Great Bahamas Bank

Underwater structures of the Great Bahamas Bank are pictured in this image from the Landsat-8 satellite on 5 February.

Sitting north of Cuba, the bank is made of limestone – mainly from the skeletal fragments of marine organisms – that has been accumulating for over 100 million years.

Currents sculpted these underwater sediments into the wavy pattern we see along the bottom of the image, just a few meters deep.

We can clearly see where the shallow waters drop off into the deep, dark water of an area known as the Tongue of the Ocean. With depths of up to about 4000 m, this trench surrounded by islands, reefs and shoals has an opening to the Atlantic Ocean at its northern end (not pictured).

The trench was carved during the last Ice Age when the land was still above sea level and exposed to erosion from draining rainwater. As the Ice Age ended and the massive ice sheets across the globe melted, global sea levels rose and flooded the canyon.

Over the deep Tongue we can see a few sparse clouds.

This image, featured in the Earth from Space video program, is ESA’s 500 Earth Observation Image of the Week. The first of the series, published in 2004, also featured the colorful waters of the Bahamas, as seen by the Envisat satellite.

Image credit: USGS/ESA

Sea-Level Detail from CryoSat

Detail of sea-surface topography: red represents higher sea levels while blue areas are lower. The ‘strips’ are the CryoSat satellite’s ground tracks.

Image credit: ESA/CNES/CLS

Note: For more information, see 2013 Sea-Surface Topography.

The Massachusetts Coast in August 1978

This Seasat synthetic aperture radar image from August 27, 1978, shows the Massachusetts coast from Nantucket Island in the south past Cape Cod and Boston to Cape Ann in the north. The dark patch east and south of Nantucket is caused by the Nantucket Shoals, where a shallow ocean bottom creates surface waves and currents that appear as variations in brightness on the image. More subtle darker and lighter stripes to the east and north of Cape Cod are caused by internal waves, which are formed within the ocean by tides, rather than on the ocean surface by winds.

Seasat, which was managed by NASA's Jet Propulsion Laboratory in Pasadena, Calif., was the first satellite mission designed specifically to observe the ocean. Launched in 1978, it suffered a mission-ending power failure after 105 days of operation. But in that short time, Seasat collected more information about the ocean than had been acquired in the previous hundred years of shipboard research. The complete catalog of Seasat images has been processed digitally and is freely available from the Alaska Satellite Facility.

Image credit: NASA/JPL-Caltech/Alaska Satellite Facility

The Iberian Peninsula

This image from the International Space Station shows the Iberian Peninsula including Spain and Portugal at night.

The lights from human settlements reveal where the major towns and activity are. The large mass of light in the middle is Madrid, Spain’s capital city. The Iberian coastline is heavily populated with Valencia and Barcelona along the Mediterranean Sea prominent at the bottom right of this photo.

Portugal to the west shows similar lighting with the coast from Lisboa to Porto a haze of light.

This astronaut-image taken from 400 km above Earth shows how close the Iberian Peninsula is to Morocco. A thin line of blackness – the Strait of Gibraltar – separates the two.

Another thin line stands out in this picture – Earth’s atmosphere, the green shroud that surrounds and protects our world and the people and animals that live on it.

Photo credit: ESA/NASA

Guinea-Bissau and the Bissagos Islands

The coast of Guinea-Bissau in West Africa is pictured in this image from the Landsat-8 satellite. Mangrove swamps are abundant along this coastline, acting as important feeding grounds for fish, birds and animals.

Flowing from the east, the Geba River empties into the Atlantic Ocean, with the country’s capital city of Bissau located on the river estuary. The city appears as a light brown area in the upper-central portion of the image.

Off the coast in the lower-left section of the image are the Bissagos (or Bijagós) islands – an archipelago of over 80 islands and islets. In 1996 the archipelago was declared a UNESCO Biosphere Reserve.

A diversity of mammals, reptiles, birds and fish can be found on the islands, including protected or rare species such as the Nile crocodile, hippopotamus, African manatee and the common bottlenose dolphin.

The archipelago has also been recognized as an important site for green sea turtles to lay their eggs.

In the lower left corner, the island of Orango looks like a tree, with the waterways like branches and land appears as foliage. This island is the center of a national park, and is known for its matrimonial tradition where marriage is formally proposed by the women – who are also responsible for building the homes.

This image was acquired by Landsat-8 satellite’s Operational Land Imager on 3 May 2013 and it is featured in the Earth from Space video program.

Image credit: USGS/ESA

Earth, by Juno

On October 9, NASA's Juno spacecraft flew past Earth, using our home planet's gravity to get the final boost it needed to reach Jupiter. The JunoCam instrument captured this monochrome view of Earth, and other instruments were tested to ensure they work as designed during a close planetary encounter.

