NASA MODIS Image: Phytoplankton Bloom Off the Coast of Iceland

A spring bloom of phytoplankton lingered in the Atlantic Ocean off the coast of Iceland in early June, 2014.

The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Aqua satellite captured this true-colour image on June 5.

At that time, swirling jewel tones of a vast bloom were visible between banks of white clouds.

According to the Icelandic Ministry of Fisheries and Agriculture, phytoplankton blooms around Iceland usually occur in early spring and fall.

The spring bloom is driven by longer daylight and the warming of surface layers. This leads to stratification of the waters, and allows the phytoplankton to stay in the surface layer and reproduce.

By summer the huge numbers of phytoplankton in the blooms decreases nutrients, and the numbers of the organisms begins to plummet.

Image Credit: NASA/Jeff Schmaltz, MODIS Land Rapid Response Team, NASA GSFC

NASA MODIS: Agricultural fires across Sierra Leone

Credit: NASA image courtesy Jeff Schmaltz, MODIS Rapid Response Team.

Marked in red, hundreds of land use fires burn in the fields across Sierra Leone.

Most fires in this region are deliberately set for a variety of reasons, including slash and burn agriculture.

When a plot of land becomes exhausted, farmers shift cultivation to another plot where they cut the trees and brush at the beginning of the dry season in January and February.

Once the dead plant material has dried, they set fire to it. Such fires peak in March and April right before farming season begins.

From space, MODIS detects thermal anomalies, including fires, flares, and volcanoes.

Each MODIS "fire pixel" or fire detection covers one square kilometer, which means that one or more fire is burning in the corresponding one-square kilometer area on the ground.

There are hundreds of fire pixels evident in this image, so there are at least that many distinct fires burning in this scene.

MODIS tends to undercount fires because it can't detect fires through smoke or clouds, nor does it see small cool fires, a fire type common to land use fires.

Where there is fire, there is also smoke, affecting air quality. Smoke contains soot and other particulates that pose a threat to human health and affect regional climate. Burning also releases greenhouse gases.

This natural-colour satellite image was collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua satellite on March 24, 2014.

Sun's energy influences 1,000 years of natural climate variability

This is a composite created from three images received from MODIS instruments carried on NASA's Terra and Aqua polar orbiting satellites. 

The images were received at the Dundee Satellite Receiving Station at 1151, 1205 and 1342 UTC on 7th Jan. 2010. 

Credit: NASA

Changes in the sun's energy output may have led to marked natural climate change in Europe over the last 1000 years, according to researchers at Cardiff University.

Scientists studied seafloor sediments to determine how the temperature of the North Atlantic and its localised atmospheric circulation had altered.

Warm surface waters flowing across the North Atlantic, an extension of the Gulf Stream, and warm westerly winds are responsible for the relatively mild climate of Europe, especially in winter.

Slight changes in the transport of heat associated with these systems can led to regional climate variability, and the study findings matched historic accounts of climate change, including the notoriously severe winters of the 16th and 18th centuries which pre-date global industrialisation.

The study found that changes in the Sun's activity can have a considerable impact on the ocean-atmospheric dynamics in the North Atlantic, with potential effects on regional climate.

Predictions suggest a prolonged period of low sun activity over the next few decades, but any associated natural temperature changes will be much smaller than those created by human carbon dioxide emissions, say researchers.

The study, led by Cardiff University scientists, in collaboration with colleagues at the University of Bern, is published today in the journal Nature Geoscience.

Paola Moffa-Sanchez

Dr Paola Moffa-Sanchez, lead author from Cardiff University School of Earth and Ocean Sciences, explained: "We used seafloor sediments taken from south of Iceland to study changes in the warm surface ocean current."

"This was done by analysing the chemical composition of fossilised microorganisms that had once lived in the surface of the ocean."

"These measurements were then used to reconstruct the seawater temperature and the salinity of this key ocean current over the past 1000 years."

The results of these analyses revealed large and abrupt temperature and salinity changes in the north-flowing warm current on time-scales of several decades to centuries.

