MIS22-01

Room:106

Time:May 27 09:00-09:15

An axisymmetric flow in a cylindrical tank with a rotating bottom: a confirmation of theory by experimental data
IGA, Keita1∗
1

AORI, The University of Tokyo

As a model for non-axisymmetric flows in the terrestrial and planetary atmospheres under axisymmetric circumstances, symmetric breaking of flows are realized by a very simple laboratory experiment where a cylindrical container is filled with waterand the disk at the bottom is rotated rapidly. We have been reported on the analytical solution of the axisymmetric flow obtainedusing boundary layer theories, which is necessary as a basic flow for the analysis of the symmetric breaking processes. This
theory can predict the parameters of the basic circular flows.
Similar theory was proposed by Tophøj et al. (2013), where they decide the basic axisymmetric flow under the condition thatthe angular momentum given from the rotating bottom disk should be balanced with that lost at the lateral boundary.
They estimated the momentum exchange with boundaries based on the assumption that it is proportional to the square of therelative velocity of the internal flow to the boundary.
We examined the data of the rotation rate of the regime transition and the change of the water depth which are obtained by thelaboratory experiments, and compared them with the present theory and that by Tophøj et al. (2013).
The comparison shows that present theory well predict the experimental results.
The assumption that the momentum exchange is proportional to the square of the velocity difference is considered to underestimate the momentum exchange at the lateral boundary and consequently to overestimate the flow speed of the rotating water.
Keywords: rotating flow, boundary layer, axisymmetric flow, laboratory experiment

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MIS22-02

Room:106

Time:May 27 09:15-09:30

Spontaneous rotation of a block ice melting on metal surface
TANAKA, Masashi1 ; HOHOKABE, Hirotaka1 ; YOSHIDA, Shigeo2 ; NAKAJIMA, Kensuke2∗
1

Department of Earth and Planetary Sciences, Graduate School of Sciences, Kyushu University, 2 Department of Earth andPlanetary Sciences, Faculty of Sciences, Kyushu University
We have discovered that a block ice placed on a flat surface of a warm brass column rotates without any external driving torque.
Air bubbles supplied to the ice-metal interface as ice melts are found to be essential to the spontaneous rotation. According toour observation, while the ice rotates, air bubbles almost remain stationary on the metal surface. Heat supplied at the bottom of
the ice block is also essential. The ice block cannot rotate when the temperature of metal column is low enough.
We carried out the experiments to examine the dependences of the rotation rate on several parameters, which are the heat flux,
the supply of air bubbles, the weight of ice, and the size of ice, under the setup with which the stability and the reproducibility
are established.
It is found that the angular velocity of the rotation is proportional to the 0.51th power of the temperature gradient in the brasscolumn and the minus 0.56th power of the size of the ice block. On the other hand, the air supply and the weight of the ice had
little effect on the angular velocity.
We have developed a scaling theory for the angular velocity assuming that the rotation is driven by the excess pressure of the
air bubbles in the water layer. Due to the difference between the thermal conductivities of water and air, the melting of ice justabove air bubbles is retarded, resulting in the growth of inverted ridges of ice. The pressure in the air bubble is higher than itin the water layer because of the surface tension. The excess pressure pushes the ridges, and the ice block rotates. The scaling
formula of the angular velocity, which is derived from the balance between the driving force and the viscous force on water ice
interface can explain many of the experimental results quantitatively.

Keywords: phase change, surface tension, heat conduction, self-propelled motion, bubble

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MIS22-03

Room:106

Time:May 27 09:30-09:45

Flow reversals under a magnetic field induced by horizontal circulation
YANAGISAWA, Takatoshi1∗ ; HAMANO, Yozo1 ; SAKURABA, Ataru2
1

