Terra Cognita: Using Earth Observing Systems to Understand Our World
Now a global effort is under way to revolutionize our
understanding of the Earth as an interconnected whole. The effort aims to
integrate Earth observing capabilities based on satellites and in situ or
ground-based sensors into a Global Earth Observation System of Systems
(GEOSS). By uniting these systems, scientists hope to take the pulse of
the planet,
and in so doing, generate a range of environmental, economic, and health
benefits.
For instance, should the effort yield even a 1°F
improvement in weather forecasting, power utilities can plan their daily
output needs more accurately, resulting in an annual $1 billion electricity
savings for consumers in the United States alone, according to the U.S. Environmental
Protection Agency (EPA). Likewise, improved monitoring of air pollution,
or better satellite mapping of habitats that harbor malaria, cholera, or
West Nile virus, could save many lives by establishing warning systems
for at-risk populations that might reduce exposure.
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A system for change. Proponents of a new Global
Earth Observation System of Systems (GEOSS) envision using data from
satellites and a variety of ground-based sensors to aid public health
goals around the world. One potential use is to compile satellite mapping
of habitats that harbor disease microbes such as Vibrio cholerae (right).
This may help provide early warning to at-risk populations, such as
the residents of Dhaka, Bangladesh, where one hospital alone (above)
received more than 300 new cholera patients every day during monsoon-related
flooding in July and August 2004.
image(s):Top to bottom: Dieter Telemans/Panos Pictures; Dennis Kunkel
Microscopy |
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A total of 54 countries, the European Union, and 33 international
organizations have joined the GEOSS thus far, providing a welcome boost to
the environmental reputation of its sponsor: the United States. The project
is also the first project of its kind to get such high-level support, says
Steve Goodman, chief of the Earth and Planetary Science Branch at the National
Aeronautics and Space Administration (NASA) Marshall Space Flight Center.
“I’ve never seen a program move at a pace like
this with such a sustained effort,” says Gary Foley, who is director
of the EPA National Exposure Research Laboratory. “It seems to be the
right thing at the right time with the right leadership. It was what everyone
seemed to be looking for.”
A Basis in Climate Change
The pioneering force behind the 15-agency U.S. effort is
Conrad C. Lautenbacher, a retired Navy vice admiral who currently heads the
National Oceanic and Atmospheric Administration (NOAA). Lautenbacher’s
efforts to promote Earth observations date back to his days with the Consortium
for Oceanographic Research and Education, a Washington, D.C.-based
advocacy group that he directed until arriving at NOAA in 2001.
Lautenbacher’s initial goal with the Consortium for
Oceanographic Research and Education was to improve studies of climate change,
which he says are severely limited by data gaps and inconsistencies in ocean
monitoring. Lautenbacher attributed the data shortages to what he calls a “principal
investigator mentality” in ocean research. “You have research by
scientists who compete for grants, publish their results, and move on,” he
says. “There’s no sustainable component to it, nothing to tell
you what’s going on over the long term. That’s what’s essential
for climate research.”
The best way to bolster ocean monitoring, Lautenbacher
reasoned, was with a sustained and globally integrated research effort based
on satellites and sensing devices in the ocean that would generate continuous
data streams. Such an approach, he says, would clarify the role of the oceans
in climate and provide immediate benefits in coastal management.
At NOAA, Lautenbacher continued to push for an ocean observing
system, but his views on the technology had begun to expand. While attending
the World Summit on Sustainable Development, held in Johannesburg in September
2002, he was exposed to other uses for Earth observations in areas such as
agriculture, forestry, and public health. Many scientists at Johannesburg were
convinced that Earth observations are necessary to promote sustainable development
across the spectrum of human activities.
