• Facebook
  • Twitter
x

RealTime Images

  • Portfolio
  • About
  • Contact
  • Video
  • Blog
  • Archive
Show Navigation
InternationalArchive
Cart Lightbox Client Area
Download
twitterlinkedinfacebook

NASA Aerials - 28 June 2017

37 images Created 29 Jun 2017

Next
View: 25 | All

Loading ()...

  • Dust and sand storms in the Middle East and other arid regions tend to come in two forms. Haboobs are dramatic events associated with storm fronts and often appear as walls of sand and dust marching across the landscape. But like thunderstorms, haboobs tend to abrupt and short-lived. Then there are the long-lived, wide-reaching dust storms that can last for days. In Iraq, such storms are often associated with the shamal, a pattern of persistent northwesterly winds.<br />
In early September 2015, a storm with characteristics of both the shamal and the haboob moved across Iraq, Iran, and the Persian Gulf region. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite captured these natural-color images of the dust storm on September 1 and September 3, 2015.<br />
The dust event first appeared in NASA satellite imagery along the Iraq–Syria border on August 31. By the next day, the storm took on the cyclonic shape visible in the top image above. By September 2, the dust cloud reached the Persian Gulf. It had spread out across the entire basin by the time of the September 3 image above.<br />
The storm appears to have been triggered by a surface low-pressure system that moved from northwest to southeast during the week. The cyclonic circulation around the center of low pressure is most obvious in the September 1 image. Weather data from ground stations in Baghdad, Khormor, and Al Asad confirm the wind circulation pattern. But the overall movement of the system from the northwest toward the Persian Gulf also suggests late-summer shamal winds.<br />
Much of northern Iraq has been in a state of exceptional drought. Anecdotal evidence and media reports in recent years suggest that dust storms have become more common in Iraq and Iran, a result of that drought and of the human and natural destruction of wetlands in the Tigris-Euphrates watersheds.<br />
News reports and social media chatter in September 2015 described wind gusts up to 80 kilometers (50 miles) per hour in Iran
    rtisipausa_20553491.jpg
  • View Image Comparison<br />
View Both Images<br />
In the 1980s, the landscape around Al<br />
Ain - a small city in the United Arab Emirates - was dominated by the colors of the Arabian desert: tan, orange, and brown. Three decades later, green is the color that is difficult to ignore.<br />
The Thematic Mapper on Landsat 5 acquired the top image on April 29, 1984. The Operational Land Imager (OLI) on Landsat 8 acquired the lower image on July 24, 2015. Turn on the image comparison tool to slide between the two images.<br />
In 1984, green areas were mostly limited to the large oasis in the historic center of the city. By 2015, several new parks, farms, nature preserves, and palace gardens had emerged, particularly to the south and west of the city. As noted in one recent study, the city now contains 12 million square meters of green space - an average of 32 square meters (344 square feet) per resident, more than any other city in the Arab world. The population has expanded rapidly as well, rising from about 50,000 people in 1975 to more than 630,000 in 2012. The expansion of urban areas - gray in the images - has primarily proceeded westward from the city center due to an abundance of open space and the presence of transportation, water, and power infrastructure.<br />
Green Mubazzarah is one of the most noticeable new green spaces. Located south of the city, at the base of a 1,200-meter mountain called Jebel Hafeet, the park is irrigated by underwater springs. Several other sprawling expanses of green have grown up along the outskirts of the city, including the Al Rawdha and Al Maqam palaces and several farms. One of the largest farms in the city, operated by Al Foah, produces dates on 1,320 hectares.<br />
Although Al Ain's climate is quite arid, the presence of a large oasis along the eastern edge of the city has made greening the city possible. While most cities in the United Arab Emirates have seen water tables fall significantly as consumption increases, groundwater levels have instead risen in some
    rtisipausa_20553507.jpg
  • View Image Comparison<br />
View Both Images<br />
If you want to get from Macau or Zhuhai to Hong Kong, you either have to take a boat or drive at least four hours (200 kilometers) across southeastern China. An ambitious engineering project intends to shorten that drive time to 40 minutes.<br />
The Hong Kong-Zhuhai-Macau (HKZM) Bridge has been dreamed about for at least 30 years and under construction for seven years so far. There are at least three or more years to go before cars and trucks will be able to pass between the Hong Kong Special Administrative Region on the eastern shores of the Pearl River estuary to Zhuhai City (Guandong Province) and the Macau Special Administrative District on the western side. The bridge will add a new transportation link in one of the fastest-growing and largest urban areas in the world. More than 50 million people live around the Delta.<br />
The Operational Land Imager (OLI) on the Landsat 8 satellite acquired two natural-color images of the bridge-tunnel construction project. The top image was acquired on November 29, 2013, while the lower image was acquired on March 27, 2016. The different shades of blue and green in the water are likely due to different sediment loads in different seasons and tides. Turn on the image comparison tool to see the detailed progress on the bridge.<br />
The HKZM connector will include roughly 42 kilometers (26 miles) of bridges over water, with another 7 kilometers (4 miles) passing through a submarine tunnel. The estimated $132 billion (Hong Kong) project will include three cable-stayed bridges and long stretches of causeways; the longest bridge section will be 29.6 kilometers (18.4 miles) long. Three lanes of traffic will move in each direction, roughly east-west across the water. Once completed, the Hong Kong-Zhuhai-Macau Bridge will be one of the longest water crossings in the world, equivalent to about 15 Golden Gate Bridges.<br />
