[ no audio ]
Sure, what we need to understand
you know, not just what's happening in our backyard, but also what's happening at the global
scale, and because we're able to observe both light rain and heavy
rain and snow. We're able to see how storm systems that originate in our part
of the world, for example Hurricane Bertha, you know we can see how that affects
other places. So Hurricane Bertha was not such an interesting storm for
the U.S. but as it moved across the Atlantic it caused
extensive flooding and actually some fatalities in the United Kingdom.
So getting that global picture and being able to track patterns of weather from
one place to another is a very powerful way to see how our water cycle
and our weather is interconnected.
It took about ten years to build the satellite and we have some great
video showing how the instruments were added to the space spacecraft bus
how they were tested, how we shipped the spacecraft
From the United States, NASA Goddard Space Flight Center
To Tanegashima Island in Japan, our partners with this satellite.
But really the concept for this mission was about 10 years prior
to that. So really from concept to launch was almost
20 years. so it takes a long time to conceive. build. and launch
such a satellite.
Well knowing where when and how
much it's raining and snowing is really vital for understanding extreme events like
landslides or floods. You know one of the things that we observed is that there's
different seasons for some of these intense hazards that can cause fatalities.
For example the monsoon season in Asia, for example
can cause extensive landsliding. Every August and September and October
we have lots of landslides and flooding as a result
of heavy rains from the monsoons. In other areas we have
flooding from the spring rains or from heavy summer rains
So it really depends on what season is and what the
the topography of the areas that can cause both strange weather and
impacts like natural disasters.
Understanding how our water cycle is connected
so where air moves and evaporates
from the surface, it condenses to cause precipitation and where that goes
whether it's over land or over ocean really tells us about what
our reservoir in the sky is doing and how that feeds our reservoir
on the surface and underground. And so with satellites we get
this remote perspective allowing us to see the whole globe at once.
You know if you look at water gauges for example, we don't have any over the oceans.
But what you can see in this rainfall accumulation
showing this Super Tyhoon Haglong is that
we have a ton of rainfall over the ocean and then also it impacts land.
and caused extensive flooding in Japan. And so if you take all of the
rain gauges in the world and put them together they only fit into two basketball courts. So we really
need that vantage point of space to tell us what's happening with our
precipitation and where it might impact society.
Well Earth is a very interesting system. We have
this very, very tropical warm region which
evaporates water from the surface and it condenses and it creates
a lot of rain in the tropics. Now when you move farther up that air
moves up and sinks at the kind of middle latitudes in the deserts and
This is where we see most of the Earth's deserts in the Sahara, but
also over the ocean. There's actually a desert over the ocean.
If you look at areas that get a lot of rainfall, you know there's sometimes where,
the fissures get really wet. You know we have these huge areas where
you have a lot of freshwater coming into our oceans. And then higher up,
we have, for example, light rainfall which is a huge contributer
to freshwater resources in high latitudes. So that circling
of and cycling of precipitation both from
land to ocean as well as from the equator to the poles
is important and vital for driving our global water cycle
and our global energy cycle. And so that's why understanding precipitation
where it is, how much we have and where it's moving is so important.
Well the United States is a really interesting place because it's kind of sandwiched between the
tropics and the higher latitudes. And what that allows us to have is a lot of
different weather patterns in different regions. Now what matters in this
region is that you see these storm systems moving from west to east
across the country and that can dump a lot of rainfall in the midwest, but we've
observed out west in California is a prolonged absense
of rain actually causing lots of draught. And so what's important is that
we can get this global picture, even this U.S. picture, to understand
where we're getting more and less rainfall and how that's impacting our society.
That really gets at the
notion of climate zones. If you have precipitation
which is very steady and dependable, then the vegetation
will grow that depends on having lots of steady vegetation.
Steady precipitation. On the other hand
if precipitation very intermitent, for example in the west coast.
Particularly in the southern California.
they have a so-called Mediterrean climate. It's very dry in the summertime
and it's supposed to rain in the wintertime, but of course the last few years that hasn't happened.
but, having that very intermittent precipitation
introduces really fundamental changes in the kind of vegetation
that's easy to grow there.
Well as you might imagine
you can see from your local ground radars
localized rain maps provided by the TV channels
You can also see from satellite imagery white cloud tops taken
at the tops of the clouds. So this new imagery allows us to provide
uniform precipitation estimates using a constellation
of satellites put all together. So you can
see all the way down to the Earth's surface, the rain falling there impacting
science and society.
GPM is able to see the type of precipiation under the clouds
because we are able to use the radar onboard. It's a new
technology that allows you to see layer by layer within the clouds
and within the precipitation. And so it provides something like a
CT-scan that a doctor might use. And every 250 meters
we see the structure of precipitation within the clouds with this radar
instrument provided by the Japanese.
Absolutely. The annual pattern is referred to as a seasonal cycle so
you certainly know in the United States it's cold in the winter
warm in the summer. But in addition there are precipitation patterns that go along with
that. That's true around the entire world. And of course in the southern hemisphere
the seasons are reversed. Our summer is their winter and vice versa.
In the tropics it's not really warm and cold is just wet and dry.
There's lots of places where it's wet part of the year and then dry part of the year.
And so these patterns repeat every year
and then there are other interesting variations that actually go from.. between years
So there is more than just the annual cycle
So the patterns change most notably
in the tropical regions because this is where the year to year
fluxuations are the largest. So you have perhaps heard of El Nino
and La Nina which originate in the Pacific Ocean.
but extend well beyond that. In El Nino you
have a massive amount of precipitation which is in the eastern Pacific Ocean
and in La Nina you get a sort of reinforcement of the usual pattern where
the equator doesn't have precipitation
in the eastern Pacific Ocean. There are other patterns which
we're less familiar with. There's something called the north Atlantic
oscillation, the Antarctic oscillation. These are sort of technical
sounding. But all it means is there's the repeating patterns that are
maybe seasonal in length. In addition there are longer
Patterns, the most notable of which is the Pacific decade of oscillation
that's a really big sounding word, but all it means is it takes about a
decade or 10 years for this pattern to work itself through.
The implication of that of course is you need say 20 years of data in order to
reliably detect the Pacific decade of oscillation.
So there's a lot of really interesting patterns to study.
Well I think debunked is maybe not
quite the term, but what we've got is a search to
understand better what's going on. And so for example we
always have known that there is snow at the top of hurricanes,
but when we get these data which are for the first time are really working
systematically to visualize snow, when you look at a hurricane, for example Hurricane
Arthur, you see snow at the top. So the warm
colors toward the surface are rain and the cool blue colors
at the top are snow. Who knew all over the tropics it's
snowing just four miles up. Another important factor
that we haven't really understood is the precipitation
in the Southern Ocean. There's very little land there. It's a very rough
weather and people don't go there unless they have to. And so this
satellite system allows us to systematically view
the Southern Ocean in a way that we haven't before and I'm really hopeful that
we will now see much more quantitative, accurate results there.