New Views of the Earth at Night

Out of the Blue and Into the Black

New Views of the Earth at Night

The night is nowhere near as dark as most of us think. In fact, the Earth is never really dark. And we don’t have to be in the dark about what is happening at night anymore either. —Steven Miller, atmospheric scientist, Colorado State University

By Michael CarlowiczDesign by Paul PrzyborskiDecember 5, 2012

The night side of Earth twinkles with light. The first thing to stand out is the cities. “Nothing tells us more about the spread of humans across the Earth than city lights,” asserts Chris Elvidge, a NOAA scientist who has studied them for 2

Away from human settlements, light still shines. Wildfires and volcanoes rage. Oil and gas wells burn like candles. Auroras dance across the polar skies. Moonlight and starlight reflect off the water, snow, clouds, and deserts. Even the air and ocean sometimes glow.

A handful of scientists have observed earthly night lights over the past four decades with military satellites and astronaut photography. But in 2012, the view became significantly clearer. The Suomi National Polar-orbiting Partnership(NPP) satellite — launched in October 2011 by NASA, the National Oceanic and Atmospheric Administration (NOAA), and the Department of Defense — carries a low-light sensor that can distinguish night lights with six times better spatial resolution and 250 times better resolution of lighting levels (dynamic range) than before. Also, because Suomi NPP is a civilian science satellite, data is available to scientists within minutes to hours of acquisition.

The Visible Infrared Imaging Radiometer Suite (VIIRS) on Suomi NPP can observe dim light down to the scale of an isolated highway lamp or fishing boat. It can even detect faint, nocturnal atmospheric light — known as airglow — and observe clouds lit by it. Through the use of its “day-night band,” VIIRS can make the first quantitative measurements of light emissions and reflections, distinguishing the intensity and the sources of night light. The sum of these measurements gives us a global view of the human footprint on the Earth.

“These lights have always been there, but we’ve never had an ability to take full advantage of them,” Miller says. “Now we finally have a way of doing that.”

“City lights provide a fairly straightforward means to map urban versus rural areas, and to show where major population centers are and where they are not,” says William Stefanov of the International Space Station program. (View Large Image - NASA Earth Observatory and NOAA National Geophysical Data Center)

Light from the aurora australis,or “southern lights,” is bright enough to reveal the ice edge in Antarctica’s Queen Maud Land. (View Large Image - NASA Earth Observatory and NOAA National Geophysical Data Center)

Moon Phases Over the Persian Gulf

The Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite captured these nighttime views of the Persian Gulf region on September 30, October 5, October 10, and October 15, 2012. The images are from the VIIRS “day-night band,” which detects light in a range of wavelengths from green to near-infrared and uses filtering techniques to observe signals such as gas flares, auroras, wildfires, city lights, and reflected moonlight.

Each image includes an inset of the Moon in four different phases. September 30 shows the Persian Gulf by the light of the full Moon; October 15 shows the effects of a new Moon. As the amount of moonlight decreases, some land surface features become harder to detect, but the lights from cities and ships become more obvious. Urbanization is most apparent along the northeastern coast of Saudi Arabia, in Qatar, and in the United Arab Emirates (UAE). In Qatar and UAE, major highways can even be discerned by nighttime lights.

In eighteenth-century England, a small group of entrepreneurs, inventors and free thinkers—James Watt and Charles Darwin’s grandfathers among them—started a club. They named it the Lunar Society, and the “lunaticks” scheduled their dinner meetings on evenings of the full Moon. The timing wasn’t based on any kind of superstition, it was based on practicality. In the days before electricity, seeing one’s way home after dark was far easier by the light of a full Moon. In the early twenty-first century, electricity has banished the need for such careful scheduling, but the light of the full Moon still makes a difference.

1.  References

2.   Uglow, J. (2002) The Lunar Men: Five Friends Whose Curiosity Changed the World. New York: Farrar, Straus and Giroux.

NASA Earth Observatory image by Jesse Allen and Robert Simmon, using VIIRS day-night band data from the Suomi National Polar-orbiting Partnership. Suomi NPP is the result of a partnership between NASA, the National Oceanic and Atmospheric Administration, and the Department of Defense. Caption by Michon Scott.

Instrument: 

Suomi NPP - VIIRS

BLUE MARBLE

Dust Plumes over the Arabian Sea گرد و غبار، دود و مه

 گرد و غبار سواحل ایران و پاکستان در اواخر ماه نوامبر 2012. 

Multiple dust plumes blew off the coasts of Iran and Pakistan on November 29, 2012. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite observed the dust plumes in the morning, and MODIS on the Aqua satellite observed the plumes in the afternoon.