The Juno spacecraft was launched from NASA's Kennedy Space Center in Florida on August 5, 2011. Juno's rocket, the Atlas 551, was only capable of giving Juno enough energy or speed to reach the asteroid belt, at which point the Sun's gravity pulled Juno back toward the inner solar system. The Earth flyby gravity assist put Juno on course for arrival at Jupiter on July 4, 2016.

Photo credit: NASA/JPL-Caltech/Malin Space Science Systems

Note: For more information, see PIA17516: Juno's Earth Flyby (Artist's Rendering).

Lighthouse Atoll, Belize

The Lighthouse Atoll in the Belize Barrier Reef is featured in this image acquired on 29 March 2011 by Japan’s ALOS satellite. In the upper-central part of the image, an underwater sinkhole known as the Great Blue Hole appears as a dark blue circle. Surrounded by the shallow waters of the coral reef, the Great Blue Hole measures over 300 m in diameter and about 123 m deep. Formed when the sea level was much lower, rain and chemical weathering eroded the exposed terrain. Water later filled the hole and covered the area when the sea level rose at the end of the ice age.

Also visible in the image are two coral islands – green with vegetation – called cayes. The larger to the west is Long Caye, and the smaller Half Moon Caye is to the east.

This image is featured on the Earth from Space video program.

Photo credit: JAXA, ESA

NASA's Aquarius Maps Ocean Salinity Structure

New research using salinity data from NASA's Aquarius instrument on the Aquarius/SAC-D observatory has given scientists an unprecedented look at a key factor involved in the formation of an oceanic wave feature in the tropical Pacific and Atlantic Oceans that influences global climate patterns.

Tropical instability waves are westward-traveling waves that form along the interface between areas of cold and warm sea surface temperatures near the equator. Existing studies suggest that these waves can have wavelengths of 1,000-2,000 kilometers and have an average period between waves of about one month. These waves redistribute various properties of seawater within the ocean, including temperature, salinity, nutrients, and carbon. They interact with ocean currents, affect large-scale climate patterns such as El Niño and La Niña, and influence marine ecosystems and the carbon cycle.

Previous observations of tropical instability waves have been limited to satellite observations of sea surface temperature, sea level, ocean surface wind, and ocean surface chlorophyll abundance, as well as sparse direct ocean measurements. Salinity has been found to play an important role in the physics of these waves, and observations of their salinity are important to understanding them and their impacts on climate variability and prediction, and biogeochemistry. However, until now salinity observations of them have been limited to very sparse direct ocean measurements. Aquarius provides an unprecedented opportunity to observe their salinity.

In a study in press in the journal Geophysical Research Letters, a team led by Tong Lee of NASA's Jet Propulsion Laboratory, Pasadena, California, and including scientists from Earth & Space Research in Seattle, Aquarius data were used to reveal the salinity structure associated with tropical instability waves in the Pacific Ocean. The figure shows sea surface salinity (color shading in panels a and b) on December 18, 2011, derived from Aquarius measurements, showing the peaks and valleys of tropical instability waves in the eastern to central equatorial Pacific Ocean. The salinity structure is coherent with those obtained from other satellite derived products such as sea surface temperature (contour lines in panel a) and ocean surface currents (arrows in panel b). The unit for the sea surface salinity (SSS) is parts per thousand (the Practical Salinity Unit or PSU). The unit for sea surface temperature (SST) is degree centigrade.

The team found that Aquarius' salinity observations showed a clear signature of the waves near the equator in the Pacific Ocean where large contrasts in salinity occur between the saltier waters of the South Pacific and fresher waters of the North Pacific. The Aquarius data reveal that the waves move much faster at the equator than they do away from the equator, a feature that had not previously been well documented.

Aquarius observations show that near the equator, the waves have a dominant period of approximately 17 days. Aquarius' ability to reveal oceanic features on such short timescales was unexpected, as the mission was designed to study salinity changes on time scales of a month and longer. Salinity variability associated with tropical instability waves is larger near the equator, while sea surface temperature and sea level variability associated with the waves is larger a few degrees away from the equator. Salinity observations from Aquarius can therefore fill an important gap in studying tropical instability waves by providing measurements that are complementary to other satellite observations and direct ocean measurements.

Reference: Lee, T.; G. Lagerloef; M. Gierach; H.-Y. Kao; S. Yueh; and K. Dohan, 2012: "Aquarius reveals salinity structure of tropical instability waves," Geophysical Research Letters, in press.

Image credit: NASA/JPL-Caltech/GSFC

Portugal and Spain

Envisat’s Medium Resolution Imaging Spectrometer (MERIS) captured this image on 8 April 2012 at 13:05 CEST. The image was transmitted in Ka-band to ESA/ESRIN though direct transmission via Artemis, the ESA Data Relay satellite. The image, which is of nominal quality, shows Portugal and Spain. It is the last Envisat data transmitted via Ka-band before the communication anomaly affected the Envisat satellite.

