The Earth Story

Anyuyskiy volcano Lying deep in far eastern Russia, Anyuyskiy is a formerly active volcano that once caused a huge lahar to flow down its western slopes. Lahars are among the most destructive effects of volcanic eruptions, commonly occurring around volcanoes that have considerable ice and snow cover. An Indonesian term, a lahar is a flowing mass of rock and sediment, ranging in size from clay to huge boulders, carried by ice and snow melted off from volcanic peaks. Lahars are often triggered by volcanic eruptions, but can also be caused by landslides or heavy rainfall. The flowing debris can move as fast a moving vehicle, be as wide as several football stadiums, and be more than ten times deeper than an Olympic-sized pool.

The glowing Earth

Did you know that if you look at any rock on Earth during night, it is still emitting light? Ok, maybe not exactly “light” in the visible light sense, but infrared “light” or radiation?

People stand out as warm spots in infrared light because they’re warmer than the surroundings and give off different wavelengths of light. Infrared detectors used to find people hiding in remote areas work on this principle – detect the energy given off at the temperature of a human body and you’ve found a person.

The Earth’s surface emits light at different wavelengths because it is at a different temperature from a human body, but that light can still be detected if an instrument is built for those wavelengths. On board NASA’s Terra satellite there is an infrared spectrometer known as ASTER - the Advance Spaceborne Thermal Emission and Reflection Radiometer, built to detect this radiation.

Vegetation gives off light at different wavelengths from bare desert ground and from soil. ASTER’s spectrometers were built to measure the emitted light at a resolution of only 90 meters/pixel – basically the size of a football field.

The amount of light emitted at five distinct wavelengths is measured by ASTER and combined into a single number known as the emissivity shown in this map. Blue areas with low emissivities are bare ground, while reddish areas are covered with vegetation (or ice). The emissivity is a measurement of how much radiation is emitted from a surface compared to its temperature - trees, moss, and vegetation are able to remove heat more efficiently than bare rock, so low-vegetation areas like deserts show low emissivity in this measurement.

These measurements can be used to observe changes in land use as vegetation is removed over time and play important roles in weather forecasting as the removal of heat from either land or water areas impacts how heat circulates through the atmosphere.

-JBB

Image credit: http://terra.nasa.gov/news/aster-global-emissivity-database-100-times-more-detailed-than-its-predecessors

Game of chess anyone? This is pretty cool. What we are seeing here is an area of 23 x 20 kilometres along the Idaho-Montana border crammed between Clearwater and Bitterroot National Forests. You will notice a checkerboard pattern within the land area; each square covering an area of around 1.6 x 1.6 kilometres. Each square hosts trees, which are harvested at different times and have different timber densities and regrowth stages. As a result, this natural pattern has formed. The image was taken with the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on-board Terra, the flagship satellite of NASA's Earth Observing System (EOS). -Jean Image courtesy of NASA

Land of Lakes During the last ice age which occurred during the Pleistocene Epoch (2.55 million – 11.7 thousand years ago) glaciers grew abundant throughout the world. Ice sheets on North America and Eurasia came to be thousands of feet thick and at one point, 1/3 of the earth’s surface was intermittently covered by ice. Large U-shaped valleys are evidence of a greater and icier past many of North America’s present day mountain ranges. Nearly all of the ice has since then melted, leaving most of the bone-chilling story hidden in the ground, the rocks, the oceans, and lakes that now surround us today. This image, for example, shows the many lakes (many of which are pluvial lakes) of just a small portion of the Nunavut Territory, the northernmost territory in Canada. The lakes and rivers are various shades of blue, while the vegetated land is represented in red. The image was taken by NASA’s Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on the Terra satellite. The technique combines various wavelengths to create false-color images. It is useful in this particular case because it allows us to see Canada’s lakes which otherwise would usually become lost in the natural greens and browns of the foliage. --Pete D Photo Credit: NASA References: 1. http://earthobservatory.nasa.gov/IOTD/view.php?id=78527 2. http://pubs.usgs.gov/gip/ice_age/ice_age.pdf 3. http://www.livescience.com/6937-ice-ages-blamed-tilted-earth.html

Colorful mountain slopes

This image combines data taken from 2 satellites – the Operational Land Imager on the Landsat 8 spacecraft and the ASTER image on NASA’s Terra Satellite – to produce a neat view at how the fall foliage draped over the slopes of Mount Katahdin, Maine.

