Colloquium, Tuesday, Nov. 10, 3:00 pm, EN6085A: (ical.ics)

Cooperative Institute for Research in Environmental Science (CIRES), University of Colorado at Boulder and NOAA Earth Systems Research Laboratory, Chemical Sciences Division. During the ship-based portion of VOCALS (VAMOS Ocean-Cloud-Atmosphere-Land Study, VAMOS = Variability of the American Monsoon Systems) in October and November 2008, we used NOAA's High Resolution Doppler lidar (HRDL) to make lower-tropospheric measurements of horizontal and vertical winds, and uncalibrated lidar backscatter. These data have been processed into profiles of horizontal mean wind, horizontal and vertical velocity variance, and vertical skewness, and into estimates of surface-based mixing heights. Examples of these observations and the resulting profiles will be presented and a new approach to studying atmospheric boundary-layer decoupling will be introduced. This approach uses the sub-cloud vertical and horizontal wind and backscatter measurements to characterize the interactions between the cloud and surface layers, including transport of surface moisture to the cloud level. Average diurnal cycles of the surface-based mixing height, atmospheric decoupling, liquid water path, and in-situ measured chemical tracers will be presented for two different synoptic regimes encountered during the VOCALS experiment. Potential implications of the results for cloud maintenance, ship-aircraft comparison studies, and modeling will be discussed.