BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Dead water effect on drift of icebergs - John Grue (University of 
 Oslo)
DTSTART:20171002T131500Z
DTEND:20171002T140000Z
UID:TALK83201@talks.cam.ac.uk
CONTACT:INI IT
DESCRIPTION:Observations/measurements of the drift of an iceberg in Antarc
 tica are motivation of the lecture. Particularly two measurements of the i
 nternal waves generated by the iceberg are discussed. These measurements a
 re connected to Fridtjof Nansen&#39\;s historical observations of the dead
  water on FRAM\, published in Nansen (1897). The dead water resistance on 
 FRAM is first obtained empirically from Nansen&#39\;s observations. A stro
 ngly nonlinear interfacial model of the dead water resistance is then outl
 ined with calculations relevant to the FRAM ship. The intersection of the 
 resistance curves obtained empirically and theoretically determines accura
 tely the speed of FRAM. This intersection becomes a function of the level 
 of the pycnocline. The nonlinear and linear dead water wakes are then obta
 ined at the low subcritical speeds. The connection between the dead water 
 effect on FRAM and the ice berg case are discussed. The considerable incre
 ase in the dead water resistance at small subcritical speed\, which FRAM d
 id not overcome\, is discussed. The same resistance slope seems to limit t
 he speed of the iceberg drift where the observed internal wave Froude numb
 er is subcritical at a value of 0.6.   References:   J. Grue (2015). Nonli
 near dead water resistance at subcritical speed. Phys. Fluids 27\, 08213. 
  J. Grue (2017). Calculating FRAM&#39\;s dead water. In: The Ocean in Moti
 on - Circulation\, waves polar oceanography. Springer-Verlag\, Oceanograph
 y Series. Eds. M.G. Velarde\, R. Yu. Tarakanov\, A.V. Marchenko. 70th Anni
 versary of Eugene G. Morozov.  J. Morison and D. Goldberg (2012). A brief 
 study of the force balance between a small iceberg\, the ocean\, sea ice\,
  and atmosphere in the Weddell Sea. Cold regions science and technology\, 
 76-77\, 69-76.
LOCATION:Seminar Room 1\, Newton Institute
END:VEVENT
END:VCALENDAR