Leafarctica is an interactive map which allows you to view NASA MODIS satellite imagery of the Antarctic. The map includes a polar view which would be impossible with the usual Web Mercator projection used by most interactive mapping platforms. The map includes a date input field which allows you to change the Antarctic satellite image displayed on the map by date.
National Geographic
NGA GNC26 map
Antarctica, Our Last Frontier : map from the Auckland Star newspaper, October, 1957.
This visualization, courtesy of the Lab's
MPAS-Ocean Model, shows ocean currents and eddies in a high-resolution
global ocean simulation with the Antarctic in the center. The
image was created using Paraview software with the assistance of Phillip
Wolfram
The oceans play an important role in the earth's climate; they transport
heat from equator to pole, provide moisture for rain, and absorb carbon
dioxide from the atmosphere.
Ocean models, such as this one from Los Alamos National Laboratory, help explain interactions between individual
eddies that may be altered in a changing climate.
This visualization,
courtesy of the Lab's MPAS-Ocean Model, shows ocean currents and eddies
in a high-resolution global ocean simulation with the Antarctic in the
center.
Colors show speed, where white is fast and blue is slow.
Detailed turbulent structures are visible throughout the Southern
Ocean, where the Antarctic circumpolar current flows eastward around the
globe.
Large eddies are particularly visible in the Agulhas current at
the southern tip of Africa.
These ocean simulations are validated
against satellite and shipboard observations.
Even though individual eddies occur on scales of 10-150 km, their
cumulative effects have large and long-ranging consequences on the
earth's climate.
In the Southern Ocean, eddies transport heat poleward.
The strength of large-scale circulations in the northern hemisphere is
sensitive to the turbulence in the Southern Ocean.
Ocean models are used
to test how these interactions may be altered in a changing climate.
This high-resolution simulation includes 90 million grid cells,
ranging from 10 to 30 km in horizontal width.
It is run on a super
computer using eight thousand processors.
The MPAS-Ocean model is developed at Los Alamos National Laboratory
by the Climate, Ocean, and Sea Ice Model team (COSIM).
MPAS-Ocean is a component of the Accelerated Climate
Model for Energy, a new climate model by the Department of Energy.
From BBC Mobula rays leap spectacularly from the sea when they gather in large groups, but scientists still don’t know why they do it
Soaring high above the waves as easily as a bird, mobula rays appear perfectly designed for this astonishing aerobatic display.
Closely
related to sharks but with long, flat bodies and wing-like pectoral
fins, they are ideally suited to swooping through the water yet seem
equally at home in the air, so much so that they have earned the name
“flying rays”.
Mobula rays can reach heights of more than two
metres (6ft 6ins), remaining airborne for several seconds, but their
landings are much less graceful, creating a loud bang as they belly-flop
back into the sea.
This behaviour - filmed in the Gulf of California, Mexico, as part of a new BBC / Discovery coproduction television series - can last for 24 hours and happens as many hundreds of rays shoal together to form huge aggregations.
“Sitting
in a boat in the midst of these aggregations is akin to sitting in a
pot of popcorn as the kernels explode into the air. Everywhere you look
mobulas are leaping out of the water and landing with a loud smack,
sometimes just a couple of meters from you,” says Joshua Stewart, from the Gulf of California Marine Program, who studies rays in Mexico and across the world.
“The
mobulas launch themselves straight up out of the water at top speed,
and most often they land flat on their belly. However, sometimes they
seem to lose control and do flips and twists before reconnecting with
the water.”
Mobula rays’ elusive nature and skittish behaviour in front of divers
has made them difficult to observe in the wild, except when they breach
the water.
Mr Stewart explains that even large aggregations, like the
one in the Gulf of California, can sometimes be hard to find, as they
can occur in different locations and at slightly different times of the
year.
In order to shed some light on these animals Mr Stewart
applies some of his findings from his research into the larger manta
rays he completed with the Manta Trust.
For example, he knows that manta rays have to start their leaps fairly
deeply, in order to build up enough speed to leave the water.
“As
far as we can tell, all mobulid rays jump, as do their myliobatid (eagle
rays) cousins. Many theories have been suggested [as to why they jump],
from feeding, courting, communicating, and ridding themselves of
parasites,” he says.
“While the jumping behaviour may occur during feeding or courting
events, we believe that the most likely purpose of the jumping behavior
is communication, which could have a variety of applications in
different behavioral scenarios. However it is very likely that mantas,
mobulas and eagle rays jump for a variety of reasons.”
Having viewed the footage of Mobula munkiana in the Gulf of California, Mr Stewart was able to confirm that both females and males jump.
His team has also uncovered what is thought to be a M. munkiana nursery ground, where juveniles were feeding along the shore, close to where the aggregations and jumping typically happen.
“There’s some evidence to suggest that females mate immediately after giving birth,” says Stewart.
