Category Archives: Earth Observatories

Copernicus Sees a Sea-Ice Swirl

Check out this swirl of sea-ice between Greenland and Iceland; click the image for a larger version.

Image: contains modified Copernicus Sentinel data (2019), processed by ESA, CC BY-SA 3.0 IGO

ESA’s caption: The Copernicus Sentinel-2 mission takes us over a swirl of sea ice off the east coast of Greenland in the Irminger Sea, which is just south of the Denmark Strait between Greenland and Iceland.

Click on the box in the lower-right corner to view this image at its full 10 m resolution directly in your browser.

In this image captured on 9 June 2019, small pieces of sea ice, known as ice floes, trace out the ocean currents beneath, resulting in a large swirl-like feature of approximately 120 km in diameter.

This ice, which formed by freezing of the sea surface further north in the Arctic Ocean, has drifted southwards along the coast of Greenland before arriving at this location. The ice swirl is considered a typical eddy or vortex, commonly found in the summer marginal ice zone off the east coast of Greenland.

The marginal ice zone is the transition region from the open ocean, visible in dark blue, to the white sea ice. Depending on wind direction, waves and ocean currents, it can consist of small, isolated ice floes drifting over a large area to smaller ice floes pressed together in bright white bands.

Strong mesoscale air—ice—ocean interactive processes drive the advance and retreat of the sea ice edge, and result in the meanders or eddies visible in this region.

Investigations of such ocean eddies and meanders began in the 1970s and 1980s in the Greenland Sea to gain a better understanding of the interactions between the ocean, ice and atmosphere.

Copernicus Sentinel-2 is a two-satellite mission. Each satellite carries a high-resolution camera that images Earth’s surface in 13 spectral bands. Together they cover all Earth’s land surfaces, large islands, inland and coastal waters every five days at the equator.

This image is also featured on the Earth from Space video programme.

Satellite Hurricane Tracking

The hurricane season for North and Central America began on 01 June, here’s how NASA’s Earth observatories keep an eye on things.

There are “crazy” people who fly into hurricanes to get detailed information too, but that’s another story.

A View of Los Angeles

From a CubeSat! This particular CubeSat is a planet hunter too.

NASA: A small satellite designed to hunt for new planets beyond the solar system recently looked down at Earth to capture an image of California’s “City of Stars.”

The greater Los Angeles area stands out in these images from ASTERIA, the Arcsecond Space Telescope Enabling Research in Astrophysics, a satellite not much larger than a briefcase. ASTERIA is a CubeSat, or a small satellite composed of cubic units that measure 10 centimeters (4.5 inches) on each side. This particular CubeSat is made up of six units.

The images, taken March 29, reveal a massive grid of illuminated city streets and freeways. A bright spot near the center of the first image marks the location of Dodger Stadium. (The Dodgers played the Arizona Diamondbacks at home that night.) To the northeast, near the darkness of the San Gabriel Mountains, is NASA’s Jet Propulsion Laboratory in Pasadena, California, which built and operates ASTERIA, and the nearby Rose Bowl Stadium. The close-cropped image shows a region of about 43.5 square miles (70 square kilometers), with a resolution of about 100 feet (30 meters) per pixel.

Lots of orbiting small satellites can take higher-quality pictures of Earth than this one. But ASTERIA is the only CubeSat in orbit that can also look for exoplanets, or planets orbiting stars other than our Sun. Its primary mission objective was to demonstrate precision-pointing technology in a small satellite.

Electrical Test Engineer Esha Murty (left) and Integration and Test Lead Cody Colley (right) prepare the ASTERIA spacecraft for mass properties measurements in April 2017 prior to spacecraft delivery.
Credits: NASA/JPL-Caltech

ASTERIA was developed under the Phaeton Program at JPL. Phaeton provided early-career hires, under the guidance of experienced mentors, with the challenges of a flight project. The mission is a collaboration with the Massachusetts Institute of Technology (MIT) in Cambridge. Sara Seager, a professor of planetary science and physics at MIT, is the mission’s principal investigator.

Bosphorus Strait

Larger version

There has been a wonderful collection of images coming in from our Earth facing satellites lately. I like this one, even though I had the name wrong, calling it the Istanbul Strait at first glance. I was close though. This is the Bosphorus Strait.

The image contains modified Copernicus Sentinel data (2018), processed by ESA, CC BY-SA 3.0 IGO, comes to us from the Copernicus Sentinel-1 mission.

ESA: Captured by the Copernicus Sentinel-1 mission, this image shows the narrow strait that connects eastern Europe to western Asia: the Bosphorus in northwest Turkey. The image contains satellite data stitched together from three radar scans acquired on 2 June, 8 July and 13 August 2018.

Separating the Black Sea and the Sea of Marmara, the strait is one of the busiest maritime passages in the world, with around 48 000 ships passing through every year. Daily traffic includes international commercial shipping vessels and oil tankers, as well as local fishing and ferries. Ships in the strait can be seen in the image as multi-coloured dots. Three bridges are also visible spanning the strait and connecting the two continents.

The two identical Copernicus Sentinel-1 satellites carry radar instruments, which can see through clouds and rain, and in the dark, to image Earth’s surface below. The multi-temporal remote sensing technique combines two or more radar images over the same area to detect changes occurring between acquisitions.

In the far-left of this image, the aqua-green patches of land show the changes in the fields between the three satellite acquisitions.

