Use of In Situ Cloud Condensation Nuclei, Extinction, and Aerosol Size Distribution Measurements to Test a Method for Retrieving Cloud Condensation Nuclei Profiles from Surface Measurements
If the aerosol composition and the shape of the aerosol size distribution below cloud are uniform the vertical profile of cloud condensation nuclei concentration can be retrieved entirely from surface measurements, thus providing the potential for long-term measurements of CCN concentrations near cloud base. We have used a combination of aircraft, surface in situ, and surface remote sensing measurements to test various aspects of the retrieval scheme. Our analysis leads us to the following conclusions. If in situ measurements of extinction are used the CCN retrieval works better than expected for the high supersaturations of the in situ CCN measurements. The retrieval works better for supersaturations of 0.1% than for 1%, because CCN concentrations at 0.1% are controlled by the same particles that control extinction and backscatter. The retrieval of the vertical profile of the humidification factor is not the major limitation of the CCN retrieval scheme. The performance of the retrieval varies significantly from day to day, particularly at 1% supersaturation. Vertical structure in the aerosol size distribution and composition is the dominant source of error in the CCN retrieval, but this vertical structure is difficult to measure from remote sensing at visible wavelengths.
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 877541
- Report Number(s):
- PNNL-SA-43767; KP1205010
- Journal Information:
- Journal of Geophysical Research - Atmospheres, Journal Name: Journal of Geophysical Research - Atmospheres Journal Issue: D5 Vol. 111; ISSN 0747-7309
- Country of Publication:
- United States
- Language:
- English
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