JAMSTEC, 2 University of Tokyo

Coherent flow structures in the outer core are controlled by the magnetic field and rotation of the Earth. It is important to know
the basic behavior of flow in relation to the magnetic field, for understanding the flow patterns observed in the real Earth andcore dynamo simulations. On the other hand, spontaneous flow reversals generally observed in high Rayleigh number thermal
convections may provide clue to the mechanism of random geomagnetic field reversals. As the most basic setting to observe
the nature of flow structures with their time variations, we performed numerical simulations of Rayleigh-Benard convection ina three-dimensional square vessel by an electrically conductive low Prandtl number fluid, under a uniform horizontal magnetic
field. Computed behaviors are consistent with the result of laboratory experiment (Yanagisawa et al., 2013) that shows flow
reversals, and detailed process of reversals is clarified. The key mechanism is the emergence of a global circulation in thehorizontal plane and following reconnection between rolls. An increase of global circulation induces bend and reconnectionof convection rolls. It establishes a reversed flow state through roll number transitions. The horizontal circulation is related tothe skewed-varicose instability of two-dimensional roll structure aligned in the direction of the magnetic field. This is a newly
identified mechanism of flow reversal that works in large-scale three-dimensional geometry.
Keywords: flow reversal, horizontal circulation, low Prandlt number, magnetic field

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MIS22-04

Room:106

Time:May 27 09:45-10:00

Hopf bifurcations on convection rolls toward flow reversals in a liquid metal layer with ahorizontal magnetic field
TASAKA, Yuji1∗ ; YAMAGUCHI, Yudai1 ; FUJITA, Kodai1 ; YANAGISAWA, Takatoshi2 ; OISHI, Yoshihiko1 ;MURAI, Yuichi1
1

Faculty of Engineering, Hokkaido University, 2 JAMSTEC

Spontaneous flow reversals of convection rolls that were recently observed in experiments using a liquid metal layer in a box
under a horizontal magnetic field (Yanagisawa, et al ., 2011) have collected attentions related to geomagnetic polarity reversals.
If applying magnetic field is strong enough, convection disappears because of energy dissipation in Hartmann boundary layer on
the side wall of box. On the other hand, the convection in liquid metal layers that have extremely small Prandtl number easily
achieves thermal turbulence condition without applying magnetic field. In the intermediate cases of magnetic field, quasi-two
dimensional rolls aligned parallel to the magnetic field are formed and instabilities occur toward losing two-dimensionality withdecreasing the intensity of magnetic field. The flow reversals appear in this way to the thermal turbulence. Decreasing theintensity of magnetic field also produces decrease of the dominant number of convection rolls in the fluid layer. Yanagisawa,
et al . (2013) explained that the flow reversals consist of competition between two modes having different number of rolls andrelatively fast switching of flow direction is caused by Skewed-Varicose instability that was reported as one of instabilities on
two-dimensional rolls in general Rayleigh-Benard convection in shallow fluid layers. Including the instability having O (1 s) timescale, there are three different time scales, oscillation of convection rolls with O (10 s) and the flow reversals with O (100 s). And
we can assume that the flow reversals consist of three different mechanisms.
We performed detailed experimental investigations of process of transitions on convection rolls with decreasing the intensityof magnetic field from quasi-two dimensional rolls toward flow reversals. For rectangular box filled by liquid gallium with
200 mm ∗200 mm ∗40 mm in dimensions, ultrasonic velocity profiling (UVP) and thermistor probes were adopted to capture
spatio-temporal velocity profiles and time fluctuation of temperature. These information provide the number of rolls, magnitude
of velocity in the directions perpendicular or parallel to the magnetic field, dominant frequency of roll oscillation and intensityof temperature fluctuations. Summarizing the results elucidated that in the process of decreasing of magnetic field primary andsecondary Hopf bifurcations occur. The first bifurcation keeps two-dimensionality on the rolls and the second one provides
three-dimensional motion on the rolls. Fluid motions parallel to the magnetic field become considerable and corresponding flow
velocity takes from 4 to 5 mm/s. Traveling time of fluid particles in the fluid layer with this velocity scale is in O (100 s). We candeduce that the development of three-dimensional motion provides large scale, long time scale motion in the fluid layer triggering
SV instability for the flow reversals.

