Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
doi:10.5194/acp-2016-1130
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
10 Jan 2017
Review status
A revision of this discussion paper is under review for the journal Atmospheric Chemistry and Physics (ACP).
Global and regional estimates of warm cloud droplet number concentration based on 13 years of AQUA-MODIS observations
Ralf Bennartz1,2 and John Rausch2 1Earth and Environmental Science Department, Vanderbilt University, Nashville, TN, 37240, USA
2Space Science and Engineering Center, University of Wisconsin – Madison, WI, 53706, USA
Abstract. We present and evaluate a climatology of cloud droplet number concentration (CDNC) based on 13 years of Aqua-MODIS observations. The climatology provides monthly mean 1 × 1 degree CDNC values plus associated uncertainties. All values are in-cloud values, that is, if the grid box is covered to 10 % with clouds, then the reported CDNC value will be valid for the cloudy part of the grid-box. Here, we provide an overview on how the climatology was generated and assess and quantify potential systematic error sources including effects of broken clouds, and remaining artefacts caused by the retrieval process or related to observation geometry. Retrievals and evaluations were performed at the scale of initial MODIS observations (in contrast to some earlier climatologies, which were created based on already gridded data). This allowed us to implement additional screening criteria, so that observations inconsistent with key assumptions made in the CDNC retrieval could be rejected. Application of these additional screening criteria led to significant changes in the annual cycle of CDNC both in terms of its phase and magnitude. After an optimal screening was established a final CDNC climatology was generated. Resulting CDNC uncertainties for the climatology are in the order of 30 % in the stratocumulus regions and 60 % to 80 % elsewhere. The climatology is available in Network Common Data Format (netCDF) and adheres to the Climate and Forecast (CF) convention. The climatology is available via Digital Object Identifier (Bennartz and Rausch, 2016, doi:10.15695/vudata.ees.1).

Citation: Bennartz, R. and Rausch, J.: Global and regional estimates of warm cloud droplet number concentration based on 13 years of AQUA-MODIS observations, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2016-1130, in review, 2017.
Ralf Bennartz and John Rausch
Ralf Bennartz and John Rausch

Data sets

Cloud Droplet Number Concentration Climatology
R. Bennartz and J. Rausch
doi:10.15695/vudata.ees.1
Ralf Bennartz and John Rausch

Viewed

Total article views: 510 (including HTML, PDF, and XML)

HTML PDF XML Total BibTeX EndNote
351 125 34 510 15 40

Views and downloads (calculated since 10 Jan 2017)

Cumulative views and downloads (calculated since 10 Jan 2017)

Viewed (geographical distribution)

Total article views: 510 (including HTML, PDF, and XML)

Thereof 507 with geography defined and 3 with unknown origin.

Country # Views %
  • 1

Saved

Discussed

Latest update: 27 May 2017
Publications Copernicus
Download
Short summary
Cloud droplet number concentration is linked to air pollution levels via indirect aerosol effects. The climatological results presented here provide constraints on cloud droplet number concentration globally thereby helping to evaluate global climate models and study the impact of pollution regionally and globally.
Cloud droplet number concentration is linked to air pollution levels via indirect aerosol...
Share