The POLDER-1 instrument was able to measure aerosol and cloud properties for eight months in 1996–1997. We use these observational data for aerosol concentration (the aerosol index), cloud optical thickness, and cloud droplet effective radius to establish statistical relationships among these parameters in order to analyze the first and second aerosol indirect effects. We also evaluate the representation of these effects as parameterized in the Laboratoire de Météorologie Dynamique–Zoom (LMDZ) general circulation model. We find a decrease in cloud top droplet radius with increasing aerosol
index in both the model and the observations. Our results are only slightly changed if the analysis is done at fixed cloud liquid water path (LWP) instead of considering all LWP conditions. We also find a positive correlation between aerosol index and cloud liquid water path, which is particularly pronounced over the Northern Hemisphere
midlatitudes. This may be interpreted as observational evidence for the second aerosol indirect effect on a large scale. The model-simulated relationship agrees well with that derived from POLDER data. Model simulations show a rather small change in the two
relationships if preindustrial rather than present-day aerosol distributions are used. However, when entirely switching off the second aerosol indirect effect in our model, we find a much steeper slope than we do when including it.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa.de:bsz:15-qucosa-177294 |
| Date | 21 August 2015 |
| Creators | Quaas, Johannes, Boucher, Olivier, Bréon, François-Marie |
| Contributors | Laboratoire de Météorologie Dynamique,, Laboratoire d’Optique Atmosphérique,, Laboratoire des Sciences du Climat et de l’Environnement,, Wiley, |
| Publisher | Universitätsbibliothek Leipzig |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | doc-type:article |
| Format | application/pdf |
| Source | Journal of Geophysical Research : Atmospheres (2004), 109, D08205 |
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