[ Music, wind and rain ]
Voice: This is what we
call severe damage.
This is the bridge out of town, and we're not going anywhere.
[ rushing water ]
Voice: A woman was stranded here all day long through the storm...
[ bridge collapses ] Voice: Oh my God!
Tropical Storm Irene bears down on New England. In Vermont
the storm pushes up agains the higher terrain, and the rain intensifies.
This is the worst flooding Vermont has seen in nearly
75 years. Tropical cyclones,
a general term for hurricanes, typhoons, and tropical storms like Irene,
don't just stick to the tropics. These storms can charge
northward and wreak havoc in areas that normally wouldn't see
this kind of extreme weather. Satellites provide us with
near real-time information about the intensity of storms
and where they're headed. Since its launch in 1997,
TRMM, the Tropical Rainfall Measuring Mission, has remained a
gold standard in collecting global rainfall data on storms.
Scott Braun: TRMM's usage for hurricanes has also been a major application.
Operational agencies use it to get
center fixes on storms to monitor how the internal structure
of a storm is changing and how that might relate to the potential for
a storm to either intensify or weaken. And while TRMM provides essential information
on cyclones for tropical areas, for regions like New England,
TRMM simply falls short. Braun: We knew going into TRMM that there
were going to be some limitations. The primary one being its relatively low
sensitivity so that it would not be able to get the very low rainfall
rates that you might see up at higher latitudes.
Carlisle: So part of what GPM is supposed to do was just continue those measurements,
but also GPM is to improve those measurements by being able to
for example, measure precipitation over a wider swath
of the Earth. TRMM is just at about 35 degrees,
GPM gets more of the Earth in its measurements, going
all the way into southern Canada, for example. The Global Precipitation
Measurement mission, or GPM, is a constellation of satellites
unified by the GPM Core Spacecraft that will provide a global picture
of rain and snow every three hours. When GPM launches in
2014, it will greatly improve upon some of the limitations
of TRMM. In addition to measuring a wider swath of the globe,
the GPM Core Spacecraft will carry more advanced instruments with
greater sensitivity. There's the GPM Microwave Imager, or
the GMI, a radiometer that will use 13 microwave
channels to capture precipitation intensities and horizontal
patterns. Then there's the Dual-frequency Precipitation Radar,
or the DPR. That uses two frequencies to
visualize in 3D the precipitation structure from the cloud down
to the surface. Braun: With GPM we have the opportunity now
with more advanced technologies to improve upon TRMM
by having that second frequency and being able to measure
the lighter rainfall and produce a more accurate rainfall estimate
by having the two combined. With GPM's more sensitive instruments
and wider coverage of the globe, we can more accurately profile a tropical
cyclone, predicting where they're likely to form, how intense
they're likely to become and tracking the path they'll take
so that agencies can make better decisions to help get people out
of harm's way. [ music ]
[ beeping, thunder ]