Development of a self BGM method with the JMANHM

科研費研究「豪雨の力学的予測のための初期値解析と予測信頼性の評価に関する研究」平成 18 年度第２回研究打合せ会　 2007/3/19 　気象研究所予報研究部輪講室

• Introduction (Downscale EPS experiment)

• Supplement of the downscale ensemble experiment of JMA one week global EPS

• Self BGM method with the JMANHM

• Future subjects

Kazuo Saito (MRI)

Heavy rainfall occurred on 13 July 2004 in the southern part of Northern Japan.

3 hour accumulated precipitation on 13 July 2004. Left ） 00 UTC, Center ） 03 UTC, Right ） 06 UTC

OBS.

MSM, 12UTC 12 July

FT=12-18

Downscale experiments

One week Global EPS at JMA Mar. 2001 ～ 12UTC initial, T106 (1.125deg) L40 25members (Mar. 2006 ～ 51members ) BGM method (12modes, 12 hour cycle ）

JMA-NHM (Saito et al., 2006; M.W.R., vol. 134, 1266-1298) 10km L40, 3600×2880km, H=22km (operation: x=5 km L50 Mar. 2006- ） Same specification as in the operation before Mar. 2006　　 Kain-Fritsch scheme, bulk cloud physics, lateral sponge layers 24 grids　a) Simple downscale experimentInitial ： Global EPS LBC ： Global EPS, updated 6 hourly

b) Incremental downscale experimentInitial ： Meso 4D-Var analysis + normalized perturbations by Global EPS LBC ： RSM forecast, updated 3 hourly

Breeding cycleBreeding cycleBreeding cycleBreeding cycle00UTC

12UTC

00UTC

コントロールラン

摂動ラン

用摂動ｻｲｸﾙ( １２時間予報 )

摂動

成長した誤差

北半球域500hPa 高度場で

規格化( 気候的変動の 14.5% 、

湿度は 21%)

予報用摂動成長した誤差

求まる１２摂動に対し直交化を行い、

規格化する

12 cycles

Breeding cycle

全層南緯 20 度以北の領域で、高度

（地表では気圧）、風、気温、比湿が成分

解析誤差の空間分布を考慮した

規格化

Breeding cycle of the one-week EPS at JMA

One-week EPS at JMA

Mar. 2001- Mar. 2006 12UTC initial 25members, T106 (1.125deg) L40 BGM method (12modes, 12 hour cycle ）

摂動作成方法：①12 時間の摂動ラン②予報誤差を北半球で求め、 500hPa 高度場振幅が気候値　変動の 10 ％になるように係数を決め、誤差成長を規格化 *　 ③上記を 00,12 ＵＴＣに行って Breeding　 12 ＵＴＣに摂動の直交化 ( 直交化係数 0.75)④アンサンブル予報用摂動は、直交化を行わず、　 500hPa 高度場振幅が気候値変動の 15 ％になるように規格化 * 、　海陸での解析誤差の違いを考慮し、低波数パターンンの　 0.7 ～ 1.0 の重み分布をかける

＊ QV については、 Breeding 、予報用摂動ともに５割増にインフレーション　（熱帯域の成長率を高めるため）

（ Kyouda, 2000)

Member M03p

Control

Forecast of JMA one week Global EPSInitial time 12UTC 12 July, 2004. 6 hour accumulated precipitation

Member M03p

Moderate precipitation in the southern part of Northern Japan at FT=12-18.

Left ） FT=00-06Right ） FT=12-18

（ Color shades: 1,5,10 mm ）

Control (M00)

Downscale experiments

One week Global EPS at JMA Mar. 2001 ～ 12UTC initial, T106 (1.125deg) L40 25members (Mar. 2006 ～ 51members ) BGM method (12modes, 12 hour cycle ）

JMA-NHM (Saito et al., 2006; M.W.R., vol. 134, 1266-1298) 10km L40, 3600×2880km, H=22km (operation: x=5 km L50 Mar. 2006- ） Same specification as in the operation before Mar. 2006　　 Kain-Fritsch scheme, bulk cloud physics, lateral sponge layers 24 grids　a) Simple downscale experimentInitial ： Global EPS LBC ： Global EPS, updated 6 hourly

b) Incremental downscale experimentInitial ： Meso 4D-Var analysis + normalized perturbations by Global EPS LBC ： RSM forecast, updated 3 hourly

Back ground error for Meso 4D-Var ：PS: 0.7 hPaU,V: about 2 m/s in lower troposphere about 3.5 m/s around jet streamT: about 0.8K in lower troposphere about 1K in upper troposphereRH: about 10 % in lower troposphere about 15 % in upper troposphere

80 % of background error was used as the rough estimation of the analysis error

Vertical error covariance obtained by NMC method in Meso 4D-Var

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NMC分散NMC誤差QV 10%層平均QV 15%層平均RH*10%RH*1 %５M03pM01p採用

PS: 0.6 hPaU, V: 1.8 m/s*(Kg/m3)

: 0.7 KQv: 12% of RH,　　 8% of RH at 850 hPa

Perturbation is normalized if its RMS exceeds above values in each level.

