Earth Weather / Space Weather

Oh Noes, Not Again!!

Posted by: Susie77, 7:24 PM GMT on October 22, 2011

German satellite to hit Earth this weekend with up to 1.7 tons of debris

By Michael Martinez, CNN
updated 2:48 PM EST, Sat October 22, 2011

Artist rendition of the ROSAT German satellite

STORY HIGHLIGHTS

A German satellite will fall between 2 p.m. Saturday and 7 a.m. Sunday, Eastern time
The Roentgen Satellite could hit the surface with 30 pieces of debris
The biggest fragment will likely be telescope's mirror, weighing up to 1.7 tons
The location of the debris' surface strikes can't be accurately predicted

(CNN) -- A decommissioned German satellite will
re-enter Earth's atmosphere as early as Saturday afternoon, and up to 30
individual pieces of debris weighing a total of 1.7 tons could slam
into the surface, the German space agency's website said.
"The largest single fragment will probably be the telescope's mirror,
which is very heat resistant and may weigh up to 1.7 tons," according
to the German Aerospace Center (DLR).
The time and location of the Roentgen Satellite's (ROSAT) re-entry
couldn't be forecast precisely, and officials estimated the fiery event
to occur any time between 2 p.m. Eastern Saturday and 7 a.m. Eastern
Sunday, the agency said.
Fragments could fall to Earth in an about 50-mile (or 80-kilometer)
path as the satellite enters the atmosphere at 17,398 miles (or about
28,000 kilometers) an hour and breaks up under extreme heat, the agency
said.
The satellite's orbit extends to 53 degrees northern and southern latitude, officials said.
The satellite -- an X-ray observatory -- doesn't have a propulsion
system on board, so officials couldn't perform a controlled re-entry at
the end of the craft's mission in 1999, the space agency said.
The satellite had been in an elliptical orbit between 351 miles and
363 miles above the surface, but in June 2011, it was only about 203
miles high, the space agency said.
When the satellite crashes into the atmosphere, German scientists
will be evaluating data from the U.S. Space Surveillance Network,
officials said. The U.S. Department of Defense says that more than
21,800 man-made objects have re-entered Earth's atmosphere since
tracking began with Sputnik, the world's first artificial satellite
launched by the Soviets in 1957.
Last month, surviving remnants of a NASA satellite re-entered Earth's
atmosphere over a remote stretch of the southern Pacific Ocean and
broke into pieces during re-entry, with 26 chunks weighing a total of
1,200 pounds considered likely to have reached the surface, NASA said.

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Orionid Meteor Shower Peak This Weekend

Posted by: Susie77, 12:20 AM GMT on October 21, 2011

Weekend Meteor Shower

Oct. 20, 2011: Earth is about to pass through a
stream of debris from Halley's comet, source of the annual Orionid
meteor shower. Forecasters expect more than 15 meteors per hour to fly
across the sky on Saturday morning, Oct. 22nd, when the shower peaks.

Orionids are most easily seen during the dark hours before
sunrise. Twilight Orionids, however, are the most beautiful of all.

"Although this isn't the biggest meteor shower of the year, it's
definitely worth waking up for," says Bill Cooke of the NASA Meteoroid
Environment Office. "The setting is dynamite."

Orionids are framed by some of the brightest and most beautiful
constellations in the night sky. The meteors emerge from mighty Orion,
the shower's glittering namesake. From there they streak through Taurus
the Bull, the twins of Gemini, Leo the Lion, and Canis Major--home to
Sirius, the most brilliant star of all.

This year, the Moon and Mars are part of the show. They'll form two vertices of a celestial triangle
in the eastern sky on Saturday morning while the shower is most active;
Regulus is the third vertex. Blue Regulus and red Mars are both
approximately of 1st magnitude, so they are easy to see alongside the
35% crescent Moon. Many Orionids will be diving through the triangle in
the hours before dawn.

Cooke's team at the Meteoroid Environment Office will be watching for Orionids that actually hit the Moon.