The tunnel section is being created to allow passage of large ships through the estuary. The co
    rtisipausa_17601808.jpg
  • View Image Comparison<br />
View Both Images<br />
Zachariæ Isstrøm has become the latest Greenland glacier to undergo rapid changes in a warming world. Research published November 2015 in Science found that Zachariæ Isstrøm broke loose from a stable position in 2012 and entered a phase of accelerated retreat.<br />
The consequences will be felt for decades to come. The reason? Zachariæ Isstrøm is big. It drains ice from a 91,780 square kilometer (35,440 square mile) area of northeast Greenland. That's about 5 percent of the Greenland Ice Sheet. The glacier holds enough water to raise global sea level by more than 46 centimeters (18 inches) if it were to melt completely. It is already shedding billions of tons of ice into the far North Atlantic each year.<br />
"North Greenland glaciers are changing rapidly," said lead author Jeremie Mouginot of the University of California, Irvine (UCI). "The shape and dynamics of Zachariæ Isstrøm have changed dramatically over the last few years. The glacier is now breaking up and calving high volumes of icebergs into the ocean, which will result in rising sea levels for decades to come."<br />
The change is apparent in the images above. The top image was acquired by the Enhanced Thematic Mapper Plus (ETM+) on Landsat 7 on August 5, 1999, when the glacier was stable. The second image was acquired on August 2, 2015, with the Operational Land Imager (OLI) on Landsat 8. The second image shows how the ice shelf and glacier have melted and retreated substantially. Turn on the image comparison tool to see the difference.<br />
As of 2015, the glacier is losing 5 billion tons of ice every year. The time-lapse animation above shows the glacier's retreat during the 2015 melt season. The animation is composed of 26 natural-color images acquired by Landsat 8 from May 19 through October 1, 2015.<br />
To better understand the changes taking place at Zachariæ Isstrøm, Mouginot and his colleagues from NASA's Jet Propulsion Laboratory (JPL), and the University of Kansas compil
    rtisipausa_20553503.jpg
  • Researchers at NASA are constantly browsing new satellite data and imagery delivered by the agency's fleet of Earth-observing satellites for new data that may help answer questions about topics that are poorly understood or hotly debated within the scientific community.<br />
While he was browsing new imagery captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Aqua satellite on May 9, 2016, NASA Goddard Space Flight Center atmospheric scientist Richard Kleidman found his attention immediately drawn toward the image above - a curling plume of smoke above a deck of clouds over Canada's Northwest Territories. The smoke was likely lofted up by the destructive fire that burned in Alberta near Fort McMurray, though other fires in Saskatchewan and Manitoba may have contributed as well. "That is a fascinating image," said Kleidman. "It is an excellent example of aerosol being transported above clouds - a topic currently of great interest to the aerosol research community."<br />
Aerosols are small airborne particles found in plumes of smoke, air pollution, dust, and volcanic ash. Scientists know that aerosols can affect the climate in critical ways, but some details about precisely how they do so remain up for debate. One of the key uncertainties relates to how aerosols interact with and affect clouds. And one of the drivers of that uncertainty stems from situations when aerosols end up above clouds.<br />
A growing body of research suggests that the climate effects of dark-colored "absorbing" aerosols, which are common in smoke, differ markedly depending on whether the particles are found above clouds or in clear skies. When skies are clear, smoke generally leads to a cooling of the Earth-atmosphere system. When they are cloudy and smoke ends up above a cloud layer, the effect reverses; the same particles that would have had a cooling effect have a warming effect. The brighter the underlying cloud layer, the greater the warming effect, explained Hongbin Yu, an atmos
    rtisipausa_17601860.jpg
  • View Image Comparison<br />
View Both Images<br />
Even for a nation known for eye-popping rates of urbanization, what has happened along China's Pearl River Delta (Zhu San Jiao)<br />
over the past few decades is extraordinary.<br />
In 1988, an interlacing network of rivers and streams flowed through fertile alluvial soils full of rice paddies, wheat fields, mulberry orchards, and fish ponds. At that time, the region was mostly rural, with a population of roughly 10 million people scattered between several medium-sized cities, including Shenzhen, Guangzhou, Foshan, and Dongguan. Nearly three decades later, these cities have grown so rapidly that they have merged into an interconnected megalopolis with a population (42 million) greater than that of Australia, Argentina, or Canada.<br />
The satellite images above illustrate the dramatic growth. The bottom image was acquired by the Thematic Mapper on Landsat 5 on November 24, 1988; the top image was acquired by the Operational Land Imager on Landsat 8 on November 16, 2014. Rural areas - mainly farmland and forest - appear green. Urban areas are gray and white. Turn on the comparison tool to slide between the two images, and download the large images to observe the changes on a much finer scale.<br />
If taken as one entity, the Pearl River Delta region has overtaken Tokyo as the world's largest urban area - by size and population - according to an analysis of satellite and demographic data published by the World Bank. Between 2000 and 2010, the Pearl River Delta's urban spaces - defined as areas where the built environment covered more than 50 percent of the landscape in a given pixel - had expanded from 4,500 square kilometers to 7,000 square kilometers. (In 2010, Tokyo had a population of about 32 million people and covered about 5,600 square kilometers.) In the study, researchers used satellite data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) and land cover data from the Landsat program. They also used demographic data pr
    rtisipausa_20553500.jpg
