Slide 1

Extreme Precipitation by High Resolution RegCM3 Over East Asia Jing ZHENG, Zhenghui Xie Institute of Atmospheric Physics (IAP),CAS, China Institute of Atmospheric Physics (IAP),CAS, China Xunqiang Bi the Abdus Salam International Centre for Theretical Physics (ICTP), Italy the Abdus Salam International Centre for Theretical Physics (ICTP), Italy Slide 2 Outline Introduction Model & Exp. Results Discussion Slide 3 Outline Introduction Model & Exp. Results Discussion Slide 4 Giorgi & Bi, 2000: The internal model variability exhibits a pronounced summer maximum. It significantly influences the day-to-day model solution, especially for summer precipitation. Also affected by the model internal variability was the frequency of occurrence of heavy daily precipitation events. A regional climate model simulation is characterized by an intrinsic level of internal variability which can be excited by any type of perturbation and is regulated by synoptic conditions, season, model domain, region of application, and specific simulation period. Slide 5 Giorgi & Bi, 2000: The internal model variability exhibits a pronounced summer maximum. It significantly influences the day-to-day model solution, especially for summer precipitation. Also affected by the model internal variability was the frequency of occurrence of heavy daily precipitation events. A regional climate model simulation is characterized by an intrinsic level of internal variability which can be excited by any type of perturbation and is regulated by synoptic conditions, season, model domain, region of application, and specific simulation period. Slide 6 Resolution? Model? Its internal model variability? the extreme precipitation,Yangzi and Huaihe Valley summer, 1998 compared to 60km resolution & observational data. the results indicated that high resolution can give more details about the region of the extreme precipitation. Additionally, the maximum of the extreme precipitation were different by the two simulations of different resolutions. Difficulties in simulating precipitation, esp. extreme prec. 20km resolution of RegCM3 Slide 7 Outline Introduction Model & Exp. Results Discussion Slide 8 Summary of RegCM3 Core Dynamics: MM5 Hydrostatic (Grell et al 1994) Radiation: CCM3 (Kiehl 1996) Large-Scale Clouds & Precipitaion: SUBEX (Pal et al 2000) Cumulus convection: Anthes-Kuo (1977) Grell (1993) Emanuel (1991) Boundary Layer: Holtslag (1990) Tracers/Aerosols/dust: Qian et al (2001); Solmon et al (2005); Zakey et al. (2006) Land Surface: BATS (Dickinson et al 1993) SUB-BATS (Giorgi et al 2003) Ocean Fluxes BATS (Dickinson et al 1993) Zeng et al (1998) Computations Parallel Code (Bi, Gao, Yeh) Multiple Platforms More User-Friendly Code (Pal et al 2006; Since Giorgi et al 1993ab) ICTP Slide 9 Experiment Design (80*100, (32N,112E) Region East China Period 1998. Jun. ~ Aug. (June: Spinup time) Resolution 2.5 o 60km 20km (80*100, (32N,112E)) ICBC Experiment ERA40.vs.NNRP2 Cumulus Scheme Experiment (ERA40) Domain Size experiment (NNRP2, icup=4) Buffer zone experiment (ERA40, icup=4) ICBC Experiment ERA40.vs.NNRP2 Cumulus Scheme Experiment (ERA40) Domain Size experiment (NNRP2, icup=4) Buffer zone experiment (ERA40, icup=4) Slide 10 60km 20km Slide 11 ICBC -- ERA40.vs. NNRP2 ERA40NNRP2 ? Slide 12 Outline Introduction Model & Exp. Results Discussion Slide 13 Time Series for Precipitation NNRP2 vs ERA40 (icup=4) 60km 20km ERA40(icup=1,2,4)60km 20km 4 observational stations: Wuhan, Hefei, Nanjing, Shanghai Slide 14 ERA[i1] ERA[i2] ERA[i4] NNRP[i4] Ensemble Obs. Slide 15 ERA[i1] ERA[i2] ERA[i4] NNRP[i4] Ensemble Obs. Slide 16 ERA[i1] ERA[i2] ERA[i4] NNRP[i4] Ensemble Obs. Slide 17 ERA[i1] ERA[i2] ERA[i4] NNRP[i4] Ensemble Obs. Slide 18 Domain Size Experiment (NNRP2,i4) LargeSmallObs Slide 19 Buffer Zone Experiment (ERA40,i4) BZ12 BZ18 Obs Slide 20 GPCP RegCM3CMAPCRU Met. stations Spatial pattern Slide 21 ERA40_i4NNRP2_i4NNRP2_S ERA40_BZ tpr.vs. prcv July1998 Slide 22 Spatial pattern ERA40_i4NNRP2_i4NNRP2_S ERA40_BZ tpr.vs. prcv Aug1998 Slide 23 Outline Introduction Model & Exp. Results Discussion Slide 24 Preliminary conclusion & Discussion simulations were different by different resolutions/ domain sizes/ cumulus schemes/ forcing fields. Resolution: higher resolution can give more details about the region of the extreme precipitation. Domain: it depends, but smaller seems much higher peaks. Cumulus schemes: MIT-Emanuel seems better here. Forcing fields: ERA40 southward rain band [vs. NNRP2 ] Difficulties in simulating precipitation, esp. extreme prec. Resolution & Precipitation? Cumulus scheme? Domain size? Forcing fields? Internal model variability? Land Component of the Model? More accurate physical process? A CASE STUDY ---- Slide 25 Thanks for Your Attention!