High resolution
LES experiment
on Marian PBL
Nishizawa, S., H. Yashiro, M. Odaka,
Y. O. Takahashi, S. Takehiro, M. Ishiwatari,
K. Nakajima, Y. Sato, K. Sugiyama, H. Tomita,and Y.-Y. Hayashi

Introduction• Martian planetary boundary layero Well mixed atmospheric layer near the surface (result ofheating by solar radiation)• Strong convection and turbulenceo Exchange heat and materials between the ground andatmosphereo Lift dust (dust storm)

http://marsrovers.jpl.nasa.gov/gallery/press/spirit/20050527a.html

http://science1.nasa.gov/science-news/science-at-nasa/2001/ast11oct_2/

Introduction (Cont.)• Purpose of this studyo To understand• Turbulent statistics• Character of dust devil

Smaller scale variability at lower layer
High resolution simulation is necessaryModel• SCALE-LES
o An LES model developed by RIKEN AICSo Fully compressive equationso Open software (http://scale.aics.riken.jp/)• Schemes used in this study
o Dynamics: full explicit (HE-VE), 3-step RK
o SGS turbulence: Smagorinsky typeo Surface flux: Louis type

Experimental configurations• Experimental configurations
oooooDomain: 19.2km x 19.2km x 21km
Lateral boundaries: double periodic
Bottom boundary: flat (no topography), uniform roughness
Moist processes: dry condition
Radiation, surface temperature: external radiative heating rate andsurface temperature obtained by a vertical 1D model experiment(Odaka et al. 2001)• Experimental parametero Spatial resolution• Δxyz: 100, 50, 25, 10, 5 m (isotropic grid)• Initial conditiono Vertical temperature profile (Odaka et al. 2001) + small random
perturbations, steady stateo For the 5m run, state at 14:00LT of the 10m run is used as the initialcondition• Temporal integrationo 1 day integration from 00:00 LT (1 hour integration for the 5m run)• Analyses are done using 14:30LT data

Vertical velocity
distribution

Dependency on resolution (z=200m)
100m run

50m run

10m run

5m run25m run1/16 domain
14:30LT2.5m height

200m height

Dependency on height (5m run)

red: upflow, blue: downflow• Narrow and strong upward flow
• Finer structure at lower level

1/16 domain
14:30LTFrequency distribution
200 m height

2 km height5m run 10m run 25m run 50m run 100m run

Maximum instantaneous vertical wind
2 km height

Upward wind

Downward windresolution

Turbulent statistics

Vertical profiles

Δxyz=100m,50m,25m,10m,5m

Energy spectrum

z=2km, Δxyz=100m,50m,25m,10m,5m

vortex

Pressure distribution

tau=0.2, Δxyz=25m, z=12.5m, t=14:00

tau=0.2, Δxyz=25m, y=20km, t=14:00

Vertical vorticity (z=200m)
100m run

50m run

10m run

5m run25m run1/16 domain
color scale is different

200 m hight

2.5 m heightVertical vorticity (5m run)Vertical velocity(2.5 m height)• Represent localized strong vortices• Hundreds m height• Larger vorticity at lower level• Located at upflow region

Frequency distribution
Number frequency distribution of isolated vortices

number100m height5m run2.5m height5m run

50m run

100m run

25m run

10m runMaximum vorticity

A logarithmic law can be seen

Maximum vorticity

Assuming the Rankine’s vortex(5mrun, 2.5m height)
Maximum wind speedRadius

Summary• 20km domain PBL experiment withseveral resolutionso Fine structure at lower level is represented with such highresolution simulationo Strong vortices are reasonably represented• A logarithmic law of intensity, maximum speed, andradius of vortices are found• 以下予備の図Introduction 1• 火星とは
o 軌道長半径: 約 1.5AU
o 公転周期 : 約 1.88地球年
o 自転周期 : 約 1.026地球日
o 赤道半径 : 約 3396km
o 大気組成 : 二酸化炭素 約95%
o 地表大気圧: 約 7hPa
o 地表温度 : 130-300K© NASA, ESA, the Hubble Heritage TeamPotential temperature
tau=0.2, Δxyz=25m, y=010 km

5 km

Dependency on resolution (z=2km)
100m run

50m run

10m run

5m run25m run14:30LT

鉛直速度 高度500m 解像度依存性
100m実験

50m実験

10m実験

5m実験

25m実験

渦度 500m 解像度依存性
100m実験

50m実験

10m実験

5m実験

25m実験

1/16領域
色階調が異なっていることに注意

鉛直速度 最下層 解像度依存性
100m実験 (高度50m)

50m実験 (高度25m)

10m実験 (高度5m)

5m実験 (高度2.5m)

25m実験 (高度12.5m)

1/16領域
14:30LT（初期値から14.5h後）

渦度 解像度依存性 (最下層)100m実験 (高度50m)

50m実験 (高度25m)

10m実験 (高度 5m)

5m実験 (高度2.5m)

25m実験 (高度12.5m)

1/16領域
色階調が異なっていることに注意

計算概要• 火星大気の境界層の高解像度ラージエディー
シミュレーション(LES)o 使用モデル: 理研AICSソフトウェア “SCALE-LES”• 構造格子 有限体積法• 完全陽解法 ３段RK(大域通信の必要無し)
o 最大問題規模: 約500億格子• 計算諸情報o 使用計算機: 京o 演算実効効率: 7.9% (5m解像度計算時)
100m実験

50m実験

25m実験

10m実験

5m実験

積分時間

24時間 x 3

24時間 x 3

24時間 x 3

19時間

1時間

Δt

0.12 s

0.06 s0.03 s

0.012 s0.006 s

時間ステップ数

720K x 3

1.4M x 3

2.9M x 3

5.7 M

600K

格子数6.8M

52M

410M

6.3G

49G

使用コア数

96

1,152

18,432

115,200

57,600Elapse time

100 h

100 h

100 h

200 h

200 h