Cometary debris streams like Halley's are so wide, the whole
Earth-Moon system fits inside. So when there is a meteor shower on
Earth, there's usually one on the Moon, too. Unlike Earth, however, the
Moon has no atmosphere to intercept meteoroids. Pieces of debris fall
all the way to the surface and explode where they hit. Flashes of light
caused by thermal heating of lunar rocks and moondust are so bright,
they can sometimes be seen through backyard-class telescopes.

A map of the morning sky on Saturday, Oct. 22nd at 5:30 a.m. local time, viewed facing southeast. Click to view a larger, more complete map.

"Since we began our monitoring program in 2005, our group has
detected more than 250 lunar meteors," says Cooke. "Some explode with
energies exceeding hundreds of pounds of TNT."

So far, they've seen 15 Orionids hitting the Moon--"two in 2007,
four in 2008, and nine in 2009," recalls Cooke. This year they hope to
add to the haul. About 25% of the Moon's dark terrain will be exposed
to Halley's debris stream, giving the team millions of square miles to
scan for explosions.

Watching meteoroids hit the Moon is a good way to learn about the
structure of comet debris streams and the energy of the particles
therein. It also allows Cooke and colleagues to calculate risk factors
for astronauts who, someday, will walk on the lunar surface again.

"Going outside to watch the Orionids might not be a good idea for a moonwalker," says Cooke.

But it is a good idea for the res

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I TOLD Him He Uses Too Much Starter Fluid on the BBQ

Posted by: Susie77, 8:48 PM GMT on October 19, 2011

NASA Releases Visual Tour of Earth's Fires10.19.11

NASA has released a series of new satellite data visualizations that
show tens of millions of fires detected worldwide from space since 2002.
The visualizations show fire observations made by the MODerate
Resolution Imaging Spectroradiometer, or MODIS, instruments onboard
NASA's Terra and Aqua satellites.

NASA maintains a comprehensive research program using satellites,
aircraft and ground resources to observe and analyze fires around the
world. The research helps scientists understand how fire affects our
environment on local, regional and global scales.

Fire observations from around the world taken over nearly 10 years are
shown in this visualization of NASA satellite data. (Credit: NASA's
Goddard Space Flight Center)

› Download this visualization in other formats from NASA Goddard's Scientific Visualization Studio

› Videos focusing on continents: Africa | Asia | Australia | N. America | S. America

"What you see here is a very good representation of the satellite data
scientists use to understand the global distribution of fires and to
determine where and how fire distribution is responding to climate
change and population growth," said Chris Justice of the University of
Maryland, College Park, a scientist who leads NASA's effort to use MODIS
data to study the world's fires.

One of the new visualizations takes viewers on a narrated global tour of
fires detected between July 2002 and July 2011. The fire data is
combined with satellite views of vegetation and snow cover to show how
fires relate to seasonal changes. The Terra and Aqua satellites were
launched in 1999 and 2002, respectively.

The tour begins by showing extensive grassland fires spreading across
interior Australia and the eucalyptus forests in the northwestern and
eastern part of the continent. The tour then shifts to Asia where large
numbers of agricultural fires are visible first in China in June 2004,
then across a huge swath of Europe and western Russia in August. It then
moves across India and Southeast Asia, through the early part of 2005.
The tour continues across Africa, South America, and concludes in North
America.

The global fire data show that Africa has more abundant burning than any
other continent. MODIS observations have shown that some 70 percent of
the world's fires occur in Africa. During a fairly average burning
season from July through September 2006, the visualizations show a huge
outbreak of savanna fires in Central Africa driven mainly by
agricultural activities, but also driven by lightning strikes.

Fires are comparatively rare in North America, making up just 2 percent
of the world's burned area each year. The fires that receive the most
attention in the United States -- the uncontrolled forest fires in the
West -- are less visible than the wave of agricultural fires prominent
in the Southeast and along the Mississippi River Valley. Some of the
large wildfires that ravaged Texas this year are visible in the
animation.

