Earth observation
Satellites, aircraft, drones and ground sensors observe floods, crops, forests, coasts, cities and infrastructure more often and more widely than ever. Earth observation is powerful evidence when its sensors, processing and limits are understood, and misleading when they are not. The Global Centre for Risk and Innovation (GCRI) uses Earth observation with attention to sensors, satellite data quality and reproducibility, so that a map or a change estimate can be checked and its uncertainty stated. This page is part of science and methods.
- Institution
- The Global Centre for Risk and Innovation (GCRI)
- Service level
- R0: information and enquiries
Country programme console
Earth observation · Country programme A · Month 5
Programme
- Formationdossier
- National Deskstaffed
- National Modelbuild
- Portfoliooptions
- Annual missiontest
- Reportedition
System coupling
dependency strength, 0 to 100
Placeholder strengths a National Model replaces with estimates.
Evidence ledger
| Reservoir storage | OBSERVED | National Desk |
| Hydropower output | MODELLED | Technical office |
| Grid stress | SCENARIO | Technical office |
| Hospital continuity | ESTIMATED | Health ministry |
GCRI · Country programme consoleCountry programme console, in outline: domain structure with placeholder names and illustrative values, not a record.
The short answer.
Earth observation is the gathering of information about the planet from satellites, aircraft, drones and ground sensors, used to watch floods, crops, forests, coasts, cities and infrastructure. GCRI treats it as powerful evidence when its sensors, processing and limits are understood, and checks quality and comparability before any claim of change.
Land surface in New Zealand.
Surface classes an Earth-observation programme reads: ranges, deserts, glaciers, lakes and reefs, shown for New Zealand as an example geography for this subject.
Different instruments answer different questions.
No single sensor sees everything. Choosing the right instrument, or combining several, is the first decision in any Earth-observation study, and the choice is recorded with the result.
| Sensor type | Good for | Limits |
|---|---|---|
| Optical multispectral | Land cover, vegetation, water extent | Clouds and darkness block the view |
| Synthetic aperture radar | Flood mapping through cloud, ground movement | Harder to interpret, sensitive to terrain and surface |
| Thermal | Heat, fire, water temperature | Coarser resolution for many missions |
| Ground sensors | Calibration, continuous local measurement | Sparse coverage, maintenance needs |
What makes satellite evidence trustworthy.
Two images of the same place are not automatically comparable. Quality checks come before any claim of change.
- 01
Comparable inputs
Images compared only when their sensor, processing level and processing version are comparable, and differences are corrected or stated.
- 02
Validation
Classifications and change estimates checked against independent reference data, with accuracy reported.
- 03
Seasonality and timing
Seasonal and acquisition-time differences are separated from real change.
- 04
Reproducibility
Inputs, code versions and parameters recorded so another team can repeat the result.
Terms used on this page.
Each term as this page uses it. Where a standard-setting body defines the term, the wording follows that body.
| Term | Definition |
|---|---|
| Remote sensing | Acquiring information about an object or area from a distance, typically by satellite or aircraft sensors. |
| Synthetic aperture radar | An active radar imaging system that sees through cloud and darkness. |
| Analysis-ready data | Satellite data processed to a minimum standard so that users can analyse it without further preprocessing. |
| Change detection | Comparing a reference image with an event image of the same place to map what changed, such as newly flooded land. |
Systems, methods and platforms.
Earth-observation search, processing and change evidence run in EOP in Nexus Foundry. Methods are described at Earth observation and remote sensing, and spatial analysis under geospatial science. Field work is organized through the Space and Earth Observation platform, in development.
Describing a capability does not imply authority to order paid acquisition, and imagery keeps its provider's licence.
Questions and answers.
Can satellite images prove damage after a disaster?
Does GCRI operate satellites?
Why do two maps of the same flood differ?
Can I reuse GCRI's Earth observation products?
How does Earth observation support risk work?
Around GCRI.
Start with an enquiry.
The current service level is R0: information and enquiries. An enquiry receives a reference and names the next step; applications, payments, compute allocations and registrations open only when their team, terms and review capacity exist.