ccnprof > Cloud Condensation Nuclei ProfileVAP Type(s) > Baseline

Hourly averaged extinction profile (top) and associated qc flags (bottom) from RL for March 2, 2009 at SGP.

The cloud condensation nuclei (CCN) concentration at cloud base is the most relevant measure of the aerosol that influences droplet formation in clouds. Since the CCN concentration depends on supersaturation, a more general measure of the CCN concentration is the CCN spectrum (values at multiple supersaturations). The CCN spectrum is now measured at the surface at several ARM observatories and by the ARM Mobile Facility (AMF), but is not measured at the cloud base. Rather than rely on expensive aircraft measurements for all studies of aerosol effects on clouds, a way to project CCN measurements at the surface to cloud base is needed.

Remote sensing of aerosol extinction provides information about the vertical profile of the aerosol, but cannot be directly related to the CCN concentration because the aerosol extinction is strongly influenced by humidification, particularly near cloud base. Ghan and Collins (2004) and Ghan et al. (2006) propose a method to remove the influence of humidification from the extinction profiles and tie the “dry extinction” retrieval to the surface CCN concentration, thus estimating the CCN profile. This methodology has been implemented as the CCN Profile (CCNPROF) value-added product (VAP).

For more details, see the Cloud Condensation Nuclei Profile Value-Added Product technical report.

Primary Derived Measurements


  • Fixed
  • AMF1
  • AMF2
  • AMF3

Data Details

Contact Laura Riihimaki
Resource(s) Data Directory
Content time range 15 September 2006 - 24 June 2014


Sivaraman C. 2013. ARM Climate Research Facility Quarterly Value-Added Product Report October 01–December 31, 2012. U.S. Department of Energy. DOE/SC-ARM-13-002.

View All Related Publications


Damao Zhang
Pacific Northwest National Laboratory

View All VAP Translators