Keywords: Geomagnetic polarity reversals, Liquid metal flow, Thermal convection

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MIS22-05

Room:106

Time:May 27 10:00-10:15

A phenomenological model for convective cell size in a fluid layer with internal heatgeneration at low Rayleigh numbers
KUMAGAI, Ichiro1∗ ; ABE, Ryuta2 ; TASAKA, Yuji2 ; DAVAILLE, Anne3 ; MURAI, Yuichi2 ;YANAGISAWA, Takatoshi4
1School of Science and Engineering, Meisei University, 2 Faculty of Engineering, Hokkaido University, 3 Laboratoire FAST,
CNRS, Universite Pairs-Sud, 4 Department of Deep Earth Structure and Dynamics Research, JAMSTEC

The convective behavior of a fluid layer with internal heat generation at low Rayleigh number (6 ≤ RaI/RaIc ≤ 12) was
experimentally investigated. The horizontal fluid layer of 0.5 wt% KCl water solution was internally heated by Joule heating
using the electric current. We quantitatively measured 2-D temperature and velocity fields by seeding the micro-encapsulated
thermo-chromic liquid crystals in the fluid layer. We experimentally obtained the fluid dynamic scaling on non-dimensionaltemperature and the maximum downwelling velocity as a function of the Rayleigh number, and also refined the experimental
data obtained by the previous studies. The scaling relations were combined with a phenomenological model based on the stabilityof the top thermal boundary layer. This phenomenological model consistently explained the increase in convective wavelengthwith increasing the Rayleigh number.
Keywords: internal heat generation, natural convection, cell size, visualization, experiment, fluid mechanics

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MIS22-06

Room:106

Time:May 27 10:15-10:30

On solid state flow induced by Joule heating in the inner core of the Earth
TAKEHIRO, Shin-ichi1∗
1

Research Institute for Mathematical Sciences, Kyoto University

The elastic anisotropy of the earth’s inner core as revealed by recent seismic observations is considered to originate from thealignment of texture formed along the solidification of the core or alignment of the preferred orientation of crystals by plastic
deformation of fluid motions. The depth dependency of the anisotropy is difficult to explain by the solidification mechanism,
whereas the various factors driving fluid flows in the inner core considered thus far do not appear to yield sufficiently strong
stresses for generation of the elastic anisotropy. Takehiro (2011) proposed Joule heating of the magnetic field penetrating diffusively from the inner core boundary (ICB) as a possible source of inner core flows. His specific calculation in the case of toroidal
magnetic field with the horizontal structure of spherical harmonics Y2 0 showed that downward flow in the equatorial region andupward flows in the polar region are induced by the Joule heating. This flow field has non-zero radial velocity component at the
ICB, causing mass exchange between the inner and the outer core. This feature is a result of the constant normal stress boundary
condition at the ICB, and it is implicitly assumed that the phase change occurs instantaneously at the ICB. However, the actual
speed of the phase change is finite. If the speed of the phase change is slow enough, the ICB would be deformed and the surface
displacement is induced by the non-zero radial velocity at the ICB. This surface displacement may prevent inner core flows dueto the buoyancy force originated from the density contrast between the inner and the outer cores. Therefore, in this study, weinvestigate influence of surface displacement on fluid motions induced by horizontally heterogeneous Joule heating in the innercore. We examine the extent of development of the surface displacement and modification of flow field of the inner core.
The difference of the governing equations from those of Takehiro (2011) is the boundary conditions at the ICB. Temperature
disturbance at the ICB coincides with the melting temperature which varies depending on the surface displacement. The normalcomponent of stress equates with buoyancy induced by the surface displacement. The toroidal magnetic field and surface displacement with the horizontal structure of Y2 0 is given. The flow fields are calculated numerically for various amplitudes of thesurface displacement with the expected values of the parameters of the cores.
The results show that, when the surface displacement is the order of 0.006–0.06m or less, the flow and stress fields are similar
to those of Takehiro (2011), where the surface displacement vanishes. As the amplitude of the surface displacement is increased,
counter flows from the polar to the equatorial regions come to emerge around the ICB, while the flow in the inner regions is
directed from the equatorial to the polar regions in the inner region and non-zero radial component of velocity at the ICB still
exists. When the surface displacement is about 0.018–1.8m, radial component of velocity at the ICB vanishes, the surface counter
flows becomes stronger than the flow in the inner region, and the amplitude of the stress field near the ICB dominates that of theinner region, which might be inconsistent for the elastic anisotropy in the inner core. However, the mechanism proposed here
might play a important role in the past, possibly because heat flux through the core-mantle boundary was larger, yielding stronger
magnetic field in the outer core.
Reference: Takehiro, S., 2011: Phys. Earth Planet. Inter., 184, 134–142.