NASA maintains multiple satellite instruments capable of detecting fires
and supports a wide range of fire-related research. Such efforts have
yielded the most widely used data records of global fire activity and
burned area in the world. NASA-supported scientists use the data to
advance understanding about Earth's climate system, ecosystem health,
and the global carbon cycle.

NASA's Applied Sciences Program seeks out innovative and practical
benefits that result from studying fires. For example, the program has
found ways to integrate space-based wildfire observations into air
quality models used by the U.S. Environmental Protection Agency that
help protect public health.

NASA will extend the United States' capability to monitor and study
global fires from space with the launch this month of the National
Polar-orbiting Operational Environmental Satellite System Preparatory
Project. The satellite is the first mission designed to collect data to
increase our understanding of long-term climate change and improve
weather forecasts.

One of National Polar-orbiting Operational Environmental Satellite
System Preparatory Project's new, state-of-the-art science instruments
will provide scientists with data to extend the long-term global fires
data record. The satellite is targeted to launch from Vandenberg Air
Force Base in California on Oct. 28. The mission is managed by NASA's
Goddard Space Flight Center in Greenbelt, Md., for the Earth Science
Division of the Science Mission Directorate at NASA Headquarters in
Washington.

MODIS data are processed by the MODIS Advanced Processing System at
Goddard. The algorithm and product validation is done by scientists at
the University of Maryland. The visualizations were created at Goddard's
Scientific Visualization Studio. The fire, vegetation and snow data all
come from the MODIS instruments on Terra and Aqua.

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600 Mysteries in the Night Sky

Posted by: Susie77, 1:45 PM GMT on October 18, 2011

600 Mysteries in the Night Sky

Oct 18, 2011:
NASA's Fermi team recently released the second catalog of gamma-ray
sources detected by their satellite's Large Area Telescope (LAT). Of the
1873 sources found, nearly 600 are complete mysteries. No one knows
what they are.

"Fermi sees gamma rays coming from directions in the sky where
there are no obvious objects likely to produce gamma rays," says David
Thompson, Fermi Deputy Project Scientist from Goddard Space Flight
Center.

An all-sky map of gamma-ray emissions made by the Fermi Space
Telescope. Hundreds of the sources in the map are complete mysteries. [larger image]

Gamma rays are by their very nature heralds of great energy and
violence. They are a super-energetic form of light produced by sources
such as black holes and massive exploding stars. Gamma-rays are so
energetic that ordinary lenses and mirrors do not work. As a result,
gamma-ray telescopes can't always get a sharp enough focus to determine
exactly where the sources are.

For two thirds of the new catalog's sources the Fermi scientists
can, with at least reasonable certainty, locate a known gamma
ray-producing object*, such as a pulsar or blazar, in the vicinity the
gamma-rays are coming from. But the remaining third – the "mystery
sources" -- have the researchers stumped, at least for now. And they are
the most tantalizing.

Nearly 600 sources in the latest Fermi catalog are unidentified.

"Some of the mystery sources could be clouds of dark matter –
something that's never been seen before," speculates Thompson.

About 85% of the gravitational mass of the universe is dark
matter. The stuff we see makes up the rest. Dark matter is something
that pulls on things with the force of its gravity but can't be detected
in any other way. It doesn't shine – doesn't emit or scatter light –
hence the adjective "dark."

Astronomers cannot detect dark matter directly using optical or
radio telescopes. But dark matter just might shine in gamma rays.

"We've been using Fermi to search for dark matter for a long
time," says the principal investigator for the Large Area Telescope,
Peter Michelson of Stanford University.

Some researchers believe that when two dark matter antiparticles
bump into each other, they will annihilate, producing gamma rays.
Concentrated clouds of dark matter could form a gamma ray source at
specific wavelengths detectable by Fermi.

"If we see a bump in the gamma-ray spectrum -- a narrow spectral
line at high energies corresponding to the energy of the annihilating
particles – we could be the first to 'apprehend' dark matter,” says
Michelson.

