NASA: Features - Blue Marble (next generation) - Links - Also a link to suscribe to NASA Earth Observatory - Enjoy science :)
Posted by Ricardo Marcenaro | Posted in NASA: Features - Blue Marble (next generation) - Links - Also a link to suscribe to NASA Earth Observatory - Enjoy science :) | Posted on 9:09
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Everyone knows that NASA studies space;
fewer people know that NASA also studies Earth. Since the agency’s
creation almost 50 years ago, NASA has been a world leader in
space-based studies of our home planet. Our mission has always been to
explore, to discover, and to understand the world in which we live from
the unique vantage point of space, and to share our newly gained
perspectives with the public. That spirit of sharing remains true today
as NASA operates 18 of the most advanced Earth-observing satellites ever
built, helping scientists make some of the most detailed observations
ever made of our world.
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To access Blue Marble images in multiple resolutions, visit Visible Earth.
Also available in Ukrainian (translation by Vlad Brown).
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In celebration of the deployment of its Earth Observing
System, NASA is pleased to share the newest in its series of stunning
Earth images, affectionately named the “Blue Marble.” This new Earth
imagery enhances the Blue Marble legacy by providing a detailed look at
an entire year in the life of our planet. In sharing these Blue Marble
images, NASA hopes the public will join with the agency in its
continuing exploration of our world from the unique perspective of
space.
To learn more about the development of NASA’s imagery of the Earth as a whole, read the History of the Blue Marble.Enhancements
Blue Marble: Next Generation offers greater spatial
detail of the surface and spans a longer data collection period than the
original. The original Blue Marble was a composite of four months of
MODIS observations with a spatial resolution (level of detail) of 1
square kilometer per pixel. Blue Marble: Next Generation offers a year’s
worth of monthly composites
at a spatial resolution of 500 meters. These monthly images reveal
seasonal changes to the land surface: the green-up and dying-back of
vegetation in temperate regions such as North America and Europe, dry
and wet seasons in the tropics, and advancing and retreating Northern
Hemisphere snow cover. From a computer processing standpoint, the major
improvement is the development of a new technique for allowing the
computer to automatically recognize and remove cloud-contaminated or
otherwise bad data—a process that was previously done manually.
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The Blue Marble: Next
Generation is a series of images that show the color of the Earth’s
surface for each month of 2004 at very high resolution (500
meters/pixel) at a global scale. This image shows South America from
September 2004. (NASA image courtesy Reto Stöckli and Robert Simmon)
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Blue Marble: Next
Generation improves the techniques for turning satellite data into
digital images. Among the key improvements is greater detail in areas
that usually appear very dark to the satellite (because a large amount
of sunlight is being absorbed), for example in dense tropical forests.
The ability to create a digital image that provides great detail in
darker regions without “washing out” brighter regions, like glaciers,
snow-covered areas, and deserts is one of the great challenges of
visualizing satellite data. The new version also improves image
clarity, and gives highly reflective land surfaces, such as salt flats, a
more realistic appearance.
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Monthly imagery
shows seasonable variability, like the change in Alpine snow-cover from
January to July. (NASA images by Reto Stöckli)
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Limitations
Those who intend to use the Blue Marble: Next
Generation in their own publications or projects should be aware of
areas that still require improvement. Areas of open water still show
some “noise.” In tropical lowlands, cloud cover during the rainy season
can be so extensive that obtaining a cloud-free view of every pixel of
the area for a given month may not be possible. Deep oceans are not
included in the source data; the creator of the Blue Marble uses a
uniform blue color for deep ocean regions, and this value has not been
completely blended with observations of shallow water in coastal areas.
The lack of blending may, in some cases, make the transition between
shallow coastal water and deep ocean appear unnatural. Finally, the data
do not completely distinguish between snow and cloud cover in areas
with short-term snow cover (less than three or four months). This
problem may be resolved in the future through the use of a more
sophisticated snow mask.
Data Access
Full-resolution, subsetted, and reduced-resolution files are available on the Blue Marble Next Generation collection on NASA’s Visible Earth.
Monthly global images
provides web-resolution copies of each of the monthly maps, along with
links to 8km/pixel and 2km/pixel JPEGs, and full-resolution torrents.500 meter/pixel images are available either via BitTorrent (see monthly global images page for links to torrent files) or from one of our mirror sites:
Sample 500 meter/pixel images.
Credits
Blue Marble: Next Generation was produced by Reto Stöckli, NASA Earth Observatory (NASA Goddard Space Flight Center). See The Blue Marble Next Generation—A true color Earth
dataset including seasonal dynamics from MODIS (880 kB PDF)
for acknowledgments. Anyone using or republishing Blue Marble: Next
Generation please credit “NASA’s Earth Observatory.”
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Improvements to the
data-processing algorithms resulted in relatively noise-free images with
few artifacts. Dry salt flats, such as the Etosha Pan in Namibia,
rendered as water in the original Blue Marble, but are now accurately
colored. (NASA images by Reto Stöckli.)
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NASA: Features - Blue Marble (next generation) - Links - Also a link to suscribe to NASA Earth Observatory - Enjoy science :)
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