  • Hurricanes in the Atlantic Ocean typically start to develop off the west coast of Africa, then move westward across the basin and intensify as they approach North America or the islands of the Caribbean and Gulf of Mexico. In the last days of August 2015, that storm development process went into overdrive.<br />
On August 30, an easterly wave from the African interior moved out over the Atlantic, where sea surface temperatures hovered around 30° Celsius (86° Fahrenheit). The unusually warm waters provided fuel for a storm that progressed from tropical depression to tropical storm to hurricane in roughly one day.<br />
According to several reports, Fred appears to be the easternmost hurricane to form in the tropical Atlantic during the satellite era. (Extra-tropical Hurricane Vince formed briefly off Portugal in 2005.) It is also believed to be the first hurricane to hit Cabo Verde (Cape Verde) islands since 1892. The storm did not cause any casualties, nor did it make direct landfall on any of the islands, but it did cause flash flooding and extensive wind damage. As much rain was predicted to fall in one day as the islands typically receive in half a year, though totals are not yet available.<br />
The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite acquired this natural-color image of Fred off the west coast Africa at 11:15 a.m. Cabo Verde time (12:15 Universal Time) on August 31, 2015. The storm was at peak intensity when the image was acquired, with sustained wind speeds of 75 knots (85 miles or 140 kilometers per hour) and a central pressure of 986 millibars. It was a category 1 storm on the Saffir-Simpson scale.<br />
The MODIS instrument on Terra got a look at Fred's remnants on September 1. Now a tropical storm, it is expected to linger for much of the week and slowly devolve into a tropical depression as it moves north and west.<br />
References<br />
BBC (2015, September 1)<br />
Hurricane Fred hits Cape Verde. Accessed September 1, 2015.<br />
Bloomberg News (2015, Sep
    rtisipausa_20553490.jpg
  • It has been more than two weeks since wildfires first broke out in Fort McMurray in the Canadian province of Alberta. The burned area continues to grow even larger, as fires are still spreading under warm, dry conditions.<br />
On May 15, 2016, the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi-NPP satellite captured a natural-color image (top) of active fires detected in Alberta and smoke that crossed into Saskatchewan. Red outlines indicate hot spots where VIIRS detected warm surface temperatures associated with fires.<br />
On the day this image was acquired, 15 wildfires burned around Fort McMurray. Nine of them were new fires, having ignited within the previous 24 hours. Two were burning out of control. The burned area's size - 2,510 square kilometers (970 square miles) - had grown somewhat, increasing by about four percent since a few days before, on May 12.<br />
The Operational Land Imager (OLI) on the Landsat 8 satellite acquired an higher resolution image (bottom) of the burn scar on May 12, when the burn area spanned about 2,410 square kilometers (930 square miles). The false-color image combines shortwave infrared, near infrared, and green light (OLI bands 7-5-3). With this combination, burned areas appear brown. Near- and short-wave infrared help penetrate clouds and smoke (white) to reveal the hot spots associated with active fires (red).<br />
The return of residents to Fort McMurray could be hampered by poor air quality, according to news reports. On May 16, the air quality index hit 38 on a scale that typically ranges from one to 10. A lower the number indicates a lower health risk.<br />
References<br />
Alberta Environment and Parks (2016, May 16) Air Quality Health Index. Accessed May 16, 2016.<br />
Alberta Government (2016, May 15) Update 15: Fort McMurray Wildfire (May 15 at 5:45 p.m.) Accessed May 16, 2016.<br />
Edmonton Journal (2016, May 16) Premier hints at delay in Fort McMurray re-entry because of extremely poor air quality. Accessed May 16, 2016.<br />
NASA image (top) by
    rtisipausa_17601843.jpg
  • Many national parks in the United States can be experienced by driving scenic roads or hiking on trails. Visit Biscayne National Park in southern Florida, however, and you might want to explore by boat; 95 percent of this park is under water.<br />
On February 25, 2016, the Operational Land Imager (OLI) on the Landsat 8 satellite acquired this natural-color image of Biscayne National Park. The park encompasses the northernmost Florida Keys, starting from Miami to just north of Key Largo.<br />
The keys run like a spine through the center of the park, with Biscayne Bay to the west and the Atlantic Ocean to the east. The water-covered areas span more than 660 square kilometers (250 square miles) of the park, making it the largest marine park in the U.S. National Park System. Biscayne protects the longest stretch of mangrove forest on the U.S. East Coast, and one of the most extensive stretches of coral reef in the world.<br />
acquired February 25, 2016<br />
acquired July 10 -<br />
14, 2001<br />
download large image (21 MB, JPEG, 10000x18000)<br />
acquired July 10 -<br />
14, 2001<br />
download<br />
GeoTIFF file (21 MB, TIFF, 10000x18000)<br />
Some of what lies below those waters is visible in data acquired by the Experimental Advanced Airborne Research Lidar (EAARL). EAARL's Lidar measured the time it took for a pulse of light to go from the aircraft, through the water, reflect off the seafloor, and back to the airplane. Researchers can convert that travel time into measurements of height, and map the underwater topography. According to C. Wayne Wright, a remote-sensing scientist who worked at NASA's Wallops Flight Facility, EAARL was designed and built by NASA specifically to get a high-resolution look at coral reef environments.<br />
The highlighted area in the second image above shows where EAARL acquired data in Biscayne National Park from July 10–14, 2001. The third image shows a detailed view of the center of the study area. White and light blue are the shallowest areas, primarily marking the location of coral reefs. Some
    rtisipausa_17601801.jpg
  • Crews aboard the International Space Station are trained to use low sun angles to add a three-dimensional effect to flat landscapes, a skill that is well illustrated by this image of central Saudi Arabia.<br />