When he returned to the United States, Lautenbacher and
his cochairs on the National Science and Technology Council Committee on
Environmental Natural Resources convened an interagency task force and charged
it with organizing
a global summit on Earth observations. When the Earth Observation Summit
was held in Washington on 31 July 2003, it was on a scale that few of its
organizers
might have anticipated--five U.S. cabinet members and ministers from 33
countries and the European Union were in attendance. U.S. secretary of state
Colin Powell launched the meeting, saying in his opening presentation, “We
need to be able to see, hear, taste, smell, and measure the blue orb we have
been given and that we call Earth.”
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It takes all kinds . . . of tools. To be fully functional, the GEOSS
will rely on a variety of tools. Simple gauges such as tipping buckets
(above), which measure rainfall, provide measurements that can be correlated
with data from more complex technologies, such as the satellite Aqua
(left). The satellite image below, taken with MODIS instrumentation aboard
Aqua, shows clouds of sediment (pictured in turquoise) in the southern
Persian Gulf mixed with microscopic marine organisms (where the clouds
appear more greenish). Such information may offer clues about potential
future disease outbreaks.
image(s): clockwise from top right: U.S. Geological
Survey; NASA; NASA |
Participants at the summit adopted a declaration calling
for a comprehensive, coordinated, and sustained Earth observation “system
of systems.” Among the goals laid out in the declaration are improved
coordination of Earth observing strategies and systems, the free-flowing exchange
of observational data, and coordinated efforts to promote the access of developing
countries to the technology. The ad hoc Group on Earth Observations (GEO) was
formed and charged with creating a 10-year implementation plan to realize these
goals. The cochairs of the ad hoc group now include Lautenbacher; Akio Yuki,
the Japanese deputy minister of education, culture, sports, science, and technology;
Achilleas Mitsos, director-general of research with the European Commission;
and Robert Adam, South Africa’s director-general of science and technology.
A framework for GEOSS’s 10-year implementation plan
was adopted at the second Earth Observation Summit, held in Tokyo on 25 April
2004. The completed 10-year plan will be adopted by ministers at a third summit,
to be held in Brussels on 16 February 2005.
The Nuts and Bolts
So, what exactly is an “Earth observing system”?
In general, the term describes any collection of tools used to take measurements
of air, water, and land. These tools can be as simple as a pH sensor or as
complex as a constellation of satellites in space. Both simple and complex
tools are necessary; orbiting satellites cover broad sections of the planet
with limited resolution whereas ground-based tools cover more limited regions
with high resolution. When combined, these technologies provide the data
needed to understand how physical and biological forces control the biosphere.
A total of 73 Earth observing satellites are in orbit now,
of which 25 are owned by the United States. Of these, most are deployed by
NASA, with the remainder operated by NOAA, the U.S. Geological Survey, and
a few private firms. A growing number of countries--among them the European
Union countries, India, Russia, China, Brazil, Japan, and Canada--also
have Earth observing satellites.
Satellites gather data by remote sensing, a process that
generates measurements of Earth surface features and the atmosphere according
to how they reflect visible or infrared radiation. Every object--down
to a single molecule--reflects radiation according to a specific wavelength,
which becomes the object’s own de facto signature. Computer
algorithms convert these signatures into measures of forest cover, soil moisture,
cloud cover, ocean chlorophyll content, and many other useful parameters.
Remote sensing is an especially powerful capability when
it is incorporated into a geographic information system. These systems integrate
satellite and other geophysical data with socioeconomic data such as population
demographics. What results are maps that allow researchers to “see” their
parameter of interest in relation to their geographic position.
Although some satellite sensors can view the Earth’s
surface through cloud cover, experts say that spatial and temporal resolution
are still inadequate, and there is no way to image what lies underwater. Thus,
it’s still necessary to use a range of additional in situ tools,
such as weather balloons, aircraft, pollution sampling devices, and buoys
that take physical measurements of the atmosphere, ocean, and land.
Fixed buoys, which are moored to the sea floor, float on
the ocean surface and transmit ocean and weather data. Of the roughly 100 fixed
buoys now in existence, most are found in equatorial waters. So-called Argos
buoys function in a different way. These buoys sink to a depth of 2,000 meters
and then drift for 10 days. Upon rising to the surface, they transmit water
temperature and salinity data into space, where it is received by satellites
that beam it back to scientists and weather agencies on Earth.