Cold ocean conditions were found to match periods of low solar energy output, corresponding to intervals of low sunspot activity observed on the surface of the sun.

Using a physics-based climate model, the authors were able to test the response of the ocean to changes in the solar output and found similar results to the data.

Ian Hall

"By using the climate model it was also possible to explore how the changes in solar output affected the surface circulation of the Atlantic Ocean," said Prof Ian Hall, a co-author of the study.

"The circulation of the surface of the Atlantic Ocean is typically tightly linked to changes in the wind patterns."

"Analysis of the atmosphere component in the climate model revealed that during periods of solar minima there was a high-pressure system located west of the British Isles."

"This feature is often referred to as atmospheric blocking, and it is called this because it blocks the warm westerly winds diverting them and allowing cold Arctic air to flow south bringing harsh winters to Europe, such as those recently experienced in 2010 and 2013."

The study concludes that although the temperature changes expected from future solar activity are much smaller than the warming from human carbon dioxide emissions, regional climate variability associated with the effects of solar output on the ocean and atmosphere should be taken into account when making future climate projections.

More information: Solar forcing of North Atlantic surface temperature and salinity over the past millennium, Nature Geoscience, DOI: 10.1038/ngeo2094

NASA Terra Aqua MODIS: UK scientists reveal Amazon rainforest satellite imaging problem - Video

US Scientists have been puzzled by the apparent ‘greening up’ of the Amazon forest during its annual dry season.

However, Swansea University scientists, in research carried out in conjunction with NASA, have found that the Amazon is not as green in the dry season as researchers previously thought, because a trick of the light skews the satellite images.

The research is published in the latest issue of the scientific journal Nature; doi:10.1038/nature13006

This natural-colour satellite image shows the importance of correcting for sun-sensor geometry. 

On the left side, sunlight is backscattered by the Amazon rainforest, creating the appearance of brighter green leaves in some areas. 

To the right, sunglint makes the dark waters of the Amazon River and surrounding flooded wetlands appear silver or white compared to the darker forest. 

 Credit: NASA's Earth Observatory

The finding of the research yeam will help scientists develop a more accurate picture of changes in the Amazon, which is more important now than ever, given the enormous role the Amazon plays in regulating carbon dioxide, and influencing climate change.

NASA's Terra and Aqua satellites make daily observations over the huge expanse of Amazon forests.

The research team were investigating why previous satellite images seemed to show that the forests became greener during the dry season each year from June to October.

More greenery indicates productive, thriving vegetation, which would not be expected at a time of limited rainfall.

The new research shows that:

• The apparent greening of the Amazon in the dry season is an illusion. The forest does not become greener at all.
• It just looks that way due to a combination of shadowing within the forest canopy and the way that satellite sensors observe the Amazon during the dry season, which can create false “hot spots” in images.

Dr Jackie Rosette

‌Swansea researchers, working with NASA, developed a mathematical model which predicts how a forest will be seen from space, and how leaf area can be measured.

One of the Swansea team, Dr Jackie Rosette, spent 2 years at Goddard Space Flight Center, working closely with NASA colleagues.

Blue colours represent areas in Amazon forests where sensors and models can overestimate the green-up of vegetation; white represents areas that lack forest cover. 

The map is based on a model that extends the sun-sensor correction to all pixels in the southern Amazon. 

Credit: Doug Morton and NASA's Earth Observatory

Professor Peter North from the Department of Geography at Swansea University, one of the authors of the research paper, said:

"The Amazon is so vast that it’s only from space that we can properly observe it, so it’s very important that the satellite data gives us as accurate a picture as possible.

Our model has helped to identify the flaws in the previous interpretation. As a result, we can be much more confident that what we are seeing is a real pattern across the Amazon, not a trick of the light.

Having an accurate picture of the Amazon is essential if we are to understand its key role in shaping the climate."

Aboard the NASA satellites are sensors called MODIS (Moderate Resolution Imaging Spectroradiometer) which measure the amount of infrared light reflected from the Amazon.

