Monday, 16 September 2013
Breckenridge Ballroom (Peak 14-17, 1st Floor) / Event Tent (Outside) (Beaver Run Resort and Conference Center)
As part of the current phase of the of the UAH Atmospheric Boundary Identification and Delineation Experiment (ABIDE) field effort, an array of instrumentation is used to investigate characteristics and evolution of the BL across the transition from the afternoon convective regime to the more stratified nocturnal regime we term this the Afternoon to Evening Transition (AET). Platforms include multiple scanning dual-polarimetric Doppler radars, and the UAH MIPS suite of sensors (915 MHz wind profiler, microwave profiling radiometer, vertically pointing X-band radar, lidar ceilometer, 2 kHZ sodar, surface instrumentation and radiosonde deployment capability). A new component of the UAH mobile instrumentation array is a 1.5 micron scanning Doppler wind lidar. Dual-Doppler wind field retrieval, changes in wind, temperature, and moisture profiles, vertical velocity variance, and other proxies for TKE are examined. The investigation expands upon a limited set of targeted vertically pointing radar observations of the BL's AET, and initial work that has considered the challenge of convective initiation (CI) during the AET period. Our integrated approach also allows comparison of multiple sensors' vertical motion estimates, permitting a diagnosis of the effects of biological targets on the vertical air motion field (discussed in more detail in another talk), and a more thorough understanding of the real vertical wind component. Changes we hypothesize and observe in the AET period are generally consistent with previous studies' conclusions for CI aiding factors, including an increase in low level moisture and enhanced convergence above the surface layer (within preexisting convergent boundaries) resulting from the decay of turbulent mixing as the surface heat flux diminishes. Select isolated spring-summer 2012-2013 AET CI events are analyzed through a synthesis of perspectives afforded by this multi-platform observing strategy.
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