The team plans to continue observing the mystery sources. Fermi
scans the entire sky ever three hours, and this ongoing sequence of
observations "piles up" gamma rays for the researchers to analyze. So
far, too few gamma rays have been collected from the mystery sources to
form definite conclusions.

Colliding galaxy clusters are one possible explanation for the mystery sources.

Another, less-dark possibility for some of the mystery sources is
colliding galaxy clusters. According to Michelson and Thompson, clashes
of such magnitude would generate super large scale shock waves that
would accelerate particles. Others of the sources, they say, might be
some brand new phenomenon, perhaps something involving galactic black
holes.

When all is said and done, many of the mystery sources could prove
to be familiar. "[They] will probably turn out to be members of known
source classes – things we know but haven't recognized yet, like
undiscovered pulsars, binary systems, and supernova remnants," says
Michelson.

"Of course we're hoping for something really exotic like dark
matter, but we have to look first at all the other options," says
Thompson. "Fermi is an ongoing mission. We'll continue to search for
answers to these puzzles and perhaps turn up even more surprises."

Will notorious dark matter finally be nabbed? Stay tuned!

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Surveying Earth's Polar Ice

Posted by: Susie77, 4:14 PM GMT on October 13, 2011

NASA Continues Critical Survey of Antarctica's Changing Ice
10.13.11

Small caps of stagnant ice cover the summits while the ice in the valley moves quickly towards the coast.

› View larger

NASA’s Operation IceBridge mission comprises the largest airborne
research campaign ever flown over Earth’s polar region. The mission is
designed to continue critical ice sheet measurements in a period between
active satellite missions and help scientists understand how much the
major ice sheets of Greenland and Antarctica could contribute to sea
level rise. Credit: Michael Studinger/NASA

WASHINGTON -- Scientists with NASA's Operation IceBridge airborne
research campaign began the mission's third year of surveys this week
over the changing ice of Antarctica.

Researchers are flying a suite of scientific instruments on two planes
from a base of operations in Punta Arenas, Chile: a DC-8 operated by
NASA and a Gulfstream V (G-V) operated by the National Science
Foundation and the National Center for Atmospheric Research. The G-V
will fly through early November. The DC-8, which completed its first
science flight Oct. 12, will fly through mid-November.

Ninety-eight percent of Antarctica is covered in ice. Scientists are
concerned about how quickly key features are thinning, such as Pine
Island Glacier, which rests on bedrock below sea level. Better
understanding this type of change is crucial to projecting impacts like
sea-level rise.

"With a third year of data-gathering underway, we are starting to build
our own record of change," said Michael Studinger, IceBridge project
scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "With
IceBridge, our aim is to understand what the world's major ice sheets
could contribute to sea-level rise. To understand that you have to
record how ice sheets and glaciers are changing over time."

In preparation for Operation IceBridge's Antarctica 2011 campaign,
flight crews at NASA Dryden worked to outfit the DC-8 aircraft -- NASA's
long-haul "workhorse" -- with an array of different instruments
designed to measure sea ice, ice sheets, and even the bedrock below
Antarctic glaciers. Credit: NASA/Goddard/Jefferson Beck

› Play/Download video

IceBridge science flights put a variety of remote-sensing instruments
above Antarctica's land and sea ice, and in some regions, above the
ocean floor. The G-V carries one instrument: a laser-ranging topography
mapper. The DC-8 carries seven instruments, including a laser altimeter
to continue the crucial ice sheet elevation record begun by the Ice,
Cloud and land Elevation Satellite (ICESat) mission, which ended in
2009. The flying laboratory also will carry radars that can distinguish
how much snow sits on top of sea ice and map the terrain of bedrock
below thick ice cover.

While scientists in recent years have produced newer, more detailed data
about the ice sheet's surface, the topography of the rocky surface
beneath the ice sheet remains unknown in many places. Without knowing
the topography of the bedrock, it is impossible to know exactly how much
ice sits on top of Antarctica.