Keywords: anisotropy of the Earth’s inner core, magnetic fields in the Earth’s outer core, flows in the Earth’s outer core, innercore boundary of the Earth, dynamo action in the Earth’s outer core

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MIS22-07

Room:106

Time:May 27 10:30-10:45

Formation mechanism of the Moon and Earth’s Deep Ocean-floor and plate edge cracks,
with multi-impact hypo
TANEKO, Akira1∗
1

SEED SCIENCE Labo.

In Multi-Impact Hypothesis,we assume that Protoplanet CERRA(about Mars size),which was on the same revolution surface,deformed as potential energy universal at the near point side of Jupiter by perturbation of Jupiter.CERRA of asteroid Ceres
position at a meeting cycle of approximately every 275 years,and after several million years elliptical orbit was flattened so as tointersect the Jupiter’s orbit.The attraction of both Sun and Jupiter,CERRA is beyond its breaking strength just before collision,totear into multiple pieces.Since orbit CERRA during tidal destruction intersects the earth orbit,mantle pieces (about a monthsize)is the collision time difference more than once.In the first collision (about 1.5 month size),the formation of the Pacific Oceanof impact craters and the moon has occurred.By isostasy, mantle is about 4700m depth of the Pacific Ocean more than half of thesize of the deep ocean’s floor was formed.Giant impact of mantle debris with Darwin raised,along with scattered melting and lossof crust and mantle, deformation and mantle,including the eccentricity of the core,to the Earth radius RE :6400km, of depth:5km
depth of the seabed surface area status quo rate of about 70 percent,to there can be no chance in the formation.Mr. Wegener had
raised issue,but the origin of the deeep ocean-floor problem had been forgotten.
As a results of plate boundary cracks and formation as the formation of a concave depression and arc archipelago of plate,and
as a result start of subduction of the plate due to boundary stress of convex plate,the correction of the power of the unbalance ofrotation and inertia secondary moment(the minimum value) has pointed out as a driving force.Trajectory and the seamount due tothe hot spot of the Pacific Ocean,Distance and residual magnetization direction conversion of even rapid 60 degrees to the moving
direction is the same time due to the earth time pattern by from the mid-ocean ridge as the Ocean-floor spreading theory,Can not
be explained by the driving force of mantle convection theory.Even if the plume tectonics,why to convection and plume occurs
in that position,what has been formed in the way any boundary of the plate,what is now the driving force is generated in any
way,there are many problems which can not be sufficiently explained.Collision(:formation of kimberlite pipe to Mirunui positionis shown) of the Drake Passage position forming the Tethys(high latitudes) is generated the moment of tilting the earth’s axis
about 23.5 degrees and Moon’s orbit radius as 60∗RE .As a result of mantle missing of the Arctic Ocean position,Antarctica is
not moving after fits to the rotation pole.But Deccan Plateau and Australia have moved actively.Indian Ocean is formed,when the
Gondwana continent is divided, divided continent occurs large-scaale move to any direction.Not the time(about 4.6 billion yearsago) of magma ocean by accumulation of planetesimals.But the flattening of the elliptical orbit of up to 40 million years ago andcooling,Mantle and core has been fully differentiated,It was tidal disruption.Part of the core-mantle CERRA loses energy andangular momentum,became Mercury by changing the orbit the sun direction.
From the intersection of Earth orbit and the elliptical orbit,the relative speed at the time of collision is 12.4km/s and impact
angle is about 34.6 degrees and the moon’s orbit radius was calculated to be 60∗RE .Second-order space velocity of the Earth is a
11.2km/s, first-order space velocity is 7.9km/s.When describes the radius of the earth as RM ,in Multi-Impact Hypothesis, Moonis formed substantially of current position(about 60∗RM ). In Giant impact hypothesis,Moon is formed at a distance of
3∗RM ,it is a 1/20 position energy of the current moon.But there is no consideration of fee-dengue zone of impactor of Marssize,that impact velocity and direction of the realization probability is too good to be accidentally.
I propose The unified formation mechanism.