The imager on Landsat took a visible-light image of this area showing the fall colors. Using modern mapping and GIS software, that image can be laid on top of data collected from other sources. That process involves lining up points that match between the two data sources and allowing a computer to combine the images. In this shot, the landsat image was draped over a model of the topography of the area, and then the position of the viewer was changed to the side so that it was possible to see the edges of the slopes.

The topography was acquired by the ASTER imager. To map out topography, images of the surface are acquired from two different viewing angles. Computers are able to combine these “Stereo” images into 3-d pictures in much the same way as your eyes can estimate distance by seeing in stereo. The vertical topography comes from a global topographic dataset assembled over years of orbits as that imager took photos of the surface.

-JBB

Image credit: NASA Earth Observatory images by Joshua Stevens, using Landsat data from the U.S. Geological Survey and ASTER GDEM data from NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team. https://earthobservatory.nasa.gov/IOTD/view.php?id=91154

Stereo imaging: https://asterweb.jpl.nasa.gov/gdem.asp

Canyonlands This fascinating photo was taken by the ASTER image on NASA’s terra satellite and provides a unique view of the Canyonlands National Park area. ASTER is a multi-spectral instrument, meaning that it takes images at different light wavelengths and those images are stitched together to give more information than would be found in a normal picture; the colors can tell more about the terrain and materials than images would otherwise. To the west of this image you see the Colorado River surrounded by a series of fault surfaces that run almost parallel to the river direction. East of the Colorado, two tributaries, the Dolores and San Miguel rivers have cut a series of highly-sinuous drainages that feed water into the main Colorado system. -JBB Image credit: NASA/GSFC http://m.flickr.com/#/photos/gsfc/10423895104/

Fanning out

When channels eroded into mountain ranges cross a boundary and expand onto open plains, the streams in them tend to spread out into wide features known as alluvial fans. This fan is found on the southern side of the Taklamakan Desert in China, where streams from the Tibetan Plateau spread out into the basin below. Flow happens only occasionally in streams like this, often taking the form of flash floods. When a major rain event happens upstream, the rain coming out of the channel picks a path towards the low ground and that path changes basically every time. The active flow heads to low ground, deposits sediment on its way that can block that channel or change the topography, and then the next time the fan becomes active the water finds a different route to the base. Thus, an alluvial fan builds up as a pile of sediment spreading out in all directions from the central point – where the channel enters the basin.

This image was taken by the ASTER instrument on NASA’s Terra Satellite – a multispectral imaging instrument capable of measuring light at a number of different wavelengths between the visible and the infrared. Different surfaces on Earth absorb light at different wavelengths, so measuring the amount of light reflecting off the surface at different wavelengths gives information about what is there. The blue color here has been tuned to a wavelength where vegetation is present – therefore, the blue light tracks a channel system where plants were able to grow. Plant growth, of course, requires water, so this image therefore shows which channels were active during the most recent rain event on this channel. That instrument has been flying for nearly 20 years, building up a database that can let scientists see how these features evolve over two decades.

-JBB

Image credit: NASA/GSFC https://flic.kr/p/7HeRA7

Instrument: https://asterweb.jpl.nasa.gov/instrument.asp

The Canals of Amsterdam

This image from the ASTER instrument on NASA’s terra satellite gives a birds-eye view on the city of Amsterdam, one of Europe’s great cities, a center of trade and culture for centuries, and, thanks to its unique engineering, a UNESCO world heritage site.

In this image, vegetation appears red and green, water is blue, and urban development appears grey. A group of blue half-circles stands out quite well and is marked by the names “Singel” and “Singelgracht”.

As the city was growing during the 16th and 17th centuries, it outgrew its original borders in the area of the Singel. Urban planners and engineers created an ambitious plan to grow the city; draining swampland around it and building a series of new canals concentric with the interior Singel canal.

