Japan Geoscience Union Meeting 2015

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Oral

Symbol M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS22] Geophysical fluid dynamics-Transfield approach to geoscience

Wed. May 27, 2015 11:00 AM - 12:45 PM 106 (1F)

Convener:*Keita Iga(Atmosphere and Ocean Research Institute, The University of Tokyo), Kensuke Nakajima(Department of Earth and Planetary Sciences,Flculty of Sciences,Kyushu University), Shigeo Yoshida(Department of Earth and Planetary Sciences, Faculty of Sciences, Kyushu University), Takatoshi Yanagisawa(Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology), Hidenori Aiki(Japan Agency for Marine-Earth Science and Technology), Chair:Kensuke Nakajima(Department of Earth and Planetary Sciences,Flculty of Sciences,Kyushu University)

11:00 AM - 11:15 AM

[MIS22-08] A divergence-form wave-induced pressure for extending the Eliassen-Palm theory to all waves at all latitudes

*Hidenori AIKI1, Koutarou TAKAYA2, Richard Greatbatch3 (1.Japan Agency for Marine-Earth Science and Technology, 2.Kyoto Sangyou University, 3.GEOMAR / University of Kiel)

Keywords:inertia-gravity waves, mid-latitude Rossby waves, equatorial waves

Classical theory concerning the Eliassen-Palm relation is extended in this study to allow for a unified treatment of mid-latitude inertia-gravity waves (MIGWs), mid-latitude Rossby waves (MRWs), and equatorial waves (EQWs). A conservation equation for (what the authors call) the impulse-bolus (IB) pseudomomentum is useful because it is applicable to ageostrophic waves and the associated three-dimensional flux is parallel to the direction of the group velocity of MRWs. The equation has previously been derived in an isentropic coordinate system or a shallow water model. The authors make an explicit comparison of prognostic equations for the IB pseudomomentum vector and the classical energy-based (CE) pseudomomentum vector, assuming inviscid linear waves in a sufficiently- weak mean flow, to provide a basis for the former quantity to be used in an Eulerian time-mean (EM) framework. The authors investigate what makes the three-dimensional fluxes in the IB and CE pseudomomentum equations look in different directions. It is found that the two fluxes are linked by a gauge transformation, previously unmentioned, associated with a divergence-form wave-induced pressure (symbolized as À in the present study). The quantity À vanishes for MIGWs and becomes nonzero for MRWs and EQWs, and may be estimated using the virial theorem. Concerning the effect of waves on the mean flow, the quantity À represents an additional effect in the pressure gradient term of both (the three-dimensional versions of) the transformed EM momentum equations and the merged form of the EM momentum equations (the latter of which is associated with the nonacceleration theorem).

http://dx.doi.org/10.1175/JAS-D-14-0172.1