Keywords: Formation mechanism of moon and Earth’s Deep Seafloor, The plate edge crack formation, Multi-impact hypothesis,
Driving force of plate move, Large extinction of over and over again of organism species, Frequency curve showing a two-peak

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MIS22-07

Room:106

Time:May 27 10:30-10:45

2/2

MIS22-08

Room:106

Time:May 27 11:00-11:15

A divergence-form wave-induced pressure for extending the Eliassen-Palm theory to all
waves at all latitudes
AIKI, Hidenori1∗ ; TAKAYA, Koutarou2 ; GREATBATCH, Richard3
1

Japan Agency for Marine-Earth Science and Technology, 2 Kyoto Sangyou University, 3 GEOMAR / University of Kiel

Classical theory concerning the Eliassen-Palm relation is extended in this study to allow for a unified treatment of mid-latitudeinertia-gravity waves (MIGWs), mid-latitude Rossby waves (MRWs), and equatorial waves (EQWs). A conservation equationfor (what the authors call) the impulse-bolus (IB) pseudomomentum is useful because it is applicable to ageostrophic waves andthe 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 lookin different directions. It is found that the two fluxes are linked by a gauge transformation, previously unmentioned, associatedwith a divergence-form wave-induced pressure (symbolized as Λ in the present study). The quantity Λ vanishes for MIGWs andbecomes nonzero for MRWs and EQWs, and may be estimated using the virial theorem. Concerning the effect of waves on themean flow, the quantity Λ 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 associatedwith the nonacceleration theorem).
http://dx.doi.org/10.1175/JAS-D-14-0172.1
Keywords: inertia-gravity waves, mid-latitude Rossby waves, equatorial waves

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MIS22-09

Room:106

Time:May 27 11:15-11:30

Atlantic meridional overturning circulation in a variable-density, two-layer model: interaction with the Southern Ocean
Julian P. McCreary1 ; FURUE, Ryo2∗ ; SCHLOESSER, Fabian3 ; BURKHARDT, Theodore4 ; NONAKA, Masami2
1

IPRC, Univ. Hawaii, 2 JAMSTEC, 3 Univ. Rhode Island, 4 Temple Univ.

The flow of the North Atlantic Deep Water (NADW) forms a global overturning circulation, in which the water sinks in thenorthern North Atlantic to deep ocean, upwells in the Southern Ocean and elsewhere to the upper ocean, and returns to the North
Atlantic within the upper layer. This circulation can be described by a 1.5-layer model with the branch of the circulation after the
upwelling and before the sinking contained in the upper layer of the model. Because the connection between the Southern Oceanand each ocean basin is not well understood, however, the description of the circulation by a 1.5-layer model is not complete.
In this study, we examine the boundary layer between the Southern Ocean (where the domain is zonally cyclic) and an ocean
basin representing the Atlantic (where the Sverdrup dynamics determines the flow) in detail to derive the matching condition
between the two regions, thereby completing the 1.5-layer description of the NADW circulation. This enables us, for example,
to theoretically predict the dependence of the strength of the NADW circulation on winds in the Southern Ocean and on themesoscale-eddy-mixing coefficient.
The governing equations are-f V = -Px - ν U + τ x ,f U = -Py - ν V ,Ux + Vy = w e + w m .
where (U,V ) = (hu,hv ) is the ”residual” transport vector in the upper layer, P = g’ h 2 /2 is the integrated pressure, h is theupper-layer thickness, g’ = g (ρ 2 - ρ 1 )/ρ 2 is the reduced gravity, τ x is a zonal wind stress, and interior upwelling due to vertical
diffusion w m is prescribed. ”Vertical viscosity” ν is actually an expression of horizontal mass transport due to parameterized
mesoscale eddies and can be written as ν = κ GM f 2 /(g’/h ), using the GM thickness diffusivity. Traditionally, κ GM is often
assumed constant, but we assume ν to be constant for simplicity.
It is easy to obtain the interior solution within each of the Atlantic basin and the Southern Ocean (not shown), but these solutions do not match, requiring a zonal boundary layer. It can be shown that the boundary layer solution (total solution minus
interior solution) approximately obeys (ignoring the western boundary layer)-P”x = r P”yy ,where r = ν/β . This is a ”diffusion equation” where -x is analogous to time. In physical terms, this equation describes
how pressure anomaly associated with Rossby waves is spread meridionally by viscosity. This equation can be solved under
the cyclicity condition P” (x=0, y ) = P” (x=-L, y ) for y >y a and the eastern boundary condition P” (x=0, y ) = P e = const. fory <y a , and the matching condition that the total pressure and its y derivative must be continuous across y = y a , where ya is thelatitude of the southern tip of South America. The solution (not shown) determines one of the unknown constants of integrationof the interior solutions, thereby closing the problem.

