BEGIN:VCALENDAR VERSION:2.0 PRODID:-//18.83.4.138//NONSGML kigkonsult.se iCalcreator 2.20// CALSCALE:GREGORIAN METHOD:PUBLISH X-WR-CALNAME:Oceans at MIT X-WR-CALDESC:Striving to understand\, harness and sustain Earth'\;s def ining frontier. X-FROM-URL:http://oceans.mit.edu X-WR-TIMEZONE:America/New_York BEGIN:VTIMEZONE TZID:America/New_York X-LIC-LOCATION:America/New_York BEGIN:STANDARD DTSTART:20171105T020000 TZOFFSETFROM:-0400 TZOFFSETTO:-0500 RDATE:20181104T020000 TZNAME:EST END:STANDARD BEGIN:DAYLIGHT DTSTART:20180311T020000 TZOFFSETFROM:-0500 TZOFFSETTO:-0400 TZNAME:EDT END:DAYLIGHT END:VTIMEZONE BEGIN:VEVENT UID:7j9i2205fbrlbhkkk9roqg5nd8@google.com DTSTAMP:20180503T103343Z CATEGORIES: CONTACT: DESCRIPTION:Title: Ocean mixing driven by tides: breaking lee waves\, hydra ulic jumps and the influence of subinertial internal tides\n\nAbstract: Th e dissipation of tidal energy in the abyssal ocean leads to diapycnal mixi ng\, raising the deep cold waters that form at high latitudes\, and provid ing an important link in the energetics of the overturning circulation. Ob servations of deep ocean mixing show that it is both intermittent and high ly inhomogeneous\, with hotspots over regions of rough topography. Determi ning when\, where and how much the ocean mixes is of critical importance f or understanding the large scale circulation\, with implications for bioge ochemistry\, heat transport and ocean modeling in a changing climate.\n\nI n this talk\, I will focus on specific processes associated with tidally d riven turbulence\, combining field observations and numerical modeling of flows through a small channel that transects the crest of the Mendocino Ri dge in the eastern Pacific\, a site of mixed (diurnal and semidiurnal) tid es. At this latitude the diurnal tide is subinertial and evanescent away f rom the topography\, in contrast to the semidiurnal tide which is superine rtial and radiating. We construct two numerical simulations to interpret o ur observations. First\, we use a two-dimensional\, nonhydrostatic\, high resolution simulation to examine flow through the channel\, and show that the observed turbulence arises from both hydraulic jumps and breaking inte rnal lee waves. To place the processes in a regional context\, we use a se cond simulation of tidally driven flow in a three-dimensional domain using realistic bathymetry\, demonstrating the presence of diurnal bottom-trapp ed waves. These energetic internal waves generate strong currents close to the topography\, and their interplay with the superinertial tidal constit uent is of leading order importance in determining the timing and magnitud e of the observed turbulence at the ridge.\n\nOur observations and models illustrate some of the mechanisms by which energy is transferred from the tides to the large scale circulation\, and highlight the role of subinerti al trapped waves at this location. We posit that these waves may be import ant contributors to ocean mixing\, especially at climatically sensitive hi gh latitudes.\n\nEvent link: https://eapsweb.mit.edu/paoc-colloquium-ruth- musgrave-mit DTSTART;TZID=America/New_York:20160919T120000 DTEND;TZID=America/New_York:20160919T130000 LOCATION:Ida Green Lounge (9th Floor)\, Building 54\, Cambridge\, MA\, Unit ed States SEQUENCE:0 SUMMARY:PAOC Colloquium: Ruth Musgrave (MIT) URL:http://oceans.mit.edu/event/paoc-colloquium-ruth-musgrave-mit X-ALT-DESC;FMTTYPE=text/html:\\n\\n\\n\\n\\nTitle: Ocean mix ing driven by tides: breaking lee waves\, hydraulic jumps and the influenc e of subinertial internal tides\n\nAbstract: The dissipation of tidal ener gy in the abyssal ocean leads to diapycnal mixing\, raising the deep cold waters that form at high latitudes\, and providing an important link in th e energetics of the overturning circulation. Observations of deep ocean mi xing show that it is both intermittent and highly inhomogeneous\, with hot spots over regions of rough topography. Determining when\, where and how m uch the ocean mixes is of critical importance for understanding the large scale circulation\, with implications for biogeochemistry\, heat transport and ocean modeling in a changing climate.\n\nIn this talk\, I will focus on specific processes associated with tidally driven turbulence\, combinin g field observations and numerical modeling of flows through a small chann el that transects the crest of the Mendocino Ridge in the eastern Pacific\ , a site of mixed (diurnal and semidiurnal) tides. At this latitude the di urnal tide is subinertial and evanescent away from the topography\, in con trast to the semidiurnal tide which is superinertial and radiating. We con struct two numerical simulations to interpret our observations. First\, we use a two-dimensional\, nonhydrostatic\, high resolution simulation to ex amine flow through the channel\, and show that the observed turbulence ari ses from both hydraulic jumps and breaking internal lee waves. To place th e processes in a regional context\, we use a second simulation of tidally driven flow in a three-dimensional domain using realistic bathymetry\, dem onstrating the presence of diurnal bottom-trapped waves. These energetic i nternal waves generate strong currents close to the topography\, and their interplay with the superinertial tidal constituent is of leading order im portance in determining the timing and magnitude of the observed turbulenc e at the ridge.\n\nOur observations and models illustrate some of the mech anisms by which energy is transferred from the tides to the large scale ci rculation\, and highlight the role of subinertial trapped waves at this lo cation. We posit that these waves may be important contributors to ocean m ixing\, especially at climatically sensitive high latitudes.\n\nEvent link : https://eapsweb.mit.edu/paoc-colloquium-ruth-musgrave-mit END:VEVENT END:VCALENDAR