The main river (upper left), located 120 kilometers (75 miles) south of the capital city Riyadh, has eroded its bed down into the rock layers, making a small canyon 250 meters (820 feet) deep. This in turn has led all of its tributaries to dig their own canyons, resulting in an elaborate, leaf-like pattern that casts shadows in the late afternoon sun. For scale, the area shown is just 12.5 kilometers (7.7 miles) across.<br />
This photograph shows the faint tracing of a road following the main river. River beds are often the smoothest places in deserts for wheeled vehicles; they connect villages that occupy river beds and terraces up and downstream because there is access to water. Dark dots within the main river bed are trees that only grow where their roots can reach subsurface water.<br />
The center of the small plateau is a slightly different color from the area surrounding it. This is a lighter-toned layer of sedimentary rock, one of many in the area. Other thin layers make benches within the canyons in the same style as seen in the Grand Canyon of the USA, but on a much smaller scale.<br />
Astronaut photograph ISS045-E-55901 was acquired on October 10, 2015, with a Nikon D4 digital camera using a 1150 millimeter lens, and is provided by the ISS Crew Earth Observations Facility and the Earth Science and Remote Sensing Unit, Johnson Space Center. The image was taken by a member of the Expedition 45 crew. The image has been cropped and enhanced to improve contrast, and lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Lab to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet. Additional images
    rtisipausa_20553492.jpg
  • Icebergs that break off from Antarctica can stay afloat in the Southern Ocean for years. Some become stuck, while others drift in the currents that circle the continent. Where those currents are interrupted by South Georgia Island, some bergs make a northward turn.<br />
These images, acquired November 27, 2015, by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite, show an array of bergs floating offshore of South Georgia Island, more than 1,600 kilometers (1,000 miles) east-northeast of South America's southern tip. Their relatively northern location is not common, but not unheard of. What is interesting, though, is that some of them appear to be making waves - in the atmosphere.<br />
The second image shows a close up of icebergs producing a "cloud wake." Just as a ship leaves behind a V-shaped wake in the water, tall bergs can leave behind similar wake in low-level clouds.<br />
"Cloud wakes are most evident in the lee of the two larger icebergs," said Kelly Brunt, a glaciologist at NASA's Goddard Space Flight Center. "But you also can see this behind one of the smaller icebergs, just south of the largest iceberg."<br />
According to Brunt, the three bergs are likely tabular - flat-topped ice that broke away from an ice shelf - which means they probably rise to roughly the same height above the water line (on the order of tens of meters). Such icebergs can come into direct contact with low-level fog to produce cloud wakes.<br />
Two of the icebergs also made ripples higher in the atmosphere. "Wave clouds" occur when a higher-level air mass is forced to move up and over a large obstacle. For example, wave clouds are commonly observed when air passes over islands. Unlike the low-level fog that leads to a cloud wake, the air mass that forms wave clouds does not have to be at the same level as the icebergs. It simply must encounter a disturbance large enough to force the air up, instead of around.<br />
"You see these features over the big icebergs," Brunt said, "but n
    rtisipausa_20553489.jpg
  • View Image Comparison<br />
View Both Images<br />
On November 5, 2015, two dams collapsed in southeastern Brazil, sending a torrent of mining sludge through the village of Bento Rodrigues. The muddy floodwaters from an iron ore mining operation destroyed hundreds of homes, killed some residents, and left others missing.<br />
The Operational Land Imager (OLI) on Landsat 8 captured these natural-color views of the village and the surrounding region. The top image shows the area on October 11, 2015; the second image shows the area on November 12, after the catastrophe. Turn on the image comparison tool to see areas where mud and sludge was still visible a week after the dams broke.<br />
The Wall Street Journal reported that 60 million cubic meters of wastewater were unleashed, with most of it affecting Bento Rodrigues. The village is located close to the breach, and sits in a river valley just below one of the dams.<br />
The effects of the flooding were felt far beyond Bento Rodrigues. The image shows multiple rivers, far from the village, that remained swollen with wastewater and mud. East of this image, in Barra Longa - a village about 80 kilometers (50 miles) from the dams - the river surged as much as 15 meters and flooded homes,<br />
according to Reuters. As health officials conducted tests, cities as far as 300 kilometers (200 miles) downstream lost access to drinking water.<br />
As of November 12, 2015, rescuers had recovered the bodies of nine people, according to ABC News; 19 people were still missing.<br />
References<br />
BBC News (2015, November 9) Brazil dams burst: ‘Hopes of finding survivors fading.' Accessed November 13, 2015.<br />
Reuters (2015, November 9) Brazil mine dam burst endangers water supply far downstream. Accessed November 13, 2015.<br />
Reuters (2015, November 8) When the river flowed backwards: a town in Brazil mining flood. Accessed November 13, 2015.<br />
The Wall Street Journal (2015, November 6) Brazil Searches for Missing After Dam Breach. Accessed November 13, 2015.<br />
NASA Earth Observatory im
    rtisipausa_20553506.jpg
  • By mid-summer each year, vibrant blue meltwater lakes dot the surface of the Greenland Ice Sheet. These lakes, also known as melt ponds, store a large amount of fresh water throughout the season, and they are an important part of the ice sheet's surface hydrology.<br />
The images above were acquired on July 15, 2015, by the Operational Land Imager (OLI) on Landsat 8. They show meltwater lakes on the ice near Greenland's west coast, about 100 kilometers (60 miles) southeast of Ilulissat. Dark debris coats the ice surface in some areas.<br />
