Category Archives: Earth Observatories

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”.

NASA:

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

Kilauea Eruption From NASA Satellite

The Kilauea volcano is getting plenty of news coverage and rightfully so.  Check out this link from KHON2 News featuring the 17th fissure to open.

The image above and the caption below is from NASA’s Multi-angle Imaging SpectroRadiometer (MISR) instrument.

Despite all of the science knowledge and the benefits potentially being derived from this eruption, I feel for the impacted residents. Be safe or e palekana (tranlation by Google Translate)

NASA: On May 3, 2018, a new eruption began at a fissure of the Kilauea volcano on the Island of Hawaii. Kilauea is the most active volcano in the world, having erupted almost continuously since 1983. Advancing lava and dangerous sulfur dioxide gas have forced thousands of residents in the neighborhood of Leilani Estates to evacuate. A number of homes have been destroyed, and no one can say how soon the eruption will abate and evacuees can return home.

On May 6, 2018, at approximately 11 a.m. local time, the Multi-angle Imaging SpectroRadiometer (MISR) instrument on NASA’s Terra satellite captured this view of the island as it passed overhead. Much of the island was shrouded by clouds, including the fissure on its eastern point. However, an eruption plume is visible streaming southwest over the ocean. The MISR instrument is unique in that it has nine cameras that view Earth at different angles: one pointing downward, four at various angles in the forward direction, and four in the backward direction. This image shows the view from one of MISR’s forward-pointing cameras (60 degrees), which shows the plume more distinctly than the near-vertical views.

The information from the images acquired at different view angles is used to calculate the height of the plume, results of which are superimposed on the right-hand image. The top of the plume near the fissure is at approximately 6,500 feet (2,000 meters) altitude, and the height of the plume decreases as it travels south and west. These relatively low altitudes mean that the ash and sulfur dioxide remained near the ground, which can cause health issues for people on the island downwind of the eruption. The “Ocean View” air quality monitor operated by the Clean Air Branch of the State of Hawaii Department of Health recorded a concentration of 18 μg/m3 of airborne particles less than 2.5 micrometers in diameter at 11 a.m. local time. This amount corresponds to an air quality rating of “moderate” and supports the MISR results indicating that ash was most likely present at ground level on this side of the island.

These data were acquired during Terra orbit 97780. The smoke plume height calculation was performed using the MISR INteractive eXplorer (MINX) software tool, which is publicly available at https://github.com/nasa/MINX. The MISR Plume Height Project maintains a database of global smoke plume heights, accessible at https://www-misr.jpl.nasa.gov/getData/accessData/MisrMinxPlumes2/.

Proba’s Looks at Pyramids

This beautiful look at the Egyptian pyramids is courtesy of the Proba-1 satellite and ESA.

ESA — A view looking north to south of Egypt’s famous Giza Pyramid Complex, as seen by ESA’s Proba-1 minisatellite.

The smaller Pyramid of Menkaure is seen to towards the centre of the image, with the larger Pyramid of Khafre down and left of it, with the Great Pyramid of Giza – the largest and oldest of the three – below and left of that.

Three smaller pyramids are adjacent to the Pyramid Menkaure. The Giza Plateau sits on the edge of Cairo, fringed by suburbs.

The cubic-metre Proba-1 is the first in ESA’s series of satellites aimed at flight-testing new space technologies. It was launched on 22 October 2001 but is still going strong, having recently became the Agency’s longest-serving Earth-observing mission.

Proba-1’s main hyperspectral CHRIS imager is supplemented by this experimental High-Resolution Camera, acquiring black and white 5 m-resolution images.

Other innovations include what were then novel gallium-arsenide solar cells, the use of startrackers for gyroless attitude control, one of the first lithium-ion batteries – now the longest such item operating in orbit – and one of ESA’s first ERC32 microprocessors to run Proba-1’s agile computer.

For more background on Proba-1, read this celebration in the ESA Bulletin.

Proba-1 led the way for the Sun-monitoring Proba-2 in 2009, the vegetation-tracking Proba-V in 2013 and the Proba-3 precise formation-flying mission planned for late 2020.

This image was acquired on 6 January 2018.

Sahara Snow

Great look at the Sahara snows. Turns out snow in the Sahara while rare, is not unheard of.

NASA — For the second time in three years, snow has accumulated in the desert near the northern Algerian town of Aïn Séfra. Sometimes called the “gateway to the desert,” the town of 35,000 people sits between the Sahara and the Atlas Mountains. On January 8, Landsat 8 captured data for these natural-color images of the snow in the Sahara. The Landsat 8 image was draped over a global digital elevation model, built from data acquired by NASA’s Shuttle Radar Topography Mission.

According to news and social media accounts, anywhere from 10 to 30 centimeters (4 to 12 inches) of snow accumulated on January 8, 2018, on some higher desert elevations (1000 meters or more above sea level). Social media photos showed citizens sliding down snow-covered sand dunes. Warming temperatures melted much of it within a day.

Snow in the Sahara and other parts of North Africa is infrequent, but not unprecedented. Measurable snow fell near Aïn Séfra in December 2016. Substantial snow also blanketed the Atlas Mountains in Morocco in February 2012 and January 2005.

Image Credits: NASA Earth Observatory image by Joshua Stevens, using Landsat data from the U.S. Geological Survey and topographic data from the Shuttle Radar Topography Mission