A gravimeter aboard the DC-8 will detect subtle differences in gravity
to map the ocean floor beneath floating ice shelves. Data on bathymetry,
or ocean depth, and ocean circulation from previous IceBridge campaigns
are helping explain why some glaciers are changing so quickly.

Flights take off from Punta Arenas and cross the Southern Ocean to reach
destinations including West Antarctica, the Antarctic Peninsula and
coastal areas. Each lasts 10 to 11 hours.

"We will be re-surveying our previous flight lines to see how much
glaciers and ice sheets have changed, and we'll cover new areas to
establish a baseline for future years and the ICESat-2 mission in 2016,"
Studinger said.

Early high-priority DC-8 flights include several flight lines over sea
ice near the Antarctic Peninsula, before too much of the ice melts in
the southern spring. IceBridge sea ice flights are designed to help
scientists understand why sea ice in the Southern Hemisphere is not
following the steady decline of sea ice thickness and extent seen in the
Arctic.

Other high priority flight lines follow ground traverses being made this
year and next, during which NASA scientists will travel different
sections of the West Antarctic Ice Sheet, measuring snowfall
accumulation and the characteristics of Pine Island Glacier.

Many flight lines will retrace either previous ICESat-1 tracks or future
ICESat-2 tracks. Some also will align with current observations made by
the European Space Agency's CryoSat-2 satellite. The overlapping flight
lines and satellite tracks ultimately will help scientists improve the
accuracy of their data.

NASA's Ames Research Center in Moffett Field, Calif., is responsible for
IceBridge project management. The DC-8 is based at NASA's Dryden
Aircraft Operations Facility in Palmdale, Calif.

To follow the mission in more detail, visit:

› Operation IceBridge mission page

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Japan Quake Disrupted Atmosphere

Posted by: Susie77, 6:54 PM GMT on October 10, 2011

View full size image

The devastating earthquake that struck Japan this year may have rattled
the highest layer of the atmosphere even before it shook the Earth, a
discovery that one day could be used to provide warnings of giant
quakes, scientists find.

The magnitude 9.0 quake that struck off the coast of Tohoku in Japan in March ushered in what might be the world's first complex megadisaster as it unleashed a catastrophic tsunami and set off microquakes and tremors around the globe.

Scientists recently found the surface motions and tsunamis this earthquake generated also triggered waves in the sky. These waves reached all the way to the ionosphere, one of the highest layers of the Earth's atmosphere.

Now geodesist and geophysicist Kosuke Heki at Hokkaido University in
Japan reports the Tohoku quake also may have generated ripples in the
ionosphere before the quake struck.

Disruptions of the electrically charged particles in the ionosphere
lead to anomalies in radio signals between global positioning system
satellites and ground receivers, data that scientists can measure.

Heki analyzed data from more than 1,000 GPS receivers in Japan. He
discovered a rise of approximately 8 percent in the total electron
content in the ionosphere above the area hit by the earthquake about 40
minutes before the temblor. This increase was greatest about the
epicenter and diminished with distance away from it.

"Before finding this phenomenon, I did not think earthquakes could be
predicted at all," Heki told OurAmazingPlanet. "Now I think large
earthquakes are predictable."

Analysis of GPS records from the magnitude 8.8 Chile earthquake in 2010
revealed a similar pattern, Heki said. These anomalies also may have
occurred with the Sumatra magnitude 9.2 earthquake in 2004 and the
magnitude 8.3 Hokkaido earthquake in 1994, he added.

If true, further research could lead to a new type of early-warning system for giant earthquakes.

The anomaly is currently seen before earthquakes only with magnitudes
of about 8.5 or larger, Heki cautioned. Still, if researchers can detect
what specifically causes this ionospheric phenomenon, it also might be
possible to detect precursory phenomena for smaller earthquakes, he
said.

Heki did caution that the ionosphere is highly variable — for instance,
solar storms can trigger large changes in total electron content there.
Before researchers could develop an early-warning system for
earthquakes based on ionospheric anomalies, they would have to rule out
non-earthquake causes.

