Author Topic: Earth from space: image of the week  (Read 244220 times)

Offline jacqmans

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Re: Earth from space: image of the week
« Reply #520 on: 05/13/2022 10:04 am »
Arc de Triomphe, Paris
13/05/2022

This striking, high-resolution image of the Arc de Triomphe, in Paris, was captured by Planet SkySat – a fleet of satellites that have just joined ESA’s Third Party Mission Programme in April 2022.

The Arc de Triomphe, or in full Arc de Triomphe de l’Étoile, is an iconic symbol of France and one of the world’s best-known commemorative monuments. The triumphal arch was commissioned by Napoleon I in 1806 to celebrate the military achievements of the French armies. Construction of the arch began the following year, on 15 August (Napoleon’s birthday).

The arch stands at the centre of the Place Charles de Gaulle, the meeting point of 12 grand avenues which form a star (or étoile), which is why it is also referred to as the Arch of Triumph of the Star. The arch is 50 m high and 45 m wide.

The names of all French victories and generals are inscribed on the arch’s inner and outer surfaces, while the Tomb of the Unknown Soldier from World War I lies beneath its vault. The tomb’s flame is rekindled every evening as a symbol of the enduring nature of the commemoration and respect shown to those who have fallen in the name of France.

The Arc de Triomphe’s location at the Place Charles de Gaulle places it at the heart of the capital and the western terminus of the Avenue des Champs-Élysées (visible in the bottom-right of the image). Often referred to as the ‘most beautiful avenue in the world’, the Champs-Élysées is known for its theatres, cafés and luxury shops, as the finish of the Tour de France cycling race, as well as for its annual Bastille Day military parade.

This image, captured on 9 April 2022, was provided by Planet SkySat – a fleet of 21 very high-resolution satellites capable of collecting images multiple times during the day. SkySat’s satellite imagery, with 50 cm spatial resolution, is high enough to focus on areas of great interest, identifying objects such as vehicles and shipping containers.

SkySat data, along with PlanetScope (both owned and operated by Planet Labs), serve numerous commercial and governmental applications. These data are now available through ESA’s Third Party Mission programme – enabling researchers, scientists and companies from around the world the ability to access Planet’s high-frequency, high-resolution satellite data for non-commercial use.

Within this programme, Planet joins more than 50 other missions to add near-daily PlanetScope imagery, 50 cm SkySat imagery, and RapidEye archive data to this global network.

Peggy Fischer, Mission Manager for ESA’s Third Party Missions, commented, “We are very pleased to welcome PlanetScope and SkySat to ESA’s Third Party Missions portfolio and to begin the distribution of the Planet data through the ESA Earthnet Programme.

“The high-resolution and high-frequency imagery from these satellite constellations will provide an invaluable resource for the European R&D and applications community, greatly benefiting research and business opportunities across a wide range of sectors.”

Offline jacqmans

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Re: Earth from space: image of the week
« Reply #521 on: 06/17/2022 12:18 pm »
Glacier Bay, Alaska
17/06/2022

Part of the Glacier Bay National Park and Preserve, which lies along the coast of southeast Alaska, is featured in this image captured by the Copernicus Sentinel-2 mission.

Covering over 13 000 sq km of rugged, snow-capped mountains, freshwater lakes, glaciers and deep fjords, Glacier Bay National Park and Preserve is one of the highlights of Alaska’s Inside Passage. As marine waters make up almost one-fifth of the park, Glacier Bay is rich with marine life, including humpback whales, orcas and sea otters. It’s also home to a large population of bears, moose, wolves and mountain goats.

The bay contains some of the world’s most impressive glaciers that descend from the ice-covered St. Elias Range in the east and the Fairweather Range in the west, with a few notable tidewater glaciers extending all the way to the sea.

John Hopkins Glacier, visible in the far left of the image, is the largest tidewater glacier in the region. Muir Glacier, formerly the most famous of the tidewater glaciers, once rose around 80 m above water and was nearly 3 km wide but has now shrunk and receded and no longer reaches the sea.

