Premium
Water vapor turbulence profiles in stationary continental convective mixed layers
Author(s) -
Turner D. D.,
Wulfmeyer V.,
Berg L. K.,
Schween J. H.
Publication year - 2014
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2014jd022202
Subject(s) - skewness , turbulence , convection , flux (metallurgy) , boundary layer , standard deviation , planetary boundary layer , turbulence kinetic energy , convective mixing , water vapor , atmospheric sciences , physics , chemistry , meteorology , mathematics , thermodynamics , statistics , organic chemistry
The U.S. Department of Energy Atmospheric Radiation Measurement (ARM) program's Raman lidar at the ARM Southern Great Plains site in north central Oklahoma has collected water vapor mixing ratio ( q ) profile data more than 90% of the time since October 2004. Three hundred (300) cases were identified where the convective boundary layer was quasi‐stationary and well mixed for a 2 h period, and q mean, variance, third‐order moment, and skewness profiles were derived from the 10 s, 75 m resolution data. These cases span the entire calendar year, and demonstrate that the q variance profiles at the mixed layer (ML) top changes seasonally and is strongly related to the gradient of q across the interfacial layer. The q variance at the top of the ML shows only weak correlations ( r < 0.3) with sensible heat flux, Deardorff convective velocity scale, and turbulence kinetic energy measured at the surface. The median q skewness profile is most negative at 0.85 z i , zero at approximately z i , and positive above z i , where z i is the depth of the convective ML. The spread in the q skewness profiles is smallest between 0.95 z i and z i . The q skewness at altitudes between 0.6 z i and 1.2 z i is correlated with the magnitude of the q variance at z i , with increasingly negative values of skewness observed lower down in the ML as the variance at z i increases, suggesting that in cases with larger variance at z i there is deeper penetration of the warm, dry free tropospheric air into the ML.