Scientists use the ratio of red and near-infrared light as a measure of vegetation.

Doug Morton, NASA’s Goddard Space Flight Center said.

"We think we have uncovered the mechanism for the appearance of seasonal greening of Amazon forests – shadowing within the canopy that changes the amount of near-infrared light observed by MODIS"

The research implies that the previous hypothesis of increased productivity during dry seasons is likely to be false, and Amazon productivity may be more limited by water availability than sunlight.

This is critical for predicting the response of the Amazon to future climate change.

NASA MODIS: Temperature Feedback magnifying climate warming in Arctic

Mosaic of images of the Arctic by MODIS. Credit: NASA

A team of researchers with the Max Planck Institute in Germany, has found that temperature feedback in the Arctic is causing more warming in that region than sea ice albedo feedback.

In their paper published in the journal Nature Geoscience, the team describes how plugging data into a computer simulation revealed a "layered cake" atmosphere that traps heat over the polar cap.

Scientists have known for several years that temperatures in the Arctic are rising faster (due to global warming) than for the rest of the planet—for the most part, most climatologists have attributed this to sea ice albedo—a feedback system where a small rise in temperature leads to melting of ice and snow.

Less ice and snow means less heat is reflected back into space, which means more warming occurs, and so on. In this new effort, the researchers suggest that while sea ice albedo is causing temperatures to rise, it's second to temperature feedback in overall impact.

To gain a better perspective on why Arctic temperatures are increasing so much, the researchers turned to highly sophisticated and data intensive climate computer models.

Their model showed a cap of cold layered air hovering over the Arctic, holding in the heat. The researchers believe their simulation accurately portrays what actually exists in the real Arctic.

Normally, they explain, changing weather patterns (such as thunderstorms) in other parts of the world keep atmospheric air churning, which in turn allows heat closer to the ground to be moved higher, allowing some of it to escape into space.

Things are very different in the Arctic—there is very little churning, which means that warm air close to ground (just one to two kilometers thick) remains where it is, trapped by a heavy layered atmosphere.

The simulation also helps to explain why Arctic warming is more pronounced in the winter than during other seasons—even less mixing of the air in the atmosphere occurs because the air is so cold.

The team reports that their simulations show that the temperature feedback that occurs in the Arctic is causing more average temperature increase than sea ice albedo, the second most critical factor in causing warming.

They have not used their findings to try to predict what sort of overall impact increasing Arctic temperatures might have on the rest of the planet, however, if the polar cap will melt completely, or if it does, when it might occur.

More information: Arctic amplification dominated by temperature feedbacks in contemporary climate models, Nature Geoscience (2014) DOI: 10.1038/ngeo2071

NASA AQUA MODIS Image: Totten Glazier melt rate linked to Sea Ice conditions

This image shows the Totten Glacier ice shelf in East Antarctica (the wrinkled white area at top left) on Sept. 25, 2013. 

Two large open-water polynyas appear on the sea ice below and to the right of the shelf, as well as several smaller ones. 

The open-water areas are bright black. 

The stippled diagonal line from lower left to upper right is the outer edge of the sea ice, with cloud cover to the right of that line. 

The image is from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA's Aqua satellite. 

Credit: NASA.

A new NASA-led study has discovered an intriguing link between sea ice conditions and the melting rate of Totten Glacier, the glacier in East Antarctica that discharges the most ice into the ocean.

The discovery, involving cold, extra salty water - brine - that forms within openings in sea ice, adds to our understanding of how ice sheets interact with the ocean, and may improve our ability to forecast and prepare for future sea level rise.

"I was curious why Totten was changing so fast when the glacier just next to it wasn't changing much," said Ala Khazender of NASA's Jet Propulsion Laboratory, Pasadena, Calif., lead author of the new study, published online Dec. 5 in the journal Nature Communications.

Combining satellite observations with ocean numerical modeling, Khazender and his colleagues developed a hypothesis that reductions in the volume of brine would increase Totten's thinning and melting.

Additional research supported that hypothesis.

