The data gathered by GPM and its international
constellation of satellites has generated an unprecedented global
view of rain and snow. We can see
daily patterns, seasonal movements, the rain in our own backyard,
and weather sweeping the continent. We can analyze regional hazards,
and precipitation that connects the globe.
We can build up months of data, to years,
and decades to look at how precipitation will change in a changing climate.
And we can explore precipitation, from pole to pole,
in a snapshot of a single week.
Daily rainstorms are a constant near the Equator.
George: The interesting thing you see when you look at this is the daily pulse in convection,
what you might call the "popcorn." So for example over Africa,
you see this regular pulsation of convection and
then there are the longer lived events, which are squall lines. Because this happens to be during
August, what we can see is the squall lines, which move across the continent
starting in Ethiopia, and when they come off the coast, they're known as easterly waves.
These are the precursors for some of the hurricanes that we see in the United States.
As you follow them across, the same kind of "popcorn" is taking place in
South America. And if you watch carefully you can see that
line of convection starts along the coast in the afternoon and starts
propogating in. And if you watch the pulsing, what you see is it takes about two days
for those squall lines in South America over the Amazon to reach
the Andes Mountains, at which point they sort of die out because they interact
with this very steep topography. The Atlantic hurricane season was relatively
quiet in 2014, but GPM was able to track storms into
higher latitudes that nevertheless had unexpected impacts.
Dalia: One of the things we can observe with the 2014 hurricane season is actually Hurricane
Bertha, which you see here. Now it was kind of an unimpressive storm, but as you track it across
the Atlantic, what you can see is that it caused massive flooding and wind damage
in the UK. And so be being able to observe tropical cyclones in their
infancy in the tropics and see how they move all the way to the high latitudes
it gives us really important clues into how storms develop and intensify,
all the way into the higher latitudes as extratropical systems.
Gail: And it's really important to know what is happening in those high latitudes because
that's where the majority of people live; it's where the populations are. And so being able
to measure everything from the very light rain, which tends to occur at these
high latitudes, and the falling snow, as well as the very heavy precipitation
that occurs throughout the world, we have this data from the Global Precipitation
Measurement mission. Meanwhile the Pacific Ocean saw a steady
barrage of tropical cyclones, slamming into Hawaii, the Philippines, and
Japan. Gail: Here you can see the different cyclones and
typhoons as they move in the Pacific Ocean, one after another.
What's also important about these is knowing where they are over the vast
ocean so that once they get closer to land, operational users can make
decisions about whether to evacuate people or not.
George: For example we see Supertyphoon Halong, which recurved
and then crossed Japan and started to interact with a mid-latitude cold front.
Once it did that it went, as we say, extratropical
and we can trace it all the way into the Northern Pacific Ocean.
As we head south through Asia, seasonal
rains drench India and its surrounding areas.
Dalia: One of the things we can observe about this dataset is where and when rain is happening.
And by being able to see, for example, this huge cluster of storms from the
monsoons, we can understand where we might get heavy rainfall that leads to
landslides and flooding. In fact what we observed during this time is actually a landslide
that caused 150 fatalities. You can actually see
what's happening just four hours after it occurred. And that near real time
capability is critical for different disaster
managers, understanding where we're getting floods and landslides around the world,
and when we look at the longer term, where we're getting the absence of rain, where we have
droughts, and understanding how those drought conditions are continuing or,
you know, maybe, improved because of rainfall that's coming.
With GPM we can look at how precipitation impacts very large populations,
and shed new light on the area where almost no one lives.
George: From South America, if we look to the south, we see the ocean that runs nearly around
the entire globe, which we call the Southern Ocean. This is really sort of
the terra incognita of precipitation, as far as I'm
concerned. The Southern Ocean has almost no land and very few ships.
It's a really challenging place; you don't go there unless you have to. As a result,
we know very little about the meteorology and the precipitation. When you look at that zone
what you see is the blue and darker purpley colors
which represent snow. Because this is the Southern Hemisphere winter,
there's some snow that we see. We've known about these storms for a long time,
in terms of the cloud patterns but this is the first time we have a really great
visualization of the rain, which is underneath. This is one of the features of these
datasets is that it's like an X-ray that looks through the clouds and actually sees the rain.
Gail: When you take a step back and look at this dataset
from a global perspective, you can see the precipitation at the tropics, that looks like these
"popcorn" convective events. As well as these long-lasting
frontal systems in the high latitudes. And it's with this data
that we can start to understand precipitation globally
and see how it interacts with humans and with the science in understanding it better.