Heki detailed his findings online Sept. 15 in the journal Geophysical Research Letters.

This story was provided by OurAmazingPlanet, sister site to SPACE.com

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Draconid Meteor Shower

Posted by: Susie77, 8:09 PM GMT on October 04, 2011

Draconid Meteor Outburst

Oct. 4, 2011: On October 8th Earth is going to
plow through a stream of dust from Comet 21P/Giacobini-Zinner, and the
result could be an outburst of Draconid meteors.

"We're predicting as many as 750 meteors per hour," says Bill
Cooke of NASA's Meteoroid Environment Office. "The timing of the shower
favors observers in the Middle East, north Africa and parts of Europe."

Comet 21P/Giacobini-Zinner in Nov. 1998 photographed by astronomers at Kitt Peak. [more]

Every 6.6 years Comet Giacobini-Zinner swings through the inner
solar system. With each visit, it lays down a narrow filament of dust,
over time forming a network of filaments that Earth encounters every
year in early October.

"Most years, we pass through gaps between filaments, maybe just
grazing one or two as we go by," says Cooke. "Occasionally, though, we
hit one nearly head on--and the fireworks begin."

2011 could be such a year. Forecasters at NASA and elsewhere agree
that Earth is heading for three or more filaments on October 8th.
Multiple encounters should produce a series of variable outbursts
beginning around 1600 Universal Time (noon EDT) with the strongest
activity between 1900 and 2100 UT (3:00 pm – 5:00 pm EDT).

Forecasters aren't sure how strong the display will be, mainly
because the comet had a close encounter with Jupiter in the late 1880s.
At that time, the giant planet's gravitational pull altered the comet's
orbit and introduced some uncertainty into the location of filaments it
has shed since then. Competing models place the filaments in slightly
different spots; as a result, estimated meteor rates range from dozens
to hundreds per hour.

Comet dust stream models suggest a succession of peaks in meteor rate between 1600 and 2100 UT on Oct. 9th. Click here for details. Credit: MSFC/Meteoroid Environment Office.

One respected forecaster, Paul Wiegert of the University of
Western Ontario, says the meteor rate could go as high as 1000 per hour
-- the definition of a meteor storm. It wouldn't be the first time.
Close encounters with dusty filaments produced storms of more than
10,000 Draconids per hour in 1933 and 1946 and lesser outbursts in 1985,
1998, and 2005.

Meteors from Comet Giacobini-Zinner stream out of the northern
constellation Draco--hence their name. Draconids are among the slowest
of all meteors, hitting the atmosphere at a relatively leisurely 20
km/s. The slow pace of Draconid meteors minimizes their danger to
satellites and spacecraft and makes them visually distinctive.

"A Draconid gliding leisurely across the sky is a beautiful sight," says Cooke.

Unfortunately, many of this year's Draconids will go unseen.
Draconids are faint to begin with, and this year they have to complete
with an almost-full Moon. Lunar glare will reduce the number of meteors
visible from Europe, Africa and the Middle East by 2- to 10-fold. The
situation is even worse in North America where the shower occurs in
broad daylight—completely obliterating the display.

That isn't stopping a group1 of middle school and high
school students from Bishop, California, however. They plan to observe
the shower from the stratosphere where the sky is dark even at noontime.

Black skies at high noon, photographed from a high-altitude
helium balloon on Sept. 3, 2011. Credit: Earth to Sky, a student group
located in Bishop, CA.

Led by Science@NASA's Tony Phillips, the 15 students have been
launching helium balloons to the edge of space since May of 2011. With
more than 95% of Earth’s atmosphere below the balloon, the sky above
looks almost as black as it would from a spacecraft—perfect for
astronomy.

"The students are going to attempt to fly one of our low-light
meteor cameras in the payload of their balloon," says Cooke. "I hope
they catch some Draconid fireballs for us to analyze. They could be the
only ones we get."

Stay tuned for results after Oct. 8th.