"One reason we're interested in the lakes is because they might be important for speeding up the ice sheet," said Allen Pope, a glaciologist at the National Snow and Ice Data Center. Once the lakes grow large enough, Pope notes, they can force open crevasses in the ice. The melt water can then move through the crevasse to the base of the glacier and temporarily speed up ice flow across the bedrock below.<br />
Ultimately, the flowing ice will reach one of the many outlet glaciers that line Greenland's coast. Nordenskiöld Glacier, for example, is visible in the top image. Greenland's fastest-moving glacier, Jakobshavn, is immediately north of this image. Glaciers like these are the gateway through which ice can exit the ice sheet, enter the ocean, and contribute to<br />
sea level rise.<br />
So how large are these lakes? As the bottom, close-up image shows, size varies. Some lakes have a greater surface area than others, but that's not the only difference. Their depth can vary dramatically too, which becomes apparent in the various shades of blue.<br />
"Intuitively, you see this beautiful blue color, and you know the darker the blue, the deeper the lake," Pope said while describing an image of the same area as it appeared in summer 2014. "Which is nice, but we want to be able to quantify that."<br />
According to Pope, some lakes are shallow and lagoon-like, while others are as much as 9 meters (30 feet) deep. Pope and colleagues have been working on a technique to de
    rtisipausa_20553493.jpg
  • View Image Comparison<br />
View Both Images<br />
In 1985, sand and coral dominated the Red Sea coast in an area about 30 kilometers (19 miles) northwest of Hurghada, Egypt. Aside from a lone road that ran along the coast, the desert landscape was largely untouched by human activity. Three decades later, development has radically reshaped the coastline.<br />
The construction of El Gouna, a resort town, began in 1989. Building proceeded in waves, with a small cluster of summer holiday homes eventually morphing into a year-round community of about 23,000 people. As of 2015, El Gouna included 16 hotels, some 2,700 villas, 3 marinas, an 18-hole golf course, and hundreds of restaurants and shops.<br />
Developers were not content to simply build on the existing landscape. To give<br />
seaside views and easy access to the water to as many El Gouna residents and guests as possible, builders dredged huge amounts of sand from coastal bays and inlets to sculpt the canals, marinas, hotels, and artificial islands of the resort.<br />
The changes to the coast are evident in this pair of natural-color images acquired by sensors on Landsat satellites. The top image was captured by the Thematic Mapper (TM) on Landsat 5 in 1985; the bottom image was captured by the Operational Land Imager (OLI) on Landsat 8 in 2014.<br />
While El Gouna has pledged to become a carbon neutral town, the resort has come with a cost for the local environment, particularly the coral reef ecosystems that make the area so appealing. Construction of coastal hotels and other infrastructure often involved the destruction of fringing reefs along the coastlines, caused by the dredging or dumping of large amounts of sediment.<br />
While it is difficult to distinguish between reefs, underwater sand, sea grass, and algae in natural-color Landsat imagery, some scientists have used other wavelengths to track changes in corals near El Gouna and neighboring Hurghada. The findings indicate the reefs may be in trouble. According to one study, corals near Hurghada
    rtisipausa_20553502.jpg
  • acquired August 31, 2015<br />
download large image (26 MB, JPEG, 12000x12000)<br />
acquired August 31, 2015<br />
download large image (26 MB, GOV/IMAGES/IMAGERECORDS/86000/86589/)<br />
There was a time when the Northwest Passage was a sort of maritime Holy Grail, a route so desired and sought after, but so elusive. For most of the recorded history of North America, the Passage has been nearly impassable and often deadly. But with the modernization of ships and the warming of the Earth, cruising and sailing through the Canadian Archipelago from Baffin Bay to the Beaufort Sea has grown more common and easier. But it's not necessarily easy.<br />
The top image above shows the Northwest Passage as it appeared on August 31, 2015, to the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi-NPP satellite. The second image was acquired the same day by the Operational Land Imager (OLI) on Landsat 8. The white box on the top image shows the area depicted in the Landsat view. Both images are natural color. Note that much of the white covering the Northwest Passage in the VIIRS image is cloud cover, not sea ice.<br />
The Northwest Passage is a complex, winding maze of sounds, channels, bays, and straits that pass through often ice-choked Arctic waters. Mariners refer to two main routes: a southern passage and a northern passage.<br />
The southern route generally follows the one taken by Roald Amundsen from 1903–1906, when his crew completed the first successful transit through the region. The southern passage goes south of Prince of Wales Island and Victoria Island (and sometimes King William Island) and enters the Beaufort Sea south of Banks Island. It includes several narrow and shallow waterways that are better suited to small ships than large commercial vessels. This southern or "Amundsen" passage has been open for several weeks in the summer of 2015.<br />
The northern passage runs through Lancaster Sound, Parry Channel, and McClure Strait - waterways that are wider, deeper, and more suited to large sh
    rtisipausa_20553510.jpg
  • acquired September 20, 2015<br />
Devastation of the sort that the fast-moving Valley Fire unleashed rarely has a single cause. Long before the blaze started burning through Boggs Mountain State Forest, decades of aggressive firefighting - and too few prescribed fires - left the woodlands overloaded with brush and other fuel. Meanwhile, extreme drought over the past four years has sucked the forests dry of moisture, leaving the trees unusually combustible. An army of destructive bark beetles also has made the pine forests vulnerable.<br />
