1. Painting with Islands and Sunglint

    The satellites in NASA’s Earth Observing System collect data and imagery for scientific research. The data goes to one of twelve Distributed Active Archive Centers (DAACs) across the United States, where it is processed and distributed to scientists who mine it for clues about our environment.

    But sometimes the imagery is remarkable simply for its beauty. When the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite looked down on the Lesser Antilles on August 1, 2013, the combination of sunlight, islands, and wind painted this scene on the surface of the Caribbean Sea. The right side of the image has a milky hue because of sunglint, an optical effect caused by the mirror-like reflection of sunlight off the water surface directly back at the satellite sensor.

    Although sunglint washes out many features, it also reveals details about the water surface and atmospheric circulation that are usually hidden. In this case, the sunglint exposed wakes in the atmosphere caused by prevailing winds arriving from the east. The wakes are likely the result of winds roughening or smoothing the water surface behind the islands. The rocky, volcanic islands create a sort of wind shadow—blocking, slowing, and redirecting the air flow. That wind, or lack of it, piles up waves and choppy water in some places and calms the surface in others, changing how light is reflected.

    NASA image courtesy LANCE/EOSDIS MODIS Rapid Response Team, GSFC. Caption by Adam Voiland and Michael Carlowicz.

    Instrument(s): Terra - MODIS
     
  2. Ship Wave Clouds Behind the Crozet Islands

    Air flows like water in the atmosphere with invisible currents and waves. On April 9, 2014, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this view that evokes fluid-like movement in the atmosphere. Ship wave clouds fan out behind the Crozet Islands over the southern Indian Ocean looking exactly like the ripples behind a rock in a stream or the waves behind a boat moving through calm water.

    The clouds take this shape in response to the flow of air in the atmosphere. Air was flowing smoothly over the ocean, and the clouds around the islands are proof of the unimpeded flow. These marine clouds are a solid bank and even in texture with little to disturb their uniformity. When the smooth-flowing air hit the Crozet Islands, it split around their rocky mass. The disturbance set up a wave pattern in the classic “v” shape we see behind similar disturbances in water. The turbulent air shaped the clouds into the wave pattern seen here.

    The Crozet Islands are in the southern Indian Ocean roughly halfway between Antarctica and Madagascar. The islands are part of France’s southern and Antarctic lands. A designated conservation area, they are home to seals, penguins, and sea birds. The islands are uninhabited except for a small research station.

    1. Reference

    2. North Dakota State University Îles Crozet. Accessed April 11, 2014.

    NASA image courtesy Jeff Schmaltz, LANCE/EOSDIS MODIS Rapid Response Team at NASA GSFC. Caption by Holli Riebeek.

    Instrument(s): Terra - MODIS
     
  3. Somerset Levels Swamped

    A low-lying tract of land in southwestern England known as the Somerset Levels stands just a few meters above sea level; some of the lowest parts even dip below sea level. A natural marshland, the Levels were drained and reclaimed for agriculture over the past few hundred years. However, the marshy character of the land still reasserts itself on occasion.

    In December 2013 and January 2014, a series of storms dropped 372 millimeters (15 inches) of rain on southern England, making that two-month period the wettest on record since 1910. The storms and rain have continuedinto February. Since January, both the River Parrett and River Tone spilled over their banks and flooded sections of the Levels. By mid-February, an estimated 17,000 hectares (66 square miles) and 150 homes were swamped.

    The Advanced Land Imager (ALI) on NASA’s Earth-Observing-1 satellite acquired this image on February 16, 2014. For comparison, the lower image shows Somerset Levels as seen by Landsat 8 on November 4, 2013.

    On February 16, brown, sediment-laden water covered large tracts of farmland. While the town of Bridgewater was still dry, villages such as Moorland, Westonzoyland, Burrowbridge, and Othery were either flooded or nearly so. Neither the King’s Sedgemoor Drain nor pumping efforts by the British government could slow the rising waters enough to prevent severe flooding.

    Although the Somerset Levels have a long history of flooding, this latest round has reignited a debate about the usefulness of dredging, a process that involves deepening and widening river channels by removing silt. Someobservers argue that dredging the river more regularly would prevent damaging floods from occurring. Others say that regular dredging does little to prevent floods, causes ecological damage to ecosystems, and is too expensive to pursue.

    NASA Earth Observatory images by Jesse Allen and Robert Simmon, using EO-1 ALI data provided courtesy ofthe NASA EO-1 team and Landsat data from the U.S. Geological Survey. Caption by Adam Voiland.

