Illustrative: satellite orbits, their ground swaths or the lines of sight a receiver keeps

Risk Academy, led by the Nexus Consortium · Earth and Environmental Sciences · Department of Climate and Ocean Sciences

Satellites, observing networks, reanalyses and Earth system twins

Earth observation and Earth system data

Every risk layer on the stage started as an observation: a satellite overpass, a gauge, a buoy or a reanalysis that joins them with a model.

01Scope

What the discipline covers

The subtopics its courses and labs teach.

Courses
In preparation
Levels
In development
Labs
In development
  • Satellite missions and sensors (optical, radar, thermal, altimetry, gravimetry)
  • In situ observing networks
  • Reanalysis datasets such as ERA5
  • GCOS Essential Climate Variables
  • Earth system digital twins and Destination Earth
  • Geospatial foundation models and satellite embeddings
  • Analysis-ready data and cloud-native formats
  • Product validation and uncertainty
  • Copernicus and open data policies
02Maps

Build a twin of any place

Search any place or open the world; the layers and generators follow earth observation and Earth system data on the planet map, the globe and in 3D.

The Po at Casale Monferrato and the Vercelli rice plain: a flat plan of the faculty twin. Terrain 63 to 471 m; River 435 km; Canal 2,280 km; River discharge, GloFAS via Open-Meteo: read live when the 3D twin opens; Vegetation index, MODIS Terra NDVI 8-day: read live when the 3D twin opens; Soil moisture, SMAP L3 (daily): read live when the 3D twin opens; Precipitation rate, GPM IMERG (30 minutes): read live when the 3D twin opens; Surface water extent, OPERA DSWx (HLS): read live when the 3D twin opens; True colour at 30 m, HLS Sentinel-2 (daily granules): read live when the 3D twin opens. Contours every 50 metres from the elevation grid; rivers and named canals by class.
The Po at Casale Monferrato and the Vercelli rice plain, Italy. Flat plan of the same data: relief as contours from the inline grid, rivers and canals, and the numbers below. The 3D twin opens on devices that can draw it, once its data and code have been checked.
  • Terrain 63 to 471 m
  • River 435 km
  • Canal 2,280 km
  • River discharge, GloFAS via Open-Meteo: read live when the 3D twin opens
  • Vegetation index, MODIS Terra NDVI 8-day: read live when the 3D twin opens
  • Soil moisture, SMAP L3 (daily): read live when the 3D twin opens
  • Precipitation rate, GPM IMERG (30 minutes): read live when the 3D twin opens
  • Surface water extent, OPERA DSWx (HLS): read live when the 3D twin opens
  • True colour at 30 m, HLS Sentinel-2 (daily granules): read live when the 3D twin opens
Credits and dates per layer are listed under the stage. Relief in the twin is exaggerated ×1.5 for legibility.

Drag to move, right drag or Shift with a drag to turn and tilt, Ctrl with the wheel to zoom. Keyboard: arrows move, Shift with arrows turn and tilt, + and – zoom, 0 resets, V steps through the views, Escape clears.

Flat plan of the same data: relief as contours from the inline grid, rivers and canals, and the numbers below. The 3D twin opens on devices that can draw it, once its data and code have been checked.

The boundaries, names and designations shown do not imply any judgement on the legal status of any territory, or any endorsement or acceptance of such boundaries. Countries: Natural Earth (public domain).

03Live map

Earth observation in Italy

True-colour imagery, land cover, vegetation, snow and sea ice, over Italy.

The interactive map needs JavaScript; the layer list and sources are below.

Layers 1

Earth observation

Latest available

NASA GIBS / EOSDIS · ASTER GDEM (METI, NASA) · Blue Marble (NASA) · © OpenStreetMap contributors (ODbL) · Natural Earth

Loading the latest NASA imagery.

Drag to move. Ctrl or ⌘ and scroll, pinch or the buttons to zoom; hover for the values under the pointer; reset returns to the region.

