ANALYSIS OF THE PLANETARY BOUNDARY LAYER IN AN URBAN VALLEY

John Horel, Steven Lazarus, and Tom Potter
University of Utah

ABSTRACT

Data assimilation and simulations at high spatial resolution will be used to study the evolution of the stable boundary layer in the Salt Lake Valley. The Oklahoma Advanced Regional Prediction (ARPS) model and its associated analysis system, the ARPS Data Analysis System (ADAS), will be used to analyze the onset and demise of strong stable layers. Analyses will be created at hourly intervals for the winter half of the year (15 September - 15 March) during three successive winter seasons. All available data resources collected routinely at the University of Utah will be used in the analyses. The analyses will be used to develop basin-averaged diagnostics such as mixed layer depth, intensity of stable layers, and total heating required to convectively overturn the near-surface layer. The evolution of the boundary layer will be documented separately for stable layers that erode daily versus stable layers that persist for several days. Composites will be used to define the roles of upper level ridges and troughs upon the formation and destruction of stable layers.

After the initial field program is completed and research data becomes available, reanalyses will be created for all intensive observing periods. Mass budgets for the urban basin will be determined to assess the importance of vertical and horizontal transport. Trajectories based upon the 3-dimensional analyses will be compared to those obtained from passive tracer releases. The ability of the ARPS model to simulate the evolution of the stably-stratified boundary layer will be tested.

During the field program, eight 3-m surface mobile mesonet stations are available for deployment, in addition to the existing network of stations in the region. All of the operational and research data resources archived at the University of Utah will be available to the VTMX science team. This includes: surface observations at several hundred locations in Utah and surrounding states that comprise the Utah Mesonet; soundings at SLC and other sites in the west; wind and temperature profiler at Dugway Army Proving Grounds; ACARS aircraft reports enroute and on ascent and descent into the SLC Airport;NIDS images and Level II archive of KMTX WSR-88D radar products; radial wind and reflectivity images from the FAA TDWR radar at Layton, Utah; RASS profiler to be located soon by the Utah Department of Air Quality in the metropolitan area; visible, infrared, and water vapor satellite imagery and satellite soundings of water vapor; NCEP operational analysis and forecast products from regional models; and research analyses and simulations developed at the University of Utah.

CONTACT:

J. Horel, tel: (801) 581-7091, e-mail: jhorel@atmos.met.utah.edu

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