In October 2000, the US Department of Energy, along with NOAA and several other labs and universities, conducted the Vertical Transport and Mixing Experiment (VTMX) and URBAN2000 field programs in Salt Lake City, Utah. The VTMX program focused on the basin-scale flow regime, where the URBAN2000 component focused on transport and dispersion in the downtown Salt Lake City area. In this paper, we will focus on a specific Intensive Operations Period, IOP-10, which occurred on October 25-26, 2000.

IOP-10 was chosen because the winds in the downtown area were fairly weak and variable early in the experiment, and became more windy in the later part of the IOP. In order to prepare initial and boundary conditions for our LES modeling studies in the downtown area, we will present an analysis of some the observations taken during IOP-10. Vertical information necessary for an inflow profile will be obtained from a collocated wind profiler and sodar upstream of the urban SF6 release location, a sodar mounted at roof level in the downtown area, and 3D sonic measurements on a tower immediately upwind of the release location. The larger scale influence on the flow downtown will be assessed by looking at 2-d and 3-d sonic anemometers in the vicinity of the release and measurements from stationary SF6 concentration samplers and mobile trace gas samplers. The relatively high density of measurements during the URBAN2000 field program provides us with a unique opportunity to understand both the building-scale and urban-scale wind fields and dispersion. These observations will be compared with large-eddy simulation of IOP-10 in a companion paper.