Earth Observation Archives

August 17, 2007December 26, 2015 by Fraser Cain

Arctic Ice Coverage Will Shrink to 2050 Projections… This Summer

Sometimes you wish records didn’t get broken. A group of Japanese science agencies announced today that the area of the Arctic Sea covered by ice is at its lowest level ever recorded. It reached this low point on August 15th, and it’s going to get worse. Ice levels should continue to shrink all the way through mid-September. If reality matches predictions, the ice levels will reach IPCC predictions 40 years ahead of schedule.

On August 15th, 2007 the area of Arctic sea ice was 5.31 million square km (2.1 million square miles). This beats the previous record of 5.32 million seen back in September 2005. That might sound like it’s almost the same amount, but just you wait, ice is expected to continue shrinking until mid-September, getting as small as 4.5 million square km.

These results were announced today by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) and the Japan Aerospace Exploration Agency (JAXA), which have been tracking Arctic ice levels by satellite since 1978. By their calculation, an amount of ice equal to the Japanese archipelago has been lost in just the last 3 years.

According to the Japanese agencies, there could be several reasons why the ice levels are so low this year. One explanation is that ice in coastal areas which is more prone to melting could have entered the Arctic Sea. It’s also possible that melting within the Arctic Sea has quickened – thanks to global warming – and is leading to the ocean absorbing more sunlight. Finally, they suggest that more sea ice could have drifted from the Arctic Sea to the warmer Atlantic Ocean and melted.

Here’s the scary part. The United Nations Intergovernmental Panel on Climate Change predicted that this level of ice coverage would be met in 2050. I’ll say that again, Arctic ice will reach levels predicted for 2050 by the end of this summer. I wonder what the levels will be in 2050?

Here’s what one official had to say about the IPCC predictions:

The IPCC forecast cannot adequately explain what is now happening in the Arctic Sea.

Original Source: JAXA News Release

August 2, 2007December 26, 2015 by Fraser Cain

Detailed Gravity Maps of the Earth will be Coming Soon

How high is Mount Everest? Really high? Nearly 9,000 metres? Come on, be precise. Don’t worry if you can’t, even geographers can’t agree. In 1999, the mountain’s height was stated as 8,850 metres, and then a Chinese survey in 2005 calculated it to be 8,844.43. That might not sound like much of a difference, but for scientists, it’s just too much uncertainty. Good thing a new spacecraft will be launching soon to settle the question once and for all.

ESA’s gravity field and steady-state Ocean Circulation Explorer (GOCE) is scheduled to blast off in early 2008. This sensitive satellite will then measure the Earth’s gravity field and geoid with unparalleled precision.

What’s the geoid? That’s a measure of the Earth’s gravity field at every point across the planet. Imagine you were able to extend the oceans across the surface of the entire planet, perhaps by cutting canals across the continents. This is how geographers can measure the height of a point above sea level, even when you’re thousands of kilometres away from the nearest ocean.

The geoid isn’t flat. Instead, it rises and falls depending on the local gravity at that exact point. If you’re traveling across the ocean on ship, you don’t stay at the exact same distance from the Earth’s centre point. Instead it varies, depending upon where on Earth you are. Pass by the Hawaiian islands, and their mass will draw the water up, raising sea level. Not a lot – the total variation is less than 200 metres, compared to a perfect mathematical ellipsoid. As you can imagine, the shape of this geoid is important to scientists.

When GOCE launches, it’ll fly at an altitude of 260 km. Instead of a traditional satellite, it’s streamlined, with fins that keep it stable as it passes through the last remnants of the Earth’s atmosphere. It will measure the Earth’s gravity to within an accuracy of 1-2 cm. In other words, they should be able to provide an answer to the Everest height question, once and for all. Not to mention, an accurate altitude for every other spot on Earth.

Here are some additional stories on measuring the Earth’s gravity, with GOCE and the previously launched GRACE satellite.

