Diurnal cycle of Southern China Monsoon: characteristics and - PowerPoint PPT Presentation

Diurnal cycle of Southern China Monsoon: characteristics and preliminary simulation Outline 1. Briefly on Southern China Monsoon. 2. Diurnal variations revealed by TRMM (1998~2006). 3 . Some results by the trial experiments . 4 . Summary and p o tential works. Hakone, 9 th Mar 2007 Diurnal cycle of Southern China Monsoon: Diurnal cycle of Southern China Monsoon: Diurnal cycle of Southern China Monsoon: characteristics and preliminary simulation characteristics and preliminary simulation characteristics and preliminary simulation Guixing CHEN and Weiming Sha Atmospheric Science Lab, Tohoku University, Sendai chen@wind.geophys.tohoku.ac.jp; sha@wind.geophys.tohoku.ac.jp Outline Outline Outline 1. Briefly on Southern China Monsoon. 1. 1. Briefly Briefly on Southern China Monsoon. on Southern China Monsoon. 2. Diurnal variations revealed by TRMM (1998~2006). 2. 2. Diurnal Diurnal variations revealed variations revealed by by TRMM TRMM (1998~2006). (1998~2006). 3 3 3 . Some results by the trial . Some results by the trial . Some results by the trial experiments experiments experiments . . . 4 . Summary and p o tential works. 4 4 . . Summary and p Summary and p o o tential works. tential works.

S easonal r ainfall and t opography around s outhern China India Baiu front Warm Pool SCS Subtropical monsoon Southern China S outh tropical monsoon China Sea presummer summer S easonal r ainfall and t opography around s outhern China S S easonal easonal r r ainfall ainfall and and t t opography opography around around s s outhern China outhern China Baiu front Baiu front Baiu front India India India SCS SCS SCS Warm Warm Warm Pool Pool Pool Subtropical monsoon Subtropical monsoon Subtropical monsoon Southern Southern Southern China China China presummer summer presummer presummer summer summer S outh S S outh outh tropical monsoon tropical monsoon tropical monsoon China China China Sea Sea Sea

A h eavy rain case , 1 9 ~2 4 June, 2005 Inland noon~afternoon peak Coastal morning peak A h A h A h eavy rain case eavy rain case eavy rain case , 1 , 1 , 1 9 9 9 ~2 ~2 ~2 4 4 4 June, June, June, 2005 2005 2005 17:00 11:00 Inland Inland Inland noon~afternoon peak noon~afternoon peak noon~afternoon peak 08:00 14:00 11:00 Coastal Coastal Coastal morning peak morning morning peak peak 05:00 08:00 08:00 11:00 South China Sea

t h g i n e t a l afternoon D iurnal cycle of rain rate in presummer (TRMM 1998~2006) midnight sunset sunrise noon e a r l y n i g h t morning D iurnal cycle of rain rate in presummer (TRMM 1998~2006) D D iurnal iurnal cycle cycle of of rain rain rate rate in presummer in presummer (TRMM (TRMM 1998~2006) 1998~2006) e e e t t t a h a a h h midnight r r r midnight midnight g g g l l l y y y i i i n n n n n n i i i g e e e g g h t t t h h a a a t t t l l l sunset sunrise sunset sunset sunrise sunrise afternoon afternoon afternoon morning morning morning noon noon noon

Regional variation of diurnal rainfall cycle Total rain Spring Spring Presummer Presummer S ummer S ummer Precentage of convetive rain c oastal c oastal c oastal Regional variation of diurnal rainfall cycle Regional variation of diurnal rainfall cycle Regional variation of diurnal rainfall cycle Total rain Total rain Total rain Precentage of convetive Precentage of convetive Precentage of convetive rain rain rain Spring Spring Spring Spring Spring Spring c c c oastal oastal oastal Presummer Presummer Presummer Presummer Presummer Presummer c oastal c c oastal oastal S ummer S ummer S S ummer ummer S S ummer ummer c oastal c c oastal oastal