Photo credit: ESA

Perpetual Ocean

Driven by wind and other forces, currents on the ocean surface cover our planet. Some span hundreds to thousands of miles across vast ocean basins in well-defined flows. Others are confined to particular regions and form slow-moving, circular pools. Seen from space, the circulating waters offer a study in both chaos and order. The visualization below, based on ocean temperature, salinity, sea surface height and sea ice data collected during field observations and by NASA satellites between July 2005 and December 2007, highlights many of the world's most important ocean surface currents. Watch powerful, fast-moving currents like the Gulf Stream in the Atlantic Ocean and the Kuroshio in the Pacific Ocean carry warm waters northeastward at speeds greater than 4 mph. View coastal currents such as the Agulhas in the Southern Hemisphere transporting equatorial waters from the Indian Ocean farther southwards. Explore the image collection to compare the direction and unique flow pattern of each of these major currents.

Video credit: NASA/Goddard Space Flight Center

The British Isles and the North Atlantic

Flying at an altitude of about 240 miles over the eastern North Atlantic, the Expedition 30 crew aboard the International Space Station photographed this nighttime scene. This view looks northeastward. Center point coordinates are 46.8 degrees north latitude and 14.3 degrees west longitude. The night lights of the cities of Ireland, in the foreground, and the United Kingdom, in the back and to the right, are contrasted by the bright sunrise in the background. The greens and purples of the Aurora Borealis are seen along the rest of the horizon.

This image was taken on March 28, 2012.

Photo credit: NASA

Update: A similar image can be found here.

Bonaire, Curaçao and Aruba

Bonaire, Curaçao and Aruba seen from the International Space Station. This picture was taken by ESA astronaut André Kuipers. A picture of this area was requested via social media. André managed to take the picture and upload it to the Internet two weeks later while onboard the Space Station.

Photo credit: ESA/NASA

West Coast of Africa

The first MERIS observation captured the huge phytoplankton patch produced by the 'upwelling' mechanism along the west coast of Africa near Mauritania. The unprecedented resolution allows fine-scale structures to be detected. In such upwelling areas, northeast trade winds bring deep and nutrient-rich water to the surface, feeding phytoplankton. Changes in climate affect the intensity of the upwelling with important consequences for marine ecosystems, fisheries and local economies.

One important task for MERIS is to provide overviews of the dynamics of upwelling areas and their primary production. This, in turn, could improve management of fish stocks within sustainable limits. Another important task for MERIS is to provide information on carbon fixation through photosynthesis within the global ocean for a better understanding of the carbon cycle.

Instrument: MEdium Resolution Imaging Spectrometer (MERIS)
Date of Acquisition: 22 March 2002
Orbit number: 00306
Instrument features: Full resolution image (300-meter resolution)
MERIS was designed to measure the concentration of phytoplankton. The colors seen by MERIS indicate the concentration of chlorophyll, the pigment that phytoplankton use for photosynthesis. MERIS can detect chlorophyll concentrations as low as 0.01 microgram, or 1/100 000 000 of a gram, per liter. MERIS data will be used to monitor the worldwide distribution of phytoplankton and to compute primary production.

Photo credit: ESA

US Eastern Seaboard at Night

An Expedition 30 crew member aboard the International Space Station took this nighttime photograph of much of the Atlantic coast of the United States. Large metropolitan areas and other easily recognizable sites from the Virginia/Maryland/Washington, D.C. area are visible in the image that spans almost to Rhode Island. Boston is just out of frame at right. Long Island and the New York City area are visible in the lower right quadrant. Philadelphia and Pittsburgh are near the center. Parts of two Russian vehicles parked at the orbital outpost are seen in left foreground.

This image was taken on February 6, 2012.

Photo credit: NASA

Morocco and Algeria

This Envisat image, acquired on 5 December 2011 by the MERIS instrument, shows part of central Morocco from the Atlantic Ocean to the west, over the Atlas mountains and into arid parts of Algeria further inland. The snow-capped High Atlas mountain range divides Morocco from the Sahara desert’s climatic influences in Algeria. The Sahara is constantly expanding southward, rendering large areas of land barren. One of the many benefits of Earth observation satellites is the possibility to monitor changes like desertification, or the degradation of land, caused by human activities or climate change.

Photo credit: ESA

Blue Marble 2012

A 'Blue Marble' image of the Earth taken from the VIIRS instrument aboard NASA's most recently launched Earth-observing satellite - Suomi NPP. This composite image uses a number of swaths of the Earth's surface taken on January 4, 2012. The NPP satellite was renamed 'Suomi NPP' on January 24, 2012 to honor the late Verner E. Suomi of the University of Wisconsin.

Suomi NPP is NASA's next Earth-observing research satellite. It is the first of a new generation of satellites that will observe many facets of our changing Earth.

Suomi NPP is carrying five instruments on board. The biggest and most important instrument is The Visible/Infrared Imager Radiometer Suite or VIIRS.

Photo credit: NASA/NOAA/GSFC/Suomi NPP/VIIRS/Norman Kuring