Fires Blaze in Chile

Smoke from dozens of forest fires billowed over central Chile in January 2017. A heat wave, coupled with strong winds, spread the flames on January 20, prompting President Michelle Bachelet to declare a state of emergency in some areas.

On January 20, 2017, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired an image of brown smoke billowing from a cluster of fires near the coastal city of Pichilemu. Red outlines indicate areas with heat signatures indicative of active burning. Smoke plumes stretch northward and over the Pacific Ocean. The second, wider view, acquired by Terra on January 21, shows fires spread across the region. Far to the north and west, brown smoke hovers over marine clouds.

At least 200 people were evacuated from the Pichilemu, Radio Santiago reported. Authorities declared a red alert in Consititución on January 19, when a fire burned through commercial pine and eucalyptus forests near residential areas. Smoke from the fires also shrouded the nation’s capital, Santiago.

There were 108 active forest fires registered in Chile on January 23, 2017. According to an update by the National Forest Corporation (CONAF), 62 had been controlled and three had been extinguished. The remaining 43 fires spanned an area of roughly 104,800 hectares (more than 400 square miles), according to CONAF.

Chile recorded roughly 5,200 forest fires per season in the decade between 1990 and 2000, according to a report by the UN Food and Agriculture Organization. The country has a Mediterranean climate and a long dry season—conditions that facilitate fires. Chile registered more than 6,700 fires during the 2015–16 fire season.

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The ‘Place of Blue Smoke’

The Cherokee Indians, the original inhabitants of the area, called these dark, fog-streaked hills “Shaconage”—the “place of blue smoke.” Scientists say the Great Smoky Mountains owe that color to a natural process. Plants exhale volatile organic compounds—gases that react with other substances in the air, creating aerosols. These aerosols can cause short wavelengths of light at the blue-violet end of the spectrum to scatter, creating a bluish haze.

The area’s relatively high humidity may also play a role. According to the National Park Service, average annual rainfall varies from roughly 55 inches (140 centimeters) in the valleys to more than 85 inches (215 centimeters) on the hills, making it one of the rainier places in the United States. At high elevations, the park’s humid air turns into fog, shrouding the mountains and giving them their iconic appearance.

Despite the feral appearance of its tree-covered hills, the park has long borne the fingerprints of human settlement. The Cherokee people lived in the area for more than a thousand years. In the late 1700s, the first European pioneer families began to clear land and make homes in the Smoky Mountains. As homesteaders populated more of the lands, President Andrew Jackson signed the Indian Removal Act in 1830, forcing the Cherokee and other tribes west in a journey known as “the Trail of Tears.”

The domestication of this stretch of land goes hand-in-hand with the story of the hog. Just as cattle ranching became popular in the American West, pig farming thrived in Appalachia. The self-sufficient animals were set free in the woods, with notches cut into their ears to indicate ownership. (The practice gave us the expression “to earmark.”) These pigs were said to have interbred with European wild boars, which escaped from a game farm in the 1900s. Their descendants still roam the mountains.

An invasive species, the wild hog has few natural predators. Hogs can damage crops and kill birds, which has earned them a reputation as a pest. Because they use their tusks to dig in the ground for food, they can also kill the park’s native plant life. Biologists have long worked to suppress the area’s wild hog population.

Not long after the park’s founding in 1934, the Great Depression brought a burst of activity to the region. In the 1930s, the Civilian Conservation Corps (CCC) brought young men seeking work to build many of the still-existing park features, like the Elkmont Bridge.

Today, with more than 10 million visitors each year, the Great Smoky Mountains National Park consistently ranks among the U.S.’s top three most visited parks. Perched on the Tennessee-North Carolina border, it is just a few hours’ driving distance from several major cities—including Charlotte, Nashville, Lexington, and Atlanta. City dwellers can seek refuge in the verdant hills and tumbling waterfalls, and peer at the still-standing colonial cabins.

The image above was stitched together from several Landsat 5 and Landsat 7 scenes. It is a best-pixel mosaic, representing the most cloud-free pixels during the summertime (June 21 - September 20) from 1986 to 2013.

http://go.nasa.gov/2jNgqgR

Ash Cloud Tells a Story of a Volcano Rising

About halfway down the Aleutian Island chain, tiny Bogoslof Island rises from the Bering Sea. Nobody lives there; the larger Unalaska and Umnak islands to the south have proven more favorable for human settlement. But when Bogoslof erupts, scientists and aircraft pilots take note.

“Bogoslof is just so off the grid, so to speak,” said Erik Klemetti, a volcanologist at Denison University and author of the Eruptions blog at Wired magazine. “However, it ends up being important to know what it’s doing for the sake of flights over the Aleutians.”