These images document the movement of the plumes southward over the Arabian Sea. The plumes apparently arose from fine sediments near the coast. Some of the plumes were thick enough to hide the water surface below, especially two large plumes off the coast of Pakistan. On the afternoon of November 29, those plumes fanned out over the ocean water.

Sand seas, saltpans, and impermanent rivers in this region provide sediments that can easily be lofted into the air. The southern coasts of Pakistan and Iran rank among the world’s leading dust-producing regions.

1.  References

2.   University Corporation for Atmospheric Research. Forecasting Dust Storms. (Registration required).

NASA images courtesy Jeff Schmaltz, LANCE MODIS Rapid Response. Caption by Michon Scott.

Instrument: 

The catastrophic mudslides

Around midnight on Aug. 8, 2010, a violent surge of loosened earth roared down mountain slopes and slammed into quietly sleeping neighborhoods in Zhouqu County in Gansu, China. The catastrophic mudslides -- the deadliest in decades according to state media -- buried some areas under as much as 23 feet (7 meters) of suffocating sludge. 1,765 people died. Property damages totaled an estimated $759 million. Cutting from right to left, this detailed image, from DigitalGlobe’s WorldView-2 satellite, shows the largest slide in the lower part of the city on Aug. 10, 2010.
Credit: Image from WorldView-2 © 2010 by DigitalGlobe

A NASA study using TRMM satellite data revealed that the year 2010 was a particularly bad year for landslides around the world.

A recent NASA study published in the October issue of the Journal of Hydrometeorology compared satellite rain data from NASA’s Tropical Rainfall Measurement Mission (TRMM) to landslides in central eastern China, Central America and the Himalayan Arc, three regions with diverse climates and topography where rainfall-triggered landslides are frequent and destructive hazards to the local populations.

The work, led by Dalia Kirschbaum, a research physical scientist in the Hydrological Sciences Laboratory at NASA's Goddard Space Flight Center in Greenbelt, Md., is part of an ongoing effort to catalog worldwide rainfall-triggered landslides—one of the world's lesser known but often catastrophic natural hazards. Locating them is a step in an effort to be able, one day, to predict and warn.

Currently, Kirschbaum explains, no consistent regional or global scale warning system exists for landslide disasters. To create one, scientists need to understand more than the individual factors that may contribute to local landslides -- the intensity and total amount of rainfall over hours to days, slope angle, soil type and saturation, among others.

"For other hazards like hurricanes, there's a clearly defined season," says Kirschbaum. "From satellite data and observations we know that hurricane season in the Atlantic spans from June 1 to Nov. 30. But we don't have that type of record for landslides around the world, and we want to know when and where to expect them in different regions."

Scientists also need a systematic way to assess landslide hazards for a region, and one way to do that, says Kirschbaum, is to look at the distribution and intensity of rain from satellite data and see how that correlates with where and how often landslides are being reported.

Mergui Archipelago

In the southernmost reaches of Burma (Myanmar), along the border with Thailand, lies the Mergui Archipelago. The archipelago in the Andaman Sea is made up of more than 800 islands surrounded by extensive coral reefs.

This natural color image acquired by Landsat 5 on Dec. 14, 2004, shows the middle portion of the archipelago, including Auckland and Whale Bays. Swirling patterns are visible in the near-shore waters as sediments carried by rivers slowly settle out and are deposited on the seafloor. The heavy sediment loads make the river appear nearly white. As those sediments settle out, the seawater appears deeper shades of blue. The tropical rainforests of the region appear deep green.

Captain Thomas Forrest of the East India Company first described the region to Europeans after a 1782 expedition in search of potential sugar-growing lands. At that time, the islands were mainly inhabited by a nomadic fishing culture. These people, known as the Moken, still call the archipelago home and mostly live a hunter-gatherer lifestyle. As of 2006, 2,000 Moken were known to inhabit the Burmese portion of Mergui.

The small population of the archipelago has helped preserve its high diversity of plants and animals. In 1997, Burma opened the region to foreign tourism and in the years since it has become a major diving destination. A valued species of pearl oyster (Pinctada maxima) are found in nearby waters. Today, overfishing is emerging as a regional problem.

1.  References

2.   Alagarswami, K. (1983). The Black-Lip Pearl Oyster Resource and Pearl Culture Potential. CMFRI Bulletin, 34: Mariculture Potential, pp. 72–78.

3.   Anderson, John (1890). The Selungs of the Mergui Archipelago. Trübner & Co., Ludgate Hill, London. (http://hdl.handle.net/2027/mdp.39015058537070)

4.   Arunotai, Narumon (2006). Moken traditional knowledge: an unrecognized form of natural resources management and conservation. UNESCO. Blackwell Publishing Ltd., Oxford, UK.