Keywords: analytic model, viscosity, eddy induced transport, wind stress, Ekman transport

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MIS22-09

Room:106

Time:May 27 11:15-11:30

2/2

MIS22-10

Room:106

Time:May 27 11:30-11:45

Snowfall on the South Kanto region under winter pressure pattern, and by south-coast
cyclones
ARAMAKI, Kento1∗ ; IGA, Keita11

Atmosphere and Ocean Research Institute, the University of Tokyo

Snowfall on the south Kanto is generally caused by synoptic-scale extratropical cyclones which pass along the southern coastof Honshu Island (so-called south-coast cyclones). However, the south Kanto on Jan. 23, 2012 experienced a heavy snowfall
without such type of cyclones, under a synoptic-scale circumstance regarded as the winter pressure pattern (Hara, 2012). With
regard to such winter pressure pattern snowfall on the south Kanto, Yamamoto (1984) reported a case in Feb. 8, 1984 and implied that it might have been associated with the lower layer convergence line caused by winter monsoon which bypasses themountains of central Honshu.
In this study, the heavy snowfall on Jan. 23, 2012 was analyzed using the data of JMA Meso-scale Analysis. According to
the analysis, in the synoptic scale, JPCZ (Japan sea Polar air mass Convergence Zone) was formed in the western Japan sea,
and another convergence zone in the Pacific side of Honshu Island. In the latter convergence zone, a meso-scale convergenceline extending to the southeast from the vicinity of the Suruga Bay located on the southwest side of the Kanto was remarkable.
Environmental profile near the convergence line was unstable due to the cold air in the upper layer and the warm moist air flowing
into the line so that relatively deep convections easily occur. In the vicinity of Kanto, northeast wind in the lower layer toward theconvergence line and southwest wind in the middle upper layer in front of the trough were blowing, which made notable vertical
shear of horizontal wind. It is believed that convections which occurred along the convergence line were advected by southwest
wind in the middle upper layer toward the south Kanto located downwind, and brought snowfall there.
The vertical structure of the equivalent potential temperature in the vicinity of the Kanto were compared between the heavy
snowfall on Jan. 23, 2012 and a typical case of the south-coast cyclones on Feb. 8, 2014. The equivalent potential temperature
difference in the vertical direction was small (weak stratification) on Jan. 23, and large (strong stratification) on Feb. 8. Basedon this result, 46 heavy snowfall events in Tokyo or Yokohama in the past 30 years were analyzed in respect to the verticalstructure of the equivalent potential temperature in the vicinity of Kanto using the data of JRA-55, and as a result, 4 out of 46(8.7%) were extracted as the cases whose stratification were as weak or weaker than that of Jan. 23, 2012, and 42 out of 46(91.3%) as the cases of stronger stratification. 86 snowfall days (no distinction between heavy and light) in Tokyo in the past 10
years were analyzed using the same technique, and as a result, 29 out of 86 (33.7%) were extracted as the cases of the “weak”
stratification, and 57 out of 86 (66.3%) as the cases of “strong” . In comparison with the contribution in the heavy snow cases, thecontribution of “weak” stratification is relatively large in the snowfall days. Although only the information of precipitation andequivalent potential temperature were used in the classification, the features of the composites of the cases classified as “weakstratification” show the winter pressure pattern which resembles that of the case of heavy snowfall on Jan. 23, 2012, and those as“strong” show the south-coast cyclone pressure pattern which brings heavy snowfall on the south Kanto; it shows the validity of
the classification. Through this analysis south-coast cyclones are confirmed to be the major factor in the south Kanto snowfall,
while it is elucidated that the event on Jan. 23, 2012 was not the sole case of heavy snowfall under winter pressure pattern.
Keywords: snowfall on the South Kanto region, winter pressure pattern, south-coast cyclones, low level convergence, stratification

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MIS22-11

Room:106

Time:May 27 11:45-12:00

Dynamic energy efficiency of tropical cyclones with long-lived concentric eyewall in numerical simulation
TSUJINO, Satoki1∗ ; TSUBOKI, Kazuhisa1 ; KUO, Hung-chi2
1