    Instrument(s): EO-1 - ALI
     
  4. Fires Cloak Sumatra in Smoke

    Dense smoke cloaks central Sumatra, Indonesia, in these images taken by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra and Aqua satellites. The smoke is coming from fires in Riau province, where palm oil and pulpwood plantations are abundant. Though illegal for all but small landowners, fire is frequently used to clear brush and trees for farming, especially plantations. The forest and peat soil produce dense smoke when burned, as shown in these images.

    The top image shows conditions in the morning (10:45 a.m. local time), while the lower image is from the afternoon (1:45 p.m. local time). The fires, which are outlined in red, build throughout the day.

    The fires and resulting air pollution have forced the Riau government to declare a state of emergency, reported the Wall Street Journal. The smoke has caused illness, closed schools for the past two weeks, and reduced visibility.

    1. Reference

    2. Wall Street Journal (2014, February 27) Fires prompt state of emergency in Indonesia’s Riau. Accessed February 28, 2014.

    NASA images courtesy Jeff Schmaltz, LANCE/EOSDIS MODIS Rapid Response Team at NASA GSFC. Caption by Holli Riebeek.

    Instrument(s): Terra - MODIS
     
  5. Five Volcanoes Erupting at Once

    Remote. Cold. Rugged. Those three adjectives capture the essence of Russia’s Kamchatka Peninsula. Another word—perhaps more applicable than anywhere else on Earth—is “fiery.”

    Of the roughly 1,550 volcanoes that have erupted in the recent geologic past, 113 are found on Kamchatka.Forty Kamchatkan volcanoes are “active,” either erupting now or capable of erupting on short notice. TheOperational Land Imager (OLI) on Landsat 8 captured activity at five of them during a single satellite pass on April 14, 2014.

    From geographic north to south (and top to bottom on this page), the volcanoes are Shiveluch, Klyuchevskaya, Bezymianny, Kizimen, and Karymsky. The tallest of the group is Klyuchevskaya, a stratovolcano with a steep, symmetrical cone that reaches 4,750 meters (15,580 feet) above sea level. The most active is Karymsky, a 1,536-meter (5,039-foot) peak that has erupted regularly since 1996.

    Plate tectonics is responsible for the many volcanoes on Kamchatka Peninsula. The Pacific Plate is slowly colliding with and sliding beneath the Okhotsk Plate. As rock from the Pacific Plate descends and encounters higher pressures and temperatures, it melts into magma. Over time, magma accumulates and migrates up toward the surface, causing volcanic eruptions.

    Long before the discovery of plate tectonics, Kamchatka’s many volcanoes and eruptions were woven into a rich tapestry of myths and creation stories. According to Koryak folklore, the raven-like deity Kutkh created Kamchatka by dropping a giant feather on the Pacific Ocean. Each of the first generation of men became one of Kamchatka’s mountains at death; many of these mountains became volcanic because the men’s hearts burned so passionately for a beautiful woman that Kutkh had also created near the beginning of time.

    In 2013, another NASA satellite collected imagery of Shiveluch, Bezymianny, Tolbachik, and Kizimen.

    NASA Earth Observatory images by Robert Simmon, using Landsat 8 data from the USGS Earth Explorer. Caption by Robert Simmon and Adam Voiland.

    Instrument(s): Landsat 8 - OLI
     
  6. Grand Canyon Geology Lessons on View

    The Grand Canyon in northern Arizona is a favorite for astronauts shooting photos from the International Space Station, as well as one of the best-known tourist attractions in the world. The steep walls of the Colorado River canyon and its many side canyons make an intricate landscape that contrasts with the dark green, forested plateau to the north and south.

    The Colorado River has done all the erosional work of carving away cubic kilometers of rock in a geologically short period of time. Visible as a darker line snaking along the bottom of the canyon, the river lies at an altitude of 715 meters (2,345 feet), thousands of meters below the North and South Rims. Temperatures are furnace-like on the river banks in the summer. But Grand Canyon Village, the classic outlook point for visitors, enjoys a milder climate at an altitude of 2,100 meters (6,890 feet).