Because the Alaskan island is so remote, scientists monitor the eruptions from a distance by satellite and seismologic data. At 11:35 a.m. local time (22:35 Universal Time) on January 18, 2017, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this image of a plume rising from the volcano.

Much of the volcano is under water; the tallest parts reach about 150 meters (500 feet) above sea level and span just a few pixels in this image. “Submarine eruptions in the Aleutian arc are rare,” said Chris Waythomas, a geophysicist at the Alaska Volcano Observatory (AVO). “This is the first submarine eruption AVO has been able to monitor with a combination of instruments and techniques—seismic, infrasound, satellite, lightning—so it’s definitely something new for us.”

Note how the plume appears to be two colors. The lower part is white and composed primarily of steam and water vapor. Because the vent has been under water for most of the eruption, its plume contains more water vapor than a plume from a typical terrestrial volcano in Alaska. The upper part of the plume is dark gray-brown and rich in ash. According to Waythomas, “this is the first significant ash-rich volcanic cloud observed during the Bogoslof eruption.”

The presence of an ash cloud has led scientists to speculate that the vent might now be above sea level, but there is no direct evidence. Still, the island is changing shape with every large eruptive event. Thermal data (not pictured) show high temperatures for the first time, a clue that lava might be finding its way to the surface above the water line.

http://go.nasa.gov/2jV0HK6

Looking Down on Potomac Water Gap

On a fall day in 1783, Thomas Jefferson stood on a slab of shale on a bluff in the small town of Harpers Ferry and looked east. Below him, the Shenandoah and Potomac Rivers converged and flowed through a gap in the sharp ridge that overlooks the town. The view “was worth a voyage across the Atlantic,” he later wrote in Notes on the State of Virginia.

“The passage of the Patowmac through the Blue Ridge is perhaps one of the most stupendous scenes in Nature,” Jefferson wrote in his chapter about Virginia’s mountains. “You stand on a very high point of land. On your right comes up the Shenandoah, having ranged along the foot of the mountain a hundred miles to seek a vent. On your left approaches the Patowmac in quest of a passage also. In the moment of their junction they rush together against the mountain, rend it asunder and pass off to the sea.”

The slab of rock where he stood, known today as Jefferson’s Rock, remains one of the best places in Harpers Ferry to see the Potomac Water Gap.

Satellites offer an even loftier view. On April 20, 2016, the Operational Land Imager (OLI) on Landsat 8 captured this view of the water gap from an altitude of about 700 kilometers (430 miles). While spring warming has cast the valleys in green, the cooler tops of the ridges remained brown.

Harpers Ferry, West Virginia, population 293, lies at the tip of the peninsula formed by the confluence of the two rivers—a location that makes the lower part of the town quite prone to flooding.

The rivers are not alone in passing through the narrow gap in the ridge. A road, railway line, the Appalachian Trail, and the Chesapeake & Ohio Canal all crowd through the water gap as well. Today, the Potomac Water Gap stands at the heart of Harpers Ferry National Historic Park, a park that honors the role the town played in the U.S. Civil War.

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Water, Water Everywhere

The palm tree-fringed beaches of the Maldives give the appearance of an island paradise. But behind the tiny island nation lies a more complicated story.

The archipelago numbers 1,190 coral islands grouped into 26 atolls. Tourism powers the country’s economy, as 80 of its islands contain resorts. But its most lucrative asset—proximity to the azure seas—threatens to bring its downfall. The Maldives stands to lose much to sea-level rise, according to the United Nations.

As the smallest Asian country, the Republic of Maldives has a total population the size of a modest European city. The islands rise just a smidgeon above the Indian Ocean: roughly 80 percent of the country stands no more than 1 meter (3 feet) above sea level, according to the CIA World Factbook.

The nation was one of the first to warn of the effects of climate change that are already taking place. In 2009, then-president Mohamed Nasheed made international headlines by holding an underwater cabinet meeting in scuba attire to draw attention to the issue.

During bad storms, knee-deep water has inundated some islands. Malé, the capital and home to one-third of the nation’s residents—as well as multi-million dollar concrete stormwalls—has borne the brunt of several large storms in the past few decades. The city has also struggled to contain vector-borne diseases like dengue fever. (Heavy rains leave behind shallow pools where disease-spreading mosquitoes lay their eggs.)

This image was acquired on April 3, 2013, by the Advanced Spaceborne Emission and Reflection Radiometer (ASTER) aboard the Terra satellite. Note: the synthetic natural color image, which combines several different spectral ranges to simulate the look of natural color, makes the islands appear slightly brighter than would an aerial photograph.

http://go.nasa.gov/2iuyB6q

Cambodia’s Forests Are Disappearing

Cambodia has one of the fastest rates of forest loss in the world. In broad swaths of the country, densely forested landscapes—even those in protected areas—have been clear-cut over the past decade. Much of the forest has been cleared for rubber plantations and timber.

