Application of the CALIOP layer product to evaluate the vertical distribution of aerosols estimated by global models: AeroCom phase I results

The CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) Layer data are used to evaluate the vertical distribution of aerosols in 12 global models from AeroCom (Aerosol Comparisons between Observations and Models) simulations prepared for the 4th IPCC assessment report. Annual and seasonal extinction profiles are analysed over 13 sub-continental regions representative of industrial, dust, and biomass burning pollution, from CALIOP (2007-2009) observations and AeroCom (2000) simulations. An extinction mean height diagnostic (Zα) is also calculated over the 0-10 km altitude range to quantitatively assess the models performance. The mean extinction profiles derived from CALIOP layer products provide a robust climatology of the aerosol vertical distribution over large regions and for the seasonal time scale. The mean extinction decreases from the surface to about 6 km and shows consistent regional specificities and low inter-annual variability. While most models are significantly correlated with the observation in terms of Zα, some do better than others and 2 of the 12 models perform particularly well in all seasons. In most regions, notably over the maritime regions, downwind of the continents, most models show higher Zα than observed by CALIOP, whereas over the African and Chinese dust source regions, Zα is underestimated during northern hemisphere spring and summer. The positive model bias in Zα is in mainly due to an overestimate of the extinction above 6 km. Potential factors related to models and observations that contribute to the differences are discussed.

KOFFI Brigitte;  SCHULZ Michael;  BREON Francois-Marie;  GRIESFELLER Jan;  BALKANSKI Yves;  BAUER S.;  BERNTSEN T.;  CHIN M.;  COLLINS W.;  COLLINS William D.;  DENTENER Franciscus;  DIEHL T.;  EASTER R.;  GHAN S.;  GINOUX P.S.;  GONG S.;  HOROWITZ L.;  IVERSEN T.;  KIRKEVAG Alf;  KOCH D. M.;  KROL M.;  MYHRE G.;  STIER Phillip;  TAKEMURA T.;  WINKER D.; 

2012-07-11

AMER GEOPHYSICAL UNION

JRC66793

0148-0227,   

http://www.agu.org/pubs/crossref/2012/2011JD016858.shtml,    https://publications.jrc.ec.europa.eu/repository/handle/JRC66793,   

10.1029/2011JD016858,