The Singelgracht boundary marked here formed the outer boundary of the city as well as a defense line. Within that area, more than one hundred kilometers of canals were dug, turning the city into a series of islands joined by bridges, streets, and walkways. Ships were able to sail into the city and dock along the canals, enabling trade and transit throughout the city.

Much of the original construction survives to this day, including hundreds of buildings dating to the 16th and 17th century.

-JBB

UNESCO report on Amsterdam: http://whc.unesco.org/en/list/1349

Image source, NASA: http://earthobservatory.nasa.gov/IOTD/view.php?id=81689

Deforestation in Brazil will not create an economic miracle.

Some time ago, we shared an image showing the border between Haiti and the Dominican Republic, outlining the enormous difference in the level of deforestation between the two countries (http://tinyurl.com/cwm427g). We now share a new image, taken by the ASTER instrument on NASA's TERRA satellite. This one depicts the border between Western Brazil's Acre province, showing the typical herringbone pattern radiating out from forest roads caused by the human transformation of the Amazon rainforest into settled farmland, and the Northwestern Bolivian province of Pando, still covered in relatively pristine forest.

A paper just published in Environmental Research Letters details evidence that this policy of converting the Amazon rainforest into cattle ranches and soya fields, while economically beneficial in the short term, is likely to prove the opposite in the longer term. This could affect global food security, since Brazillian soya ( it is the world's top supplier) and beef are exported worldwide. The degradation of the productive capacity of the soil engendered by deforestation (via erosion and the fact that most of the Amazon's soil comes from the perpetual recycling of forest biomass above what is essentially a desert) could mean less calories to go round as the whole global food system is transformed by climate change.

The research shows that deforestation is already leading to reduced rainfall and drought, affecting the productive capacity of the newly created farmlands in what could become an uncontrollable feedback loop. The more the farmed area expands, the less productive it will be. Their models, based on what has happened so far, expect a 34% decline in pastoral productivity and a 28% drop in soya yield by 2050.

This makes an economic argument against deforestation, since the environmental ones are having trouble gaining traction within business and government circles worldwide. It adds detail to the big picture painted by Lord Stern in his report on the economic costs of climate change a few years back. While the global environmental impact of the loss of the rainforest is well studied, this is the first paper focussing on the local economic consequences, and with luck, the Brazillian government will work even harder to reduce deforestation. The researchers also point out that improved efficiency in the use of already cleared land and water resources could offset some of this productivity loss, without extending the area of converted rainforest.

More of this type of regional level research is needed, to demonstrate the effects of our environmental abuse of the Earth on our collective pocketbooks. Whether it will lead to a paradigm shift in our economic model, in which short term quarterly figures are the standard by which politicians and CEO's are judged, rather than the long term effects of their policies, remains to be seen. After all, with such short periods in office, the bad consequences are bound to happen on someone else's watch, which is basically the generational gamble we are all undertaking with the only planet we have.

Loz

Image credit: NASA

Original paper: http://iopscience.iop.org/1748-9326/8/2/024021/article

http://www.guardian.co.uk/environment/2013/may/10/amazon-clearance-agriculture-economic-own-goal

http://www.guardian.co.uk/environment/2012/nov/14/brazil-amazon-rangers-farmers-burning

A Glacier of Salt?

The Landsat image below shows a diapir, or salt glacier in the Zagros Mountains of Iran.

A salt dome is is a column of salt that has risen toward the earth's surface due to a lower density than the surrounding rock. A salt glacier occurs when a salt dome breaks through the surface and forms a slowly flowing "glacier" of salt. Because the Zagros Mountains area in Iran is very arid, the salt is not dissolved and carried away by rainwater.

Salt glaciers are not common because they require a certain set of events to coincide. A thick layer of salt is required below the surface that forms salt domes. The salt domes need to rise to the surface, and the surface must receive little rainfall. Most salt glaciers are found in the arid regions around the Persian Gulf.