Scientists from the University of Maryland and the World Resources Institute’s Global Forest Watch have been using Landsat satellite data to track the rate of forest loss on a global scale. Though other countries have lost more acres in recent years, Cambodia stands out for how rapidly its forests are being cleared.

Between 2001 and 2014, the annual forest loss rate in Cambodia increased by 14.4 percent. Put another way, the country lost a total of 1.44 million hectares—or 5,560 square miles—of forest. Other countries with accelerating rates of forest loss include Sierra Leone (12.6 percent), Madagascar (8.3 percent), Uruguay (8.1 percent), and Paraguay (7.7 percent).

Researchers working with Landsat data and other economic datasets have demonstrated that changes in global rubber prices and a surge of land-concession deals have played key roles in accelerating Cambodia’s rate of deforestation. Concession lands are leased by the Cambodian government to domestic and foreign investors for agriculture, timber production, and other uses. Researchers found that the rate of forest loss within concession lands was anywhere from 29 to 105 percent higher than in comparable lands outside the concessions.

Work by Matthew Hansen and his University of Maryland Global Land Analysis and Discovery (GLAD) lab has played a key role in revealing the scope of deforestation. In 2013, the group published their first global map of forest change. The map above, based on Hansen’s work, depicts the extent of forest loss throughout Cambodia between 2000 and 2014. Much of it has occurred in the past five years.

In conjunction with the World Resources Institute, GLAD has developed a new weekly alert system: deforestation is detected by satellites with each new Landsat image, and users can subscribe for email updates. The freely available alert system is already operating for Congo, Uganda, Indonesia, Peru, and Brazil. The researchers hope to have the system operating for Cambodia and the rest of the tropics in 2017.

http://go.nasa.gov/2j10fMf

Lake Powell and Grand Staircase-Escalante

This panorama, photographed by an astronaut aboard the International Space Station, shows nearly the full length of Lake Powell, the reservoir on the Colorado River in southern Utah and northern Arizona. At full capacity, the reservoir impounds 24,322,000 acre-feet of water, a vast amount that is used to generate and supply water to several western United States, while also aiding in flood control for the region. It is the second largest reservoir by maximum water capacity in the United States (behind Lake Mead).

Landscape elevation changes are hard to see from space, but astronauts learn to interpret high and low places by their color. Green forests indicate two high places in the image that are cooler and receive more rain than the dry, low country surrounding the lake. The isolated Navajo Mountain is a sacred mountain of the Native American Navajo tribe and rises to 3,154 meters (10,348 feet). The long, narrow Kaiparowits Plateau rises nearly 1200 meters (4,000 feet) from Lake Powell to an elevation of more than 2300 meters (7,550 feet). More than 80 kilometers (50 miles) long, the plateau gives a sense of horizontal scale.

The region draws nearly 2 million people every year, even though it is remote and has few roads. Most of the area in view is protected as part of the Glen Canyon National Recreation Area and the Grand Staircase-Escalante National Monument—the largest amount of protected land in a U.S. national monument.

http://go.nasa.gov/2jQJGmS

Earth and Moon from Mars

A new composite image that shows Earth and the Moon in one frame is neither the first nor the clearest of its type. Still, this recent image from a powerful telescope orbiting Mars is a humbling reminder of how small and interconnected our planet appears when viewed from afar.

The image combines two separate exposures taken on November 20, 2016, by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter. The satellite was about 205 million kilometers (127 million miles) away from Earth when the images were acquired. For comparison, the circumference of the Earth at the equator is about 40,000 kilometers (25,000 miles). The distance between Earth and the Moon is about 30 times the diameter of Earth.

The images were taken in order to calibrate HiRISE data, since the reflectance of the Earth-facing side of the Moon is well known. These new images were processed separately to optimize detail on both Earth and the Moon because the Moon is much darker than Earth and would barely be visible if shown at the same brightness scale. The separate images were then were combined into one at the correct relative positions and sizes.

This portrait of home is a false-color image. HiRISE takes images in three wavelength bands: infrared, red, and blue-green, which are displayed here as red, green, and blue, respectively. This treatment of the data causes green vegetation to appear red. The landmass shown in the middle of Earth is Australia. Northwest of it, the lush vegetation of Southeast Asia and Asia gives that continent a red hue. The bright area near Earth’s southern pole is Antarctica. Other bright areas are clouds. The image also shows the western near-side of the Moon, which has large, dark, basaltic plains called maria.

http://go.nasa.gov/2kcqHAc

Colima’s Plume Casts a Shadow

Colima Volcano in western Mexico displayed explosive activity throughout 2016; the sequence of lava-dome building and destruction earned the volcano second place in Wired magazine’s volcanic events of the year. Now, in the first month of 2017, Colima continues to erupt.