“This
is pure speculation, but it's possible that the females could give
birth in the nursery habitat and then mate shortly thereafter in the
same area.”
In the Maldives reef mantas (Manta alfredi) have been observed jumping at the beginning of a feeding frenzy.
“We
believe that they're jumping to inform other mantas in the area that
food is available, and using the jumping as a sort of signal to
aggregate,” Mr Stewart says.
“Along these lines, we're thinking that the M. munkiana may
be jumping to identify the aggregation to other nearby individuals. In
theory, this would increase the density and overall number of
individuals, providing a higher mate choice ability and increasing the
likelihood that any one individual gets to mate.”
What is known
about mobula rays is that they reach sexual maturity late and their
investment in their offspring is more akin to mammals than other fishes,
usually producing just a single pup after long pregnancies, all of
which makes them extremely vulnerable to commercial fishing.
As a
species that likes to come together, they are an easy target for
fishermen and many rays can be caught in a single attempt.
Fishing
spawning aggregations of other species is known to cause numbers to
plummet.
“Because of this, we know that the mobula aggregations in the Gulf of
California are extremely vulnerable to human impacts, and the greatest
threat is most likely bycatch in drift gill net fisheries,” says Mr
Stewart.
“Huge numbers of these animals are moving through
relatively constricted geographic areas and just a few large catches
could have dramatic negative impacts on their populations.”
Mr
Stewart is now planning research to confirm the reasons behind the
aggregating behaviour in the Gulf of California and how many of the
population is represented, as well as further work on seasonal locations
and habitat use.
IPCC climate modelling proves right as scientists find a glitch in satellite led to inaccurate records in 1990s suggesting rate of sea level rise was slowing
Sea level rise sped up over the last two decades rather than slowing down as previously thought, according to new research.
Records from tide gauges and satellites have shown sea level rise
slowing slightly over the past 20 years.
But as the ice sheets of West Antarctica and Greenland shed ever more water into the ocean, climate models show it should be doing the opposite.
“The thing that was really puzzling us was that the last decade of
sea level rise was marginally slower, ever so subtly slower, than the
decade before it,” said Dr Christopher Watson from the University of
Tasmania who led the new study.
he leading edge of the remaining part of the Larsen B ice shelf.
A separate ice shelf, Larsen C, is thinning from above and below, scientists found.
Photograph: HO/Reuters
Watson’s team found that the record of sea level rise during the
early 1990s was too high.
The error gave the illusion of the rate of sea
level rise decreasing by 0.058 mm/year 2 between 1993 and 2014 , when in reality it accelerated by between 0.041 and 0.058 mm/year 2.
This brings the records into line with the modelling of the UN’s climate science body, the Intergovernmental Panel on Climate Change (IPCC).
“We see acceleration, and what I find striking about that is the fact
that it’s consistent with the projections of sea level rise published
by the IPCC,” said Watson.
“Sea level rise is getting faster. We know
it’s been getting faster over the last two decades than its been over
the 20th century and its getting faster again.”
Professor Jonathan Gregory from the University of Reading and a lead author of the IPCC’s most recent climate report said the study was “interesting and useful” and shored up the predictions of the models.
“The better agreement of the altimeter record after the correction
... is a reason for greater confidence in the projections,” he said.
Sea level rise is measured using tide gauges on shorelines around the
world and, since 1993, altimetric satellites. But both sets of data are
imperfect.
The land the tide gauges sit on is constantly shifting.
For example,
said Watson, measurements in Alaska are thrown out by the continent
rebounding upwards after being covered in a heavy ice sheet during the
last ice age.
While in Perth, Australia, the continental plate is
subsiding.
The satellites orbit 746 miles above the Earth at 4 miles per second,
firing beams of radar at the sea’s surface and recording the time it
takes to bounce back.
Watson said their accuracy was “staggering”.
But
the level of precision required to measure the slight but significant
changes in sea level driven by climate change is very high.
During the
1990s the satellite instrumentation degraded, losing some of its
accuracy.
Watson’s team were able to compare the two data sets and identify
where each was going wrong.
The results revise downwards the average
rate of sea level rise since the 1990s.
The IPCC’s landmark report in 2013
found the sea had risen on average by 3.2 mm per year since 1993.
Waston’s study found the rate was slightly slower, between 2.6 and 2.9
mm per year.
“I have no doubt there are members of the community who may wish to
reevaluate [the predictions for sea level rise]. But as a scientist I
come back to the data,” said Watson, preempting claims that the study
was a scaling down of the threat of climate change to coastal
communities.
“A single number implies that that rate is constant over time. And I
think what is emerging here is that that’s not the case. That rate of
change is actually increasing. For everyone that lives around the
coastal margin, that’s a really concerning fact.”
In 2013, Gregory’s report
to the IPCC predicted that sea level could rise between 28cm and 98cm
by 2100 depending on how much carbon human industry emits this century.
“There is no reason to change the projections,” said Gregory.