-Amy

References: http://earthobservatory.nasa.gov/IOTD/view.php?id=4168 http://geology.com/stories/13/salt-glacier/

Landsat Image, credit NASA

Snowy Himalayas

This image was taken by NASA’s ASTER device, on board the Terra satellite in 2002, showing dendritic river drainages and confluences in Southwestern China that bear some resemblance at first glance to a snowflake.

The image is a false colour composite, produced by allocating different wavelengths of light received at the satellite to what your screen produces as red, green and blue. In this case, near-infrared wavelengths are allocated to red, red wavelengths are allocated to green and originally green wavelengths are shown as blue. This combination of wavelengths and colour channels is regularly used by those studying satellite imagery to highlight vegetation, as chlorophyll has a particularly high reflectance of near-infrared wavelengths. That reflectance causes vegetation to appear an obvious bright-red in the images, as seen here at lower altitudes around the channels.

The Himalayas began uplifting 50 million years ago, when India collided with the Eurasian plate after a 6,000km journey away from its original location, attached to Madagascar. The mountain range is still being uplifted today at approximately 5mm per year, lifting 9 of the 10 tallest peaks in the world even higher above sea level.

-WAV

Image credit: NASA (http://bit.ly/1LhPX4h)

References:

http://bit.ly/1nEbTez http://bit.ly/1UmMNh6 http://go.nasa.gov/1pCAZMq http://to.pbs.org/1LXRc8Z

RUBʿ AL-KHALI FROM SPACE

Earlier we posted about Rubʿ al-Khali, aka the Empty Quarter; a desert in the southern Arabian Peninsula: http://on.fb.me/UYddKy. Rubʿ al-Khali covers about 650,000 square km (250,000 square miles) and lies mainly in southeastern Saudi Arabia, with some portions in Yemen, Oman, and the United Arab Emirates. The desert was largely unexplored until recently; the first documented journeys made by Westerners were those of Bertram Thomas in 1931 and St. John Philby in 1932.

This image, captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) aboard NASA's Terra Earth-orbiting satellite, shows the sea of sand and sand dunes that makes up the Rubʿ al-Khali, from above. The image was acquired on December 2, 2005.

-TEL

http://on.fb.me/UYddKy http://www.nasa.gov/multimedia/imagegallery/image_feature_1200.html Image Credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

The glowing Earth Did you know that if you look at any rock on Earth during night, it is still emitting light? Ok, maybe not exactly “light” in the visible light sense, but infrared “light” or radiation? People stand out as warm spots in infrared light because they’re warmer than the surroundings and give off different wavelengths of light. Infrared detectors used to find people hiding in remote areas work on this principle – detect the energy given off at the temperature of a human body and you’ve found a person. The Earth’s surface emits light at different wavelengths because it is at a different temperature from a human body, but that light can still be detected if an instrument is built for those wavelengths. On board NASA’s Terra satellite there is an infrared spectrometer known as ASTER - the Advance Spaceborne Thermal Emission and Reflection Radiometer, built to detect this radiation. Vegetation gives off light at different wavelengths from bare desert ground and from soil. ASTER’s spectrometers were built to measure the emitted light at a resolution of only 90 meters/pixel – basically the size of a football field. The amount of light emitted at five distinct wavelengths is measured by ASTER and combined into a single number known as the emissivity shown in this map. Blue areas with low emissivities are bare ground, while reddish areas are covered with vegetation (or ice). This is the most precise map of the Earth’s emissivity ever produced. These measurements can be used to observe changes in land use as vegetation is removed over time and play important roles in weather forecasting as the removal of heat from either land or water areas impacts how heat circulates through the atmosphere.  One final detail to understand about this data involves climate change; the reason why a greenhouse effect happens is actually found in this data. When energy comes in to the Earth from the sun, it warms the exposed surface. When that surface rotates away from the sun, it radiates the energy away. But, the wavelength of light given off depends on the temperature. The sun is hot enough to send out visible light, while rocks throughout the solar system give off heat in the infrared – the same type measured by ASTER. On a body with no atmosphere, that energy just heads out to space. But, on a planet with an atmosphere, molecules like water and carbon dioxide actually absorb infrared light, keeping it from escaping. Once that energy is captured by the atmosphere, it turns back into heat, so a larger amount of a greenhouse gas in the atmosphere must translate to an overall increase in the temperature.  This effect keeps the planet from being a frozen ball of ice like other places in the solar system, but it also can be pushed too far by increasing concentrations of greenhouse gases. The ASTER instrument therefore is measuring the balance of the types of light that actually drive the greenhouse effect – changes in emission of light at various wavelengths as the atmosphere absorbs more energy and warms up. This data therefore is directly applicable to climate models that allow us to estimate how the planet will behave in the future as greenhouse gases continue to build up in the atmosphere. -JBB Image credit: http://terra.nasa.gov/news/aster-global-emissivity-database-100-times-more-detailed-than-its-predecessors

