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CATEGORIES:Isaac Newton Institute Seminar Series
SUMMARY:Formation of large-scale zonal flows in two-dimens
ional turbulence on a rotating sphere - Kiori Obus
e (Okayama University)
DTSTART;TZID=Europe/London:20240116T100000
DTEND;TZID=Europe/London:20240116T104500
UID:TALK208465AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/208465
DESCRIPTION:Two-dimensional barotropic flow on a rotating sphe
re is one of the simplest mathematical models desc
ribing the dynamics of planetary atmospheres. This
model is very simple and does not take into accou
nt three-dimensional fluid motion\, planetary topo
graphy\, or\, in many cases\, heat distribution fo
r example. Nevertheless\, it exhibits rich fluid d
ynamics\, including the formation of large-scale z
onal flows [1\,2\,3\,4]. This model also has the i
nteresting aspect that it has the same mathematica
l structure as the special case of Hasegawa-Mima e
quation when a plane approximation is applied to i
t.\nIn this talk\, we consider unforced two-dimens
ional turbulence on a rotating sphere and discuss
how the nonlinear interactions of Rossby waves\, w
hich are linear wave solutions unique to rotating
systems\, are involved in the formation of the lar
ge-scale zonal flows (westward circumpolar flows i
n this case. ). It is known that when the rotation
rate of the sphere is very high\, the three-wave
resonance non-linear interaction of Rossby wave st
rongly dominates the dynamics of the flow field [5
\,6]. However\, it is not possible to transfer ene
rgy to Rossby waves corresponding to zonal flows (
zonal Rossby waves) directly by three-wave resonan
ce interactions [7\,8]. This means that the format
ion of zonal flows takes place by weakly existing
non-resonant interactions\, but the details have b
een little understood. In particular\, we still do
not know why the zonal flows that develop due to
non-resonant interactions consist of waves that ar
e capable of resonant interactions\, rather than w
aves that are incapable of non-resonant interactio
ns. [8].\nBased on our recent detailed numerical c
alculations of energy transfer by Rossby wave thre
e-wave non-resonant interactions\, we report that
the formation of the westward circumpolar flow is
due to non-local energy transfer by three-wave nea
r-resonant interactions (special cases of non-reso
nant interactions).\n \;\nReferences\n[1] S. Y
oden and M. Yamada\, J. Atomos. Sci. 50\, 631 (199
3)\n[2] S. Takehiro et al.\, J. Atmos. Sci. 64\, 4
084 (2007)\n[3] T. Nozawa and S. Yoden\, Phys. Flu
ids 9\, 2081 (1997)\n[4] K. Obuse et al.\, Phys. F
luids. 22\, 056601 (2010)\n[5] M. Yamada and T. Yo
neda\, Physica D 245\, 1 (2013)\n[6] A. Dutrifoy a
nd M. Yamada\, In preparation.\n[7] G. M. Reznik e
t al.\, Dyn. Atmos. Oceans 18\, 235 (1993).\n[8] K
. Obuse and M. Yamada\, Phys. Rev. Fluids 4\, 0246
01 (2019)\n \;\n \;
LOCATION:Seminar Room 1\, Newton Institute
CONTACT:
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