Original Source: ESA News Release

July 17, 2007December 26, 2015 by Fraser Cain

Satellite Sees Mysterious Noctilucent Clouds

During the summer, observers can sometimes see beautiful clouds called “night-shining” clouds, or noctilucent clouds. And while lucky observers were seeing from below this summer, a NASA satellite was watching them from above.

Noctilucent clouds form in an upper layer of the Earth’s atmosphere called the mesosphere during the Northern Hemisphere’s summer – at an altitude of 80 km (50 miles). They can start forming as early as May, and extend through August. They can also be seen in high latitudes during the summer months in the Southern Hemisphere.

The images were gathered by NASA’s AIM satellite (aka, Aeronomy of Ice in the Mesosphere), which snapped pictures of the clouds on May 25th, 2007.

A puzzling aspect to the phenomenon is that it’s changing dramatically. The clouds are growing brighter, seen more frequently, and visible at lower and lower latitudes than ever before. AIM will observe the clouds above the Earth’s poles for two complete clouds seasons, documenting their entire life cycle to try and help uncover an explanation for this mystery.

Original Source: NASA News Release

July 10, 2007December 26, 2015 by Fraser Cain

Killer Electrons From Space!

Space travel is dangerous, make no mistake. So many ways to die. But now scientists think they’ve got a handle on how one of the threats operates: killer electrons from space.

Using data from a fleet of spacecraft, scientists at the Los Alamos National Laboratory have puzzled out how electromagnetic waves accelerate normal electrons in the Earth’s radiation belts to killer velocities. These electrons are then hazardous to satellites, spacecraft, and especially astronauts.

Their research, entitled The Energization of Relativistic Electrons in the Outer Van Allen Radiation Belt was published in the July issue of Nature Physics.

They measured the fluxes of electrons striking a satellite-mounted detector, and the converted the measurements to magnetic coordinates. This showed them that the local peaks in electrons could have only been caused by the acceleration of electrons by electromagnetic waves. They still don’t understand the exact mechanism that’s causing the acceleration, though.

Two new NASA spacecraft are due to be launched in 2012 – the Radiation Belt Storm probes – these will help scientists understand the mechanism more deeply.

Original Source: Los Alamos National Lab

June 13, 2007December 26, 2015 by Fraser Cain

Three Gorges Dam from Space

When it’s finally completed in 2009, China’s Three Gorges Dam will be a colossal man made structure. But even partially completed, it’s already a dramatic change to the region; it’s even visible from space with the unaided eye. NASA’s space satellites have been tracking the construction since it began in 1994, and NASA has released an animation that shows both the dam today, and the changes over time.

The Yangtze River is the third largest river in the world, reaching 6,200 km (3,900 miles) across China. The river is prone to flooding, and overflows its banks every 10 years or so. The dam is designed to control this flooding, protecting inhabitants down river, as well as producing a tremendous amount of electricity.

When it’s fully operational, the dam will produce 20 times the electricity of the Hoover Dam, and allow huge freighters to travel into the Chinese interior, delivering supplies and retrieving manufactured goods.

The construction of the dam has also had a serious impact on the local environment, flooding out residents, changing rainfall patterns, and concentrating pollution.

Original Source: NASA News Release

June 12, 2007December 26, 2015 by Fraser Cain

Journey to the Centre of the Earth’s Position in Space

NASA researchers have developed a new technique that gives them a precise measurement for the position of the centre of the Earth, to the closest millimetre. This is harder than it sounds, since the centre doesn’t stay in one position.

As the Earth rotates in space, its centre of mass ranges over a distance of 2 to 5 millimetres (.08 to .20 inches) a year. Until now, the best calculations differed by 1.8 millimetres a year. That doesn’t sound like much, but its actually important for very precise measurements. For example, the rise in global sea level due to increasing temperatures is measured in a handful millimetres. In other places, the Earth is rebounding after the weight of glaciers during the last ice age, 20,000 years ago.

The researchers combined 4 different space-based techniques to get this accurate measurement: the global positioning system, laser stations that track orbiting satellites, radio telescopes that measure the position of the Earth against quasars, and a French network of tracking satellites called DORIS.

