Fog Formation Related to Gravity Currents Interacting with Coastal Topography

Details

• Journal Title:
  Boundary-Layer Meteorolgy
• Personal Author:
  Bardoel, Stef L. ; Horna Muñoz, Daniel V. ; Grachev, Andrey A. ; Krishnamurthy, Raghavendra ; Chamorro, Leonardo P. ; Fernando, Harindra J. S.
• NOAA Program & Office:
  OAR (Oceanic and Atmospheric Research) ; PSL (Physical Sciences Laboratory)
• Description:
  An interesting mixing-fog event was identified during the C-FOG field campaign, where a cold-frontal airmass arriving from the north-east collided with The Downs peninsula in Ferryland, Newfoundland, Canada, to produce misty/foggy conditions. A comprehensive set of field observations suggests that this collision caused turbulent mixing of nearly saturated ambient air with an almost saturated cold-frontal airmass, creating conditions for mixing fog. To delve into the physical processes underlying this phenomenon, laboratory experiments were performed on the interaction of lock-exchange-induced gravity currents with a rectangular obstacle. Instantaneous velocity and density fields were obtained using particle image velocimetry and planar laser-induced fluorescence. The observations suggest that the obstacle starts affecting the approaching gravity-current propagation at an upstream distance of 2H and, upon collision, the mixing occurs over a length of 0.83H, where H is the depth of the ambient fluid layer. The time for larger-scale turbulent stirring to permeate to the smallest scales of turbulence and activate the condensation nuclei is estimated as 3t∗, where t∗=H/g′−−−−√ is the intrinsic time scale of the gravity current, and g′ is the reduced gravity. Extrapolation of laboratory results to field conditions shows a good agreement with observations.
• Keywords:
  Fog Topography Gravity currents
• Source:
  Boundary-Layer Meteorol 181, 499-521
• DOI:
  https://doi.org/10.1007/s10546-021-00638-w
• Document Type:
  Journal Article
• Rights Information:
  Accepted Manuscript
• Compliance:
  Submitted
• Main Document Checksum:
  urn:sha256:f06e9af3634a97dcab4b9e85d26c727ebde2dcf7a2134940d52771b68b7b52d4
• Download URL:
  https://repository.library.noaa.gov/view/noaa/44369/noaa_44369_DS1.pdf
• File Type:
  [PDF - 1.83 MB ]