BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Memento EPFL//
BEGIN:VEVENT
SUMMARY:EESS talk on "High-resolution observations of internal wave induce
 d turbulence in the deep ocean"
DTSTART:20170307T121500
DTEND:20170307T131500
DTSTAMP:20260531T063744Z
UID:ec03a44bd3627bc5c72d0677d70ed9c28f18f511cf1ede35354912f5
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr Hans Van Haren\, Senior scientist\,  Ocean Systems Sciences
  (OCS)\, Royal Netherlands Institute for Sea Research - NIOZ\, Texel (NL)\
 n\nShort biography: Hans van Haren is a senior scientist at the Royal Neth
 erlands Institute of Oceanography (NIOZ). He graduated from Utrecht Univer
 sity\, completing his MsC (physics and geophysics—physical oceanography)
  in 1985 and PhD in 1990 (working at NIOZ). He worked as a Post-Doc in Can
 ada 1990-1992 with Chris Garrett and Neil Oakey\, first at Dalhousie Unive
 rsity and Bedford Institute of Oceanography (Halifax)\, later at Universit
 y of Victoria (BC). In 1992 he returned to NIOZ\, first 3 years as Post-Do
 c\, from 1995 onwards as permanent staff. His work is on ocean observation
 s\, including development of new instrumentation\, and focusing on the stu
 dy of turbulent exchange processes governed by internal waves and affectin
 g ocean life. Over the years\, he has participated and led more than 50 se
 a-campaign cruises\, varying from shallow seas like the North Sea and Balt
 ic to deep open Atlantic Ocean.\nAbstract:\nAn overview is presented of hi
 gh-resolution temperature observations above underwater topography in the 
 deep\, stably stratified ocean. The Eulerian mooring technique is used to 
 monitor temperature variations by typically 100 sensors distributed over l
 ines between 40 and 400 m  long. The independent sensors sample at a rate
  of 1 Hz for up to one year with a precision better than 0.1 mK. This prec
 ision and sampling rate are sufficient to resolve the large\, energy conta
 ining turbulent eddies and all of the internal waves and their breaking ab
 ove underwater topography. Such underwater wave breaking is the key mechan
 ism for the redistribution of nutrients and heat (to maintain the ocean st
 ably stratified)\, and the resuspension of sediment.\nUnder conditions of 
 tight temperature-salinity (temperature-density) relationship\, the temper
 ature data are used to quantify turbulent overturns. These observations sh
 ow two distinctive turbulence processes that are associated with different
  phases of a large-scale (mainly tidal) internal gravity wave: i) highly n
 onlinear turbulent bores during the upslope propagating phase\, and ii) Ke
 lvin-Helmholtz billows\, at some distance above the slope\, during the dow
 nslope phase. While the former may be associated in part with convective t
 urbulent overturning following Rayleigh-Taylor instabilities\, the latter 
 are mainly related to shear-induced instabilities. Under weaker stratified
  conditions\, away from boundaries\, free convection is the more dominant 
 mixing process observed. With a newly developed five-lines mooring\, the t
 ransition from isotropy (full turbulence) to anisotropy (stratified turbul
 ence/internal waves) is revealed.
LOCATION:GR C0 01 https://plan.epfl.ch/theme/generalite_thm_v2?room=GR%20C
 0%2001&dim_floor=0&lang=en&dim_lang=en&tree_groups=centres_nevralgiques%2C
 acces%2Cmobilite_reduite%2Censeignement%2Ccommerces_et_services%2Cvehi
STATUS:CONFIRMED
END:VEVENT
END:VCALENDAR