The Indian Monsoon ATS 553
Dec 17, 2015
The Indian Monsoon
ATS 553
Geography Lesson
Indian Subcontinent
Arabian SeaBay of Bengal
Himalayas/Tibetan Plateau
Paki
stanAf
ghan
ista
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Reversal of the Winds
• Most dramatic seasonal reversal of the winds in the world.
Northern Summer Flow @ SFC
Northern Winter Flow @ SFC
SST in the Arabian Sea
SST in the Arabian Sea
Wind Direction:
Notice the shift in direction with the onset of the southwest monsoon.
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SST in the Arabian Sea
Wind Speed:
Notice that the southwest Monsoon (summer) is much stronger than the northeast monsoon.
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SST in the Arabian Sea
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
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 fall—Arabian Sea is actually
COLDER in the summer than it is in the winter!
– Results in even stronger monsoon flow!
Onset/Withdrawal Dates
Monsoon Trough Location
Extremely high temperatures in northern India and Southern Pakistan.
A strong heat low!
Extremely high dewpoints in northern India and Southern Pakistan. Notice Myanmar!
Why is the Southwest Monsoon so much stronger than the Northeast
Monsoon?
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.
The Himalayas are in the way!
Seasonality
• In Summer:– The continent heats up a lot.– Feedbacks keep SSTs low.– Southwest monsoon is strong.
• In Winter:– The continent doesn’t cool down all that
much.– SSTs aren’t particularly warm.– Northeast monsoon is weak.
Southeast Asian Monsoon
• Which is why the winter monsoon is so strong in southeast asia!