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Simulation of aerosol optical thickness during IMPACT (May 2008, The Netherlands) with ECHAM5-HAM

Roelofs, Geert-Jan and ten Brink, Harry and Kiendler-Scharr, Astrid and de Leeuw, Gerrit and Mensah, Amewu and Minikin, Andreas and Otjes, Rene (2010) Simulation of aerosol optical thickness during IMPACT (May 2008, The Netherlands) with ECHAM5-HAM. Atmospheric Chemistry and Physics Discussions, 10, pp. 5911-5945.

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In May 2008 the measurement campaign IMPACT for observation of atmospheric aerosol and cloud properties was conducted in Cabauw (The Netherlands). With a nudged version of the coupled aerosol-climate model ECHAM5-HAM we simulate aerosol and aerosol optical thickness (AOT) for the campaign period. Synoptic scale meteorology is represented realistically and simulated concentrations of aerosol sulfate and organics at the surface are generally within a factor of two from observed values. The monthly averaged AOT from the model is 0.33, about 20% larger than observed. For selected periods of the month with relatively dry and moist conditions discrepancies are approximately −30% and +15%, respectively. Discrepancies during the dry period are partly caused by inaccurate representation of boundary layer (BL) dynamics by the model affecting the simulated AOT. The model simulates too strong exchange between the BL and the free troposphere, resulting in weaker concentration gradients at the BL top than observed for aerosol and humidity, while upward mixing from the surface layers into the BL appears to be underestimated. The results indicate that beside aerosol sulfate and organics also aerosol ammonium and nitrate significantly contribute to aerosol water uptake. The relation between particle concentration and AOT is rather weak during IMPACT. The simulated day-to-day variability of AOT follows synoptic scale advection of humidity rather than particle concentration. Even for relatively dry conditions AOT appears to be strongly influenced by the diurnal cycle of RH in the lower boundary layer, further enhanced by uptake and release of nitric acid and ammonia by aerosol water.

Document Type:Article
Title:Simulation of aerosol optical thickness during IMPACT (May 2008, The Netherlands) with ECHAM5-HAM
AuthorsInstitution or Email of Authors
Roelofs, Geert-JanUtrecht Univ., NL
ten Brink, HarryECN, Petten, NL
Kiendler-Scharr, AstridFZ Jülich
de Leeuw, GerritTNO, Utrecht, NL
Mensah, AmewuFZ Jülich
Minikin, AndreasUNSPECIFIED
Otjes, ReneECN, Petten, NL
Journal or Publication Title:Atmospheric Chemistry and Physics Discussions
Refereed publication:No
In Open Access:Yes
In ISI Web of Science:No
Page Range:pp. 5911-5945
Keywords:aerosol optical thickness, EUCAARI
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Space (old)
HGF - Program Themes:W EO - Erdbeobachtung
DLR - Research area:Space
DLR - Program:W EO - Erdbeobachtung
DLR - Research theme (Project):W - Vorhaben Atmosphären- und Klimaforschung (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics > Atmospheric Trace Species
Deposited By: Dr.rer.nat. Andreas Minikin
Deposited On:09 Mar 2010 11:36
Last Modified:27 Feb 2015 16:09

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