Characteristics of colliding sea breeze gravity current fronts : a laboratory study

Date
2017-02Author
van der Wiel, Karin
Concept link
Gille, Sarah T.
Concept link
Llewellyn Smith, Stefan
Concept link
Linden, P. F.
Concept link
Cenedese, Claudia
Concept link
Metadata
Show full item recordCitable URI
https://hdl.handle.net/1912/9083As published
https://doi.org/10.1002/qj.3015Keyword
Sea breeze; Land breeze; Gravity current; Convergence; Deep convection; GFD; Fluid dynamicsAbstract
Sea and land breeze circulations driven by surface temperature differences between
land and sea often evolve into gravity currents with sharp fronts. Along narrow
peninsulas, islands and enclosed seas, sea/land breeze fronts from opposing shorelines
may converge and collide and may initiate deep convection and heavy precipitation.
Here we investigate the collision of two sea breeze gravity current fronts in an
analogue laboratory setting. We examine these collisions by means of ‘lock-exchange’
experiments in a rectangular channel. The effects of differences in gravity current
density and height are studied. Upon collision, a sharp front separating the two currents
develops. For symmetric collisions (the same current densities and heights) this front is
vertical and stationary. For asymmetric collisions (density differences, similar heights)
the front is tilted, changes shape in time and propagates in the same direction as the
heavier current before the collision. Both symmetric and asymmetric collisions lead to
upward displacement of fluid from the gravity currents and mixing along the plane
of contact. The amount of mixing along the collision front decreases with asymmetry.
Height differences impact post-collision horizontal propagation: there is significant
propagation in the same direction as the higher current before collision, independent
of density differences. Collisions of two gravity current fronts force sustained ascending
motions which increase the potential for deep convection. From our experiments we
conclude that this potential is larger in stationary collision fronts from symmetric
sea breeze collisions than in propagating collision fronts from asymmetric sea breeze
collisions.
Description
Author Posting. © The Author(s), 2017. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Quarterly Journal of the Royal Meteorological Society 143 (2017): 1434–1441, doi:10.1002/qj.3015.
Collections
Suggested Citation
Preprint: van der Wiel, Karin, Gille, Sarah T., Llewellyn Smith, Stefan, Linden, P. F., Cenedese, Claudia, "Characteristics of colliding sea breeze gravity current fronts : a laboratory study", 2017-02, https://doi.org/10.1002/qj.3015, https://hdl.handle.net/1912/9083Related items
Showing items related by title, author, creator and subject.
-
Coral reef drag coefficients—surface gravity wave enhancement
Lentz, Steven J.; Churchill, James H.; Davis, Kristen A. (American Meteorological Society, 2018-07-13)A primary challenge in modeling flow over shallow coral reefs is accurately characterizing the bottom drag. Previous studies over continental shelves and sandy beaches suggest surface gravity waves should enhance the drag ... -
Measurements and models of fine-structure, internal gravity waves and wave breaking in the deep ocean
Eriksen, Charles C. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1976-09)Measurements of horizontal and vertical current by propeller cluster current meters and temperature by thermistors mounted on a rigid array 8 m high and 20 m long moored in the oceanic main thermocline near Bermuda are ... -
Seasonal variation of ocean bottom pressure derived from Gravity Recovery and Climate Experiment (GRACE) : local validation and global patterns
Kanzow, Torsten; Flechtner, Frank; Chave, Alan D.; Schmidt, Roland; Schwintzer, Peter; Send, Uwe (American Geophysical Union, 2005-09-02)The Gravity Recovery and Climate Experiment (GRACE) processing centers at the GeoForschungsZentrum Potsdam (GFZ) and the University of Texas Center for Space Research (UTCSR) provide time series of monthly gravity field ...