Normalization of perturbation

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Predicted precipitation over a rectangle in northern Japan 400km×250km. Horizontal and vertical axis is for FT=0-6 and FT=12-18, respectively. Upper) Area averaged value. Lower) peak value.

Global EPS Simple downscaling Incremental downscaling

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M03p FT=9-12 M04p FT=12-15

M08p FT=15-18

Enlarged view- Errors were found in initial interpolation of MA

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M06p FT=12-15

Supplement of the downscale ensemble experiment of JMA one week global EPS

・ Errors had been included in the vertical level settings in initial interpolation of MA;

DZ2 =1080. was used in NEST/Prm/CONFIG (must be DZ2=1180.)

・ Use of the latest version of JMANHM with MY3 closure model

M08p FT=15-18

Re-experiment of incremental EPSwith JMANHM ver. Sep 2005

コントロール

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M04p FT=12-15 M03p FT=15-18

Three hour precipitation at 03 UTC 13 July 2004 with Dx=5km. a) Observed Radar-AMeDAS rain. b) Predicted rain with the original MSM at FT=18 (Initial time is 09 UTC 12 July 2004). c) Same as in b) but with the MY3 closure model and the modified radiation scheme using the partial condensation for cloudiness. After Hara (2007).

New NHM with the Mellor Yamada Level 3 closure model

TKE, l’2, qw’2, l’qw’ are added to the prognostic variables

Scheduled operation in May 2007

12 TUC 12 July 2004Control run with MADX=10km

Left ： Operational version(ver. Sep 2005 ）

Right ： New version(ver. Jan 2007 ）

Difference of the results by model versions

M03p FT=15-18

M08p FT=15-18 M11m FT=12-15

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Re-experiment of incremental EPSwith JMANHM ver. Jan 2007

コントロール

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Difference of QPF by model versions

Difference of model physics acts in later half of the forecast period

A self breeding method using JMA-NHM was tested. Barkmeijer et al (2001)’s moist total energy norm

dSPP

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dSdPqqc

Lw

cVVUUTE

seaCseaPr

CPp

qCPp

CPCP

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)(})({})(){(2

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was computed over entire model domain below 5.3 km. Here, =300K 、 Pr=800hPa, wq=0.1. Perturbations bred in 12 hour forecast cycles are normalized by above total norm assuming the initial perturbation is 50% of background error of analysis: PS: 0.35 hPa, U,V: 1 m/s*(Kg/m3), : 0.4 K, Qv: 5% of RH

12 hour breeding cycle from 12 UTC 10 July 2004, targeting 13 July 2004

Self BGM method using JMA-NHM

12 July 2004 12UTC initial FT=18 RR6M01p

Very similar results in different members

M03p

Failure presented in the former meeting

The self breeding method using JMA-NHM has been reconducted. Barkmeijer et al (2001)’s moist total energy norm

dSPP

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dSdPqqc

Lw

cVVUUTE

seaCseaPr

CPp

qCPp

CPCP

})({2

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)(})({})(){(2

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is computed over entire model domain below 5.3 km. Here, =300K 、 Pr=800hPa, wq=0.1. Perturbations bred in 12 hour forecast cycles are normalized by above total norm assuming the initial perturbation is 50% of background error of analysis: PS: 0.35 hPa, U,V: 1 m/s*(Kg/m3), : 0.4 K, Qv: 5% of RH

12 hour breeding cycle from 12 UTC 09 July 2004, targeting 13 July 2004Initial perturbations for 18 hour forecast from 12 July 2004 are doubledErrors in the former experiment have been fixed

Self BGM method using JMA-NHM

Initial　:　2004.07.12　12　UTC　BGM　method

CNTLFT=06 M01p M01m

FT=12

M01p M03p

12 July 2004 12UTC initial FT=18 RR6

Different results in different members

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Predicted precipitation over a rectangle domain in northern Japan 400km×250km. Horizontal and vertical axis is for FT=0-6 and FT=12-18, respectively. Left: Area averaged value, Right: peak value.In case of global EPS perturbations.

Same as in upper figures.In case of BGM perturbations.

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Predicted precipitation over a rectangle domain in northern Japan 400km×250km. Horizontal and vertical axis is for FT=0-6 and FT=12-18, respectively. Left: Area averaged value, Right: peak value.In case of global EPS perturbations.

Enlarged view M03p 摂動計算時刻に FT=6 を用いていた誤り発見

　　 Future works

・ Reexamination of BGM cycle and perturbation magnitude

・ Perturbation in lateral (and lower) boundary conditions

・ (Orthogonalization, stochastic seeding)

・ Evaluation of EPS performance (application to B08RDP)

・ Evaluation of forecast and analysis errors from EPS

・ Application of LETKF to ensemble update