HyARC, Nagoya University, 2 Department of Atmospheric Sciences, NTU”Eyewall” is a ring of convective clouds that encircles the eye of a tropical cyclone (TC) such as typhoon and hurricane. Multiple eyewalls, named ”concentric eyewall”, are observed in some TCs, and ”eyewall replacement cycle” is also observed after theformation of concentric eyewall. In the process of an eyewall replacement, the inner eyewall gradually disappears while then theouter eyewall moves towards the TC center in closing to the previous inner eyewall. During the period of a replacement cycle,
the TC intensity changes drastically. 24 percentages of TCs with concentric eyewalls maintained in a long time (over 20 hours)in satellite observations (Yang et al., 2013). The result suggests that a TC with concentric eyewall does not always undergo
the replacement cycle. There are very few studies of long-lived concentric eyewall. Moreover the maintenance mechanism of
long-lived concentric eyewall is also not clear.
To understand the maintaining mechanism of concentric eyewall, we employ dynamic energy efficiency in considering thechange of kinetic energy (KE) and available potential energy (APE) due to the internal dynamics of a TC. We focus on a parameter of dynamic energy efficiency, which is proposed as an index of conversion efficiency of potential energy to KE. In
this study, dynamic energy efficiency of idealized TCs with replaced and long-lived concentric eyewall, and then, real typhoon
Bolaven (2012) with long-lived concentric eyewall was investigated, using numerical simulation results which were performed
by Tsujino and Tsuboki (2013, 2014). TC simulation data in this study were supported by an atmospheric numerical model of athree-dimensional, non-hydrostatic and full-physics, which is called by CReSS (Cloud Resolving Storm Simulator; Tsuboki and
Sakakibara, 2007).
The formula for the dynamic energy efficiency of heat and of momentum in balanced vortex, whose the primary circulation
is gradient wind balance, and the secondary circulation is induced due to convective heating and surface friction, was derived
by Kuo et al. (2013). The dynamic energy efficiency of heat and of momentum is determined by the solution of the Eliassentransverse circulation equation with the radial temperature gradient instead of the radial heating gradient. They showed thatdynamic energy efficiency enables to explain intensity change of TC through diabatic heating and friction with analytical profile
of idealized TCs. The dynamic energy efficiency of an idealized TC with replaced concentric eyewall was increasing drasticallyduring the replacement cycle, and the value of dynamic energy efficiency had maximum when inner eyewall dissipated. Low(high) dynamic energy efficiency indicates that conversion of APE to KE is inefficient (efficient) for TC’s intensification. The
tendency of dynamic energy efficiency of TC with replaced concentric eyewall was consistent with the TC’s intensity change
during the replacement cycle. On the other hand, the dynamic energy efficiency of the idealized TC with long-lived concentriceyewall did not increase apparently after the outer eyewall formed. The result suggests that the conversion of APE to KE in theouter eyewall does not control much the TC intensity change. The tendency of dynamic energy efficiency resembled that of atypical TC with single eyewall which was shown by Kuo et al. (2013). Moreover, in typhoon Bolaven (2012), the tendency ofdynamic energy efficiency also resembled that of the idealized TC with long-lived concentric eyewall. These results imply thatthe dynamic energy efficiency of TCs with long-lived concentric eyewall may describe one of the universal characters of a TC
development process.

Keywords: Eliassen transverse circulation, concentric eyewall, tropical cyclone

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MIS22-12

Room:106

Time:May 27 12:00-12:15

Optimal excitation of asymmetric perturbations on an axisymmetric barotropic vortex
with piecewise constant vorticity
ITANO, Toshihisa1∗
1