T op ographic impacts on rainfall amplification mean flow Green area: Mountain (>500m) Green area: Mountain (>500m) T op ographic impacts on rainfall amplification T T op op ographic ographic impacts impacts on on rainfall amplification rainfall amplification Accumulated rain 19~24Jun 2005 Accumulated rain in presummer(1998~2006) mean flow mean flow mean flow Green area: Mountain (>500m) Green area: Mountain (>500m) Green Green area: area: Mountain Mountain (>500m) (>500m) Green Green area: area: Mountain Mountain (>500m) (>500m) JJA rainfall (1997~2004)TRMM-PR Orography in Asia (proposed by Xie et al. JC 2006)

Introduction on DS ( D own S caling S imulation S ystem ) 00 z 19 June2005 DS - 30km( 7 2 * 7 2) 00 z 24 June2005 00 z 19 June2005 DS - 1 0km( 10 2 * 10 2) 00 z 24 June2005 3 3 3 3 3 3 Introduction on Introduction on Introduction on DS DS DS ( ( ( D D D own own own S S S caling caling caling S S S imulation imulation imulation S S S ystem ystem ystem ) ) ) DS 3 (a 'small' JMA): NHM model (dx=15km→4km→1km) Coupled with CFD•LES model (dx~100m) elevation of domain 1 Schemes for two trial experiments: 00 00 00 z z z 19 19 19 June2005 June2005 June2005 DS DS DS - - - 30km( 30km( 30km( 7 7 7 2 2 2 * * * 7 7 7 2) 2) 2) 00 00 00 z z z 24 24 24 June2005 June2005 June2005 3 3 3 Inintial & boundary: JMA-GSM, NOAA-OISST Convection scheme: Kain-Fritsch elevation of domain 2 Cloud physics: mixed-phase, graupel process simplified Time step: 60 Sec 00 z 19 June2005 DS - 1 0km( 10 2 * 10 2) 00 z 24 June2005 00 00 z z 19 19 June2005 June2005 DS DS - - 1 1 0km( 0km( 10 10 2 2 * * 10 10 2) 2) 00 00 z z 24 24 June2005 June2005 3 3 3

Accumulated precipitation TRMM-3G42 simulated by DS 3 (30km) North rainbelt along baroclinic front is good. Rainfall due to mountains are weak. South rainbelt along coast is too weak.

Evolution of precipitation TRMM-3G42 simulated by DS 3 (30km) 17:00 11:00 Inland Inland 08:00 08:00 14:00 08:00 16:00 10:00 Coastal Coastal 05:00 08:00 08:00 17:00 11:00 11:00 13:00 14:00 14:00

Accumulated precipitation TRMM-3G42 simulated by DS 3 (10km) North rainbelt along baroclinic front is weak. Rainfall due to mountains are weak. South rainbelt along coast is good.

Evolution of precipitation TRMM-3G42 simulated by DS 3 (10km) 17:00 11:00 Inland Inland 08:00 11:00 14:00 14:00 12:00 13:00 Coastal Coastal 05:00 08:00 08:00 14:00 17:00 11:00 10:00 10:00 09:00

Summary and potential works 1.Monsoon on southern China has distinct diurnal variations with morning peak in coast & noon~afternoon peak over inland. 2.Along with surface heating, disturbances developed in coast & eastern Tibetan plateau may merge to bring the noon~afternoon peak over inland in presummer season. 3.With topographic effects, these diurnal cycles play an important role on the location and timing of heavy rains. With DS 3 , high resolution experiments with are on the way: (1) Sensitive Exp. on interactions between baroclinic system, monsoon flow and local land-sea breeze; (2) Sensitive Exp. on topographic impacts (small mountains & complex coast) on disturbance gensis and rainfall amplification; (3) Sensitive Exp. on convection, radiation schemes & surface processes and their impacts on diurnal rainfall cycle.