M. Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge,
United Kingdom and New York, NY, USA, 996 pp.
Abstracts 282