[music]
[music, rain falling] Lau: A monsoon is a very
special kind of climate system.
It is classified in terms of a prevailing
strong winds that reverse distinctly as the
season. And also it is described
by a very distinct a very wet and dry season.
The rainfall that falls within that wet season should
be more than sixty percent of the entire year.
Huffman: The fundamental drive for the monsoon, both in India and
other parts of the world, is that there's a large area of land, which gets warm compared
to the surrounding ocean. And that surrounding ocean provides the moisture, which is
then driving the precipitation that constitutes what we think of as
monsoon. Lau: If you simply look at the Asian monsoon, you
can estimate--the various estimates--more than sixty percent of the world's population
live right in that area. And the monsoon--
the water--provides the freshwater supply for this population.
Not just for the daily life, for agriculture, for the industry. And so
the entire region, the people's livelihoods depend
on the very delicate balance, the water balance, in that region.
Huffman: GPM gives us a chance to look at precipitation around the
world. And so in addition to the hurricanes and typhoons, we're also
looking at the monsoons because those storm systems are very important for driving
floods, and the advancements in GPM
will allow us to do a better job of providing precipitation information so they can make better
forecasts of the floods. Lau: Monsoon is not just simply a local problem,
a curiosity, it actually has a huge amount of societal
impact in terms of how it changes in that region, the economy
in that region can affect the entire world, as well as many, many things that
happen in that region. GPM has the most advanced dual-frequency
radar that actually measures
the vertical structure of the rainfall itself. And that's very
important. Huffman: The DPR gives us an unprecendented
capability of teasing out relative sizes of particles, and this is really important for
understanding how the microphysics, the rain process, works,
and the snow process, and also how those then can be represented in
numerical models that are critical for forecasting future events.
Lau: To study the monsoon, one thing we didn't know is to know what we call
the predictability of the monsoon, how well can we predict the monsoon at a time.
And in order to do the prediction, we need to know the variability
very well, and this ranges from daily to weekly, seasonal,
and then to what we call decadal variability. Huffman: The monsoon was first
named in India, but it turns out that the same driving force happens
in other parts of the world. And so, for example, in the Northern Hemisphere summer
you have monsoon in West Africa, you have the monsoon
in southwestern North America, and then in our winter,
the Southern Hemisphere's summer, there's a monsoon that happens across northern
Australia. The great thing about GPM is that it allows you to see
the rain systems as a whole. You get to see them over the ocean and over the land,
you can see what the transitions are. And so even before it gets to land, where we
have surface observations, we can tell what's going to come in,
we can see what's been happening. And of course scientifically that also allows us
to understand the complete water cycle that's taking place in the South Asia region.
[stream flowing, rain drops, music]