5.   Brown, R.N.R. (1907). The Mergui Archipelago: Its People and Products. Scottish Geographical Magazine, vol. 23, issue 9, pp. 463–483. (http://www.tandfonline.com/doi/abs/10.1080/00369220708733785)

6.   Wikipedia (2012). Mergui Archipelago. Accessed 23 Nov. 2012.

Landsat image created by Michael Taylor, Landsat Project Science Office. Caption by Laura Rocchio.

Prominent View

The Sun is constantly roiling with nuclear heat and intense magnetism that make sunspots, flares, coronal mass ejections, and all sorts of space weather. When directed toward Earth, those solar blasts can disrupt satellite and radio communications, damage our electric-powered tools and toys, and create auroras.

But it is not always easy to know when the Sun is spitting plasma and energy in our direction. This is why NASA launched the Solar Terrestrial Relations Observatory, or STEREO, in October 2006. The twin satellites were sent out along roughly the same orbit around the Sun as the Earth itself. The orbit of STEREO-A (ahead) is slightly closer to the Sun and moving faster than Earth; the STEREO-B (behind) orbit is slightly farther from the Sun and moving a little slower than our planet. The difference in speed creates separation between the satellites and a stereoscopic view of our nearest star.

The images above show the surface of the Sun from two different angles on October 14, 2012. The top image is from STEREO-B and shows a dark vertical stripe on the upper middle face of the Sun. The lower image comes from STEREO-A, which was more than 90 degrees ahead of STEREO-B; that is, somewhat beyond a right angle from that vertical stripe. In the lower image, the vertical stripe instead shows up as a large loop stretching into the solar atmosphere, or corona.

The stripe and the loop are differing views of the same dense mass of electrified gas (plasma) held in place by a magnetic field. When viewed straight on, as in the STEREO-B image, the line of plasma appears darker because it is relatively cooler than the solar surface below. (More of its energy is magnetic than radiant.) Solar scientists call these dark lines “filaments.” When viewed from the side, however, the line of plasma looks like a bright loop stretched out against the blackness of space; solar physicists call this a prominence. Essentially, filaments and prominences are the same phenomenon, just viewed from a different perspective.

As of September 1, 2012, STEREO-A and STEREO-B formed an equal-sided triangle together with NASA’s Solar Dynamics Observatory (SDO), which views the Sun from orbit around Earth. This geometry allowed the three craft to provide overlapping views of the entire Sun. It also allows solar physicists to study solar events in three dimensions.

1.  Further Reading

2.   NASA STEREO Mission.

3.   NASA STEREO Science team.

NASA image courtesy of the STEREO science team. Caption by Mike Carlowicz, based on information from Karen Fox 

Ashfall from the Karymsky Volcano

The Karymsky stratovolcano stands 1,536 meters (5,039 feet) above sea level, and most of its eruptions and occasional lava flows originate from the summit. Karymsky is the most active of Kamchatka’s eastern volcanoes, with almost constant (on a geologic time scale) volcanism occurring since at least the late 18th century, when the historical record for the region began.

Because of the high levels of volcanic activity on the Kamchatka Peninsula, the Kamchatka Volcanic Eruption Response Team (KVERT) monitors the activity levels of several volcanoes and issues updates including aviation alerts and webcams. KVERT reported moderate seismic activity at Karymsky between November 2–9, 2012. Such activity can indicate the movement of magma beneath or within a volcanic structure and that an eruption may be imminent. The Tokyo Volcanic Ash Advisory Center (VAAC) subsequently reported an explosive eruption at Karymsky on November 9 at 22:15 Universal Time.

This astronaut photograph of the resulting ash plume was taken approximately 1 hour and 35 minutes after the eruption began. The plume extends from the summit of Karymsky to the southeast, with brown ash deposits darkening the snow cover below the plume.

The Akademia Nauk caldera—now filled with water to form the present-day Karymsky Lake—is located to the south of Karymsky volcano. Calderas are formed by explosive eruption and emptying of a volcano’s magma chamber, leading to collapse of the structure to form a crater-like depression. Akademia Nauk last erupted in 1996.

Astronaut photograph ISS033-E-19822 was acquired on November 9, 2012, with a Nikon D3S digital camera using an 800 millimeter lens, and is provided by the ISS Crew Earth Observations experiment and Image Science & Analysis Laboratory, Johnson Space Center. The image was taken by the Expedition 33 crew. It 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 William L. Stefanov, Jacobs/ESCG at NASA-JSC.

