The Indian Monsoon

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The Indian Monsoon

• ATS 553

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Geography Lesson
Himalayas/Tibetan Plateau
Afghanistan
Pakistan
Indian Subcontinent
Arabian Sea
Bay of Bengal
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Reversal of the Winds

• Most dramatic seasonal reversal of the winds in
  the world.

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Northern Summer Flow _at_ SFC
"Southwest Monsoon"
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Northern Winter Flow _at_ SFC
"Northeast Monsoon"
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SST in the Arabian Sea
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SST in the Arabian Sea
0 90 180 270 0
Wind Direction Notice the shift in direction
with the onset of the southwest monsoon.
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SST in the Arabian Sea
0 90 180 270 0
Wind Speed Notice that the southwest Monsoon
(summer) is much stronger than the northeast
monsoon.
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SST in the Arabian Sea
0 90 180 270 0
Temperature Once the southwest monsoon begins,
SST begins to fall, despite the fact that it is
June!
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SST in the Arabian Sea
0 90 180 270 0
Heat Flux During the southwest monsoon, heat
flux is often negative due to huge amounts of
evaporation!
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Positive Feedback in the Winds

• In the Summer
• Continent heats up more than the oceans do.
• Strong flow from the ocean towards the land.
• Very strong flow results in greater mixing in the
  Arabian Sea.
• Therefore, SSTs fallArabian Sea is actually
  COLDER in the summer than it is in the winter!
• Results in even stronger monsoon flow!

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Onset/Withdrawal Dates
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Monsoon Trough Location
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Extremely high temperatures in northern India and
Southern Pakistan.
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A strong heat low!
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Extremely high dewpoints in northern India and
Southern Pakistan. Notice Myanmar!
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Why is the Southwest Monsoon so much stronger
than the Northeast Monsoon?
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To have a strong winter monsoon

• you need the continent to cool down in the
  winter.
• Best accomplished by cold air outbreaks from the
  north.

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The Himalayas are in the way!
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Seasonality

• In Summer
• The continent heats up a lot.
• Feedbacks keep SSTs low.
• Southwest monsoon is strong.
• In Winter
• The continent doesnt cool down all that much.
• SSTs arent particularly warm.
• Northeast monsoon is weak.

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Southeast Asian Monsoon

• Which is why the winter monsoon is so strong in
  southeast asia!

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