The idea of using low-earth-orbit satellites to provide greater GPS/GNSS accuracy isn’t limited to commandeering the Starlink constellation. The European Space Agency is exploring the idea of using low-flying satellites to increase Galileo’s accuracy and robustness: make it possible to use indoors, make it more resistant to jamming and interference, and enable positioning at the centimetre level. They’re planning an in-orbit demonstration of around six satellites to test the proposition. The satellites would supplement the existing Galileo constellation rather than replace it: for one thing, they would rely on the Galileo satellites’ atomic clocks, which would allow the low-flying satellites to be an order of magnitude smaller in size. [Universe Today]
Tag: ESA
The Mediterranean’s Summer Heat Wave
Europe’s summer heat wave wasn’t just felt on land; the Mediterranean Sea saw surface temperatures as much as 5°C above the average. The ESA’s animated map, above, shows the difference between sea surface temperatures from March to August 2022 and the 1985-2005 average for those months. The redder, the hotter than average. [ESA]
Spacecraft Will Test Satnav Reception from Lunar Orbit
More on the astonishing idea that Earth-orbiting GNSS satellites can be used for navigation at the Moon. The European Space Agency reports that among the instruments carried by the upcoming Lunar Pathfinder commercial mission will be a 1.4 kg satnav receiver that will test its ability to receive GPS and Galileo signals from lunar orbit. “Satnav position fixes from the receiver will be compared with conventional radio ranging carried out using Lunar Pathfinder’s X-band transmitter as well as laser ranging performed using a retroreflector contributed by NASA and developed by the KBR company.” Lunar Pathfinder is currently scheduled to launch in 2024.
Previously: Many Moon Maps; Can GPS Be Used on the Moon?
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.
Monitoring the Arctic Heat Wave
The European Space Agency has a post about monitoring the Arctic heat wave (mainly, it seems, through the Copernicus program). It’s illustrated by a few startling images from this summer: of Siberia’s wildfires, the record-low levels of Arctic sea ice, and (above) a map showing the land surface temperatures on Ellesmere Island, Nunavut on 11 August, when Eureka, Nunavut—80° N—had a record high of 21.9°C (71.4°F).
Online Map Tracks Nitrogen Dioxide Concentrations
A new online map tracks tropospheric global nitrogen dioxide concentrations—which we’ve seen drop sharply this year as the pandemic shut down economic activity. “This online platform uses data from the Copernicus Sentinel-5P satellite and shows the averaged nitrogen dioxide concentrations across the globe—using a 14-day moving average. Concentrations of short-lived pollutants, such as nitrogen dioxide, are indicators of changes in economic slowdowns and are comparable to changes in emissions. Using a 14 day average eliminates some effects which are caused by short term weather changes and cloud cover. The average gives an overview over the whole time period and therefore reflects trends better than shorter time periods.” [ESA]
Previously: Mapping the Lockdown-Related Drop in Emissions; Emissions Drop Due to Coronavirus Outbreak.
Mapping the Lockdown-Related Drop in Emissions
The European Space Agency maps the drop in nitrogen dioxide concentrations in the atmosphere in the wake of coronavirus lockdowns in many countries (see above). [GIS Lounge]
Meanwhile, CESBIO researcher Simon Gascoin built a map that compares NO2 concentrations over the last 30 days with the same period in 2019.
Data for these analyses generally come from the Copernicus Programme’s Sentinel-5P satellite. The Copernicus Atmosphere Monitoring Service issued a warning last week about using the data improperly.
Concentrations of NO2 in the atmosphere are highly variable in space and time: they typically vary by one order of magnitude within each day and quite substantially from one day to another because of the variations in emissions (for example the impacts of commuter traffic, weekdays and weekend days) as well as changes in the weather conditions. This is why, even if observations are available on a daily (currently available from satellites) or even hourly (ground-based observations) basis, it is necessary to acquire data for a substantial period of time in order to check that a statistically robust departure from normal conditions has emerged.
Cloud cover is a factor that needs to be taken into account as well.
Previously: Emissions Drop Due to Coronavirus Outbreak.
Emissions Drop Due to Coronavirus Outbreak
As you may have seen elsewhere, the coronavirus pandemic is having an impact on air pollution, as countries shut down human and economic activity in an attempt to deal with the outbreak. Take nitrogen dioxide. Tropospheric NO2 density decreased significantly over China between January and February, and the same seems to be happening in northern Italy, which normally has some of the most severe air pollution in Europe. See the ESA’s animation:
More broadly, try this online map, which compares NO2 emissions before and after 20 February 2020 anywhere on the planet. [Maps Mania]
Previously: Mapping Nitrogen Dioxide Pollution.
Europe’s Heat Wave, as Seen from Orbit
Europe is in the middle of a severe heat wave. The European Space Agency has released a map of land temperatures in Europe as of 26 June, produced from the Copernicus Sentinel-3 satellite’s temperature radiometer, “which measures energy radiating from Earth’s surface in nine spectral bands—the map therefore represents temperature of the land surface, not air temperature which is normally used in forecasts. The white areas in the image are where cloud obscured readings of land temperature and the light blue patches are either low temperatures at the top of cloud or snow-covered areas.”
Satellite Imagery of Scottish and Swedish Wildfires
BBC News looks at how satellite imagery from the European Space Agency’s Copernicus program is being used to help fight wildfires in the Scottish highlands.
Meanwhile, the Copernicus program captured images of wildfires in Sweden last month.
Mapping Arctic Sea Ice
Something’s going on in the Arctic. As the Washington Post reported last month, the Arctic Ocean was far, far warmer than normal—about 20 degrees Celsius higher than average. (Meanwhile, the air over Sibera is at record cold levels.) According to the Post, the higher temperatures are the result of record low amounts of thinning sea ice, as well as warm air being brought north by an increasingly errant jet stream.
https://youtu.be/6ZAuRpK4tkc
NASA has been tracking sea ice levels and thickness by looking at the age of the ice in the sea ice cap. The video above shows “how Arctic sea ice has been growing and shrinking, spinning, melting in place, and drifting out of the Arctic for the past three decades. The age of the ice is represented in shades of blue-gray to white, with the brightest whites representing the oldest ice.”
The ESA reports that their CryoSat satellite “has found that the Arctic has one of the lowest volumes of sea ice of any November, matching record lows in 2011 and 2012.” The animated GIF below shows the change in November sea ice from 2011 to 2016, as observed by CryoSat.
Gaia’s First Sky Map
Yesterday the European Space Agency released a sky map based on the first 14 months of data collected by the Gaia spacecraft, an astrometric observatory whose mission is to create a precise catalogue of astronomical objects’ position and relative motion. Several versions are available: annotated, unannotated, annotated with titles (above), unannotated with titles. The maps contain artifacts (curves and stripes) from Gaia’s scanning procedures, but they’ll improve as more data is added over the course of Gaia’s five-year mission.
Ireland Mosaic
The European Space Agency has released this false-colour composite image of Ireland based on 16 radar scans by the Sentinel-1A satellite in May 2015. The colours show change over the 12 days of coverage: “The blues across the entire image represent strong changes in bodies of water or agricultural activities such as ploughing. […] Vegetated fields and forests appear in green. The reds and oranges represent unchanging features such as bare soil or possibly rocks that border the forests, as is clear on the left side of the image, along the tips of the island.” [ESA]
Map of Northern Biomass
The European Space Agency has released a map showing the northern hemisphere’s biomass — specifically, its growing stock volume (GSV), which is the amount of wood per hectare in cubic metres. The map is based on radar images taken by the now-defunct Envisat satellite between October 2009 and February 2011.
Previously: Herbal Earth.