Ice loss seen in Antarctica is generally attributed to the well-documented rise in temperature of the surrounding ocean, but scientists are still puzzling out the mechanisms behind the regional variations that they are observing.

The new study highlights the key role of processes occurring on small geographic scales in determining how global climate change can affect the stability of ice sheets.

Satellite observations from NASA's ICESat-1, which measures how much ice surfaces are rising or falling over time, revealed that Totten Glacier was thinning rapidly.

It currently discharges enough ice into the surrounding ocean to fill Lake Erie in just over a week.

The nearby Moscow University Glacier and its floating ice shelf were showing little change. Why the difference?

"We were convinced that the answer must be in the ocean," Khazender said.

The ocean around Antarctica is warmer than both the continent's icy surface and the polar air. Ice shelves (the floating front edges of glaciers that extend tens to hundreds of miles offshore) melt more because of contact with ocean water below them than they do because of sunlight.

Melting at the undersides of ice shelves is part of Antarctica's natural water cycle, but when glaciers start melting unusually quickly, it's a sign that something is off balance.

Khazender and his team of colleagues from JPL; UCLA; the University of California, Irvine; and Utrecht University in the Netherlands combined ICESat remote sensing observations from 2003 to 2008 with ocean numerical computer models to seek insights into the interaction between the ice shelves and their ocean basin.

More information: For more information on ICESat, visit: icesat.gsfc.nasa.gov/ .For more information on the ECCO2 ocean modeling and data synthesis project, visit: ecco2.jpl.nasa.gov/

MODIS Image: Phytoplankton Bloom in the Norwegian Sea

Credit: NASA/Jeff Schmaltz

The waters off Iceland rank among the world's most productive fisheries.

The reason for the abundance is an ample supply of phytoplankton, the base of the marine food chain.

Like any plant, microscopic phytoplankton need sunlight and nutrients to survive.

Iceland's coastal waters offer both during the long days of summer.

The Moderate Resolution Imaging Spectroradiometer (MODIS) flying aboard NASA's Aqua satellite acquired this true-colour image of a large phytoplankton bloom in the Norwegian Sea, off of Iceland, on July 6, 2013.

The range of colors from milky blue to green suggests that a range of different species make up this bloom, most likely including diatoms and perhaps chalky white coccolithophores, says Sergion Signorini, and ocean scientist at NASA Goddard Space Flight Center.

Floating in the water, phytoplankton act like tracers, revealing the course of mixing currents and the swirling eddies where they clash.

A branch of the North Atlantic Current (the Gulf Stream) flows north, bringing warm Atlantic water to mix with the cold Arctic currents circling in from the east.

NASA MODIS image: Pollution and Fires in Eastern China

Images are generated at NASA's Goddard Space Flight Center in Greenbelt, Md. 

Credit: Image: Jeff Schmaltz, NASA Goddard MODIS Rapid Response Team

NASA's Aqua satellite captured multiple plumes of smoke from agricultural fires and further evidence of growing industrial pollution in China.

China has long since denied it's destructive role in climate change, despite evidence to the contrary.

The smoke and haze stretches from Inner Mongolia, located north of Beijing, south and west including the provinces of Hebei, Shedong, Henan, Shanxi, Hubai, Hunan, and Chongqing.

The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard NASA's Aqua satellite has infrared capabilities that can detect heat from the various wildfires.

In the MODIS images, fires, or hot spots are colour coded as red areas in imagery and smoke appears in light brown. Images are generated at NASA's Goddard Space Flight Center in Greenbelt, Md.

CHINA: Stench of Air Pollution Soars unabated

Residents of Beijing and many other cities in China were warned to stay inside in mid-January 2013 as the nation faced one of the worst periods of air quality in recent history.

The Chinese government ordered factories to scale back emissions, while hospitals saw spikes of more than 20 to 30 percent in patients complaining of respiratory issues, according to news reports.

At the time that this Jan. 14 image was taken by satellite, ground-based sensors at the U.S. Embassy in Beijing reported PM2.5 measurements of 291 micrograms per cubic meter of air.

