HR: 09:00h
AN: A51G-05    [Abstracts]
TI: Investigation of Orographic Venting of Atmospheric Boundary Layer Air Using Observations and the WRF-Chem Model
AU: * Bao, J
EM: Jian-Wen.Bao@noaa.gov
AF: NOAA/ESRL/PSD, 325 Broadway Mail Stop: PSD3, Boulder, CO 80305,
AU: Michelson, S
EM: sara.a.michelson@noaa.gov
AF: NOAA/ESRL/PSD and CIRES/University of Colorado, 325 Broadway Mail Stop: PSD3, Boulder, CO 80305,
AU: Grell, E
EM: Evelyn.Grell@noaa.gov
AF: NOAA/ESRL/PSD and STC, 325 Broadway Mail Stop: PSD3, Boulder, CO 80305,
AU: Grell, G A
EM: Georg.A.Grell@noaa.gov
AF: NOAA/ESRL/GSD and CIRES/University of Colorado, 325 Broadway Mail Stop: GSD1, Boulder, CO 80305,
AU: Djalalova, I
EM: Irina.V.Djalalova@noaa.gov
AF: NOAA/ESRL/PSD and CIRES/University of Colorado, 325 Broadway Mail Stop: PSD3, Boulder, CO 80305,
AB: Three-dimensional air-mass transport under fair weather conditions in California's Central Valley between the atmospheric boundary layer (ABL) to the free troposphere (FT) is investigated with a case study using the observations from the Central California Ozone Study (CCOS) 2000 field experiment and the WRF-Chem model. First, the comparisons of the observations and the model simulation are carried out to show that the WRF-Chem model simulates the meteorological processes of this case well. Then, the movement of the tracers simulated by the WRF-Chem model is analyzed to reveal the characteristics of three-dimensional transport. Our results indicate that the three-dimensional air-mass transport is very complex under fair weather conditions in the Central Valley. During the day, the development of the convective ABL acts as an efficient "air pump" that transports pollutants upward as the ABL grows. However, the slope wind system around the Central Valley plays an important role in redistributing pollutants vertically as well as horizontally. The tracer movement indicts that once lifted to the FT, the pollutants that originate in the ABL are vertically recirculated downward toward the ABL and horizontally transported by the synoptic flow. During the night, as the two major horizontal mesoscale low- level eddies (i.e., the Schultz and Fresno Eddies) are formed, the remnants of the pollution in the ABL converge horizontally and are recirculated along the foothills, where they remain at low-levels until sunrise and are then vertically redistributed as the daytime ABL develops. Under typical fair weather conditions in summer, there are two major lower tropospheric pathways for the ABL air masses to move out the Central Valley: eastward over the Sierra Nevada and southward through the Tehachapi Pass.
DE: 3307 Boundary layer processes
DE: 3322 Land/atmosphere interactions (1218, 1631, 1843)
DE: 3329 Mesoscale meteorology
DE: 3355 Regional modeling
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting