GFD オンラインセミナー (第 20 回)

日時: 2025 年 3 月 7 日 (金) 15:00--16:30

場所: zoom / 京大数理研本館 110 号室

講演者: Prof. Julian Mak
       (Associate Professor of Department of Ocean Science,
        Hong Kong University of Science and Technology,
	and Senior NOC fellow at the UK National Oceanography Center)

講演タイトル: Baroclinic turbulence in the presence of slopes

講演要旨:

Baroclinic dynamics refers to dynamics of rapidly rotating and stratified
fluid systems, of relevance for example to geophysical systems such as the
atmosphere or the ocean. The classical theory often neglect the constraints
imposed by the bottom topography, but baroclinic dynamics and the subsequent
turbulent characteristics in the presence of slopes is of particular
relevance, for example, to the accurate modelling of ocean flows, which has
implications for predictions of marine ecosystems and climate. 

The presentation here presents two rather different pieces of work towards
understanding baroclinic dynamics in the presence of slopes. The first focuses
on the issue of parameterisation using numerical simulations with ocean
general circulation models. We first introduce an established framework for
studying eddy-mean interaction called GEOMETRIC, which phrases eddy flux
characteristics in terms of geometric quantities such as angles, eccentricity
and anisotropy. Some results relating to GEOMETRIC and ocean modelling are
presented, focusing on the empirical work towards how standard scalings
derived from GEOMETRIC in terms of a measure of efficiency is modified to
include the influence of bottom topography on the resulting eddy-mean
interactions. The second part revisits the standard Eady problem for
baroclinic instability to take into account of the presence of a bottom
slopes, and is largely analytical. We provide a possible explanation for the
observed decreased efficiency in the presence of slopes, framed in terms of
the instability characteristics and in the GEOMETRIC framework. We provide an
internally consistent mechanistic picture for the reduction in efficiency that
is valid over the instability parameter space. Further mathematical properties
of the Eady problem in terms of the underlying symmetries and further research
directions are discussed.


開催方法: 対面 + zoom のハイブリッド形式

トピック: 第２０回 GFD オンラインセミナー
時刻: 2025年3月7日 03:00 PM 大阪、札幌、東京
Zoom ミーティングに参加する
https://kyoto-u-edu.zoom.us/j/99185353448?pwd=Stf3KaLa052GTuNUA5cFo01UfaHEus.1

ミーティング ID: 991 8535 3448
パスコード: 727572