[data sounds]
The GPM mission is a sophisticated
network of satellites, covering the entire globe in less than three hours,
giving us an unprecedented picture of precipitation,
from rain to falling snow, hurricanes to monsoons,
droughts and floods. So how do we get all of that information
out of this? The short answer: Tons of data
from all over.
As GPM takes snapshots at precipitation,
like in a major storm, the data gathered is transmitted
to a network of satellites called TDRSS.
Erich Stocker: The important thing to recognize is that the GPM satellite does not
talk directly to the Earth; it talks to the communications satellite
which is known as TDRSS. And the TDRSS satellites
talk to a ground station, which is at White Sands, New Mexico,
and that's a very effective way to get
continuous data, which cannot be gotten otherwise, unless you do
direct broadcast and have many, many ground stations, which isn't
as effective as going through the TDRSS system.
The White Sands Ground Station then sends information about the health and
geolocation of the GPM Core satellite to the hub of all
of this activity, the Missions Operations Center, located at NASA's
Goddard Space Flight Center. The raw data streams
into Goddard's Precipitation Processing System, or PPS.
The data from the radar is routed through GPM's partner,
the Japan Aerospace Exploration Agency, for initial processing
and then is sent back to the PPS. George Huffman: The data that come down from
the satellite are actually not precipitation. They're in the form of radiances,
in the case of the microwave instruments, or reflectivities, in the case
of the radar. The computer codes I've been talking about--the algorithms--
are the way we get from numbers
that nobody including me can directly interpret to the thing we care about,
which is precipitation. The GPM mission is not just the Core
spacecraft, but also a constellation of existing satellites
from partners around the world. Each constellation member may have its own
unique scientific objectives, but they all contribute data to the PPS
in order to develop global precipitation products.
Erich Stocker: The Precipitation Processing System gets data from the satellite and
various other sources and creates the science products
that are going to be used for both applications purposes, that is
societal benefits, and scientific research. The PPS then produces
a suite of data products, including both instrument specific and
merged data, unifying the data gathered by the international
partner satellites that make up the GPM constellation.
George Huffman: You could compare this to making soup. We have
carrots, and we have onions, and we have potatoes.
They're all vegetables. And so you have to wash them, peel them,
take out the bad spots. That's a really important step, you don't want your soup to
taste bad. When you get done, of course, you have to taste test it to make sure the
seasoning right, and then you have to serve it. And so each of those steps
in a mathematical sense, is what we have to do in order to take all the
diverse sources of information and end up with a unified product
which the user finds to be useful. These precipitation
products will be useful in many societal applications, like
hydrologic modeling, mapping potential natural disasters,
agricultural modeling, weather prediction,
and climate research. Erich Stocker: As we improve the precipitation
retrievals that form the basis for these merged products
that will get better and better, and we'll be seeing actual satellite data
rather than just forecasts. [raindrops falling]