Glacier Bay is just one of the many areas suffering from the effects of global warming. The bay is expected to become warmer and drier over the next century, with widespread effects including the further shrinking glaciers, reduced sea ice and shoreline erosion.

Monitoring glaciers is often a challenge considering their sheer size, remoteness and rugged terrain they occupy. Satellites, including ESA’s CryoSat mission, with its elite spaceborne sensor – the radar altimeter – allows for the mapping of glaciers in fine detail. In a study published last year in the Cryosphere, scientists utilised data from the CryoSat mission to show how much ice had been lost from mountain glaciers in the Gulf of Alaska.

Today marks the opening of the ‘Earth’s Memory - glaciers witnesses to the climate crisis’ exhibition, that follows the scientific and photographic journey of glaciers around the world, premiering the results of the ‘On the trail of the glaciers’ project directed by Italian photographer Fabiano Ventura. The exhibition, which is being held in the Forte di Bard Museum, Aosta Valley, Italy, offers its visitors the opportunity to witness the effects of global warming through the power of both photography and ESA satellite imagery.

The exhibition focuses on the world’s largest mountain glaciers with 90 photographic comparisons displayed alongside scientific data collected during the team’s expedition to the world’s largest mountain glaciers. It runs until 18 November 2022 and includes images such as the one featured on this week’s Earth from Space programme. More information on the exhibition, which is part of a scientific collaboration between ESA and is sponsored by UNESCO, can be found here.

Offline jacqmans

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Re: Earth from space: image of the week
« Reply #522 on: 06/24/2022 11:29 am »
Lake Balkhash, Kazakhastan
24/06/2022

Lake Balkhash, the largest lake in Central Asia, is featured in this false-colour image captured by the Copernicus Sentinel-2 mission.

The lake, which is situated in east-central Kazakhastan, is around 605 km in length from east to west, with a maximum depth of around 25 m. The lake’s size varies depending on water balance, with its area fluctuating from around 15 000 sq km to 19 000 sq km.

Jutting out into the lake is the Sarymsek Peninsula which divides Balkhash into two separate hydraulic parts. The west part is wide and shallow with its water on this side particularly fresh and suitable for drinking. The east part, on the other hand, is narrow and relatively deep, with its waters on this side of the basin brackish and salty. The two parts of the lake are united by a narrow strait, the Uzynaral visible in the centre of the image, with a depth of around 6 m.

The sediment plume passing through the Uzynaral Strait is most likely due to waves stirring up sediments from the bottom of the lake. This has led to a higher reflection and thus a brighter water colour in this part of the lake.

The north banks of Lake Balkhash are high and rocky while the south banks are low and sandy, with wide belts covered with thickets of reeds and numerous small lakes. These low-lying banks are periodically flooded by the waters of the lake.

A high presence of sea ice can be seen in bright blue-greenish colours especially near the southern shoreline. This colour is due to ice having a higher reflectance in the visible parts of the spectrum than in the near-infrared. Balkhash usually remains frozen from the end of November to the beginning of April, with this image captured on 29 November 2021.

South of Balkhash lies the Saryesik-Atyrau Desert, which stretches for around 400 km in east Kazakhastan. There are a great number of small lakes, ponds and wetlands in the desert (visible in brown), as well as occasional grasslands, that support a varied animal and bird population.

Sentinel-2 is a two-satellite mission to supply the coverage and data delivery needed for Europe’s Copernicus programme. The mission’s frequent revisits over the same area and high spatial resolution allow changes in water bodies to be closely monitored.

Offline jacqmans

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Re: Earth from space: image of the week
« Reply #523 on: 07/01/2022 08:24 am »
Patagonia
01/07/2022

The Copernicus Sentinel-3 mission captured this impressive, wide-angled view of Patagonia at the southern end of South America, as well as the Falkland Islands.

Covering an area of around 673 000 sq km, Patagonia is split by Argentina and Chile. The region comprises the southern section of the Andes Mountains, with lakes, fjords, rainforests and glaciers in the west and deserts and tablelands to the east.

