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Chinese Academy of Meteorological Sciences

Chinese Academy of Meteorological Sciences

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Chinese Academy of Meteorological Sciences

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  1. Decadal Climate Shift of the East Asian Summer Monsoon in Late 1980s and Its Possible Causes Renhe Zhang Bingyi Wu Ping Zhao Chinese Academy of Meteorological Sciences

  2. Content I. Decadal Climate shift in China II. Association with the Eurasian Snow Cover III. Association with the Arctic Sea Ice IV. Association with the SSTA in the North-West Pacific V. Conclusion

  3. Global and China Surface Temperature Variations GLOBAL CHINA (全球资料取自HadCRUTv3,中国资料由王绍武(1998)改绘)

  4. a NW Pacific-East Asian Summer Monsoon Index (7yr running mean;Wang et al.,2001) b First Mode of East Asian Summer Monsoon (7yr running mean;Wu et al., 2008) A decadal Climate shift happened in late 1980s for the East Asian summer monsoon.

  5. Summer Precipitation Anom. 1973-1989 Thick black line denotes 0. Blue and red shadings denotes positive and negative anomalies, respectively. (618 staions are used. Unit: mm. The interval: 10mm.) Summer Precipitation Anom. 1990-2002 “Flood in south and draught in north”

  6. East Asian summer monsoon has its own decadal change, which is different from the continuously increasing of surface temperature. A decadal climate shift of east Asian summer monsoon occurred in the late 1980s. What are formation causes of the decadal climate shift of the East Asian summer monsoon?

  7. Content I. Decadal Climate Change in China II. Association with the Eurasian Snow Cover III. Association with the Arctic Sea Ice IV. Association with the SSTA in the North-West Pacific V. Conclusion

  8. Eurasian Snow cover Summer precipitation Spring snow cover SVD 1st Mode Decreasing of snow cover after 1980s and increasing of rainfall in South China. Snow cover (solid line) Precipitation (dash line)

  9. 42 stations Observed precipitation averaged at 42 stations and the time series of SVD 1st mode. Correlation of averaged 42stn summer precipitation to spring snow cover

  10. Regressed 500hPa geopotential heights in summer by the average summer precipitation averaged at 42stn. Tele-correlation wave train

  11. Regressed 500hPa geopotential heights by spring snow cover Spring summer

  12. Content I. Decadal Climate Change in China II. Association with the Eurasian Snow Cover III. Association with the Arctic Sea Ice IV. Association with the SSTA in the North-West Pacific V. Conclusion

  13. SVD1 of spring Arctic sea ice concentration (left) and summer precipitation in China (right)

  14. 2003 1998 1979 1988 Time series of the SVD 1st mode for spring Arctic sea ice concentration (dashed line) and summer precipitation in China (correlation coefficient: 0.83)

  15. SVD 1st mode of spring Arctic sea ice concentration and its correlations to spring Arctic sea ice concentration and the summer precipitation in China spring Arctic sea ice Significant positive correlation Significant negative correlation

  16. Content I. Decadal Climate Change in China II. Association with the Eurasian Snow Cover III. Association with the Arctic Sea Ice IV. Association with the SSTA in the North-West Pacific V. Conclusion

  17. EOF 1st mode (a) and 2nd mode (b) of the sea surface temperature in north-west Pacific

  18. Time series for the EOF 1st (a) and 2nd (b) mode

  19. Averaged SSTA in summer for 1968-1987 (a) and 1988-2002 (b). (c) Is the difference between (b) and (a). Shadings denote the significance higher than 0.05.

  20. Correlation of the SST EOF 1st mode to the precipitation in summer Circle and triangle represent significant negative and positive correlation, respectively. 5yr running mean

  21. 51 stations South China Variation of averaged precipitation at 51stn (dotted line) and the time series of the SST EOF1 Less land-sea thermal contrast, weaker summer monsoon

  22. Content I. Decadal Climate Change in China II. Association with the Eurasian Snow Cover III. Association with the Arctic Sea Ice IV. Association with the SSTA in the North-West Pacific V. Conclusion

  23. Conclusion • There was a decadal climate shift in east Asian summer monsoon in the late 1980s. • East Asian summer monsoon changed from a strong phase to a weak phase. • More precipitation appeared in South China after the late 1980s. • Eurasian snow cover, Arctic sea ice and SSTA in northwest Pacific also experienced same decadal climate shift.

  24. Conclusion • The decadal shifts of the Eurasian snow cover, Arctic sea ice and SSTA in northwest Pacific can be possible formation causes of the decadal climate shift in China. • The Eurasian snow cover and Arctic sea ice are associated with tele-connection from high latitudes to East Asia, which affect summer climate in East Asia. • Increasing of the SSTA in northwest Pacific can reduce the thermal contrast between land and sea, which weakens the East Asian summer monsoon.

  25. 谢谢! Thank you for your attention!