Original Source: NASA/JPL News Release

June 12, 2007December 26, 2015 by Fraser Cain

Arctic Explorers are Getting Some Help from Above

A duo of Belgian adventurers are receiving some guidance from the heavens during their 2,000 km (1,200 mile) trek across the Arctic Ocean. Okay, it’s nothing magical, they’re just received detailed observations from ESA’s Envisat Mission, which is providing readings on sea ice.

The explorers, Alan Hubert and Dixie Dansercoer, are collecting snow depth data which will help calibrate the upcoming CryoSat-2 mission. They’re used to dealing with the harsh and rapidly changing Arctic environment, but they were caught off guard when a portion of the ice in the Lincoln Sea broke up. Thanks to observations from Envisat, they were able to avoid the rapidly disintegrating ice pack, and steer to safer conditions further to the east.

Their Arctic Arc expedition is part of the International Polar Year 2007-2008. They started in March 1, 2007, and have already traveled 1,600 km (1,000 miles) taking snow depth measurements along the way. When CryoSat-2 finally launches in 2009, scientists will compare the satellite’s observations against these measurements, to better calibrate its data on snow levels.

Original Source: ESA News Release

June 7, 2007December 26, 2015 by Fraser Cain

Tangled Seaweed Viewed From Space

This strange looking photograph is actually the Gulf of Mexico, seen from space by ESA’s Envisat Earth imaging satellite. Specifically, the spacecraft has picked up huge lines of Sargassam seaweed floating in the warm waters off the coast of the US.

To make this observation, Envisat used the Medium Resolution Imaging Spectrometer (MERIS), which has the ability to see objects with large quantities of chlorophyll – in this case, seaweed. Since marine plants absorb half of the carbon dioxide emitted into the atmosphere, being able to track the density of marine vegetation is very important for climate research.

By using a new processing algorithm, researchers are now working to calculate global estimates of Sargassum biomass, to help keep track of its contribution to ocean productivity. This will also give them the ability to spot any changes in biomass, and better fine tune climate models.

Original Source: ESA News Release

May 29, 2007December 26, 2015 by Fraser Cain

Snow Melt is on the Rise in Greenland

The island of Greenland experienced more days of melting during 2006 on average than in the last 18 years, according to new NASA-funded research.

The data were gathered by the Special Sensor Microwave Imaging radiometer (SSM/I) flying aboard the Defense Meteorological Satellite Program spacecraft. It can peer through the clouds, and measure the rates of melting every day. During 2006, researchers estimated that portions of Greenland melted for an additional 10 days beyond averages.

Melting water on Greenland will impact global water levels. But the water can also slip down through cracks in glaciers, and lubricate the ice sheet. This can speed up the movement of glaciers, which eject ice into the ocean, and further accelerate sea level rise.

Original Source: NASA News Release

May 15, 2007December 26, 2015 by Fraser Cain

Antarctica Had Vast Regions Melt Recently

Much of the concern for global warming has been focused on the Arctic Ocean, where sea ice is disappearing faster than scientists had predicted. The southern regions of the Earth didn’t seem to be as affected. But new satellite images from NASA’s QuikScat satellite are showing that Antarctica is melting too.

QuikScat measured snowfall accumulation and melting in Antarctica, tracking the period from July 1999 through July 2005. Scientists analyzing the results found that several distinct regions across the continent were accelerating their rate of snow melt. And these regions were places nobody would have anticipated. There was evidence of melting 900 km (560 miles) inland from the open ocean, only 500 km (310 miles) from the South Pole, and 2,000 metres (6,600 feet) above sea level.

These melting regions don’t actually reach the sea; however, they refreeze into an extensive ice layer. The water can penetrate into ice sheets through cracks and glacial shafts, and then lubricate the underside of the ice sheet at the bedrock, causing the ice mass to move more quickly towards the ocean, and raising sea levels.

Original Source: NASA/JPL News Release