Instrument: 

ISS - Digital Camera

Falkland Islands

About 400 million years ago, some of the rocks that make up the Falkland Islands were part of the supercontinent ofGondwana, crunched between southern Africa and what is now Queen Maud Land, Antarctica. When tectonic forces tore Gondwana apart, the Falkland Islands were left behind like crumbs as a massive geologic cookie was split into pieces.

Today, the islands are situated about 600 kilometers (400 miles) east of Argentina and 1,350 kilometers (850 miles) north of the Antarctic Circle. There are 778 islands in this territory of the United Kingdom, but just two large islands—East Falkland and West Falkland—comprise the bulk of the Connecticut-sized landmass.

The Falkland Islands have a cool, moist climate that varies minimally throughout the year. Average annual temperatures are about 5.6°C (42°F). Temperatures reach as high as 24°C (76°F) in summer and as low as -5°C (22°F). Rainfall is comparatively low and evenly distributed throughout the year, averaging 625 millimeters (25 inches) in Stanley, the capital city.

Few trees grow on the islands. Intead, grassland and heath—which is widely used as pastureland for sheep and cattle—dominate the landscape. The islands are home to nearly 500,000 sheep and 5,000 cattle, and the animals far outnumber the 2,600 people permanent human residents. About 80 percent of the people reside in Stanley.

Farmers often burn pastureland in the early spring to encourage growth. When ewes and lambs are born, they move the young animals to recently-burned areas to graze. On November 17, 2012, the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA’s Aqua satellite captured a glimpse of a few of agricultural fires west of Stanley. Red outlines indicate hot spots where MODIS detected the unusually warm surface temperatures associated with fires.

The same satellite instrument captured another view of agricultural fires on East Falkland in October 2012.

·      References

·      CIA. (n.d.) Falkland Islands. Accessed November 19, 2012.

·      British Geological Survey. (n.d.) The Geology of the Falkland Islands. Accessed November 19, 2012.

·      Falkland Islands Government. (n.d.) Falkland Islands. Accessed November 19, 2012.

·      Falkland Islands Government. (n.d.) Farming in the Falkland Islands. Accessed November 19, 2012.

NASA image by Jeff Schmaltz, MODIS Rapid Response Team, Goddard Space Flight Center. Caption by Adam Voiland.

Instrument: 

Fires Across Cape York Peninsula

Summer bushfires near densely-populated areas in southern Australia attract the most public attention, but the continent’s largest and most frequent fires actually occur in the spring in the tropical savannas of northern Australia.

On November 25, 2012, the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard

NASA’s Aqua satellite captured this natural-color image of wildfires burning on Cape York Peninsula, the northernmost part of Australia. Smoke plumes from multiple fires are visible streaming west; red outlines indicate hot spots where MODIS detected unusually warm surface temperatures associated with fires.

Three main meteorological variables affect fire behavior: atmospheric humidity, air temperature, and wind strength. On Cape York Peninsula, humidity drops and temperatures rise beginning with the arrival of the dry season in March. By the end of November, grasses and woodland trees in the region have reached their most flammable state. In this case, steady winds (about 20 kilometers/12 miles per hour) have helped sustain fires that were likely started by lightning and human activity.

About half of the savanna woodlands on Cape York Peninsula burn either every year or so, typically late in the dry season. Dried grasses, which receive ample sunshine and rain during the wet season, provide the bulk of the fuel. As the dry season progresses, trees also drop loads of leaves and twigs that help fuel fires. Key grasses and trees in the region include Sorghum, Eucalyptus, and Corymbia.

Despite the frequency of the burning, wildfires on Cape York Peninsula are generally less severe than in southern Australia because fungi, bacteria, and other decomposers that thrive in the region continuously break dried grass and leaf litter down. Fewer decomposers live in southern Australia, making it possible for leaf litter and other fuel to build up for decades and prime the landscape for extremely destructive fires.

·      References

·      NAFI. (2012, Nov. 27) North Australia fire information map: Cape York. Accessed Nov. 27, 2012.

·      NASA. (2012, Nov. 27) Cape York Peninsula fires. Accessed Nov. 27, 2012.

·      Queensland Government. (n.d.) Rural fire service. Accessed Nov. 27, 2012.

·      Savannah Explorer. (n.d.) Fire in Australia’s tropical savannas. Accessed Nov. 27, 2012.

1.    Further Reading

2.     CSIRO. (2012, Oct. 26). Bushfire in Australia. Accessed Nov. 27, 2012.

3.     Crowley, G.M. (2008, Oct. 9). Changing fire management in the pastoral lands of Cape York Peninsula of northeast Australia. Geographical Research.