The First International Workshop on Prevention and
Palace Side Hotel, Kyoto, Japan
Mitigation of Meteorological Disasters in Southeast Asia March 3 - 5, 2008
Simulation Experiments of Typhoons
and Tornadoes Using
the Cloud-Resolving Model
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Introduction
Cloud Resolving Strom Simulator (CReSS)
Numerical experiment of Toyohashi tornado
Simulations of Typhoon 0613 and tornado
Summary
Kazuhisa Tsuboki
Hydrospheric Atmospheric Research Center (HyARC),
Nagoya University
Introduction
‹ Tornadoes and waterspouts are a violently rotating air below a
convective cloud. Both are called “tatsumaki” in Japanese.
‹ About 20 % of tatsumakis occur in association with typhoons
in Japan. More than 60 % in the western Japan in warm
season.
‹ Even through a typhoon center is located in the distance, a
tatsumaki occasionally causes a severe disaster due to wind.
‹ For simulation of convective clouds and storms, we have been
developing a cloud resolving model named “CReSS” (the
Cloud Resolving Storm Simulator).
‹ Intense tatsumakis occurred in Toyohashi City on September
24, 1999 and in Nobeoka City on September 17, 2006.
‹ Using the CReSS model, we studied supercell storms and
tatsumakis in association with typhoons.
Characteristics of the CReSS model
‹CReSS is formulated on the basis of the nonhydrostatic and compressible equation system.
‹Coordinate system is a terrain-following in a two or
three dimensional domain.
‹Finite difference method is used for the spatial
representation.
‹Ground model and surface processes is implemented.
‹Conformal Map projections are available.
‹The CReSS model is optimized for parallel computers
to perform large computations as well as a single
processor (parallel and serial versions).
‹Parallel processing is performed by the Message
Passing Interface (MPI) and OpenMP.
Diagram of cloud micro-physical processes in CReSS
Typhoon simulation with Δx=1km :T0418
Typhoon simulation with Δx=1km :T0418
Snow storm over the Great Lakes in North America
grid size: Δx=500m
Snow storm over the Great Lakes in North America
grid size: Δx=500m
Heavy rainfall associated with Baiu front: Niigata heavy rain
CReSS simulation
Radar observation
Rainfall intensity (mm/hr)
Rain by Typhoon
Bars:Observation
Solid line: CReSS
Dashed line: RSM
Time (UTC)
grid size: Δx=1km
7 days simulation of T0418
Tiling extension
function of CReSS
ver.3
Precipitation rate
(mm/hr) at 5 days
from initial time.
Red line: JMA best
track of Typhoon 18.
Black line: CReSS
simulation result.
Typhoons and tornadoes (tatsumakis)
ーTornado with Typhoon 9918,
September 24, 1999 in Toyohashi Cityー
ーTornado with Typhoon 0613,
September 17, 2006 in Nobeoka Cityー
11JST, 24 September 1999; T9918
Cloud images (IR)
14JST, 17 September 2006; T0613
ーTornado with Typhoon 9918,
September 24, 1999 in Toyohashi Cityー
24 September 1999, Toyohash (from Yomiuri Shinbun )
Doppler radar observation of the supercell
PPI of Doppler velocity
theta
U-wind
V-wind
theta_e
Experimental design of Toyohashi tornado
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domain
horizontal grid size
vertical grid size
grid numbers
integration time
time increment
microphysics
initial condition
` initial disturbance
` boundary condition
` platform
48km × 48km × 12km
75m
25 ～ 200m
603 × 603 × 63
4 hours
large: 0.5s, small: 0.1s
the bulk cold rain type
Shionomisaki sounding data at
09JST, 24 September 1999.
warm bubble
the wave-radiating type
HITACH SR8000, 8nodes
Vorticity (/s)
Pressure perturbation (hPa)
ーTornado with Typhoon 0613,
on September 17, 2006 in Nobeoka Cityー
Rainbands of T0613
JMA radar
14JST, 17 Sept.
Nobeoka
CReSS Experimental Design
Exp.500m
Objectives convective clouds
Resolution 500m
Domain
896 km ×896 km
Grid number x:1795, y:1795, z:67
Integration 6 hours
Initial value JMA-RSM(40km)
Boundary
JMA-RSM(40km)
Cloud phyc. cold rain
Plat form
the Earth Simulator
128nodes(1024CPU)
Exp.75m
torunadoes
75m
rainband area
x:1795, y:2435, z:67
1.5 hours
CReSS 500m
CReSS 500m
cold rain
the Earth Simulator
128nodes (1024CPU)
Experimental Design of Typhoon T0613
` Domain
H: 896 km × 896 km × V: 20 km
` H-gird size
500 m
` V-grid size
100 ~ 320 m (stretched)
` Grid numbers
H: 1795 × 1795× V: 67
` Integration time
6 hours
` Time increment
large: 2 sec, small: 0.5 sec
` Micro-physics
the bulk cold rain type
` Initial condition
JMA Regional Spectral model (40km)
` Boundary
JMA Regional Spectral model (40km)
` Surface
real topography and observed SST
` ES node number
128 nodes (1024 CPU)
3 rainbands formed
CReSS500m
Velocity and rain
mixing ratio (shadings)
at a height of 1.9km.