    The Grand Canyon has become a geologic icon—a place where you can almost sense the invisible tectonic forces within the Earth. The North and South Rims are part of the Kaibab Plateau, a gentle tectonic swell in the landscape. The uplift of the plateau had two pronounced effects on the landscape that show up in this image. First, in drier parts of the world, forests usually indicate higher places; higher altitudes are cooler and wetter, conditions that allow trees to grow. The other geologic lesson on view is the canyon itself. Geologists now know that a river can cut a canyon only if the Earth surface rises vertically. If such uplift is not rapid, a river can maintain its course by eroding huge quantities of rock and forming a canyon.

    A more detailed view shows the canyon in an astronaut photo that looks west.

    Astronaut photograph ISS039-E-5258 was acquired on March 25, 2014, with a Nikon D3S digital camera using a 180 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 the Expedition 39 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 M. Justin Wilkinson, Jacobs at NASA-JSC.

    Instrument(s): ISS - Digital Camera
     
  7. Tehuano Winds

    Cool air often follows storm systems passing through North America in the winter and early spring. In some cases, the cool air surges as far south as Mexico, where it encounters the Sierra Madre Oriental Mountains, a long chain oriented roughly parallel to Mexico’s Atlantic coast. The mountains behave like a wall, funneling winds to the south until they reach Chivela Pass, a gap in the range on the Isthmus of Tehuantepec.

    At the gap, pressure differences between cool, dry air from the north and warm, moist air from the south cause winds to rush toward the Pacific Ocean. Northerlies that last for more than a day are known as Tehuano winds. Such winds can be extremely strong, reaching gale or even hurricane force on the Beaufort wind scale.

    The Moderate Resolution Imaging Spectroradiometer (MODIS) on the Aqua satellite captured this image on April 8, 2014, when Tehuano winds carried dust over the Gulf of Tehuantepec. A thin arc cloud marked the leading edge of this pulse of wind.

    Read this blog post from the Cooperative Institute for Meteorological Satellite Studies (CMISS) to learn more about the event and to see a sequence of images showing the wind front fanning outward over time.

    NASA image courtesy, LANCE/EOSDIS MODIS Rapid Response Team at NASA GSFC. Caption by Adam Voiland.

    Instrument(s): Aqua - MODIS
     
  8. Cyclone Ita Approaching Australia

    NASA’s Aqua satellite captured this image of Tropical Cyclone Ita as it bore down on Australia’s Cook Peninsula in April 2014. About 30,000 residents of Cairns were asked to evacuate in advance of the storm, and storm surge and wind damage alerts were issued across northern Queensland.

    The image was acquired by Aqua’s Moderate Resolution Imaging Spectroradiometer (MODIS) at 2 p.m. local time (0400 Universal Time) on April 11. About two hours later, according to Unisys Weather, the storm had maximum sustained winds of 232 kilometers (144 miles) per hour, a category 4 cyclone.

    Ita later made landfall near Cape Flattery, north of Cooktown, around 9 p.m. on April 11. By 4 a.m. local time on April 12, meteorologists reported that the storm was moving south-southwest through the state of Queensland with sustained winds at roughly 140 kilometers (90 miles) per hour. Ita was predicted to remain at least a category 1 cyclone though late afternoon on April 12.

    In the days before arriving in Queensland, the tropical weather system that became Ita dumped intense rain on theSolomon Islands, leading to flash floods and landslides that killed at least 20 people and affected at least 50,000. It also brought flooding and power outages to eastern Papua New Guinea and nearby islands.

    MODIS captured earlier images of Ita on April 6, April 8, and April 10.

    NASA image courtesy Jeff Schmaltz, LANCE/EOSDIS MODIS Rapid Response Team at NASA GSFC. Caption by Mike Carlowicz.

      Instrument(s): Aqua - MODIS
     
  9. Houston, Texas at Night

    Houston, Texas, has been called the “energy capital of the world” due to its role as a major hub of the petroleum and other energy resource industries. The Houston metropolitan area covers almost 2,331,000 hectares (9,000 square miles) along the southeast Texas coastline, with an average elevation of 13 meters (43 feet) above sea level and a population of over 5 million (2006 US Census estimate).

    The Houston metropolitan area is also noteworthy as being the largest in the United States without formal zoning restrictions on where and how people can build. This freedom has led to a highly diverse pattern of land use at the neighborhood scale; nevertheless, more general spatial patterns of land use can be recognized in remotely sensed data. These general patterns are particularly evident in nighttime photography of the urban area taken by astronauts on board the International Space Station.

