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F Kucharski, A Bracco, R Barimalala, JH Yoo Abdus Salam ICTP,

EGU, Vienna, 3-8 April , 2011. Contribution of the east-west thermal heating contrast to the South Asian Monsoon and consequences for its variability. F Kucharski, A Bracco, R Barimalala, JH Yoo Abdus Salam ICTP, Earth System Physics Section, Climate Variability Group, Trieste, Italy.

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F Kucharski, A Bracco, R Barimalala, JH Yoo Abdus Salam ICTP,

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  1. EGU, Vienna, 3-8 April , 2011 Contribution of the east-west thermal heating contrast to the South Asian Monsoon and consequences for its variability F Kucharski, A Bracco, R Barimalala, JH Yoo Abdus Salam ICTP, Earth System Physics Section, Climate Variability Group, Trieste, Italy

  2. One of the classical views of monsoon mechanisms

  3. There are other views, for example:

  4. Global JJAS rainfall distribution: Does the east-west contrast play a role?

  5. The South Asian monsoon system is also located in the centre between the western Pacific heating maximum and the Atlantic heating minimum. Sverdrup-Balance:

  6. A few numerical experiments to this topic Global modeled distributions of climatological 200 hPa streamfunction and velocitypotential Upper-level monsoon high; What’s the reason? (in low-levels we find the monsoon trough)

  7. Kucharski et al., Climate Dynamics, 2010, DOI 10.1007/s00382-010-0858-3 Rainfall: mm/day Ocean and land configuration for the numerical experimentation

  8. Reason: Walker circulation influences monsoon high via Sverdrup balance! Units: 106 m2 /s We may interpret therefore the ENSO influence as shifts in the centres of velocity potential…….

  9. Another motivation: How will the Pacific mean-state change in global warming? EOS, 2008 To this topic also: Kucharski, F., I.-S. Kang, R. Farneti, and L. Feudale (2011), Tropical Pacific response to 20th century Atlantic warming, Geophys. Res. Lett., 38, L03702,doi:10.1029/2010GL046248.

  10. Another experiment regarding the land-sea contrast: Also the land-sea contrasts influences the South Asian monsoon (as expected), but more inland! The monsoon high is influenced more in the north-western parts

  11. ENSO influence on interannual time-scale Correlation of a JJAS IM rainfall index (70-85E, 10-30N), with JJAS SSTs at every gridpoint. Lead-lag correlation of JJAS IMR with Nino3.4 index

  12. ENSO influence: Composites Analysis using linear regression Kucharski et al., Climate Dynamics, 2010, DOI 10.1007/s00382-010-0858-3 mm/day Hypothesis: ENSO (pos) response can be interpreted as eastward shift of streamfunction maximum and therefore of rainfall.

  13. Summary • The South-Asianmonsoonclimatologyispartiallydeterminedby the land-sea • contrast, butalsoby the large-scaleeast-westheatingcontrast. • The influenceof global warming on the mean state in the tropicalPacific • (even in the past) isstill under debate, and couldbeEl Nino or La Nina like. • On interannualtime-scale, ENSO exerts the strongestinfluence on the South • Asianmonsoon (apartfrominternalatmosphericvariability). • A part ofthisinfluencemaybeinterpretedaszonalshiftof the streamfunction • and velocitypotentialextremes.

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