A total of 1,500 Argos buoys are now at work throughout
the world; a global consortium responsible for the effort plans to deploy 1,500
more over the next several years.
Establishing the GEOSS
The problem with current Earth observing systems, experts
say, is that they operate in isolation without “speaking” to each
other. GEOSS members often describe the systems as “research stovepipes,” with
limited flexibility and focused application to particular needs. “For
instance, some weather satellite instruments look only at cloud temperatures,
but these same instruments, if tuned differently, could provide better detection
of wildfires,” explains Helen Wood, senior advisor for systems and services
in NOAA’s National Environmental Satellite, Data, and Information Service,
and director of the GEO Secretariat, the forum through which GEOSS members
will organize their work. One of the GEOSS’s main goals, she says,
is simply to get researchers talking to each other and to end users about
what
they do. Just by discussing mutual needs, researchers might be prompted to
design enhanced instruments that can be used for multiple purposes, she says.
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The delta blues tell a story. Data gathered over the long
term may help researchers better predict how Earth systems will change
in the future. The Landsat images above show how sedimentation of the
Mississippi Delta has changed over the past 30 years. The first image,
taken in 1973, shows a rich swell of sediment (visualized in blue). But
the building of dams and artificial channeling along the Mississippi-Missouri
River system decreased the amount of sediment that the currents carry;
the second image, taken in 1989, shows how the delta began to lose marshland
along its southeast edge. By 2003, when the third shot was taken, the
addition of channels in the natural river levee had resulted in new marsh
formation.
image(s): NASA |
Another important GEOSS goal, Wood adds, is to establish
a coordinated system of data sharing that is freely accessible to users throughout
the globe. Achieving this aim won’t be easy--many countries differ
with respect to data standards, formats, and their own commercial views on
the technology. For instance, the United States provides much of its satellite
data for free, but the European Space Agency often charges for its data to
recoup investment costs. Lautenbacher emphasizes that the need for consensus
on business models for data sharing is critical and will likely take years
to sort out.
Just the fact that GEOSS members agreed in principle to
full and open data sharing with minimal time delays (as described in the
2003 declaration) was a big step forward, says Rick Ohlemacher, manager of
environmental
systems at Northrop Grumman Space Technology. “That in and of itself
was a huge political milestone,” he says. “For several decades,
no one was able to get beyond that, so now the door is open.” Northrop
Grumman is one of the founding members of the Alliance for Earth Observations,
an industry group established to support the GEOSS vision. The company is
also the prime contractor for the future National Polar-Orbiting Operational
Environmental
Satellite System, which Ohlemacher says will be a key component to the satellite
backbone of the GEOSS.
What the GEOSS provides, Ohlemacher says, is an enabling
landscape where members can discuss how to expand global use of Earth observing
technology. Ideally, the GEOSS would serve Earth observations in much the same
way that the World Meteorological Organization serves weather forecasting,
many experts suggest. The latter organization is an optimal model for the GEOSS
for several reasons, Lautenbacher explains. It has a relatively long history
(dating back to 1950), an effective governance structure, a permanent secretariat,
and a mechanism for building and maintaining agreements. It also provides nations
a way to manage technical issues while respecting each other’s sovereignty. “There’s
no hint of language that says ‘we’re going to come into your country
and tell you what to do,’” Lautenbacher says. “But you can
go anywhere in the world and get a weather forecast.”
Capacity Building
To achieve similar value, the GEOSS must not only stimulate
dialogue and open access, but also must find a way to bring poorer nations
into the technology loop and get the developing world actively engaged in the
system. Most developing countries lack the resources needed to use Earth observations
effectively. Moreover, Ohlemacher says, it can be hard for scientists in these
countries to communicate the benefits of Earth observations to more traditional
populations, who might not understand how information derived from space could
be useful or even desirable.
