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Monsoon Climate Part1

Monsoon Climate Part1. W4930 Earth’s oceans and atmosphere 03/24/05 Chie Ihara. What is monsoon? Where can we see monsoons? Why are monsoons important? What is the physical mechanism of monsoon? Examples: Asian monsoon, North American monsoon, West African monsoon

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Monsoon Climate Part1

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  1. Monsoon Climate Part1 W4930 Earth’s oceans and atmosphere 03/24/05 Chie Ihara

  2. What is monsoon? • Where can we see monsoons? • Why are monsoons important? • What is the physical mechanism of monsoon? • Examples: Asian monsoon, North American monsoon, West African monsoon • Can we predict monsoons?

  3. What is monsoon? ‘A name for a wind system that changes in speed and direction with season.’ (derived from an Arab word)

  4. Surface Wind: January

  5. July

  6. Where? • Asian monsoon • Australian monsoon • North American monsoon • African monsoon Asian-Australian monsoon

  7. Cold season: Dry winds blow from land to ocean Warm season: Wet winds blow from ocean to land transport moisture large rainfall

  8. Why are monsoon rainfalls important? water management, disaster mitigation, agricultural efficiency e.g.) Asian monsoons About 60% of the world’s population depends on monsoon • e.g.) Asian monsoons (India) • 8.2 % economic growth in the year ending 2004 March with the help of the good monsoon • 5.5-6.5% in this year’s growth because of the late onset of monsoon last summer. (Asian Development Bank) • Onset, extent and overall amount of monsoon rainfall play a key role

  9. Relationship between Indian rice production and Indian monsoon rainfall (Webster et al. 1998)

  10. Mechanisms of monsoon 1. Difference in heat capacity of land and ocean

  11. Mechanisms of monsoon Temperatures over oceans do not change as much as over lands January Surface Air Temperature

  12. July Surface Air Temperature

  13. Large differences occur over the continents and smaller ones over the oceans- an indication of the heat capacity of the surface Difference between the January and July surface temperature

  14. Mechanisms of monsoon July SLP

  15. Mechanisms of monsoon January SLP

  16. Mechanisms of monsoon

  17. July SLP Wind

  18. Surface Wind: January SLP Wind

  19. ~ Gigantic land-sea breeze ~ Warm season L H cold warm H L wet Ocean Land Chen et al. 2002

  20. Cold season H L warm cold L H dry Ocean Land Chen et al. 2002

  21. Examples of monsoons Asian monsoon : the largest monsoon India, Sri Lanka, Bangladesh, Indonesia and etc SW monsoon NE monsoon From:http://snrs.unl.edu/amet351/ogren/monsoons.html

  22. The Current system of the Indian Ocean From:Tomczak, Matthias & J Stuart Godfrey: Regional Oceanography:

  23. History of Indian summer monsoon rainfall prediction From:http://www.met.rdg.ac.uk/cag/MOL/Introduction/frameindex.html Motivated by the Great Indian Drought of 1877, the India Meteorological Department is established in 1875 for the seasonal forecast of Indian monsoon rainfall.  In the early part of the 20th century, Sir Gilbert Walker studied the global teleconnections of monsoon for the monsoon rainfall prediction, which led him to the discovery of Southern Oscillation.  . 

  24. The factors influencing interannual variability Indian summer monsoon rainfall • Himalayan snow cover more snow higher albedo  less ∆T  weaker monsoon • Soil moisture more moisture  less ∆T  weaker monsoon • ENSO • ? • ?

  25. 2. North American monsoon ~ Southwest United States monsoon ~ Mexican monsoon ~ Arizona monsoon Increase in rainfall during summer over the dry regions about 35% of Arizona's annual precipitation about 45% of New Mexico's annual precipitation, about 60% of northern Mexico’s annual precipitation

  26. Seasonal distribution of precipitation across southwestern North America. Note that northwestern Mexico shows the strongest monsoon signal, which diminishes through Arizona, New Mexico, and Nevada. Northeastern Mexico and Texas display early summer–late fall precipitation peaks, while the West Coast has a dry summer Mediterranean distribution (vertical axis of all graphs represents 180 mm with 20 mm increments). Areas south of the broken line receive greater than 50% of their annual rainfall in July, August, and September (after Douglas et al. 1993). Mid-to late summer rainfall max following extremely dry condition

  27. Vertical cross section Warm season

  28. Predictability Monsoon rainfall : Important water resources Hazards(storms) Monsoon influenced thunderstorm USA today 06/25/2004 The North American Monsoon Experiment, announced Friday, is getting underway this month to help better understand the weather in northwest Mexico and the southwestern United States…

  29. 3. West African monsoon Precipitation SST June August

  30. Interannual variability ofAfrican monsoon Wet 50-60s, Dry 70-90s

  31. Warmer SST Weaker monsoon Global warming Dryer ??

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