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Huffman: The monsoon is a seasonal wind and rain pattern that was first described

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over south Asia. You see the clouds

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blossoming here during the summer part of the monsoon.

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For centuries people have known about it, but only recently have we received

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enough data from satellites to really describe what's going on.

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Skofronick-Jackson: What you can see here is moist air that has evaporated from the ocean,

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coming across India and providing rainfall, driving the monsoon

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season. The great thing about GPM is that it allows us

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to see precipitating systems as a whole, over land and

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oceans, and then as they transition from one boundary to the next.

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Huffman: All this rainfall drives soil moisture over land. It's

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beneficial because it promotes the economic activity that people depend on,

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for example, agriculture. As well it fills the rivers,

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which provides water for human activity and the natural environment, as well as

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transportation. If the rivers get too full,

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of course, it becomes flooding. At first the floods you see here are fairly

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minor and broad-scale but then they concentrate in the few wiggly lines

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which are the river basins, for example, in central eastern China.

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Skofronick-Jackson: In mountainous regions

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when the ground becomes saturated due to heavy rains it can lead to

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landslides. Landslides kill thousands of

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people every year and are primarily triggered by rainfall. They

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are especially common in the Himalayan region each monsoon season.

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Huffman: One really cool way to look at the monsoon

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is to do a split-screen and look at the summer and the winter at the same time.

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In the summer the wind is blowing onshore, bringing

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the moist rain-laden air into the continent. In the

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winter time, it blows off the continent.
Skofronick-Jackson: Now those winds are

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basically driven by temperature differences between the ocean and the land.

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And where the land is nice and warm, the air expands and it draws

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in the moist precipitation from the ocean waters, but in the winter

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time, it's very cold and you can see that the moisture then it goes

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from the continent back into the oceans. Over the past fifty

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years or so, satellites have been used to measure precipitation all around

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our Earth. With that dataset we're able to understand

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that monsoons occur not only in south Asia and India,

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but in other parts of the world as well.
Huffman: For example, Africa, where the

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temperature gradient is between the Atlantic Ocean and the Sahara Desert, the

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wind blows from the moist Atlantic Ocean onto west Africa

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providing the moisture for the precipitation. Some of these westward

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moving storms provoke hurricanes over the Atlantic that occasionally make it to

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the U.S. Southwestern North America also has a summertime

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monsoon. You see high soil moisture in regions where there's a lot

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of precipitation in western Mexico, and later in the season this extends up

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into the southwestern U.S. And the Southern Hemisphere has

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a monsoon as well. This occurs in the Northern Hemisphere winter,

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which is the Southern Hemisphere summer when Australia is warmer

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than the ocean to the north.
Skofronick-Jackson: Having a better

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understanding of the global water cycle and monitoring changes over time

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is important for society, for our everyday lives

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and our long-term future.