Twomey effect observed from collocated microphysical and remote sensing measurements over shallow cumulus

• DOI: 10.1002/2013jd020131
• Publication Date: 2014-01-10T17:18:49Z
• Authors: F. Werner; F. Ditas; H. Siebert; M. Simmel; B. Wehner; P. Pilewskie; T. Schmeissner; R. A. Shaw; S. Hartmann; H. Wex; G. C. Roberts; M. Wendisch
• Keywords: Effective radius; Liquid water content

Clear experimental evidence of the Twomey effect for shallow trade wind cumuli near Barbados is presented. Effective droplet radius ( r eff ) and cloud optical thickness τ ), retrieved from helicopter‐borne spectral cloud‐reflected radiance measurements, reflectivity γ λ are correlated with collocated in situ observations number concentration aerosol particles subcloud layer N ). denotes larger than 80 nm diameter represents activation mode. In microphysical parameters were sampled by Airborne Cloud Turbulence Observation System (ACTOS). Spectral data collected Modular Radiation measurement sysTem (SMART‐HELIOS). With increasing a shift probability density functions toward values observed, while mean observed ranges decrease. The relative susceptibilities RS , to derived bins constant liquid water path. resulting range 0.35 0.27 . These results close maximum susceptibility possible theory. Overall, show characteristics homogeneous, plane‐parallel clouds. Comparisons measured parcel model agreement.