Fine, airborne particulate matter (PM) that is smaller than 2.5 microns (about one thirtieth the width of a human hair) is considered dangerous because it is small enough to enter the passages of the human lungs.

Most PM2.5 aerosol particles come from the burning of fossil fuels and biomass (wood fires and agricultural burning). The World Health Organization (WHO) considers PM2.5 to be safe when it is below 25.

Also at the time of the image, the air quality index (AQI) in Beijing was 341. An AQI above 300 is considered hazardous to all humans, not just those with heart or lung ailments. AQI below 50 is considered good.

On January 12, the peak of the current air crisis, AQI was 775 the U.S Embassy Beijing Air Quality Monitor—off the U.S. Environmental Protection Agency scale—and PM2.5 was 886 micrograms per cubic meter.

› View image comparisons with annotations.

Image Credit: NASA/Terra - MODIS

NASA Aqua MODIS Image: Taklimakan Desert in Western China

Snow-covered deserts are rare, but that’s exactly what the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite observed as it passed over the Taklimakan Desert in western China on January 2, 2013.

NASA image courtesy Jeff Schmaltz, LANCE MODIS Rapid Response. Caption by Adam Voiland.

The day after the storm Chinese Central Television (CNTV) reported that the Xinjian Uygyr autonomous region was one of the areas hardest hit.

The Taklimakan is one of the world’s largest and hottest, sandy deserts. Water flowing into the Tarim Basin has no outlet, so over the years, sediments have steadily accumulated.

In parts of the desert, sand can pile up to 300 meters (roughly 1,000 feet) high.

The mountains that enclose the sea of sand, the Tien Shan in the north and the Kunlun Shan in the south, were also covered with what appeared to be a significantly thicker layer of snow in January 2013.

NASA Terra Satellite Image: Capturing the Fading Colours of the US Fall

NASA Terra Satellite Image; 21 November 2012. There is still a lot of Autumn Fall colours showing over southern Virginia.

NASA MODIS Image: Sea Ice Off Eastern Greenland

The MODIS instrument on NASA's Aqua satellite captured this visible image of Sea Ice off eastern Greenland on October 16, 2012.

Image Credit: NASA/GSFC/Jeff Schmaltz/MODIS Land Rapid Response Team

Terra (formerly known as EOS/AM-1) is a joint Earth observing mission within NASA's ESE (Earth Science Enterprise) program between the United States, Japan, and Canada. 

The US provided the spacecraft, the launch, and three instruments developed by NASA (CERES, MISR, MODIS). 

Japan provided ASTER and Canada MOPITT. 

The Terra spacecraft is considered the flagship of NASA's EOS (Earth Observing Satellite) program. In February 1999, the EOS/AM-1 satellite was renamed by NASA to “Terra”.

NASA Aqua /Terra Satellite Image: Sicily and Mount Etna volcanic eruption

Credit: NASA

Italy's Mount Etna, one of the most active volcanoes on Earth, is spewing out plumes of bluish volcanic gas, as revealed in a recent satellite image.

The restive peak, located on the island of Sicily, has been erupting in spectacular fashion on and off since it ramped up activity in January 2011.

The mountain last spewed out fountains of glowing lava on April 24, and has been relatively quiet ever since.

NASA Modis Image: Wildfire Blaze on Greek Island of Chios

In this image captured by a Nasa Earth Observation satellite, a thick plume of smoke from an intense wildfire on the Greek island of Chios can be seen drifting southward over the island of Crete

Picture: NASA

A major forest blaze broke out shortly after 2 am on Saturday morning, August 18, 2012, on the Greek eastern Aegean Sea island of Chios.

Hundreds of firefighters, soldiers and volunteers were struggling for a third day Monday (August 20) to tame a fire that burnt some 17,000 acres of forest, cultivated land and groves of the island's famed mastic trees.

Chios is famous for the production of mastic, a gum-like resin with a distinctive flavor produced only by trees on certain parts of the island.

It is used widely in confectionery, cooking and cosmetics and a major source of income.