The island archipelago of Tierra del Fuego, located at the southern tip of Patagonia (the southernmost tip of the image), is shared by Argentina and Chile, with the eastern part of the main island belonging to Argentina and the southern point of the archipelago, which forms Cape Horn, belonging to Chile. The Strait of Magellan, named after the discoverer, lies between Tierra del Fuego and mainland Argentina.

Part of the Alberto de Agostini National Park can be seen in the bottom of the image. The park features a highly irregular coastline, which is deeply indented by fjords. Deemed a designated UNESCO Biosphere Reserve, the park has several tidewater glaciers and comprises the Gordon, Cook and Londonderry islands.

The Falkland Islands can be seen in the far-right of the image. The islands lie in the South Atlantic Ocean, around 600 km east of Patagonia. The Falklands comprise two main islands, West Falkland and East Falkland, which are separated by the Falkland Sound – a channel that averages around 20 km in width.

The swirling green and blue coloured areas are densely concentrated phytoplankton blooms. These microscopic organisms thrive in the cool, nutrient-rich waters between the coast of southern Argentina and the Falkland Islands. Nutrients carried by rivers promote phytoplankton growth, which may explain the plankton hugging the South American coastline in the image, as well as dust carried from Patagonia offshore which is then diffused on the ocean surface by strong westerly winds.

In spring and summer, populations of algae in the South Atlantic often explode into enormous blooms – which float with the meandering ocean currents. Carrying a suite of cutting-edge instruments, Copernicus Sentinel-3 measures systematically Earth’s oceans, land, ice and atmosphere to monitor and understand large-scale global dynamics.

Sentinel-3 measures the temperature, colour and height of the sea surface as well as the thickness of sea ice, while over land maps land, provides indices of vegetation state and measures the height of rivers and lakes.

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Re: Earth from space: image of the week
« Reply #524 on: 07/08/2022 09:42 am »
Fuerteventura and Lanzarote
08/07/2022

Fuerteventura and Lanzarote, part of the Canary Islands lying in the North Atlantic Ocean, are featured in this false-colour image captured by the Copernicus Sentinel-2 mission.

The Canary Islands are a group of ocean island volcanoes that were formed by volcanic activity millions of years ago. The Spanish region and archipelago is located around 100 km off the north coast of Africa and 1000 km from the Iberian Peninsula. The eight main islands are (in order of largest to smallest in area) Tenerife, Fuerteventura, Gran Canaria, Lanzarote, La Palma, La Gomera, El Hierro and La Graciosa. The archipelago also includes many smaller islands and islets.

Lanzarote, the easternmost of the Canary Islands, is visible in the top-right of the image. With over 150 000 inhabitants, it is the third most populous Canary Island, after Tenerife and Gran Canaria. It covers an area of 845 sq km, making it the fourth-largest of the islands in the archipelago.

Lanzarote has a long history of eruptions and is often referred to as the ‘Island of the 1000 volcanoes’, yet it is actually the least mountainous Canarian Island. The highest mountain is the volcano Peñas del Chache near Haría in the northern part of the island, which is 670 m above sea level. The Timanfaya National Park can be seen in the southwest part of the island and is entirely made up of volcanic soil.

Fuerteventura Island, the second largest of the Canaries, lies southwest of Lanzarote, across the Bocaina Strait. Its total area is 1731 sq km and the island is around 110 km long and no more than 30 km wide. Fuerteventura is the oldest island in the Canary Archipelago, having risen between 12 and 20 million years ago owing largely to volcanic activity.

The island is fairly flat and has a desert landscape of sand and stones as well as long beaches. The centre of the island is made up of a wide, elongated valley and, from north to south, is dissected by a series of extinct, eroded volcanoes. The west coast is dotted with rugged cliffs and small bays.

To the northeast of Fuerteventura, separated by the 15 m deep strait El Río, lies the island of Isla de Lobos. The only six sq km island is home to a 127 m high extinct volcano.