So when a weather system delivered abnormally hot temperatures and gusty winds to Napa, Sonoma, and Lake counties in northern California, the forests were primed to burn intensely. The first spark likely came from a shed fire in the town of Cobb on September 12, 2015. Once it had escaped the shed, the fire spread with such speed and intensity that firefighters could do little to slow it. Within 48 hours, the inferno had burned an area twice as large as Manhattan as it raced southeast along ridges in Boggs Mountain State Forest toward the communities of Harbin Springs, Anderson Springs, and Middletown.<br />
As flames pushed toward these towns, thousands of people were forced to flee their homes with little warming. In all, authorities report that 1,910 structures were destroyed, including many at a popular hot springs resort in Harbin Springs. At least three civilians lost their lives; four firefighters were injured. The Valley Fire has already become one of California's most damaging fires. Only two other blazes - the Cedar fire in 2003 and the Tunnel Fire in 1991 - destroyed more structures.<br />
The Operational Land Imager (OLI) on Landsat 8 captured false-color view of the charred landscape on September 20, 2015. The image is a composite based on data OLI collected with its short-wave infrared and near-infrared bands. Newly burned land has a strong signal in short-wave infrared bands, visible as dark red-orange areas. Unburned forests appear gray. B
    rtisipausa_20553509.jpg
  • View Image Comparison<br />
View Both Images<br />
Fog is common in winter in northwestern North America. Moist Pacific air rides up into the Cascade Mountains, the Coast Range, and the Columbia Plateau, then cools at altitude or at night and sinks into the surrounding valleys. As that air gives up its heat to the upper atmosphere, the layer near the surface becomes saturated (reaching the dew point) and essentially forms clouds at ground level. Often a temperature inversion - warm air, higher in the atmosphere, moving over the cooler denser air near the surface - will trap this moisture in the valleys for days.<br />
Such fog would have been easy to see in late November 2015 if you were standing in any of those valleys. And it would not have been hard to distinguish fog from snow if you were standing in it. But the line between snow and fog might have been tougher to spot if you were looking across one of those valley at the fresh snow on the mountains. It can be hard for satellite eyes, too, when viewing things as the human eye sees them.<br />
The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite acquired these images of Oregon and Washington at 11:20 a.m. Pacific Standard Time (19:20 Universal Time) on November 29, 2015. The top image shows the region in natural color, as the human eye would see it. Note how snow and clouds can be difficult to distinguish from each other. The second, false-color image was composed from blue and shortwave infrared light (MODIS bands 3-6-7, or 479 nm: 1,652 nm: 2,155 nm). Scientists turn to these wavelengths to reveal what the human eye cannot. Turn on the image comparison tool to see the difference.<br />
Fog is liquid water, while snow is ice; fog droplets are much smaller than ice crystals. Those distinctions are visible from space with the MODIS radiometer. In natural color, condensed water - liquid or solid - does not absorb light, so it reflects equally at all wavelengths and appears white, explained Robert Pincus, an atmosp
    rtisipausa_20553499.jpg
  • An astronaut aboard the International Space Station focused near the Sun's reflection point to shoot this photograph of grid-patterned fish farms on the coast of China's northeast province of Liaoning. The aquaculture basins have been built out from the wooded coast to a distance of nearly 6 kilometers (4 miles). Fish farms have been constructed at many points along the provincial coastline, but this group of basins facing the Yellow Sea is the largest. (Liaoning Province is the sixth in China in terms of aquaculture production.)<br />
The basins are built on shallow seabeds, mudflats, and bays.<br />
Islands, such as the one at image center, often help anchor the construction of basins. Outer barriers protect the basins from winter storms. Water flow lines and a ship wake are visible near the river estuary.<br />
Most aquaculture products are marketed live in China, with less than 5 percent processed for local or overseas markets.<br />
Shellfish, a traditional marine food source, still dominates the marine species production (77 percent), with sea fish a distant second (5 percent).<br />
About 4.3 million people are involved in freshwater and marine fish production in China (as of 2007).<br />
Click here to view another high-contrast astronaut photograph of fish farms near the Nile Delta.<br />
Astronaut photograph ISS044-E-89407 was acquired on September 6, 2015, with a Nikon D4 digital camera using an 1150 millimeter lens, and is provided by the ISS Crew Earth Observations Facility and the Earth Science and Remote Sensing Unit, Johnson Space Center. The image was taken by a member of the Expedition 44 crew. The image has been cropped and enhanced to improve contrast, and lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Lab to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet. Additional images taken by astronauts and
    rtisipausa_20553486.jpg
  • A destructive wildfire burned through Canada's Northern Alberta region, razing neighborhoods in Fort McMurray and displacing tens of thousands of residents.<br />
At 12:34 p.m. local time on May 3, 2016, the Operational Land Imager (OLI) on the Landsat 8 satellite acquired this false-color image of the fire. The image combines shortwave infrared, near infrared, and green light (OLI bands 7-5-3). Near- and short-wave infrared help penetrate clouds and smoke to reveal the hot spots associated with active fires, which appear red. Smoke appears white and burned areas appear brown.<br />
When this image was acquired, the fire was burning southwest of downtown Fort McMurray. Across the day, a growing number of neighborhoods were placed under mandatory evacuation orders. By the evening of May 3, the mandatory evacuation covered all of Fort McMurray - the largest evacuation on record in Canada.<br />
As of May 4, the fire had burned almost 77 square kilometers (7,700 hectares), and its cause was still under investigation. Fire restrictions were in place for most of the province due to hot, dry conditions.<br />
References<br />
Alberta Agriculture and Forestry (2016, May 4) Fort McMurray Area Update. Accessed May 4, 2016.<br />