Local authorities said many of the trees had been burned, while the island's beekeepers had also lost 60 percent of their hives.

Smoke from the blaze, which was swept on by gale-force winds, was carried as far as the southern island of Crete, more than 230 miles away.

Those gale-force winds are hampering efforts by about 360 firefighters, soldiers and volunteers, as well as firefighting planes, helicopters and 50 vehicles.

Residents of nine villages and hamlets evacuated their homes over the weekend as a precaution. This natural-color image was taken by the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA's Aqua satellites on August 18, 2012.

NASA image courtesy Jeff Schmaltz, LANCE MODIS Rapid Response Team at NASA GSFC.

2012 Greenland Ice Melt Strongest On Record, More to Come

New data shows that melting of the vast ice sheet that covers more than three-quarters of Greenland is the strongest ever seen -- and there are still four weeks to go in the melting season.

Marco Tedesco, a researcher at the City College of New York, says the melting that scientists have observed in 2012 has already outstripped the melt in 2010. The melting season typically lasts from June to early September.

"With more yet to come in August, this year's overall melting will fall way above the old records," Tedesco said in a statement Monday.

"That's a goliath year, the greatest melt since satellite recording began in 1979."

This latest observation has not yet been published in a peer-reviewed journal, but Tedesco and his colleagues have a forthcoming paper looking at models projecting gains and losses to the ice sheet throughout the rest of this century.

NASA announced in July that its Earth Observation satellites (Modis, Aqua, Terra) had found that about 97 percent of the ice sheet's 660,000 square-mile surface had undergone melting.

This latest data from Tedesco and his colleagues jives with that finding. They used data from microwave satellite sensors in order to calculate the cumulative melting index, which gauges the "strength" of the melting season.

The index is generated by multiplying the number of days the ice sheet has melted by the total area of the ice sheet that has melted.

Rutgers University in Greenland

Åsa Rennermalm, a Rutgers University Hydrologist and researcher unaffiliated with the current project, studies the streams and rivers both on the ice sheet and those that are fed by meltwater.

She says the residents of Kangerlussauq, a town near her research site, confirm that this season's melt is the biggest they remember.

Kangerlussauq, which contains Greenland's major airport, was directly impacted by the higher melt on July 11, when a major bridge was destroyed by rising river, fed by melt-water.

"It was pretty dramatic," Rennermalm said.

Byrd Polar Research centre

Tedesco's colleague Jason Box, a researcher at Ohio State University's Byrd Polar Research Center, says there's a positive feedback mechanism at play in the ice sheet's melting; as the surface melts, it gets darker, which absorbs more heat from the sun.

In a downward spiraling action, the melted surfaces absorb more heat and this encourages further melting.

NASA Aqua Image: Cloud Patterns over South Sandwich Islands

Credit: NASA

A volcano in the South Sandwich islands creates a pattern in the clouds over the Southern Ocean in this photo taken by NASA's Aqua satellite

NASA Aqua Image: A Rare 'Glory' Rainbow captured

Credit: Jeff Schmaltz, LANCE MODIS Rapid Response

A view from space of a rainbow-like optical phenomenon called a Glory, consisting of brilliant lines of colour, taken by NASA's Aqua satellite.

A Glory is an optical phenomenon that resembles an iconic saint's halo about the shadow of the observer's head. 

The effect is believed to happen due to classical wave tunneling, when light nearby the droplet tunnels through air inside the droplet and, in the case of Glory, is emitted backwards due to resonance effects.

Credit: Michael Studinger. 

In this image, taken over Antarctica's Brunt Ice Shelf, a Glory surrounds the shadow of the DC-8 plane that is flying NASA's IceBridge mission to survey the state of Antarctic ice. 

NOAA MODIS Image: Hurricane Ernesto Set to Hit Yucatan Peninsula

The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this natural-colour image of Tropical Storm Ernesto around 11:35 a.m. EDT on Aug. 6, 2012.

