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First measurements of the Twomey indirect effect using ground‐based remote sensors
Author(s) -
Feingold Graham,
Eberhard Wynn L.,
Veron Dana E.,
Previdi Michael
Publication year - 2003
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2002gl016633
Subject(s) - effective radius , aerosol , liquid water path , environmental science , lidar , cloud base , cloud height , liquid water content , atmospheric sciences , remote sensing , extinction (optical mineralogy) , meteorology , drop (telecommunication) , cloud physics , cloud computing , cloud cover , geology , physics , mineralogy , telecommunications , quantum mechanics , galaxy , computer science , operating system
We demonstrate first measurements of the aerosol indirect effect using ground‐based remote sensors at a continental US site. The response of nonprecipitating, ice‐free clouds to changes in aerosol loading is quantified in terms of a relative change in cloud‐drop effective radius for a relative change in aerosol extinction under conditions of equivalent cloud liquid water path. This is done in a single column of air at a temporal resolution of 20 s (spatial resolution of ∼100 m). Cloud‐drop effective radius is derived from a cloud radar and microwave radiometer. Aerosol extinction is measured below cloud base by a Raman lidar. Results suggest that aerosols associated with maritime or northerly air trajectories tend to have a stronger effect on clouds than aerosols associated with northwesterly trajectories that also have local influence. There is good correlation (0.67) between the cloud response and a measure of cloud turbulence.