Turkey’s most populous city, Istanbul, can be seen on both sides of the Bosphorus. The city appears in shades of white owing to the stronger reflection of the radar signal from buildings, which contrasts with the dark black colour of the inland lakes and surrounding waters.

This image is also featured on the Earth from Space video programme.

ICESat-2 Delivers the Icy Data

ICESat-2 is delivering great data. If you are a student in need of a science project check out the project website and you are sure to find something useful including actual data – one of the best project websites around.

NASA: Less than three months into its mission, NASA’s Ice, Cloud and land Elevation Satellite-2, or ICESat-2, is already exceeding scientists’ expectations. The satellite is measuring the height of sea ice to within an inch, tracing the terrain of previously unmapped Antarctic valleys, surveying remote ice sheets, and peering through forest canopies and shallow coastal waters.

With each pass of the ICESat-2 satellite, the mission is adding to datasets tracking Earth’s rapidly changing ice. Researchers are ready to use the information to study sea level rise resulting from melting ice sheets and glaciers, and to improve sea ice and climate forecasts.

In this image, sea ice forms in the open water between floes, called leads, in the Bellingshausen Sea. ICESat-2 is able to detect the thin sea ice, allowing scientists to more accurately track seasonal ice formation.

Image Credit: NASA/Kate Ramsayer

Bellingshausen Sea

Valley Fog from Space

I remember valley fog fondly. When I was a youngster I’d ride the bus and looking down into the valley it would actually look like the valleys were filled in with a solid white mass and we would have to descend into it to get to the school. It’s one of those things you have to experience to appreciate I suppose.

This image was taken by the the Suomi NPP satellite (credit: NASA/Joshua Stevens/Adam Voiland). One of the most striking thing about the image is the “light pollution”.


It’s autumn in the Northern Hemisphere, which means many people living in mountainous areas are awakening to fog-filled valleys.

As nights lengthen with the season, the atmosphere has more time to cool down and approach the dew point—the temperature at which the air becomes saturated and water vapor condenses into fog. Since cold air is denser than warm air, it sinks and drain into valleys, meaning fog develops there first. Many valleys also have rivers and streams, which amplifies the process by providing a ready supply of water vapor.

The Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite captured a glimpse of this process at work in the mountains of West Virginia on October 24, 2018. The sensor acquired the nighttime image at about 2 a.m., when fog had filled many valleys of the Cumberland Mountains.

Guatemala Damage Proxy Map

An Advanced Rapid Imaging and Analysis team at NASA took a look at the recent Guatemala eruption with ESA’s Sentinel-1 data among others.

Original caption from NASA: The Advanced Rapid Imaging and Analysis (ARIA) team at NASA’s Jet Propulsion Laboratory in Pasadena, California, and Caltech, also in Pasadena, created this Damage Proxy Map (DPM) depicting areas around Fuego volcano, Guatemala, that are likely damaged (shown by red and yellow pixels) as a result of pyroclastic flows and heavy ash spewed by Fuego volcano. The map is derived from synthetic aperture radar (SAR) images from the Copernicus Sentinel-1 satellites, operated by the European Space Agency (ESA). The images were taken before (June 1, 2018 6 p.m.) and after (June 7, 2018 6 p.m., both Guatemala Time) the onset of the volcanic eruption.

The map covers an area of 57 by 13 miles (91 by 21 kilometers), shown by the large red polygon. Each pixel measures about 33 yards (30 meters) across. The color variation from yellow to red indicates increasingly more significant ground surface change. This damage proxy map may be used as guidance to identify damaged areas and may be less reliable over vegetated areas. For example, the scattered single colored pixels over vegetated areas may be false positives, and the lack of colored pixels over vegetated areas does not necessarily mean no damage.

Sentinel-1 data were accessed through the Copernicus Open Access Hub. The image contains modified Copernicus Sentinel data (2018), processed by ESA and analyzed by the NASA-JPL/Caltech ARIA team. This research was carried out at JPL under a contract with NASA.

Image: NASA/JPL-Caltech/ESA/Copernicus/Google

Antarctic Sunset

Remember the Sentinel-3B launch a few weeks ago (25 April)? Not wasting any time we already have the first image. Actually the image was taken on 07 May, barely two weeks after launch. And what an image it is – a look at the Antarctic sunset!

Sentinel-3B joins Sentinel-3A in the Earth observation mission: oceanography and land-vegetation monitoring, as part of the European GMES programme.

By the looks the data should be second to none. Great stuff – makes me smile.

About the image from ESA: The Copernicus Sentinel-3B satellite captured its first image on 7 May 2018 at 10:33 GMT (12:33 CEST), less than two weeks after it was launched. The image shows the sunset over the Weddell Sea off the coast of Antarctica. While the line between day and night is clearly visible, bright streaks glint on the clouds from the sunset. The image was taken by the satellite’s ocean and land colour instrument, which features 21 distinct bands, a resolution of 300 m and a swath width of 1270 km. The instrument can be used to monitor aquatic biological productivity and marine pollution, and over land it can be used to monitor the health of vegetation. Sentinel-3B’s instrument package also includes a sea and land surface temperature radiometer, a synthetic aperture radar altimeter and a microwave radiometer. Sentinel-3B was launched from Russia on 25 April and joins its twin, Sentinel-3A, in orbit. The pairing of the two satellites optimises coverage and data delivery for Europe’s Copernicus environmental monitoring programme.

The include image contains modified Copernicus Sentinel data (2018), processed by EUMETSAT, CC BY-SA 3.0 IGO