Interaction of sub-mesoscale flows in complex terrain during nocturnal drainage conditions
Flow visualization studies of the interaction of tributary airflow with main valley airflow under nocturnal drainage conditions were conducted in Brush Creek Valley, Colorado, in June and September-October 1984. The field experiment was designed to document the transport and diffusion of potential local emissions, simulated in this case by release of three chemically inert perfluorocarbons, in a region of highly variable topography. Flow visualization experiments were conducted using smoke releases and nighttime photography. Results indicate that drainage flow entering Pack Canyon from above the ridge is entrained only marginally, if at all, into the near-surface drainage layer within the lower portions of Pack Canyon. This may be due partly to the turbulence and entrainment created at the head of the canyon by the two merging gulches. This mixing may give the descending drainage air at that point enough buoyance to remain aloft and be carried over the south ridge of Pack Canyon by the impetus from the northernmost gully forming Pack Canyon. The split flow evidenced by the smoke plumes shows that the external wind field above the Brush Creek Canyon sidewalls sometimes descends below the ridge to disrupt flows within the canyon. Data from the minisodar and tethersonde show that there is a weak shallow near-surface downslope flow within the canyon that is sometimes disrupted in a periodic fashion by fluctuations in the layers directly above it and in Brush Creek Canyon itself, as indicated by the decrease in periodicity after the Brush Creek Canyon drainage flow has weakened or reversed.
- Research Organization:
- Pacific Northwest Labs., Richland, WA (USA); Argonne National Lab., IL (USA)
- DOE Contract Number:
- W-31-109-ENG-38; AC06-76RL01830
- OSTI ID:
- 5231556
- Report Number(s):
- CONF-851177-3; ON: DE85018390
- Resource Relation:
- Conference: 7. symposium on turbulence and diffusion of the AMS, Boulder, CO, USA, 12 Nov 1985
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
AIR FLOW
AERIAL SURVEYING
COMPLEX TERRAIN
FLUORINATED ALIPHATIC HYDROCARBONS
ENVIRONMENTAL TRANSPORT
AIR POLLUTION
COLORADO
METEOROLOGY
PHOTOGRAPHY
PLUMES
SIMULATION
TURBULENCE
WIND
FEDERAL REGION VIII
FLUID FLOW
GAS FLOW
HALOGENATED ALIPHATIC HYDROCARBONS
MASS TRANSFER
NORTH AMERICA
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
POLLUTION
USA
500100* - Environment
Atmospheric- Basic Studies- (-1989)
500200 - Environment
Atmospheric- Chemicals Monitoring & Transport- (-1989)