Boundary-Layer Evolution over Phoenix, Arizona, and the Premature Mixing of Pollutants in the Early Morning

Journal Article · Tue Feb 01 04:00:00 EST 2005 · Atmospheric Environment

DOI:https://doi.org/10.1016/j.atmosenv.2004.08.055· OSTI ID:15020535

Shaw, William J; Doran, J C; Coulter, Richard L

The 2001 Phoenix Sunrise campaign was a field measurement program to investigate the early-morning chemical and meteorological processes associated with the development of ozone pollution in Phoenix, Arizona. As part of that study, atmospheric structure was measured using wind profiling radars, sodars, and radiosondes at several locations in the Phoenix metropolitan area. Chemical measurements made by other investigators showed that vertical mixing of pollutants began prior to sunrise on a number of occasions. This was surprising, since we expected sustained mixing to occur only after sunrise and the onset of solar heating. We have used the meteorological measurements to identify a density current that commonly arrives in downtown Phoenix in the hour or two before sunrise when conditions are undisturbed. Both winds and cold advection associated with this feature act to destabilize the lower atmosphere, and the resulting mixing continues through the morning transition to convective conditions. Because photochemical production of ozone is non-linearly dependent on the concentrations of precursor species, this early mixing will need to be properly represented in combined meteorological and chemical models if they are to be fully successful in simulating ozone concentrations.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 15020535
• Report Number(s): PNNL-SA-40637; KP1202010
• Journal Information: Atmospheric Environment, Journal Name: Atmospheric Environment Journal Issue: 4 Vol. 39
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
ADVECTION
OZONE
POLLUTANTS
POLLUTION
PRECURSOR
PRODUCTION
SOLAR HEATING
URBAN AREAS
boundary layer
complex terrain
density current
ozone
air pollution