Category: Earth Observation

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

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

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

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

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