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Development of a self BGM method with the JMA NHM

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. Development of a self BGM method with the JMA NHM. Kazuo Saito (MRI). Introduction (Downscale EPS experiment) Supplement of the downscale ensemble experiment of JMA one week global EPS

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Development of a self BGM method with the JMA NHM

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  1. 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」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 Development of a self BGMmethod with the JMANHM Kazuo Saito (MRI) • Introduction (Downscale EPS experiment) • Supplement of the downscale ensemble experiment of JMA one week global EPS • Self BGM method with the JMANHM • Future subjects

  2. Heavy rainfall occurred on 13 July 2004 in the southern part of Northern Japan. OBS. MSM, 12UTC 12 July FT=12-18 3 hour accumulated precipitation on 13 July 2004. Left）00 UTC, Center）03 UTC, Right）06 UTC

  3. Downscale experiments One week Global EPS at JMA Mar. 2001～ 12UTCinitial, 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: Dx=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 experiment Initial：Global EPS LBC：Global EPS, updated 6 hourly b) Incremental downscale experiment Initial：Meso 4D-Var analysis + normalized perturbations by Global EPS LBC：RSM forecast, updated 3 hourly

  4. Breeding cycle of the one-week EPS at JMA 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 北半球域 500hPa高度場で 規格化 (気候的変動の14.5%、 湿度は21%) Breeding cycle Breeding cycle Breeding cycle Breeding cycle Breeding cycle 00UTC 摂動 解析誤差の 空間分布を考慮した 規格化 摂動ラン コントロールラン 成長した誤差 12UTC 予報用摂動 ｻｲｸﾙ用摂動 求まる１２摂動に 対し直交化を行い、 規格化する (１２時間予報) 00UTC 成長した誤差 12 cycles

  5. One-week EPS at JMA （Kyouda, 2000) Mar. 2001- Mar. 200612UTCinitial 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00,12ＵＴＣに行ってBreeding 12ＵＴＣ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）

  6. Forecast of JMA one week Global EPS Initial time 12UTC 12 July, 2004. 6 hour accumulated precipitation Control (M00) Left） FT=00-06 Right） FT=12-18 （Color shades: 1,5,10 mm） Control Member M03p Moderate precipitation in the southern part of Northern Japan at FT=12-18. Member M03p ５図　６図と同じ。メンバー'M03p'

  7. Downscale experiments One week Global EPS at JMA Mar. 2001～ 12UTCinitial, 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: Dx=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 experiment Initial：Global EPS LBC：Global EPS, updated 6 hourly b) Incremental downscale experiment Initial：Meso 4D-Var analysis + normalized perturbations by Global EPS LBC：RSM forecast, updated 3 hourly

  8. Normalization of perturbation 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 stream T: about 0.8K in lower troposphere about 1K in upper troposphere RH: 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 PS: 0.6 hParU, rV: 1.8 m/s*(Kg/m3) q: 0.7 K Qv: 12% of RH, 8% of RH at 850 hPa Perturbation is normalized if its RMS exceeds above values in each level.

  9. Global EPS Simple downscaling Incremental downscaling 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.

  10. Enlarged view - Errors were found in initial interpolation of MA M03p FT=9-12 M04p FT=12-15 M08p FT=15-18 M06p FT=12-15

  11. 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

  12. Re-experiment of incremental EPS with JMANHM ver. Sep 2005 M04p FT=12-15 M03p FT=15-18 M08p FT=15-18 M11m FT=12-15

  13. New NHM with the Mellor Yamada Level 3 closure model 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 is09 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). TKE, ql’2, qw’2, ql’qw’ are added to the prognostic variables Scheduled operation in May 2007

  14. Difference of the results by model versions 12 TUC 12 July 2004 Control run with MA DX=10km Left ：Operational version (ver. Sep 2005） Right ：New version (ver. Jan 2007）

  15. Re-experiment of incremental EPS with JMANHM ver. Jan 2007 M03p FT=15-18 M04p FT=12-15 M08p FT=15-18 M11m FT=12-15

  16. Difference of QPF by model versions Difference of model physics acts in later half of the forecast period

  17. Self BGM method using JMA-NHM A self breeding method using JMA-NHM was tested. Barkmeijer et al (2001)’s moist total energy norm was computed over entire model domain below 5.3 km. Here, Q=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, rU,rV: 1 m/s*(Kg/m3), q: 0.4 K, Qv: 5% of RH 12 hour breeding cycle from 12 UTC10July 2004, targeting 13 July 2004

  18. Failure presented in the former meeting M03p M01p 12 July 2004 12UTCinitial FT=18 RR6 Very similar results in different members

  19. Self BGM method using JMA-NHM The self breeding method using JMA-NHM has been reconducted. Barkmeijer et al (2001)’s moist total energy norm is computed over entire model domain below 5.3 km. Here, Q=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, rU,rV: 1 m/s*(Kg/m3), q: 0.4 K, Qv: 5% of RH 12 hour breeding cycle from 12 UTC 09 July 2004, targeting 13 July 2004 Initial perturbations for 18 hour forecast from 12 July 2004 are doubled Errors in the former experiment have been fixed

  20. Initial : 2004.07.12 12 UTC BGM method CNTL FT=06 M01p M01m FT=12

  21. M03p M01p 12 July 2004 12UTCinitial FT=18 RR6 Different results in different members

  22. 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.

  23. 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

  24. 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 LETKFto ensemble update

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