Alberta Government (2016, May 4) Emergency updates. Accessed May 4, 2016.<br />
Regional Municipality of Wood Buffalo (2016, May 4) Fort McMurray Wildfire Updates. Accessed May 4, 2016.<br />
The Washington Post (2016, May 4) A Canadian oil-sands town is on fire; 80,000 residents must evacuate. Accessed May 4, 2016.<br />
NASA Earth Observatory image by Joshua Stevens, using Landsat data from the U.S. Geological Survey. Caption by Kathryn Hansen.<br />
  Please note: Fees charged by the agency are for the agency’s services only, and do not, nor are they intended to, convey to the user any ownership of Copyright or License in the material. The agency does not claim any ownership including but not limited to Copyright or License in the attached material. By publishing this material you expressly agree to inde
    rtisipausa_17601841.jpg
  • November can be a stormy month in the Great Lakes region, as it was again in 2015. Toward the middle of the month, a low-pressure system and cold front swept up from the Central Plains and across the lakes. In Detroit, media outlets reported wind gusts as high as 52 miles (84 kilometers) per hour that left 13,000 residents without power. On Lake Erie, gale force winds halted shipping.<br />
Winds were not the only reason ships sought safe anchorage. The high winds created a seiche - a large standing wave that occurs when strong winds and a quick change in atmospheric pressure push water from one end of a body of water to the other, according to NOAA. Seiches occur periodically on Lake Erie. In 1844, a 22-foot seiche breached a sea wall with deadly consequences. In 2008, Buffalo was flooded by waves that measured 16 feet. That's about the height of the seiche measured by a buoy at the lake's east side on November 12, 2015.<br />
Two weeks after the seiche, its effects were still evident. On November 25, 2015, the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite acquired this natural-color image of colorful green and tan swirls.<br />
"The seiche stirred up a lot of sediment," said Kevin Czajkowski, a remote-sensing scientist at the University of Toledo. Not all of the colorful swirls are necessarily the result of resuspended sediments. "I wonder if Lake Erie is having a whiting event as well."<br />
Particles of calcium carbonate in the water can cause lightening, or "whiting," of the water. That usually happens in response to changes in the water temperature, or due to increased photosynthesis by phytoplankton and other microscopic marine life.<br />
But Thomas Bridgeman, an environmental scientist at the University of Toledo, agrees that the swirls of color are mostly due to sediments. "Little patterns along the shoreline suggest wind-driven sediment resuspension," he said. "There is an olive-green tint to part of the image that might be a diatom bloom, but I think t
    rtisipausa_20553495.jpg
  • An astronaut aboard the International Space Station took this photograph of the strange rounded shapes along the coastline of Zambia's Chilubi Island. The light-toned sand island stands out from the dark waters of Lake Bangweulu.<br />
In the photo we see a few patches of open water between the fingers of the island. The waters are crowded by areas of aquatic vegetation and wetland (reeds, papyrus, and floating grass) in green. Lake Bangweulu, which is only 4 meters (13 feet) deep on average, is rich enough to supply fish for the copper-mining towns to the west.<br />
Chilubi Island has 100 kilometers (60 miles) of coastline, providing prime access to the richest fishing waters in northern Zambia. Those coastlines are smoothed by easterly winds that erode ancient sand dunes. The narrow strips of lighter toned land along the shorelines are areas that have been mostly denuded of vegetation by residents of the densely populated fishing villages.<br />
The explorer and missionary David Livingstone was the first European to visit the lake (1868).<br />
Astronaut photograph ISS044-E-00661 was acquired on June 14, 2015, with a Nikon D4 digital camera using an 1150 millimeter lens, and is provided by the ISS Crew Earth Observations Facility and the Earth Science and Remote Sensing Unit, Johnson Space Center. The image was taken by a member of the Expedition 44 crew. The image has been cropped and enhanced to improve contrast, and lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Lab to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet. Additional images taken by astronauts and cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth. Caption by M. Justin Wilkinson, Texas State University, Jacobs Contract at NASA-JSC.<br />
 *** Please Use Credit from Credit Field ***
    rtisipausa_20553487.jpg
  • A long lens and low sun angle allowed an astronaut to take this striking photograph as the International Space Station flew over the remote desert landscape of northern Tibet. Sunlight reflects brilliantly off the ice of several glaciers in one of the highest sectors of the Kunlun Mountains. The major peaks of the mountains cast dark, pointed shadows in mid-afternoon. The surrounding landscape is a nearly barren, dun-colored desert.<br />
Mountains tend to look flat from orbit, particularly when viewed from directly above. The mountain in the center of the image - Ulugh Muztagh - appears insignificant. But being the highest (6,973 meters or 22,877 feet) peak, it casts the longest shadow, which helps astronauts get a three-dimensional sense of the landscape. If this were an unmapped planet, the length of the shadows could be used to calculate the height of each mountain peak (assuming you knew a ground distance and the Sun angle).<br />
The low sun angle reveals rough textures at the snout (terminal) end of the glaciers, which otherwise appear remarkably smooth. Rough textures show where the ice is melting fast. Although the peaks receive very little precipitation (less than 5 inches or 13 centimeters per year), the cold desert preserves more snow than can melt on the highest, coldest parts of the mountains. The preserved ice slowly accumulates and begins to flow very slowly downhill, away from the high peaks. At the snout of the glaciers, melting at the warmer low altitude balances the flow of ice from the mountain peaks.<br />