The lack of developing country resources also extends to
coverage; indeed, much of the developing world is a blind spot for Earth observations,
says Goodman. “We have geostationary weather satellites ringing the planet,” says
Goodman, “but what we need is greater temporal sampling from [higher-resolution]
lower-orbiting satellites that pass over a point on Earth much less frequently --two
to four times per day--to achieve the needed global coverage.” Goodman
says the gaps in surface measurements are significant in the developing world--where
there is less Earth-based monitoring--compared to European nations and
the United States.”
The gaps are problematic because without surface observations,
scientists can’t adequately validate measurements made from space. Furthermore,
some parameters are not well observed from space. One example is rainfall volume,
which satellites are not yet able to measure directly. In Europe and North
America, thousands of simple “tipping buckets” measure minutely
to hourly rainfall, which is combined with satellite remote sensing to model
weather patterns and local hydrology. But tipping buckets are rare in developing
countries, as are more sophisticated instruments like weather radar, which
detects clouds and precipitation. “There are possibly as few as three
weather radar in the entire African continent,” Goodman says. “Here,
every state has one, and TV stations tend to also have their own.”
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Poseidon adventure? The Northeast Pacific Time-Series Undersea
Networked Experiments (NEPTUNE) Program is an ambitious plan to wire
an entire tectonic plate off the Pacific Northwest with sensors delivering
real-time data from above and below the sea floor.
image(s): University of Washington School
of Oceanography |
Global blind spots have numerous consequences. Obviously,
without sufficient coverage, developing nations don’t have access to
global observation data that might be useful to them [for more on this topic,
see “Building a Tsunami Warning System,” p. A90 this issue].
But the consequences also extend to developed countries
and the Earth as a whole. Goodman points out that long-term weather forecasts
in North America are less accurate than they could be thanks to a lack of data
from the oceans as well as from Asia, Africa, and Latin America. Moreover,
studies of long-term trends such as climate change depend on knowledge of events
taking place throughout the biosphere. If scientists can’t quantify the
effects of, say, carbon fluxes in the Amazon basin, they will be unable to
generate the more comprehensive climate models they desire.
Earth Observation in Action
And yet, scientists interviewed for this article unanimously
agree that Earth observations are useful now, and are becoming more so. Michael
Emch, a spatial epidemiologist at Columbia University, has spent years using
remote sensing to study tropical disease epidemiology. Much of his work is
devoted to studies of cholera in the coastal nations of Bangladesh, Vietnam,
and Mozambique. Using remote sensing data from NASA’s Terra and Aqua
satellites--which are both components of the agency’s Earth Observing
System program--Emch has correlated cholera incidence with sea surface
height, sea surface temperature, and ocean chlorophyll content. These parameters
are all potentially linked to the generation of plankton blooms that harbor Vibrio
cholerae, the bacterium that causes cholera. “If we can sort out
the role of these variables, then we might be able to predict epidemics months
before they occur,” he says. “That’s the ultimate goal, but
it’s a long way off.”
Emch concedes there is an ever-growing need for new instrumentation.
For instance, satellites are unable to detect the salinity levels that are
key to the survival of V. cholerae. Greater image resolution is also
needed to quantify and monitor environmental changes, he says.
The multichannel remote sensing device carried by the Terra
and Aqua satellites, which is known as the Moderate-Resolution Imaging Spectroradiometer,
or MODIS, measures ocean chlorophyll levels in spatial increments of 1,000
meters and land boundary changes at increments of 250 meters [for more information
on this instrument, see “MODIS
Operandi for Mapping Haze,” EHP 111:A458
(2003)].
This is a significant improvement over previous sensing
technologies, but one that still falls short of some research needs. In most
cases, remote sensing won’t provide conclusive evidence that an outbreak
is going to occur, Emch says. Scientists also need ground-based observations--for
instance, of the micro-scale environments inhabited by disease vectors, or
of actual human populations at risk.