How do we find supercells in
such many convective clouds ?
Identification of supercells
¾ Convective cells are explicitly simulated in the
experiment with a horizontal resolution of 500m.
¾ A supercell is defined as “a convective cell with a
vorticity larger than 0.01 /s within an upward motion”.
¾ We identify a convective cloud as supercell in the
simulation using the following index.
¾ SCI(Supre Cell Index)：above the cloud base ( at a
height of 2～4km)
⎛ ∂v ∂u ⎞
SCI = ⎜⎜ − ⎟⎟ ⋅ w
⎝ ∂x ∂y ⎠
A convective cloud with SCI > 0.1 is super cell.
Velocity vectors, rain
mixing ratio (shadings)
and SCI (contours)
at 1.9 km in height.
The east
coast of
Kyushu
The outer rainband is composed of supercells.
Toyohashi Supercell
Supercell and tornado in T0613
` Domain
H: 60 km × 60 km × V: ～20 km
` H-gird size
75 m
` V-grid size
40 ~ 300 m (stretched)
` Grid numbers
H: 803 × 803× V: 67
` Integration time
6 hours
` Time increment
large: 0.5 sec, small: 0.1 sec
` Micro-physics
the bulk cold rain type
` Initial condition
CReSS 500m simulation output
` Boundary
CReSS 500m simulation output
` Surface
real topography and observed SST
` Computer
HITACHI SR11000 (4nodes)
Vorticity (contour) and rain (color)
central vorticity: 0.9/s
1000m
vorticity (contour) and pressure (color)
pressure perturbation：27hPa
1000m
vorticity (contour) and speed (color)
maximum speed: 70m/s
1000m
vorticity (contour) and vertical velocity (color)
1000m
Vorticity (contour) and rain mixing ratio (color)
1000m
vorticity (contour) and pressure perturbation (color)
1000m
hPa
vorticity (contour) and speed (color)
1000m
m/s
vorticity (contour) and vertical velocity (color)
1000m
m/s
Domain of 75m-resol.
CReSS Exp-75m
Rainfall intensity
East coast
of Kyushu
How are tornadoes found in the domain?
Index to find tatsumakis
¾ The definition of tatsumaki (tornadoes and
waterspouts) is a violently rotating air column below a
convective.
¾ We define a tatsumaki more strictly to distinguish it in
a model output as “rotating air in a dynamic balance
between pressure gradient force and centrifugal force
(the cyclostrophic balance) in a high accuracy.”
¾ Tatsumaki Index (TI) is defined as follows in the lower
atmosphere.
⎛ ∂v ∂u ⎞
TI = ⎜⎜ − ⎟⎟ ⋅ p '
⎝ ∂x ∂y ⎠
Vortex with TI <-1 is distinguish as tatsumaki.
CReSS Exp-75m
rainfall intensity (shading)
TI(contour)
1000m
CReSS75m
rainfall intensity (shading)
TI(contour)
1000m
Result of Exp-75m
Rainfall intensify
Many tornadoes occur along the outer rainband.
Summary
‹ Typhoons occasionally accompany tornadoes (tatsumakis in
Japnese) and cause disasters due to strong winds.
‹ CReSS simulated the tornado within the supercell with the
uniformly fine grid (75m) in the large domain.
‹ The simulation shows that successive formation of tornado
vortices within the maximum updraft of the supercell.
‹ When the typhoon 0613 approached the western Japan on
September 17, 2006, it accompanied a severe tornado. It
killed three people and caused a train accident.
‹ In the experiment with a resolutoin of 500m, 3 rainbands
were simulated on the east side of Typhoon 0613. They are
composed of supercells.
‹ The high resolution (75m) simulation showed that one of the
supercells spouted an intense tornado. The detailed
structure of the tornado was successfully simulated.
‹ Simulation of tornado in the large domain showed that
many tornadoes occur along the outer rainband.
Thank you !!
The CReSS model (Ver.2.3) is free for
scientific researches. If you are interested in
CReSS, Please contact with me (K. Tsuboki).
(HyARC, Nagoya University)