1. Monsoon Part Ⅰ What is a monsoon What makes a monsoon

2. What is a monsoon A term from early Arabs called the "Mausin," or "the season of winds." The seasonally shifting winds in the Indian Ocean and surrounding regions, including the Arabian Sea and the Bay of Bengal.

3. monsoon—A monsoon results from the circulation induced by temperature contrasts between a warm (cold) continent and a cold (warm) ocean.

4. Ramage (1971) based on wind directions

5. It is now more applied to tropical and subtropical seasonal reversals in both winds and associated precipitation. People are more concerned about the precipitation for two reasons: a ： natural disasters, like flooding and drought ; b: latent heat in the global diabatic heating.

6. The hydrologic cycle and latent heat absorb latent heat release latent heat ice vapor Liquid Absorb latent heat Condensation release latent heat evaporation This heat anomalies produce circulation anomalies

7. Monsoonal or non-monsoonal? Total summer precipitation Annual range of rain Ratio of summer rain to yearly rain

8. Members in the Asian-Australian summer monsoon system B: trade wind C: cross- equatorial flow D: SW monsoon India monsoon, East Asian monsoon, Meiyu front A c A EASM H L L H TAO. 1987 L Austrilian high

9. Mean onset date of the summer monsoon

10. Monsoon is a mixed blessing Life-giving rain & Wild storms It annually shapes the lives of both the people and the wildlife of the monsoon regions. In late spring, the grassy plains and forested hillsides of southwestern India are among the hottest places on the earth. "The air is on fire and the leaves are perfectly still as if holding their breath." "there is a curious sense of anticipation.“ ——— Shantipriya

11. Animals and human alike await the monsoon

12. Monsoon onset As clear blue sky just gives its way to white clouds, the dark clouds that carry rains are coming. Monsoon Race Clouds : Ci, Sc, Ns, Cu

13. Before monsoon hits the Arabian coast, the fishing boats are pulled on the coast, packed, and tightly tied with the ropes for the support.

14. Weaver birds build their nests during monsoon break. Crocodiles spawn Monsoon break

15. Farmers plant rice paddies after monsoon rains. Monsoon withdrawal

16. Wild storms: People rest on the pavement of a flooded street in Bombay.

17. Monsoon rains have killed 41 people across India over the past two days. (Yahoo News. Wed,Jul 5,2006) Monsoon peak

18. India's financial capital Bombay came to a virtual standstill Tuesday in the torrential rainfall, killing 7 people. (Yahoo News. Jul.4,2006)

19. Yangtzs valley in China East Asian monsoon area Meiyu front

20. Monsoon rains come too late this year (2006).

21. Mei-yu front does not come to the middle-lower reaches of Yangtzs River this year. Monthly precipitation anomaly in Jun.2006 Monthly rainfall anomaly:-80%

22. Flooding 1998

24. The most densely populated areas are in monsoon regions. 1.37b in China 1.03b in India Global population distribution

25. From Simona 2004 From Ramage 1971 Regional summer monsoon domains From Berbery et al. 2005, North African monsoon from Reddiman 2001

26. Global summer monsoon rainy season Summer rain Winter rain

27. Global summer monsoon rainy season

28. Summary Monsoon means seasonal reversals both in winds and precipitation Monsoon’s onset, peak and withdrawal Monsoon rainy season has inter-annual variations (floods, droughts)

29. What makes a monsoon How is the atmosphere heated at the earth’s surface? Energies driving the atmosphere to move are primarily come from the sun.

30. Nearly half of the total sun’s energy is concentrated within the visible light wavelength Solar radiation

31. Solar radiation absorbed by atmosphere Visible solar radiation is not absorbed by air

32. About 51% of solar radiation is absorbed by surface

33. How is the atmosphere heated Energy gained by atmosphere: +160 51% of the solar radiation is absorbed by the earth Ocean currents move heat downward into deep water +7 +23 +111 +19 Energy lost by atmosphere: -160

34. summer (JJA) winter (DJF) Temperature at 1000hPa Land-sea distribution makes the imbalance of the heat

35. Just as sea breeze Warmer air Low pressure High pressure Warmer air

36. The earth’s rotation around the sun produces the heat imbalance between the two hemispheres. Seasonal variations of solar radiation

37. The pattern of Absorbed Solar Radiation has a strong zonal component that is dominated by orbital effects.

38. Tibetan Plateau, the third pole of the earth. It is a heat source at its surface. Average elevation is 4500m.Total area is about 2,400,000km 2

39. Rainfall center Latent heat is most intense over Tibet

40. Interaction between the two hemispheres EASM ISM HH

41. Three factors contribute to monsoon Tibetan Plateau Interactions between the two hemispheres

42. Seasonal overturning in winds

43. Summary The first driving force is solar radiation The second driving force is land-sea distribution The three is the huge topography.