This NASA Earth Observatory video looks at the retreat of Alaska’s Columbia Glacier since 1986. Transcript here.
Tag: remote sensing
How Satellites Revealed the Hunga-Tonga Hunga-Ha’apai Eruption
The BBC’s Jonathan Amos looks at the ways satellites have collected imagery and data on the Hunga-Tonga Hunga-Ha’apai1 volcanic eruption.
First Images from Landsat 9 Released
The latest of the Landsat satellites, Landsat 9, launched on September 27. Similar to Landsat 8 with slight equipment upgrades, it will replace Landsat 7 when it is fully operational next year. Right now it’s going through its 100-day check-out, after which NASA will hand it over to the USGS. As part of that check-out, its first images were recently released. [NASA Earth Observatory]
The Mother of Landsat
Virginia Tower Northwood is sometimes called “the mother of Landsat” for her invention of the multispectral scanner that was launched aboard Landsat 1. An alumna of MIT, she is the subject of this long profile by Alice Dragoon in the MIT Technology Review, which looks her entire career, which prior to Landsat involved radar and antenna design—including, notably, the transmitter on the Surveyor 1 lunar lander. See also this profile on NASA’s Landsat Science page.
Climate from Space
The European Space Agency’s new Climate from Space website presents satellite data on a host of different climate indicators, from aerosols to CO2, from land cover to sea ice, via 3D virtual globes. From the announcement:
The new, easy-to-use site provides access to the same satellite observations used by scientists to understand climate change and support international organisations such as the United Nations Framework Convention on Climate Change (UNFCCC) and Intergovernmental Panel on Climate Change (IPCC) to drive action.
There is a suite of 21 climate data records to explore, which are generated by ESA’s Climate Change Initiative. The suite includes sea level, sea surface temperature, soil moisture, snow depth and the greenhouse gases, carbon dioxide and methane, as well as new visualisations for the latest climate variables records such as permafrost and lakes.
Satellite Image Guide for Journalists and Media
Pierre Markuse’s Satellite Image Guide for Journalists and Media:
So you would like to use a satellite image in your article and you would like to explain it to your viewers? Here is a short guide covering some of the most frequently asked questions and giving some general explanations on satellite images. It by no means covers all aspects, as there are far too many types of satellite images, but should give you a good start to find out more on your own and maybe motivate you to create your own images, which has become quite easy and quick even with no prior knowledge of it.
Complete with examples of imagery, examples of how to use it properly, and links to resources.
The Changing Padma River
Landsat observations have charted the erosion of the banks of the ever-changing Padma River, a major distributary of the Ganges in Bangladesh. This is vividly shown in this animation produced by NASA Earth Observatory, which “shows 14 false-color images of the Padma river between 1988 and 2018 taken by the Landsat 5 and 8 satellites. All of the images include a combination of shortwave infrared, near infrared, and visible light to highlight differences between land and water.” More on the erosion of the Padma River here.
Mapping Global Fresh Water Availability
NASA Earth Observatory: “The map above depicts changes in water storage on Earth—on the surface, underground, and locked in ice and snow—between 2002 and 2016. Shades of green represent areas where freshwater levels have increased, while browns depict areas where they have been depleted. Data were collected by the GRACE mission, which precisely measured the distance between twin spacecraft as they responded to changes in Earth’s gravity field. In sensing the subtle movements of mass around the planet, the satellites could decipher monthly variations in terrestrial water storage.” The GRACE observations form the basis of a study published this month in Nature on changes in global fresh water availability. More at the JPL’s GRACE-FO project page. [Benjamin Hennig]
Hurricanes and Aerosols
NASA’s Goddard Space Flight Center produced this visualization, based on computer modelling and data from Earth observing satellites, tracking how hurricanes transport sea salt, dust, and smoke across the globe.
During the 2017 hurricane season, the storms are visible because of the sea salt that is captured by the storms. Strong winds at the surface lift the sea salt into the atmosphere and the particles are incorporated into the storm. Hurricane Irma is the first big storm that spawns off the coast of Africa. As the storm spins up, the Saharan dust is absorbed in cloud droplets and washed out of the storm as rain. This process happens with most of the storms, except for Hurricane Ophelia. Forming more northward than most storms, Ophelia traveled to the east picking up dust from the Sahara and smoke from large fires in Portugal. Retaining its tropical storm state farther northward than any system in the Atlantic, Ophelia carried the smoke and dust into Ireland and the UK.
Video at the link, or here’s the YouTube version. [APOD/Kottke]
20 Years of Observing Our Living Planet
NASA: “Satellites measured land and ocean life from space as early as the 1970s. But it wasn’t until the launch of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) in 1997 that the space agency began what is now a continuous, global view of both land and ocean life. A new animation captures the entirety of this 20-year record, made possible by multiple satellites, compressing a decades-long view of life on Earth into a captivating few minutes.” Here’s a video about it:
Animations available for download here. Guardian coverage. [Benjamin Hennig]
Mapping Glacial Retreat
Using elevation data from stereo satellite observations, David Shean is mapping the retreat of some 1,200 mountain glaciers in the continental United States. “Until recently, glaciers in the United States have been measured in two ways: placing stakes in the snow, as federal scientists have done each year since 1957 at South Cascade Glacier in Washington state; or tracking glacier area using photographs from airplanes and satellites.” Shean’s method, which measures each glacier twice a year and uses automated software to track changes, seems to cover a lot more territory. [GIS and Science]
Mapping the Thaw
Scientists have been tracking seasonal freeze-thaw patterns for 30 years. This map, produced from data collected by NASA’s Soil Moisture Active Passive satellite, “shows the freeze-thaw status of areas north of 45 degrees latitude on March 5, 2015, as spring approached. Frozen land is blue; thawed land is pink. The measurement is possible because frozen water forms crystalline structures that can be detected by satellites.” NASA Earth Observatory.
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