Author: Dr. Tony Phillips | Credit: Science@NASA

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Good-bye, Polar Bears :(

Posted by: Susie77, 4:31 PM GMT on October 04, 2011

Steve Cole

Headquarters, Washington

202-358-0918

stephen.e.cole@nasa.gov

Patrick Lynch

Goddard Space Flight Center

301-286-3854/757-897-2047

patrick.lynch@nasa.gov

RELEASE: 11-337

ARCTIC SEA ICE CONTINUES DECLINE, HITS SECOND-LOWEST LEVEL

WASHINGTON -- Last month the extent of sea ice covering the Arctic

Ocean declined to the second-lowest extent on record. Satellite data

from NASA and the NASA-supported National Snow and Ice Data Center

(NSIDC) at the University of Colorado in Boulder showed that the

summertime sea ice cover narrowly avoided a new record low.

The Arctic ice cap grows each winter as the sun sets for several

months and shrinks each summer as the sun rises higher in the

northern sky. Each year the Arctic sea ice reaches its annual minimum

extent in September. It hit a record low in 2007.

The near-record ice-melt followed higher-than-average summer

temperatures, but without the unusual weather conditions that

contributed to the extreme melt of 2007. "Atmospheric and oceanic

conditions were not as conducive to ice loss this year, but the melt

still neared 2007 levels," said NSIDC scientist Walt Meier. "This

probably reflects loss of multiyear ice in the Beaufort and Chukchi

seas as well as other factors that are making the ice more

vulnerable."

Joey Comiso, senior scientist at NASA's Goddard Space Flight Center in

Greenbelt, Md., said the continued low minimum sea ice levels fits

into the large-scale decline pattern that scientists have watched

unfold over the past three decades.

"The sea ice is not only declining, the pace of the decline is

becoming more drastic," Comiso said. "The older, thicker ice is

declining faster than the rest, making for a more vulnerable

perennial ice cover."

While the sea ice extent did not dip below the 2007 record, the sea

ice area as measured by the microwave radiometer on NASA's Aqua

satellite did drop slightly lower than 2007 levels for about 10 days

in early September, Comiso said. Sea ice "area" differs from extent

in that it equals the actual surface area covered by ice, while

extent includes any area where ice covers at least 15 percent of the

ocean.

Arctic sea ice extent on Sept. 9, the lowest point this year, was 4.33

million square kilometers (1.67 million square miles). Averaged over

the month of September, ice extent was 4.61 million square kilometers

(1.78 million square miles). This places 2011 as the second lowest

ice extent both for the daily minimum extent and the monthly average.

Ice extent was 2.43 million square kilometers (938,000 square miles)

below the 1979 to 2000 average.

This summer's low ice extent continued the downward trend seen over

the last 30 years, which scientists attribute largely to warming

temperatures caused by climate change. Data show that Arctic sea ice

has been declining both in extent and thickness. Since 1979,

September Arctic sea ice extent has declined by 12 percent per

decade.

"The oldest and thickest ice in the Arctic continues to decline,

especially in the Beaufort Sea and the Canada Basin," NSIDC scientist

Julienne Stroeve said. "This appears to be an important driver for

the low sea ice conditions over the past few summers."

Climate models have suggested that the Arctic could lose almost all of

its summer ice cover by 2100, but in recent years, ice extent has

declined faster than the models predicted.

NASA monitors and studies changing sea ice conditions in both the

Arctic and Antarctic with a variety of spaceborne and airborne

research capabilities. This month NASA resumes Operation IceBridge, a

multi-year series of flights over sea ice and ice sheets at both

poles. This fall's campaign will be based out of Punta Arenas, Chile,

and make flights over Antarctica . NASA also continues work toward

launching ICESat-2 in 2016, which will continue its predecessor's

crucial laser altimetry observations of ice cover from space.

To see a NASA data visualization of the 2011 Arctic sea ice minimum as

measured by the Advanced Microwave Scanning Radiometer - Earth

Observing System (AMSR-E) on Aqua, visit:

http://www.nasa.gov/topics/earth/features/20 11-ice-min.html

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