One other area of glacier roughness (lower left), however, is not located at the snout end of the glacier. This is a region of crevassing, where glacial ice is splitting to make deep clefts. It is likely because the ice is flowing faster over a steeper part of the valley.<br />
Astronaut photograph ISS045-E-53329 was acquired on October 10, 2015, with a Nikon D4 digital camera using a 500 millimeter lens, and is provided by the ISS Crew Earth Observations Facility a
    rtisipausa_20553485.jpg
  • While in orbit over the Brazilian coast, an astronaut aboard the International Space Station took this photograph of some of the country's famous coastal lagoons. This view shows a short 20-kilometer (12-mile) stretch of a lagoon shoreline where pointed sand spits jut into waters of Mangueira Lagoon (Lagoa Mangueira). The ends of the spits are under water, growing less visible with increasing depth.<br />
The space station crew had flown a similar orbital track a week earlier, taking panoramic shots like this one with Lagoa Mangueira on the lower right. They were likely in "discovery mode," looking for features that might be worth tighter shots later in the Expedition.<br />
The spits and bays have a somewhat regular spacing, at least in geological terms. They are created as lagoon water slowly circulates while being driven by persistent sea breezes out of the east (top of the image). The water washes into the bays and then curves back out into the lagoon, carrying sand eroded from the shoreline. This sand is deposited in the tight, tan-colored lines we see as spits. The cells of circulating water tend to be the same size, depending on water depth, dominant wind strength, and the amount of sand available - translating into spits at roughly regular intervals. Regularly spaced spits form in many parts of the world, for instance along the coast of the Sea of Azov in southern Ukraine.<br />
Details in the photo suggest that strong winds from the north (left to right) have swept sand into thin tendrils on the south side of each spit. A single spit, whose origin is less clear, is also visible beneath the water surface of Lagoa Mangueira near the opposite side of the lagoon (top right).<br />
Astronaut photograph ISS043-E-101410 was acquired on April 10, 2015, with a Nikon D4 digital camera using an 800 millimeter lens, and is provided by the ISS Crew Earth Observations Facility and the Earth Science and Remote Sensing Unit, Johnson Space Center. The image was taken by a member of the Expedition
    rtisipausa_17601805.jpg
  • As world leaders converged on Paris for a United Nations conference on climate change, residents of Beijing and other cities in eastern China faced the most severe air pollution the nation has seen in 2015. Chinese authorities issued an "orange" air pollution alert, the second highest level on a four-tiered warning scale. They advised millions of people to stay indoors, halted construction at some sites, and ordered factories to close, according to news reports.<br />
The Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite acquired this natural-color image of northeastern China on November 30, 2015. The image shows extensive haze, low clouds, and fog over the region. The brightest areas are clouds or fog, which have tinges of gray or yellow because of the air pollution. Other cloud-free areas have a pall of gray haze that mostly blots out the cities below. In areas where the ground is visible, some of the landscape is covered with snow. The haze extended southwest from Beijing for hundreds of kilometers and was particularly dense in low-lying areas in the Guanzhong Plain.<br />
On the day VIIRS acquired the image, PM2.5 measurements peaked at 666 micrograms per cubic meter of air, according to ground-based sensors at the U.S. Embassy in Beijing. 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 human lungs. Most PM2.5 aerosol particles result from the burning of fossil fuels and biomass (wood fires and agricultural burning). The World Health Organization considers PM2.5 levels to be safe when they are below 25.<br />
Outbreaks of haze like this generally occur during the winter because of temperature inversions. Air normally cools with altitude, but during an inversion warm air settles above a layer of cool air near the surface. The warm air acts like a lid and traps pollutants near the surface, especially in basins and valleys.<br />
Ma
    rtisipausa_20553488.jpg
  • The Taklimakan desert is one of the driest, most barren expanses on Earth. Flanked by mountain ranges on three sides and parched by the resulting rain shadow, parts of the Tarim Basin receive no more than 10 millimeters (0.4 inches) of rain per year. It is no surprise that plant life is scarce. With little vegetation to hold sand in place, some 85 percent of the Taklimakan consists of shifting sand dunes. Only the dune fields of Saudi Arabia's Rub' al Khali cover a larger area. Taklimakan's dunes can soar up 200 to 300 meters (650 to 900 feet).<br />
With so much sand and so little vegetation or moisture, dust storms are a regular occurrence, particularly in the spring. On May 1, 2016, the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite captured this natural-color image of northeasterly winds pushing a wall of dust southwest across the Tarim Basin.<br />
The Tarim Basin is bordered by the Kunlun Shan mountains to the south and the Tian Shan mountains to the north. (The Tian Shan is covered with snow and partly obscured by clouds in this image.) The basin opens up on its eastern edge, but that is not generally a way out for dust. Prevailing low-altitude winds almost always blow from the east, keeping most dust below 5 kilometers (3 miles) - about the height of the mountain ranges - and trapped within the basin. In spring, strong surface winds can sometimes lift dust up to 10 kilometers (6 miles). These particles can then be transported by higher-altitude winds that send them across China and the Pacific. In this case, however, the dust appears to be relatively low in the atmosphere.<br />
Dust storms can lead to public health problems in populated areas downwind by transporting small particles, bacteria, and viruses that infiltrate human respiratory systems. Dust storms also affect Earth's climate by scattering and absorbing incoming solar radiation and changing the properties of clouds.<br />
References and Related Reading<br />
Ge, J. M. et al. (2014, October 28) Ch
    rtisipausa_17601918.jpg
Next