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Re: Earth from space: image of the week
« Reply #525 on: 08/17/2022 01:53 pm »
Rhine river runs dry
17/08/2022

Water levels on the Rhine River, Europe’s second-largest river, have continued to drop owing to soaring temperatures and lack of rainfall, preventing many vessels from navigating through the waters at full capacity. The Copernicus Sentinel-2 mission captured part of the Rhine River near Cologne – showing the stark difference between August 2021 and August 2022.

Flowing from the Swiss Alps to the North Sea, the Rhine River is an important shipping route for many products from grains to chemicals to coal. When water levels drop, cargo vessels need to sail with reduced load, so they don’t run aground.

Water levels at the chokepoint of Kaub, near Frankfurt, fell to 32 cm in depth on Monday, down from 42 cm last week. Ships, however, need around 1.5 m to be able to sail fully loaded making it difficult for larger ships to navigate through the waters. Freight ships continue to sail, but only with around 25% to 35% of the ship’s capacity.

The low water levels are emerging earlier than usual, with the lowest water levels typically recorded in September or October. However, reduced temperatures and predicted rainfall forecasted for this week may offer relief to the Rhine.

The phenomenon facing the Rhine is common across much of Europe after an unusually hot and dry summer – causing wildfires and water shortages.

The Copernicus Sentinel-2 satellites capture high-resolution imagery that provide information about the conditions on Earth, such as plant life, soil and coastal areas. The mission consists of two satellites both of which carry an innovative multispectral imager – a camera that captures optical images over a range of wavelengths beyond visible light.

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Re: Earth from space: image of the week
« Reply #526 on: 09/16/2022 11:36 am »
UK heatwave
16/09/2022

This summer, heatwaves struck Europe, North Africa, the US and Asia with temperatures reaching over 40°C in places – breaking many long-standing records. Images from the Copernicus Sentinel-3 mission show the scale of Britain’s heatwave as it baked in extreme temperatures in August.

The image, captured on 12 August 2022, shows the United Kingdom’s previously green land appear brown (particularly in the southeast) amid the scorching conditions. The heatwave comes after months of extreme temperatures and low rainfall left the landscape parched. The dry conditions are also visible in parts of France, Belgium and the Netherlands.

The severe heatwaves experienced across Europe this summer are a harsh reminder of what is in store for our future.  Extreme weather events will happen more frequently and intensely according to the Intergovernmental Panel on Climate Change (IPCC). This trend is set to worsen unless the rise in atmospheric greenhouse gas emissions caused by human activities is addressed.

Satellites orbiting our planet play an important role in delivering data to understand and monitor how our world is changing. Their observations and data are critical for improving model predictions of our future climate, mitigation strategies and policymaking.

The Copernicus Sentinel-3 mission not only provides two-day global coverage optical data, but it also carries a Sea and Land Surface Temperature Radiometer instrument that measures Earth’s land surface temperature (how hot the actual surface would feel to touch). During August 2022, the Sentinel-3 mission recorded extreme land surface temperatures of more than 45°C in the United Kingdom, 50°C in France and 60°C in Spain.

Sentinel-3 data has also been merged with archived satellite observations to form a recently released 25-year record of global land surface temperatures (from 1995 to 2020) developed by ESA’s Climate Change Initiative along with Europe’s leading climate scientists. This data record shows a stable increase in global land surface temperature of 0.2°C per decade, with strong regional variability.

Monitoring land-surface temperatures is useful for scientists because the warmth rising from Earth’s surface influences weather and climate patterns. These measurements are particularly important for farmers evaluating how much water their crops need and for urban planners looking to improve heat-mitigating strategies.

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Re: Earth from space: image of the week
« Reply #527 on: 09/23/2022 09:22 am »
Lake Trasimeno, Italy
23/09/2022

Lake Trasimeno, the fourth largest lake in Italy

Lake Trasimeno is located in central Italy, around 20 km west of Perugia, and has an area of around 128 sq km. It is shallow, with its maximum depth of approximately 6 m, although the lake’s water level varies depending on meteorological and climatic conditions.

