Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
doi:10.5194/acpd-9-9551-2009
© Author(s) 2009. This work is distributed
under the Creative Commons Attribution 3.0 License.
 
16 Apr 2009
Review status
A revision of this discussion paper for further review has not been submitted.
A comparison of water uptake by aerosols using two thermodynamic models
L. Xu1, J. E. Penner1, S. Metzger2, and J. Lelieveld2 1Department of Atmospheric, Oceanic and Space Science, University of Michigan, Ann Arbor, Michigan, USA
2Max Planck Institute for Chemistry, Mainz, Germany
Abstract. A comprehensive comparison between two aerosol thermodynamic equilibrium models used in chemistry-climate simulations, EQUISOLV II and EQSAM3, is conducted for various relative humidities and chemical compositions. Our results show that the concentration of total particulate matter as well as the associated aerosol liquid water content predicted by these two models is comparable for all conditions, which is important for radiative forcing estimates. The normalized absolute difference in the concentration of total particulate matter is 6% on average for all 200 conditions studied, leading to a regression coefficient of about 0.8 for the water associated with the aerosol between these two models. Relatively large discrepancies occur, however, at high ammonium, low nitrate/sodium concentrations at low and medium relative humidities (RH<60–70%), which is analyzed and discussed in detail. In addition, the prediction of the partitioning of ammonium and nitrate is investigated under realistic atmospheric conditions. The data collected during the Mediterranean Intensive Oxidant Study (MINOS) campaign are simulated using both models. The results show that both models can reproduce the concentration of total particulate matter for 90% of the time within a factor of 2, while the predicted concentration of aerosol water by these two models is significantly correlated. The largest difference exists near RH's of 70–80% which is the RH range for the transition of mixed ammonium salts from the solid to the liquid phase.

Citation: Xu, L., Penner, J. E., Metzger, S., and Lelieveld, J.: A comparison of water uptake by aerosols using two thermodynamic models, Atmos. Chem. Phys. Discuss., 9, 9551-9595, doi:10.5194/acpd-9-9551-2009, 2009.
L. Xu et al.
Interactive discussionStatus: closed (peer review stopped)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version      Supplement - Supplement
 
RC C1578: 'Review of article comparing two thermodynamic modules', Anonymous Referee #1, 08 Jun 2009 Printer-friendly Version 
AC C4065: 'Response to Referee #1 by L. Xu, J. E. Penner, S. Metzger, and J. Lelieveld', Li Xu, 21 Aug 2009 Printer-friendly Version 
 
RC C1686: 'Review of the article entitled "A comparison of water uptake by aerosols using two thermodynamic models"', Anonymous Referee #2, 10 Jun 2009 Printer-friendly Version 
AC C4073: 'Response to Referee #2 by L. Xu, J. E. Penner, S. Metzger, and J. Lelieveld', Li Xu, 21 Aug 2009 Printer-friendly Version 
 
SC C1712: 'Comment on the pertinence of comparing EQSAM3 to thermodynamic models', Ralph Lescroart, 10 Jun 2009 Printer-friendly Version 
SC C1775: 'Reply to R. Lescroart', Dr. Swen Metzger, 11 Jun 2009 Printer-friendly Version 
SC C2057: 'Reply to Dr. S. Metzger', Ralph Lescroart, 21 Jun 2009 Printer-friendly Version 
SC C3221: 'Reply to R. Lescroart et al., by S. Metzger and J. Lelieveld', Swen Metzger, 23 Jul 2009 Printer-friendly Version 
SC C3233: 'Reply to R. Lescroart et al., by S. Metzger and J. Lelieveld', Swen Metzger, 23 Jul 2009 Printer-friendly Version Supplement 
 
SC C1779: 'Comment on specific figures and discussion of results', Philippe Marbaix, 12 Jun 2009 Printer-friendly Version 
SC C1783: 'Reply to Dr P. Marbaix', Dr. Swen Metzger, 12 Jun 2009 Printer-friendly Version 
EC C1791: 'Extension of Open Discussion', Dr. Gordon McFiggans, 12 Jun 2009 Printer-friendly Version 
 
RC C1904: 'Xu et al. ms.', Anonymous Referee #3, 16 Jun 2009 Printer-friendly Version 
 
SC C2148: 'Comments on EQSAM3 and its use in global models', Rahul Zaveri, 24 Jun 2009 Printer-friendly Version 
SC C3246: 'Reply to R. Zaveri et al., by S. Metzger and J. Lelieveld', Swen Metzger, 23 Jul 2009 Printer-friendly Version 
 
EC C3819: 'Editor's decision on A comparison of water uptake by aerosols using two thermodynamic models by Xu et al.', Gordon McFiggans, 12 Aug 2009 Printer-friendly Version 
 
AC C4103: 'Response to Referee #3 by L. Xu, J. E. Penner, S. Metzger, and J. Lelieveld', Li Xu, 21 Aug 2009 Printer-friendly Version 
L. Xu et al.
L. Xu et al.

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