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Observed impacts of vertical velocity on cloud microphysics and implications for aerosol indirect effects
Author(s) -
Lu Chunsong,
Liu Yangang,
Niu Shengjie,
Vogelmann Andrew M.
Publication year - 2012
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 - 10.1029/2012gl053599
Subject(s) - aerosol , vertical velocity , atmospheric sciences , dispersion (optics) , environmental science , relative velocity , radius , atmospheric dispersion modeling , meteorology , effective radius , standard deviation , physics , mechanics , optics , chemistry , astrophysics , statistics , air pollution , mathematics , classical mechanics , computer security , organic chemistry , galaxy , computer science
The simultaneous measurements of vertical velocity and cloud droplet size distributions in cumuli collected during the RACORO field campaign over the Atmospheric Radiation Measurement Program's Southern Great Plains site near Lamont, Oklahoma, US, are analyzed to determine the effects of vertical velocity on droplet number concentration, relative dispersion (the ratio of standard deviation to mean radius), and their relationship. The results show that with increasing vertical velocity the droplet number concentration increases while the relative dispersion decreases. The data also exhibit a negative correlation between relative dispersion and droplet number concentration. These empirical relationships can be fitted well with power law functions. This observational study confirms the theoretical and numerical expectations of the effects of vertical velocity on cloud microphysics by analyzing the data of vertical velocity directly. The effects of vertical velocity on relative dispersion and its relationship with droplet number concentration are opposite to that associated with aerosol loading, posing a confounding challenge for separating aerosol indirect effects from dynamical effects.