In this Copernicus Sentinel-2 image, captured on 6 August 2022, the lake’s emerald green colour is likely due to the presence of phytoplankton. Streaks in the water, particularly visible in the west, indicate the presence of soil and sediments which have been stirred up by winds. Dark coloured waters in the southern part of the lake indicate a presence of submerged and floating macrophytes (aquatic plants) as well as algae.

Surrounded by hills on three sides, Trasimeno is subject to heavy storms created by winds, especially from the north and west. There are three islets in the lake: Maggiore, Minore and Polvese (the largest). The lake’s shores are sparsely inhabited with only two popular villages: Castiglione del Lago and Passignano sul Trasimeno.

Italy is experiencing its worst drought in 70 years which has affected drinking water supplies, hydroelectric power and agricultural production. High temperatures, hot winds and lack of rainfall are the main causes of drought in the Umbrian region which saw Lake Trasimeno’s drop 1.3 m, reaching the limit of the hydrometric zero in July 2022.

Lake Trasimeno wasn’t the only Italian water body affected by drought this summer, with the Po River hitting record-lows. The Copernicus Sentinel-2 satellites capture high-resolution imagery that provides information about the conditions on Earth, such as water quality, plant life and coastal areas.

The mountainous terrain of the Umbrian Apennine Mountains surrounds Lake Trasimeno with many agricultural fields dotted around the area. Several other smaller lakes including Lake Montepulciano, Lake Chiusi and Lake Pietrafitta, can be seen south of Lake Trasimeno. Perugia, capital of the Umbria region, is a well-known cultural and artistic centre in Italy known for its chocolate and jazz festivals.

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Re: Earth from space: image of the week
« Reply #528 on: 09/30/2022 08:42 am »
Melt ponds in West Greenland
30/09/2022

During spring and summer, as the air warms up and the sun beats down on the Greenland Ice Sheet, melt ponds pop up. Melt ponds are vast pools of open water that form on both sea ice and ice sheets and are visible as turquoise-blue pools of water in this Copernicus Sentinel-2 image.

When snow and ice melts atop glaciers, water flows in channels and streams and collects in depressions on the surface. These melt ponds can speed up the melting of the surrounding ice since they greatly reduce the ice’s ability to reflect sunlight. This can create a positive feedback where an increasing number of melt ponds absorb more heat which causes ice cover to melt even faster. In this image, captured on 29 August 2022, melt ponds in the province of Avannaata can be easily spotted from space as they are usually much darker than the surrounding ice. In some ponds, chunks of ice float atop the pond’s waters.

The bay visible here is Sugar Loaf Bay (an indentation of the northeast Baffin Bay) in the Upernavik Archipelago. The archipelago extends from the northwest coast of Sigguup Nunaa peninsula to the southern end of Melville Bay.

The Greenland Ice Sheet is the largest ice mass in the northern hemisphere. It extends 2220 km north-south with an average thickness of around 1500 m and spans 1100 km at its widest point.

As most of the northern hemisphere baked under a prolonged heatwave this summer, Greenland has been hit with an unusual late-season heatwave and melt event in early September – the kind of melt that usually occurs in the middle of summer.

The first day of September typically marks the end of the Greenland melt season, as the sun moves lower in the sky with temperatures usually cooling. However, at the beginning of September 2022, temperatures began to rise again when a strong air pressure region parked at the southeast edge of Greenland and drew warmer air northwards across Baffin Bay and the west coast of Greenland.

This led to meltwater runoff, the amount of surface water entering the ocean, to increase with its extensive melting contributing to global sea level rise – which impacts the millions of people living in coastal communities.

In a recent paper published in Nature Climate Change, scientists found that major sea-level rise from the melting of the Greenland ice cap is now ‘inevitable’ even if the burning of fossil fuels were to halt overnight. Using satellite observations of Greenland ice loss and ice cap from 2000 to 2019, the team found the losses will lead to a minimum rise of 27 cm regardless of climate change.

Earth observation satellites are key to monitoring ice as they carry instruments that measure changes in the thickness of the ice sheets, fluctuations in the speed of the outlet glaciers and even small changes in Earth’s gravity field caused by melting ice as well as sea-level rise.

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