Dept. Earth & Ocean Sciences, National Defense Academy

Regarding the hierarchal structure seen in natural and artificial vortices, where the multiple secondary vortices revolve aroundthe core of their parent vortex, a linear singular value problem is formulated and solved analytically based on the axisymmetric barotropic vortex consisting of three piecewise constant vorticity regions: i.e. from the non-divergent barotropic vorticity
equation linearized around the basic tangential flow with three regions of piecewise constant vorticity, the simultaneous ordinary
differential equation on the vector, whose components are the amplitude of the Rossby waves evoked by the vorticity discontinuity of the basic flow. This equation is solved as an initial value problem, and the resultant resolvent matrix is applied to obtainthe singular values and the corresponding forward and backward singular vectors under the L2 norm.
The results can be categorized into the two kinds based on the shape of the basic vortex. For Michalke & Timme’s vortex
characterized by a ring of high vorticity, the forward and backward singular vectors and the growing eigenvector are rather
similar in shape with each other. On the contrary, for Syono’s vortex incorporating a negative vorticity region surrounding thepositive vorticity core, the shape of the forward singular vector is quite different from that of the backward singular vector andthe growing eigenvector. Some results in the case adopting energy norm are also introduced.

Keywords: optimal excitation, singular value, singular vector, barotropic vortex, multiple vortex

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MIS22-13

Room:106

Time:May 27 12:15-12:30

Development of a general circulation model for planetary atmospheres: Single column
model experiments
TAKAHASHI, Yoshiyuki O.1∗ ; OGIHARA, Hirotaka2 ; NISHIZAWA, Seiya3 ; HARA, Tabito4 ;ISHIWATARI, Masaki2 ; HAYASHI, Yoshi-yuki1
1

Department of Earth and Planetary Sciences, Kobe University, 2 Department of Cosmosciences, Hokkaido University, 3 RIKEN
Advanced Institute for Computational Science, 4 Japan Meteorological Agency
We have been developing a general circulation model for planetary atmospheres, DCPAM (http://www.gfd-dennou.org/library/dcpam/),to investigate various structures of atmospheric general circulation and surface environments of planets in our solar system andexoplanets. In this talk, some single column model (SCM) experiments by use of the DCPAM are reported. These SCM experiments are useful to check implementation of the parameterizations and to investigate its nature. On the other hand, it is also
useful to investigate how a parameterization based on the Earth’s atmosphere observations behaves under planetary atmosphericconditions. This study is performed as a part of developing a common physical process library in partnership with groups in
RIKEN AICS and Japan Meteorological Agency.
The DCPAM is a general circulation model for planetary atmospheres which some members of GFD Dennou Club have beendeveloping. The model is composed of spectral dynamics based on primitive equation system and physical processes of radiation, turbulence, condensation, cloud process, and surface processes. Further, this model is designed to be used for axisymmetrictwo-dimensional and vertical one-dimensional experiments with almost no code modifications.
In this study, four kinds of SCM experiments to check parameterizations implemented in the DCPAM: (1) ICRCCM (InterComparison of Radiation Codes in Climate Models; Ellingson et al., 1991) experiment, (2) GABLS2 (GEWEX Atmospheric
Boundary Layer Study 2; Svensson et al., 2011) experiment, (3) TWP-ICE (Tropical Warm Pool International Cloud Experiment)
experiment (Davies et al., 2013), (4) Mars atmosphere boundary layer experiment. Below, experiments 3 and 4 are describedbriefly.
In TWP-ICE experiments, atmospheric structure formed by radiation, turbulence, and condensation under an observationbased forcing is investigated. In our TWP-ICE experiment, relaxed Arakawa-Schubert scheme (Moorthi and Suarez, 1992),
non-convective condensation by Le Treut and Li (1991), and turbulence by Mellor and Yamada (1982) level 2.5 are used. Experimental results show that temporal variation of precipitation is roughly consistent with other SCM results (Davies et al., 2013).
However, relative humidity in DCPAM is lower than those in other SCMs in lower troposphere. We will examine what causes
this difference between our and other SCMs.
In Mars atmosphere boundary layer experiments, structure of Martian atmospheric boundary layer formed by radiation, turbulence, and surface processes under a prescribed large scale pressure gradient is investigated. We use turbulence scheme of Mellor
and Yamada (1982) level 2.5 in this experiment. The boundary layer height and its diurnal variation represented by the model areroughly consistent with those of previous studies with two- or three- dimensional convection resolving model simulations (e.g.,
Odaka, 2001). For example, top of the boundary layer on Mars is located about 5 km with a typical atmospheric dust condition.
In future, we will use the SCM experiments as fundamental experiments for other planetary atmospheres.
Keywords: planetary atmosphere, general circulation model, Earth, Mars, Single column model

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