On January 4, 2017, the Enhanced Thematic Mapper Plus (ETM+) on the Landsat 7 satellite captured this image of ash rising from Colima. The plume’s dark shadow obscures much of the summit, but you can still trace the plume back to its source.

http://go.nasa.gov/2jDSfBk

Lagoa Mirim

An astronaut aboard the International Space Station captured this photograph of the north end of Lagoa Mirim, a 180-kilometer-long coastal lagoon straddling the border of Brazil and Uruguay.

Three rivers enter the lagoon (top), and rectangular agricultural fields (dark tones in the image) cover nearly all of the dry land in the scene. In contrast, the water has a bright grey, mirror-like appearance due to sunlight reflected off the surface directly back to the camera. This sunglint emphasizes the meandering courses of the rivers and reveals a group of recently inundated fields (top left) that are mainly used for rice farming.

Around 400,000 years ago, sea level was higher and the Atlantic Ocean covered this part of Brazil’s coast. The lagoons on the southern coast of Brazil, including Lagoa Mirim, were formed by the natural rise and fall of sea level over time, a process geologists call the transgression-regression cycle. Eventually the connection between the lagoon and the Atlantic Ocean closed up, and the main source of water became the rivers draining the Brazilian interior—making Lagoa Mirim a freshwater lagoon.

On both sides of the narrow part of the lagoon (center), ancient beach ridges are visible as a set of curved stripes and islands. Water circulation formed these ridges, which were built up over the past thousand years as waves and currents moved sediment along the shoreline.

http://go.nasa.gov/2iyMPmZ

Kashgar, China

Kashgar has a rich cultural history dating back thousands of years, having served as an important hub along the Silk Road. The rising of this remarkable landscape dates back even further.

A modern view of the remote oasis in China, located at the western end of the Tarim Basin and the Taklimakan Desert, is visible in this image acquired on July 23, 2014, by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite. The image is false-color infrared (bands 3, 2, 1) to better highlight the composition of Earth’s surface. Urban areas appear gray, including the famed city of Kashgar in the bottom-right corner. Networks of roads are interspersed with buildings, which appear as rectangles in various shades of blue and purple.

Not all of the notable features in this image were shaped by humans. The long, light-colored ridges running horizontally are active folds—areas where the land is deforming upward as landmasses collide. In this case, India is pushing northward into Eurasia. The folds rise up to absorb the convergence of land (3 to 8 millimeters per year) between the Pamir Mountains to the south (China) and the Tien Shan ranges to the north (Kyrgyzstan). The southern ridge is the Kashi Fold, and the Atushi Fold lies to the north.

The folds appear various colors due to distinct rock formations with different mineral abundances. The green-yellow color across the Atushi Fold, for example, is likely related to a higher concentration of gypsum compared to the lighter tan and darker grey-brown areas. In general, the lighter-colored areas within the folds are mostly floodplain sediments—siltstones and sandstones about 1 to 5 million years old. The dark beds flanking the folds are thick conglomerates, generally less than 1 million years old.

The folds are uplifting relatively quickly on a geologic timescale at a rate of about 1 to 3 kilometers per million years. In spite of the rapid uplift, large areas of the folds have been beveled almost flat by small rivers that were more active during the last Ice Age. Today, rivers bounded by irrigated farmland (red in this image) cut through these folds in narrow gorges. The long gray area at the base of the image is the Kezilesu River, which means “red river”—a name that stems from its turbidity.

The forces deforming the region’s landscape occasionally give rise to earthquakes. In 1985, a magnitude-7.4 earthquake occurred on a branch of the Pamir Frontal Thrust fault. The quake destroyed about 85 percent of Wuqia County (northwest of this image) and left 15,000 people homeless.

http://go.nasa.gov/2irALEb

Floods Swamp Southern Thailand

Several days of heavy rainfall swamped much of southern Thailand in January 2017. While monsoon-related floods are common in the region, the wet season usually ends in November.

The Operational Land Imager (OLI) on the Landsat 8 satellite captured an image of flooded land near the Pra River on January 9, 2017. Much of the tan and yellow color on the landscape is sediment-laden flood water. For comparison, the second image shows the same area on February 2, 2014, when waters were lower.

The rainfall, which began on January 1, 2017, is some of the most severe to hit Thailand in three decades, according to Thai authorities. More than 300,000 homes have been affected, and damage to infrastructure is widespread. At least 36 people have died.

While the worst of the rain and floods have subsided and cleanup has begun in many areas, forecasters warn that additional bursts of heavy rain may hit southern Thailand in the coming days.

http://go.nasa.gov/2jfTUwR