    The image depicts the roughly 100-kilometer (60-mile) east-west extent of the Houston metropolitan area. Houston proper is at image center, indicated by a “bull’s-eye” of elliptical white- to orange-lighted beltways and brightly lit white freeways radiating outwards from the central downtown area. Suburban and primarily residential urban areas are indicated by both reddish-brown and gray-green lighted regions, which indicate a higher proportion of tree cover and lower light density.

    Petroleum refineries along the Houston Ship Channel are identified by densely lit areas of golden yellow light. Rural and undeveloped land rings the metropolitan area, and Galveston Bay to the southeast (image lower right) provides access to the Gulf of Mexico. Both types of non-urban surface appear dark in the image.

    You can see more nighttime imagery of cities and learn about techniques that astronauts use to photograph them in the Earth Observatory feature Cities at Night.

    Astronaut photograph ISS022-E-78463 was acquired on February 28, 2010, with a Nikon D3 digital camera 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 22 crew. The image in this article has been cropped and enhanced to improve contrast. 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/JSCGateway to Astronaut Photography of Earth. Caption by William L. Stefanov, NASA-JSC.

    Instrument(s): ISS - Digital Camera
     
  10. Dallas, Texas

    The Dallas-Fort Worth metropolitan area is the largest in Texas, with an approximate population of 6 million people in 2005. Founded by John Neely Bryan in 1841, the city became the center for the United States oil economy with the discovery of oilfields to the east of the city in 1930. The darkest day in the city’s history occurred on November 22, 1963 when President John F. Kennedy was assassinated while traveling by motorcade through Dealey Plaza. The Dallas-Forth Worth region today is a major corporate, banking, and technological center.

    This astronaut photograph captures the northwestern portion of the metropolitan area. Standing water bodies such as Lake Lewisville and Grapevine Lake are highlighted by sunglint, where the surface of the water acts as a mirror reflecting sunlight back towards the astronauts in the International Space Station (read Sunglint in Astronaut Photography of Earthfor a more detailed explanation of sunglint). Using the sunglint to define edges of water helps when mapping water bodies and stream courses on a landscape—note the region of small ponds to the north of Grapevine Lake highlighted by sunglint. Images such as these help characterize surface hydrology and areas of potential flooding hazard.

    Astronaut photograph ISS010-E-24596 was acquired April 14, 2005, with a Kodak 760C digital camera with a 180 mm lens, and is provided by the ISS Crew Earth Observations experiment and the Image Science & Analysis Group, Johnson Space Center. The International Space Station Program supports the laboratory 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.

    Instrument(s): ISS - Digital Camera
     
  11. Austin, Texas

    It was Texas hot when this view of the capital city of Austin was taken in late July by astronaut Ed Lu. Adding to the rising temperatures were heated debates in the Texas Capitol Building, where a special session had convened. Eleven senate Democrats thwarted a redistricting vote by disappearing from the state. Were Lu, and his Expedition 7 partner Yuri Malenchenko looking for the missing Democrats? We’ll never know, but they expanded their Austin search a week later with a wider view of Austin, taken with a 400 mm lens on August 6.

    Austin is an expanding city in the Texas hill country. A few decades ago Austin was known as a place where University of Texas students and state politicians co-existed along the banks of the Colorado River (seen snaking along the lower left of the image). Today, the exploding population (44% growth between 1990 and 2000) and increasing development stresses local resources like water, green space, and transportation networks, prompting city planners to think through scenarios for future development.

    Documenting city environments and city footprints over time is one of the science objectives of the Crew Earth Observations payload on the International Space Station. Astronauts have always enjoyed observing cities around the world. These images of Austin provide a 2003 baseline for monitoring its regional development and growth.

    Astronaut photograph ISS007-E-11256 was taken July 29, 2003 with a Kodak DCS760 digital camera equipped with an 800mm lens and provided by Cynthia A. Evans (Lockheed Martin / Earth Observations Laboratory, Johnson Space Center). The International Space Station Program supports the laboratory 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.

    Instrument(s): ISS - Digital Camera
     
  12. Kansas Prairie Fires

    Fire is as much a part of the prairie landscape as grass. Before settlement, tallgrass prairie covered 170 million acres of North America from Texas to Canada. Frequent fires (ignited by native peoples or lightning) maintained the grassland, destroying shrubs and trees that would otherwise encroach on the land while letting native fire-adapted grasses thrive. Today, less than four percent of the prairie remains, mostly in eastern Kansas and Oklahoma, and fire is still a critical component of the ecosystem.

