Guoxiong WU, Yimin LIU, Bian HE, Anmin DUAN, Qing BAO, Rongcai REN, Xiaying ZHU, Jieli Hong LASG, Institute of Atmospheric Physics (IAP), CAS, China Buwen DONG, University of Reading, UK Feifei JIN, Hawai University, US November 5-6, Taipei

Presentation based on:

Outline 1.Introduction 2.Thermal Control of the ASM 3.Change in TP-SHAP 4.Change of ASM 5.Summary

1. Introduction A.Monsoon- water vapor B.Water vapor: 85% of water vapor resides bellow 700mb C.Lifting:  Internal- baroclinity: winter and extratropics  External- mechanicl: deflected or lifted <1km  External- thermal: SW- hardly absorbed LW- escape into space Latent heating- in the free atmosphere Surface Sensible heating- effective!---mountain slope

If Convection dominates “Equivalent topography height” Linearized QG thermodynamic equation: (Held, I., 1983) [u] H Q /H 1 summer winter Schematic Diagram

Zonal Wind Summer Winter WW E The TP- mechanical forcing is important in winter, and its thermal forcing is dominating in summer ! The TP- mechanical forcing is important in winter, and its thermal forcing is dominating in summer !

Aqua-Planet Experiment (APE): Diff of V and w at s=0.991 Wu et al., JHM, 2007

U, w and  vertical cross- section Pumping No Pumping             TP Sensible Heat Driven Air-Pump (TP SHAP) mainly happens on the slopes

Outline 1.Introduction 2.Thermal Control of the ASM 3.Change in TP-SHAP 4.Change of ASM 5.Summary

IRTP V and Precipitation July IRTP- TRO Formation of the Asian monsoon Wu et al. Cli. Dyn 2012

L_S b OBS CON a Preci. & 850-hPa V Land-Sea

DIFF a Required V and Precip. to make up the Asian summer monsoon DIFF = Total – Land-Sea

IPTP_M b DIFF a Required Circul. and Precip. to make up the Asian summer monsoon IP_M c d TP_M L_S Impacts of mountain mechanical forcing

a b c IP_SH TP_SH IPTP_SH Impacts of SH thermal forcing

DIFF a Required Circul. and Precip. to make up the Asian summer monsoon DIFF = Total – Land-Sea Impacts of IPTP thermal forcing c IPTP_SH DIFF = IPTP_SH – IPTP_M

Mechanism: Relative contributions of the climbing and deflecting effects of mountains b IPTP_M a CON c HIM d HIM_M ☆ Thermal Adaptation ☆ TP Sensible Heat Air-Pump (TP-SHAP)

S E Z ( km ) 5 10 Eq. India China Tibetan Plateau Iran Plateau SASM North Branch SASM South Branch Meridional Circulation To EASM IP T P TP L_S L_S S-SASM  Land_Sea thermal contrast; N-SASM  ITTP SHAP EASM  Land_Sea thermal contrast +TP SHAP Wu et al. Sci. Rep. 2012

Conclusion 1: Thermal Control of the Asian Summer Monsoon TP Air- Pump is driven by surface sensible heating (SHAP), which regulates the surrounding circulation and affects at least circulation over the Northern hemisphere; S-SASM  Land_Sea thermal contrast; N-SASM  ITTP SHAP; EASM  Land_Sea thermal contrast +TP SHAP

Outline 1.Introduction 2.Thermal Control of the ASM 3.Change in TP-SHAP 4.Change of ASM 5.Summary

Mean over the TP, JJA (1) A weakening trend in the TP forcing in spring and summer from station data stations Liu et al. Cli. Dyn 2012

SH Ts – Ta V10  Difference: strength  Consistency: seasonal and interannual variation and weakening trend Zhu, Liu, Wu, China Sci. 2012

Outline 1.Introduction 2.Thermal Control of the ASM 3.Change in TP-SHAP 4.Change of ASM 5.Summary

Fig. 7 Correlation of SH averaged over TP and Pre_Land, 11-year running mean SH=(Tg-Ta)V (2) Correlation: Stronger TP heating, more rain in North China

(3) Verify the correlation by sensitivity experiment Negative surface sensible heating over TP in HadAM3

Weakened Subtropical High over Western Pacific Weakened South Asian High Response

Fig. 5 Less rain in north More rain in South Response

Conclusion II Weakening of sensible heating over the TP results in weakening of near-surface cyclonic circulation. Consequently, the convergence of water vapor transport is confined to South China, contributes to “wet in south and dry in north.” Liu et al., Cli. Dyn. 2012

Conclusion III The change in the TP-SHAP can provide a complementary means for understanding the regional Climate change projection Conclusion IV The TP-SHAP trend is changing recently, and indicating the EASM may change in the near future.

Outline 1.Introduction 2.Thermal Control of the ASM 3.Change in TP-SHAP 4.Change of ASM 5.Summary

The Asian Summer Monsoon is mainly under the thermal control of 1.Land-sea contrast; and 2.Large-scale topographic forcing!

Recent Reference

8 data sets DataTypeResolusionSource NCEPR1Reana. T62 NCEP/NCAR NCEPR2Reana. T62 NCEP/DOE CFSR Reana. T62 NCEP ERA40 Reana. T106 ECMWF JRA Reana. T106 JMA G2_Noah Land Model 1 ° x1 ° NASA YSiB2 Land Model TP 76 stations Kun Yang ObCh Estimite TP 76 stations Xiaying Zhu ect. (2012) Comparing of SH data

SH JJA

Tibetan Plateau (TP) acts - Enhance coupling between surface and upper tropospheric circulations, and between subtropical and tropical monsoon circulations TRO run TP run TP-TRO v, -  mean of 90E-120E, July

Thermal Adaptation- heating heating

Thermal Adaptation-cooling cooling