CREDIT: NASA

Tropical Storm Ernesto has strengthened and officially become a hurricane, according to the latest update from the U.S. National Hurricane Center (NHC) and hurricane hunters who flew through the storm.

Ernesto, situated about 185 miles (295 kilometers) east of Chetumal, Mexico, is packing winds of 80 mph (130 kph), making it a Category 1 hurricane on the Saffir-Simpson scale.

A hurricane warning is in effect from Chetumal to Tulum on the east coast of the Yucatan Peninsula and the entire coast of Belize. The island of Cozumel has also been included in the warning.

The storm is expected to strengthen further before making landfall.

Hurricane Ernesto is expected to pass over the east coast of the Yucatan on Aug. 7. After it passes over the peninsula, it will emerge over the Bay of Campeche on Wednesday afternoon or evening.

Parts of the Gulf of Mexico coat of Mexico will likely experience tropical storm conditions.

Throughout the day today, the coast of Honduras may still experience tropical storm conditions.

Belize and the Yucatan are expected to see rainfall totals between 4 and 8 inches (10 and 20 centimeters) with localized areas seeing up to 12 inches (30 cm) of rain.

Storm surge is expected to raise sea levels by 2 to 4 feet (0.6 to 1.2 meters) above normal tide levels in some areas and will be accompanied by "large and dangerous waves," the NHC warned in its forecast.

Ernest is the second hurricane of the 2012 Atlantic hurricane season. Hurricane Chris was the first.

Ernesto is also the fifth named storm of the hurricane season. So far there have been six named storms, a category that includes tropical storms and hurricanes.

The National Oceanic and Atmospheric Administration (NOAA) will be issuing an updated forecast for the remainder of the 2012 season on Thursday (Aug. 9). August and September are typically the busiest months of the hurricane season.

NASA Earth Observation Satellites reveal sudden Greenland ice melt

Image Credit: Reuters

Greenland's massive ice sheet has melted this month over an unusually large area, Nasa has said.

Scientists said the "unprecedented" melting took place over a larger area than has been detected in three decades of satellite observation.

Melting even occurred at Greenland's coldest and highest place, Summit station.

The thawed ice area jumped from 40% of the ice sheet to 97% in just four days from 8 July.

Although about half of Greenland's ice sheet normally melts over the summer months, the speed and scale of this year's melting surprised scientists, who described the phenomenon as "extraordinary".

Nasa said that nearly the entire ice cover of Greenland, from its thin, low-lying coastal edges to its centre, which is 3km (two miles) thick, experienced some degree of melting at its surface.

"When we see melt in places that we haven't seen before, at least in a long period of time, it makes you sit up and ask what's happening," Nasa chief scientist Waleed Abdalati said.

"It's a big signal, the meaning of which we're going to sort out for years to come."

He said that, because this Greenland-wide melting has happened before, Nasa is not yet able to determine whether this is a natural but rare event, or if it has been sparked by man-made global warming.

Scientists said they believed that much of Greenland's ice was already freezing again.

Until now, the most extensive melting seen by satellites in the past three decades was about 55% of the area.

Ice last melted at Summit station in 1889, ice core records show.

The news comes just days after Nasa satellite imagery revealed that a massive iceberg, twice the size of Manhattan, had broken off a glacier in Greenland.

"This event, combined with other natural but uncommon phenomena, such as the large calving event last week on Petermann Glacier, are part of a complex story," said Nasa's Tom Wagner.

NASA - Petermann Glacier, Greenland

The Petermann Glacier grinds and slides toward the sea along the northwestern coast of Greenland, terminating in a giant floating ice tongue.

Like other glaciers that end in the ocean, Petermann periodically calves icebergs.

A massive iceberg, or ice island, broke off of the Petermann Glacier in 2010. Now, nearly two years later, another chunk of ice has broken free.

The Moderate Resolution Imaging Spectroradiometer, or MODIS, on NASA’s Aqua satellite observed the new iceberg calving and drifting downstream on July 16–17, 2012. Because Aqua is a polar-orbiting satellite, it makes multiple passes over the polar regions each day.

Image Credit: NASA