Lawrence Livermore National Laboratory



The URBAN 2000 meteorological and tracer field campaign was conducted during October 2000 and was highlighted by seven night-long intensive operations periods. The experiments were designed as multi-scale experiments with three scales investigated: urban scale, downtown scale and building scale. The study was extended beyond the urban scale by embedding the URBAN 2000 study in the regional-scale VTMX study.

Meteorological Instruments deployed by CBNP investigators with the Salt Lake City urban area included:

  • 29 temperature loggers for mapping surface temperature across the urban area
  • 14 two-dimensional sonic anemometers for measuring the horizontal components of winds and turbulence
  • 9 three-dimensional sonic anemometers for measuring all three components of winds and turbulence
  • 1 doppler lidar for mapping winds across the urban area
  • 1 radar wind profiler yielding a vertical profile of the horizontal winds
  • 1 lidar ceilometer for characterizing the vertical structure of the planetary boundary layer
  • 3 acoustic sodars for vertical profiling of the horizontal winds
  • 16 surface weather stations
  • 1 mobile van for mapping the surface temperature
  • 1 energy budget station measuring net radiation, sensible heat flux and 4 levels of temperature to 16 meters above ground level

The instruments were generally operated continuously through October, with the exception of the lidars, the temperature van and some of the sonic anemometers. These instruments were operated only during the IOPs.

In addition to the instruments deployed by the CBNP during the URBAN experiment, the VTMX program operated numerous instruments around the Salt Lake valley during October 2000. The details of that program are described at http://www.pnl.gov/vtmx/.

Sulfur hexafluoride (SF6) was released at ground level from one location in downtown Salt Lake City near the intersection of 400 South and 200 East streets. During the first four IOPs (corresponding to VTMX IOP numbers 2, 4, 5 and 7), SF6 was released at 1g/s from a 30 meter-long line source for three 1-hour periods from 00-01, 02-03, and 04-05 MST. For the last IOP (number 10), SF6 was released as a point source with the same release rate and for the same time periods. During IOP 9, SF6 was released as a point source at a higher concentration (2g/s) and at three 1-hour periods from 21-22, 23-00 and 01-2MST, as higher winds were expected.

In addition to the SF6 releases, perfluorocarbon tracers (PFT) were also released by VTMX researchers. Two of these PFTs were released in downtown Salt Lake City, two others south of the city within the Salt Lake valley. They are included here as PFT samplers were fielded as part of the CBNP experiments.

The tracer sampling information is included in the following table.

Table. SF6 and PFT sampler information. Building domain samplers collected at 1 m AGL and all other samples collected at 3 m AGL (except building top samplers). The valley domain samplers were within the VTMX program.

Domain Tracer No. of
Samplers
No. of  Sampler
Locations
Ave. Time
(h)
Duration
(h)
Period
(MST)
Valley1 PFT 50 50 2 14 2200-1200
Valley PFT 6 Collocated with above 4 48 2200-------
Urban SF6 10 10 1 12 0000-1200
Urban SF6 26 26 ½ 6 0000-0600
Downtown SF6/PFT 8 8 1 12 0000-1200
Downtown2 SF6/PFT 31 31 ½ 6 0000-0600
Downtown3 SF6/PFT 1 Collocated with above ½ 6 0600-1200
Downtown SF6 12 12 ¼ 3 0000-0300
Downtown SF6 12 Collocated with above ¼ 3 0300-0600
Building SF6 15 15 5 min. 50 min 0005-0055
Building SF6 15 Collocated with above 5 min. 50 min 0205-0255
Building SF6 15 Collocated with above 5 min. 50 min 0405-0455

1Four samplers on building tops; 2Three samplers on building tops; 3Sampler on building top.