Earth observation, framed on Italy.Satellite and model products as NASA publishes them, each with its own date. They are indicators, not assessments of any place.

Data: NASA GIBS · ASTER GDEM · Blue Marble · © OpenStreetMap contributors · Natural Earth · NASA EONETSources and licences

  • We acknowledge the use of imagery provided by services from NASA's Global Imagery Browse Services (GIBS), part of NASA's Earth Science Data and Information System (ESDIS). Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
  • We acknowledge the use of imagery provided by services from NASA's Global Imagery Browse Services (GIBS), part of NASA's Earth Science Data and Information System (ESDIS). Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
  • VIIRS near-real-time products (flood, land surface temperature, snow cover, corrected reflectance), NASA LANCE; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
  • MODIS land products (vegetation indices, gross primary production, land cover), NASA LP DAAC and LANCE; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
  • GHRSST Level 4 MUR analyses, NASA Jet Propulsion Laboratory; distributed by the NASA Physical Oceanography DAAC (PO.DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
  • ASTER GDEM is a product of METI and NASA (ASTER Global Digital Elevation Model V003, NASA LP DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). Cite as: NASA/METI/AIST/Japan Spacesystems and U.S./Japan ASTER Science Team (2019). ASTER Global Digital Elevation Model V003. doi:10.5067/ASTER/ASTGTM.003. NASA open data
  • Made with Natural Earth. Free vector and raster map data @ naturalearthdata.com. Public domain
  • © OpenStreetMap contributors (ODbL), via NASA GIBS (coastlines, boundaries, roads and place names). Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). ODbL
  • Blue Marble, NASA Earth Observatory; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
  • Context on the globe and flat map: coastlines, boundaries, roads and place names from NASA GIBS reference layers (OpenStreetMap data, ODbL, © OpenStreetMap contributors); Blue Marble imagery as an optional base; 3D terrain and the elevation read-out from the ASTER GDEM elevation colour index (5 m to 200 m classes, exaggerated for legibility). Boundaries are drawn as published and imply no position on any territory.
  • Globe: MapLibre GL JS 6.9.1, BSD-3-Clause, © MapLibre contributors.
  • Live events: NASA Earth Observatory Natural Event Tracker (EONET); events are indicative and keep their original source links.
  • Live: NASA EONET Events are indicative, not authority warnings.
  • NASA GIBS: We acknowledge the use of imagery provided by services from NASA's Global Imagery Browse Services (GIBS), part of NASA's Earth Science Data and Information System (ESDIS).
  • Past year, daily temperature and sunshine (NASA POWER): These data were obtained from the NASA Langley Research Center (LaRC) POWER Project funded through the NASA Earth Science/Applied Science Program..
  • Weather data by Open-Meteo.com (https://open-meteo.com/), licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/).
  • Optional layers (10 sources in the layer list: live, forecast, observed and context) print their provider credit on the map and here when switched on; forecasts are model output and derived indices are estimates.

Layers and dates

  • True colour: VIIRS NOAA-20 corrected reflectance, NASA LANCE · 13 Oct 2026
  • Land cover type (IGBP), yearly: MODIS Terra and Aqua land cover (MCD12Q1), NASA LP DAAC · 2024
  • Enhanced vegetation index, rolling 8 days: MODIS Terra EVI, NASA LANCE · 13 Oct 2026
  • Snow cover: VIIRS NOAA-20 NDSI, NASA LANCE · 13 Oct 2026
  • Sea ice concentration: GHRSST MUR, NASA JPL PO.DAAC · 12 Oct 2026

04The subject

The subject, methods and measures and debates and bodies

The field and its scope

For data scientists, GIS analysts, remote-sensing practitioners and risk modellers who need to choose an Earth observation product, read its resolution and error, and know when a reanalysis or a satellite field can be trusted.