Another active proponent of Earth observing technology
is Foley, who says Earth observations are increasingly relevant to the EPA’s
mission. For more than 10 years, the EPA has used remote sensing data generated
by NASA’s Landsat satellite program (now in its 33rd year) to monitor
changes in urban landscapes, among other uses. Remote sensing will ideally
advance new public warning systems for air and water pollution hazards, Foley
says. But in the meantime, his biggest challenge is convincing EPA decision
makers of the technology’s potential. “They often don’t know
how to use the data,” he explains. “It’s not traditional,
so we need to do some education and capacity building right here. But we intend
to go all the way with this--resources, time, and science permitting.
John Delaney is as close to the technology’s forefront
as anyone on Earth. A professor of oceanography at the University of Washington
in Seattle, Delaney directs the Northeast Pacific Time-Series Undersea Networked
Experiments (NEPTUNE) Program, one of the most comprehensive Earth observing
efforts ever launched. NEPTUNE scientists seek to wire an entire tectonic
plate off the Pacific Northwest with thousands of sensors both above and
below the
sea floor, all of them delivering real-time data to scientists on shore.
The plan also calls for a fleet of underwater robots that will travel toward
volcano
eruptions, earthquakes, storms, and any number of other events to collect
data. The $250 million price tag for the system is gradually being met through
a
variety of grant programs.
“[This program] gives us the ability to be in the
environment continuously,” Delaney says. “To really understand
the ocean we have to be in the environment all the time and be flexible enough
to adapt, observe, quantify, and sample.” Lautenbacher describes NEPTUNE
as being on the cutting edge of research. “It’s where we will develop
new sensors and ways to measure things we can now only dream of,” he
says.
Moving Forward
In the years to come, GEOSS stakeholders will be focused
on a number of priorities. According to Lautenbacher, these include the creation
of a governance structure for the organization, the resolution of technical
issues related to data sharing, and an inventory of Earth observing capacity
needs.
Meanwhile, many of the countries working toward the GEOSS
are also pursuing systems integration efforts at home. The United States, for
instance, has convened an Interagency Working Group on Earth Observations,
which is cochaired by representatives from NASA, NOAA, and the White House
Office of Science and Technology Policy.
On 8 September 2004, the group released a draft version
of its Strategic Plan for the U.S. Integrated Earth Observation System.
The report lays out a framework for U.S. participation in the GEOSS and describes
opportunities in nine “societal benefits areas” where the technology
can advance environmental goals.
Mary Gant, a program analyst at the NIEHS and a member
of the interagency working group, says Earth observations will be broadly useful
for environmental health, and for exposure assessment in particular. “One
of the most difficult problems with which the health communities must cope
is the accuracy of exposure assessment,” she says. “The data and
data products from an enhanced, integrated Earth observation system should
greatly increase our ability to do exposure assessment.”
Other countries are also proceeding with their own domestic
and regional programs, albeit inconsistently, Lautenbacher says. In terms of
countries that could propel the GEOSS, those represented by the European Union
are perhaps best prepared, he suggests. The European Union has a Global Monitoring
for Environment and Security initiative, which has created partnerships among
the European Space Agency, the European Environment Agency, and other institutions.
The initiative lays out a process for ensuring that Earth observing data needs
are met in both the near and long terms.
Initiative members are now establishing a uniform architecture
for integrating space, terrestrial, seaborne, and airborne monitoring platforms.
Thus, the initiative may provide a model for technical integration throughout
the GEOSS, Lautenbacher says.
Earth observations could do much to improve our views and
our understanding of the world around us. Many challenges remain for GEOSS,
not just in terms of technical barriers but also cultural and institutional
ones. But this growing network of sensors and satellites may represent the
best opportunity to discover and quantify the fundamental drivers of the biosphere.
Just as satellites and space exploration programs turn our attention outward,
similar tools focus our attention inward, toward the unifying forces that hold
life in a balance.
Charles W. Schmidt
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