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SUMMARY:Deep convection and ocean overturning  - Bishakh Gayen\, Universit
 y of Melbourne
DTSTART:20250404T120000Z
DTEND:20250404T130000Z
UID:TALK229498@talks.cam.ac.uk
CONTACT:Dr Birgit Rogalla
DESCRIPTION:The ocean's circulation plays a pivotal role in Earth's climat
 e system\, with its changes during climate\ntransitions being of critical 
 importance. This study\, grounded in the principle of dynamical similarity
 \,\nemploys Direct Numerical Simulation (DNS) in an idealized setup to dis
 sect the complexities of\nocean circulation\, with a particular focus on t
 he North Atlantic and the role of buoyancy and wind in\nshaping the hydrol
 ogical cycle.\n\nWe begin with a simple system—a non-rotating ocean forc
 ed by a single scalar—then gradually\nintroduce complexity by adding con
 stant/variable rotation\, wind forcing\, and a second scalar.\nSurprisingl
 y\, our results show the spontaneous formation of gyres and a western boun
 dary current\,\nalong with full-depth overturning\, even without the intro
 duction of wind. Wind forcing further\nlocalizes upwelling near the wester
 n boundary current and primarily strengthens the gyres while\nhaving less 
 influence on overturning circulation. With the introduction of a second sc
 alar (salinity)\,\nour results become more representative of the real ocea
 n\, reproducing key features such as mode\nwater formation\, mid-latitude 
 deeper thermocline structures\, and polar haloclines\, both with and\nwith
 out wind forcing. Our DNS framework is well-suited for resolving convectio
 n processes\,\nincluding diffusive convection near the poles and salt fing
 ering in mid-latitudes\, both of which are\ncrucial for establishing mixed
  layers and pycnoclines in these regions.\n\nA key highlight of our study 
 is capturing ocean circulation across multiple scales—from basin-scale\n
 overturning and gyres to mesoscale eddies\, submesoscale dynamics\, and mi
 llimeter-scale\nconvection. These multiscale interactions regulate heat\, 
 salt\, and tracer transport. Our highresolution approach explicitly resolv
 es the interplay between large-scale circulation and small-scale\nturbulen
 t mixing\, offering deeper insights into ocean stratification\, ventilatio
 n\, and buoyancy-driven\nflows\, providing critical insights for forecasti
 ng the evolving dynamics of the North Atlantic.
LOCATION:BAS Seminar Room 1
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