CIRCULAR CROPS IN KANSAS Believe it or not this is not a painting, but an image captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on June 24, 2001. Variegated green crop circles cover what was once shortgrass prairie in Finney County, south-western Kansas USA; the most common crops in this region are corn, wheat and sorghum. The crops were each at a different point in development when the image was attained, which accounts for the varying shades of green and yellow. The healthy and growing crops are green. Corn grows into leafy stalks by late June while sorghum grows more slowly and would be smaller and therefore paler. Wheat is a bright gold as it is harvested in June, while the brown fields are those that have been recently harvested and ploughed under or are lying fallow for the year. These crops are partly fed by water from the Ogallala Aquifer, like many crops throughout large sections of the U.S. Midwest. The rivers and streams that fed the aquifer long ago have disappeared; water now takes a long time to travel through the soil to recharge the aquifer although the rates vary from region to region. The image shows centre-pivot irrigation systems that are 800 and 1,600 metres in diameter (0.5 and 1 mile), and the image covers an area of 37.2 x 38.8 km. -TEL http://www.nasa.gov/multimedia/imagegallery/image_feature_434.html Image credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team.

Game of chess anyone? This is pretty cool. What we are seeing here is an area of 23 x 20 kilometres along the Idaho-Montana border crammed between Clearwater and Bitterroot National Forests. You will notice a checkerboard pattern within the land area; each square covering an area of around 1.6 x 1.6 kilometres. Each square hosts trees, which are harvested at different times and have different timber densities and regrowth stages. As a result, this natural pattern has formed. The image was taken with the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on-board Terra, the flagship satellite of NASA's Earth Observing System (EOS). -Jean Image courtesy of NASA

Land of Lakes During the last ice age which occurred during the Pleistocene Epoch (2.55 million – 11.7 thousand years ago) glaciers grew abundant throughout the world. Ice sheets on North America and Eurasia came to be thousands of feet thick and at one point, 1/3 of the earth’s surface was intermittently covered by ice. Large U-shaped valleys are evidence of a greater and icier past many of North America’s present day mountain ranges. Nearly all of the ice has since then melted, leaving most of the bone-chilling story hidden in the ground, the rocks, the oceans, and lakes that now surround us today. This image, for example, shows the many lakes (many of which are pluvial lakes) of just a small portion of the Nunavut Territory, the northernmost territory in Canada. The lakes and rivers are various shades of blue, while the vegetated land is represented in red. The image was taken by NASA’s Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on the Terra satellite. The technique combines various wavelengths to create false-color images. It is useful in this particular case because it allows us to see Canada’s lakes which otherwise would usually become lost in the natural greens and browns of the foliage. --Pete D Photo Credit: NASA References: 1. http://earthobservatory.nasa.gov/IOTD/view.php?id=78527 2. http://pubs.usgs.gov/gip/ice_age/ice_age.pdf 3. http://www.livescience.com/6937-ice-ages-blamed-tilted-earth.html

Alaska's Susitna Glacier revealed some of its long, grinding journey when the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite passed overhead on August 27, 2009. This satellite image combines infrared, red, and green wavelengths to form a false-color image. Vegetation is red and the glacier's surface is marbled with dirt-free blue ice and dirt-coated brown ice. -E