    “We can’t have prairie without fire,” says Jason Hartman of the Kansas Forest Service. “Doing controlled burns is safer for the public than wildfires.“ While fires are helpful year-round, most prescribed burns occur in the spring, peaking in late March and April, as shown in the image above. Outlined in red, widespread fires were burning on March 29, 2014, when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite acquired the image. Freshly burned land is dark brown or black.

    Because Kansas does not have a reporting system for prescribed burns and wildfires, it’s unclear just how much land burns every year, says Hartman. Satellite images help scientists assess how extensive fires are in a given year. The false-color image below, taken by Aqua MODIS on March 31, illustrates the extent of recent fires. The image includes both infrared and visible light so that newly burned land is dark red.

    Fire has many roles in preserving the prairie. Fires remove old plant material, consuming dry, dead grass and woody shrubs and trees and returning nutrients to the soil. The burn exposes soil to the sunlight, and new grasses grow quickly in the warmed soil. Young plants are more palatable to grazing animals, including cows, buffalo, and deer. As a result, newly burned land attracts animals. Native Americans recognized this fact and used fire to bring game. Today, ranchers also use fire to improve rangeland for their cattle. The new plants are more nutritious and contain more protein, and so animals that graze on fire-controlled grassland are 10 to 15 percent larger.

    Fire is also an inexpensive way to control invasive species, including the Eastern red cedar, without pesticides. While the tree does grow in Kansas and Oklahoma, fire has confined it to protected landscapes like sheltered ravines. If fires did not occur, the trees and other woody plants would quickly infiltrate the grassland. Within 30 years, the prairie would become a forest and grassland habitats would disappear.

    1. References

    2. K-State Research and Extension (2013, April 17) Preserving the tallgrass prairie. Accessed April 8, 2014.
    3. Kansas Flint Hills Smoke Management (2011) Kansas Flint Hills smoke management. Accessed April 8, 2014.
    4. Kansas Grazing Lands Coalition Kansas prairie primer. Accessed April 8, 2014.
    5. National Park Service Tallgrass Prairie National Preserve Kansas. Accessed April 8, 2014.
    6. National Park Service Inventory & Monitoring Program (2010, January 28) Fire ecology and Fire ecology networks. Accessed April 8, 2014.
    7. Oklahoma State University Fire effects on the prairie. Accessed April 8, 2014.
    8. The Topeka Capital-Journal (2014, April 6) Fires, while beneficial, keep fire crews busy. Accessed April 8, 2014.
    9. University of Nebraska Lincoln (2007) Grassland management with prescribed fire. Accessed April 8, 2014.

    NASA images courtesy Jeff Schmaltz, LANCE/EOSDIS MODIS Rapid Response Team at NASA GSFC. Caption by Holli Riebeek.

    Instrument(s): Aqua - MODIS
     
  13. Alluvial Fan in Kazakhstan

    Mountain streams are usually confined to narrow channels and tend to transport sizable amounts of gravel, sand, clay, and silt—material that geologists call alluvium. The type and quantity of alluvium transported depends on the volume of the water flow and the gradient of the stream. Larger rivers pick up more alluvium than smaller ones; fast-flowing streams on steep slopes transport coarser sediment than slow-moving ones on shallow slopes.

    When a rushing stream emerges from the mountains onto a relatively flat valley or basin, it often spreads out to become abraided stream with multiple, interlacing channels. As a mountain stream moves into a flat area, it also slows down. It loses its capacity to carry as much alluvium and deposits the excess in sandbars throughout the channels. Over time, the channel migrates back and forth, creating fan-shaped deposits known as alluvial fans.

    The narrowest point of an alluvial fan—closest to the mountain front—is known as the apex; the broader part is called the apron. Alluvium deposited closer to the apex tends to be coarser than the material that makes up the apron. Alluvial fans are particularly apt to form in deserts because there is usually plenty of loose alluvium and not much vegetation to prevent stream channels from shifting.

    The Advanced Land Imager (ALI) on Earth-Observing 1 (EO-1) captured this view of an alluvial fan in Kazakhstan’s Almaty province on September 9, 2013. In the lower left of the image, the Tente River flows through a narrow channel in the foothills of the Dzungarian Alatau range. Where the Tente emerges from the hills near Lake Alakol, it spreads out and becomes a braided stream. The movement of the channel over time has left a large fan that’s about 20 kilometers (12 miles) across at its widest point.