05The method

From a pixel to an area with error bars: how revisit, cloud and accuracy decide what a change map can claim

Revisit interval and cloud cover set how many clear looks a sensor gets in a season; the classifier's user's and producer's accuracy set how far the mapped area of change is from the true area; a reference sample of stated size gives the adjusted area and its confidence interval, and only that interval supports a decision.

Sources: Olofsson et al., Good practices for estimating area and assessing accuracy of land change (2014); Drusch et al., Sentinel-2: ESA's optical high-resolution mission for GMES operational services (2012); Stehman, Estimating area and map accuracy for stratified random sampling when the strata are different from the map classes (2014); Gorelick et al., Google Earth Engine: planetary-scale geospatial analysis for everyone (2017); Dwyer et al., Analysis ready data: enabling analysis of the Landsat archive (2018).

06At a glance

At a glance, hub and courses

Earth observation and Earth system data at a glance

risksacademy.comearth-environmentdiscipline

Earth observation and Earth system data: 0 primary courses open, 0 in preparation and 0 also taught here, across 9 subtopics. Courses: none yet.
Earth observation and Earth system data at a glance
  • Open, 0
  • In preparation, 0
  • Subtopics, 9
Course codes from the curriculum; study levels L1 to L4.
Twin builderBuild a twin of any placeWorked example: the Po at Casale Monferrato and the Vercelli rice plain · 5 generators · 14 layers · 3 instruments
07Console

How Earth observation and Earth system data is taught, as a process you can run

Press Play to run this process from this page's own data.

08Practice

Practice, learning and connections

How technology helps and what risk it brings

09Take part

Take part in Earth and Environmental Sciences

Start from who you are.

10References

Core references and where to begin

Start with Bojinski, then Hersbach, then Olofsson.

11Questions

Questions, answers and key terms

Is study here free?
Yes. Every course and learning material of Risk Academy, led by the Nexus Consortium, is free to study, self-paced or with a cohort. Ordinary participation has no fee; paid work, internships and fellowships are separate arrangements.
What does completing a course give me?
A completion record: the course, its version, the date and what was assessed, private by default and shared by you. It stacks into discipline, department and programme achievements. A record states what was studied and assessed and does not certify competence; it is not a licence, a professional title or an employment status.
Where do the data and the places come from?
Every faculty teaches on a twin of a real place built from open data; each layer carries its provider, licence and date, and every result on the Academy states its source. Maps and figures are indicators for teaching, never an assessment of a place.
How do I take part beyond the courses in earth observation and Earth system data?
Form a competence cell of three to seven people, study a shared pathway, take a supervised assignment in the National Working Groups, or bring a cohort from your institution. For organisations.

Key terms

Term

Essential Climate Variable

A physical, chemical or biological variable that GCOS defines as critical to characterising the Earth's climate.

Term

Reanalysis

A consistent reconstruction of past weather and climate that combines observations with a fixed model and data assimilation.

Term

Data assimilation

The combination of observations with a model to give the best estimate of the state of a system.

Term

Digital twin of the Earth

A system that combines observations and high-resolution models to simulate and explore the Earth system interactively.

ReportsContribute

Contribute evidence from this page.

Reports is the Consortium's quarterly publication. What you know about this subject can become evidence, a case or a correction in the next edition, credited to you and published under CC BY 4.0 where it is your own work.

Risk Academy
Earth observation and Earth system data

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Open courses in connected disciplines teach the methods this discipline will build on.

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Not for profit

Our articles, maps and twins are free to read and free to republish. Readers and partners keep it that way.

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Who funds us

Risk Academy is a not-for-profit institution. To ask who funds a piece of work, use the funding questions form.

Independence

Editors and the expert reviewers named on each article decide what we publish. Funders and partners do not review or approve articles before publication.

Licence

Articles: CC BY 4.0. Figures, maps, twins and data: CC BY 4.0. Other uses: ask through the permissions form.