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Extreme Precipitation by High Resolution RegCM3. Over East Asia. Jing ZHENG , Zhenghui Xie Institute of Atmospheric Physics (IAP),CAS, China Xunqiang Bi the Abdus Salam International Centre for Theretical Physics (ICTP), Italy. Outline. Introduction Model & Exp. Results

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Extreme precipitation by high resolution regcm3

Extreme Precipitation by High Resolution RegCM3

Over East Asia

Jing ZHENG , Zhenghui Xie

Institute of Atmospheric Physics (IAP),CAS, China

Xunqiang Bi

the Abdus Salam International Centre for Theretical Physics (ICTP), Italy


Outline
Outline

  • Introduction

  • Model & Exp.

  • Results

  • Discussion


Outline1
Outline

  • Introduction

  • Model & Exp.

  • Results

  • Discussion


  • 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.


  • 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.


20km resolution of RegCM3

  • 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.


Outline2
Outline

  • Introduction

  • Model & Exp.

  • Results

  • Discussion


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

Summary of RegCM3 Core

ICTP…

(Pal et al 2006; Since Giorgi et al 1993ab)


Experiment design
Experiment Design

Region – East ChinaPeriod – 1998. Jun. ~ Aug. (June: Spinup time)Resolution – 2.5o60km20km (80*100, (32N,112E))

ICBC Experiment ERA40.vs.NNRP2Cumulus Scheme Experiment(ERA40)Domain Size experiment(NNRP2, icup=4)Buffer zone experiment(ERA40, icup=4)


60km

20km


?

ICBC -- ERA40 .vs. NNRP2

ERA40

NNRP2


Outline3
Outline

  • Introduction

  • Model & Exp.

  • Results

  • Discussion


Time series for precipitation
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


ERA[i1]

ERA[i2]

ERA[i4]

NNRP[i4]

Ensemble

Obs.


ERA[i1]

ERA[i2]

ERA[i4]

NNRP[i4]

Ensemble

Obs.


ERA[i1]

ERA[i2]

ERA[i4]

NNRP[i4]

Ensemble

Obs.


ERA[i1]

ERA[i2]

ERA[i4]

NNRP[i4]

Ensemble

Obs.




Spatial pattern

Met. stations

RegCM3

CRU

CMAP

GPCP


Spatial pattern
Spatial pattern

tpr .vs. prcv July1998

ERA40_BZ

ERA40_i4

NNRP2_i4

NNRP2_S


Spatial pattern

tpr .vs. prcv Aug1998

ERA40_BZ

ERA40_i4

NNRP2_i4

NNRP2_S


Outline4
Outline

  • Introduction

  • Model & Exp.

  • Results

  • Discussion


Preliminary conclusion discussion
Preliminary conclusion & Discussion

A CASE STUDY ----

  • 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?



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