    Alluvial fans in arid areas are often used for agriculture because they are relatively flat and provide groundwater for irrigation. This fan is no exception. The blocky green pattern across the apron are fields or pasture land. A number of towns and villages, including Usharal and Beskol, are visible along the fan’s outer edge. The straight feature cutting through Beskol and along the northeastern portion of the fan is a railroad.

    NASA Earth Observatory image by Jesse Allen and Robert Simmon, using Landsat data from the U.S. Geological Survey.Caption by Adam Voiland

    Instrument(s): Landsat 8 - OLI
     
  14. Port Aransas and the Intracoastal Waterway, Texas

    This photograph from the International Space Station shows 18 kilometers (11.2 mile) of the Intracoastal Waterway, the 4,800 kilometer-long (3,000 mile) barge channel that lies on the protected inshore of coastal islands of the southern and eastern United States, including coastal Texas. The small city of Port Aransas lies on a barrier island fully 18 kilometers (11.2 miles) seaward of the mainland and its sister city, Aransas Pass (lower left). This photo shows parts of the waterway that are artificial, such as the straight sector leading into Corpus Christi Bay (lies outside the lower margin of the image.) Other sectors of the waterway are natural bays such as Aransas Bay.

    Jetties protect the inlet into the Gulf of Mexico (image top right). Inlets at many points along the Intracoastal Waterway cut through barrier islands to give ships access to the Gulf of Mexico and the Atlantic Ocean. Several large rivers allow access from the waterway to distant inland ports, as in the cases of the Mississippi and Hudson Rivers. A recent study concluded that shipments by barge in the Gulf Coast sector of the waterway remain the lowest-cost alternative for many commodities, with petroleum and petroleum products amounting to 30 percent of the total tonnage.

    Astronaut photograph ISS038-E-57806 was acquired on February 21, 2014, with a Nikon D3X digital camera using a 1000 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 the Expedition 38 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 M. Justin Wilkinson, Jacobs at NASA-JSC.

    Instrument(s): ISS - Digital Camera
     
  15. Near Miss in Madagascar

    On Sunday, March 30, 2014, the outlook appeared grim for cities in northwestern Madagascar. Tropical cyclone Hellen spun offshore, gaining strength with surprising rapidity and with a track destined to bring it ashore. The day started with the storm being the equivalent of a Category 2 storm with winds of 170 kilometers per hour (100 miles per hour or 90 knots). Twelve hours later, winds reached 240 kilometers per hour (150 miles per hour or 130 knots), making it a strong Category 4 storm.

    The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired this image of Cyclone Hellen at 7:20 UTC on March 30 in the middle of the storm’s rapid intensification. The storm had a distinct open eye and a classic tight circular shape. Its outer bands were already over northwestern Madagascar.

    The rapid intensification prompted the Regional Specialized Meteorological Center (a branch of the French meteorology agency, Meteo France), to warn residents to prepare for a “worst case scenario.” The March 30 warning also said, “Hellen is likely to be one of the most powerful tropical cyclones ever seen over the Northern Channel since the satellite era (1967).“ With clockwise-blowing winds that pushed a mound of water towards the southeastern side of the storm, Hellen was likely to bring a strong storm surge as high as 7 meters (23 feet) to the coast of Madagascar.

    Fortunately, Hellen weakened substantially not long before it made landfall, minimizing the damage. Just before landfall, warning bulletins advised residents to prepare for periods of heavy rain and wind and a possible storm surge of 2 meters (7 feet). An early assessment from the UN Office for the Coordination of Humanitarian Affairs indicates that approximately 170 homes were destroyed and just over 900 people evacuated in Madagascar.

    1. References

    2. Regional Specialized Meteorological Center (2014, March 31) Warning number 14/14/20132014. Accessed April 4, 2014.
    3. Regional Specialized Meteorological Center (2014, March 30) Warning number 12/14/20132014. Accessed April 4, 2014.
    4. UN Office for the Coordination of Humanitarian Affairs. (2014, April 2) Thousands affected in Comoros and Mozambique; alerts lifted in Madagascar. Accessed April 4, 2014.
    5. Unisys Weather (2014, April 1) Cyclone-4 Hellen. Accessed April 4, 2014.
    6. The Weather Channel (2014, March 31) Tropical Cyclone Hellen: Worst case scenario avoided in Madagascar. Accessed April 4, 2014.

    NASA image courtesy Jeff Schmaltz, LANCE/EOSDIS MODIS Rapid Response Team at NASA GSFC. Caption by Holli Riebeek.

    Instrument(s): Terra - MODIS