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GCRIFood NexusEstablished
Method page · Earth observation and remote sensing

Earth observation for crop monitoring

Satellites observe cropland every few days and across borders: greenness, water stress, planted area, flooding, burnt land and land cover change. Earth observation underpins crop monitoring and food security early warning, filling gaps where ground statistics are late, sparse or unavailable.

Method recordearth-observation
  1. MethodEarth observation and remote sensing
  2. Applied inFood Nexus
  3. Canonical pageSTEM Commons

GCRI · Established · service level R0

01In brief

The short answer.

Earth observation for crop monitoring is the use of satellite imagery to track crop condition, planted area, crop type, irrigation and flood or fire damage across whole regions every few days. It underpins food security early warning where ground statistics are late or sparse, and every map is checked against ground reference samples.

02Application

What earth observation and remote sensing does here.

Earth observation and remote sensing gather information about the Earth's surface and atmosphere from airborne and spaceborne sensors. They provide consistent, repeatable measurements over areas that are hard to monitor on the ground. In food and agriculture, trade, resources and supply chains and climate and hazards, earth observation maps exposure, damage and environmental change across borders and sectors. It supports rapid assessment after disasters and long-term monitoring of risk drivers. The canonical description is on the STEM Commons.

Crop condition monitoring

Vegetation indices and land-surface temperature are compared with their historical range for each cropland area and season, then summarised by region for the consensus assessments of GEOGLAM partners.

Crop type and area mapping

Optical and radar time series are classified with ground samples to estimate planted area by crop, with an accuracy assessment that states commission and omission error.

Irrigation and water productivity

Satellite evapotranspiration and biomass estimates map irrigated fields and how much crop is produced per unit of water consumed, as in FAO WaPOR.

03Key terms

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.

TermDefinition
NDVIThe normalised difference vegetation index, a ratio of red and near-infrared reflectance that rises with green vegetation cover and vigour.
Crop type mapA classification of satellite imagery into crops, trained and tested on field-collected reference samples.
Ground reference sampleA field observation of what is actually on the ground at a location, used to train and validate satellite maps.
04Geography

Food systems and trade routes in Thailand.

Plains, deltas and basins, the corridors that carry food to ports, and how far each division sits from one, shown for Thailand as an example geography for this subject.

Plains, deltas and basins, the corridors that carry food to ports, and how far each division sits from one.Indicator derived from Natural Earth at map scale; a screening view, not an assessment.
GCRI · Food Nexus · fieldDESIGN FIGURE
05Canvas

The method as a run graph.

Data from the source register feeds the methods; calibration and an independent test gate the estimate and its limits; the decision stays with the competent authority.

Method canvas · Earth observation and remote sensing as applied hereDesign, not a record
Earth observation and remote sensing in Food Nexus: Earth observation processing chainAcquisitions are calibrated and corrected into analysis-ready data, masked for cloud, analysed for change and validated against ground truth before the product reaches its user. Design of the process, not a record of a run.

Fig. 01Nodes carry their type, metrics and state; connectors show what feeds what; the gates are the validation steps; the timeline is one application. Design of the method's use, not a record of a run.

06Data

What the method consumes.

Datasets and records used by earth observation and remote sensing on this platform, with the role each plays and the label its values carry. Sources are listed in the source register.

DataRoleLabel
Sentinel-2 and Landsat optical imageryCrop condition, type and areaOBSERVED
Sentinel-1 radarCrop mapping through cloud, flood extentOBSERVED
MODIS and VIIRSVegetation and temperature time seriesOBSERVED
FAO WaPOREvapotranspiration and biomassMODELLED
Ground reference samplesTraining and validationOBSERVED
07Validation

How results are checked.

Products are assessed against ground reference data using accuracy matrices and independent samples. Cross-calibration between sensors checks consistency over time.

CheckHow it is done
Accuracy assessmentMaps are scored against an independent probability sample of ground reference points, and area estimates are adjusted for classification error
Cross-sensor consistencyTrends are checked across sensors and processing versions before they are reported
Cloud and gap reportingMissing observations are reported as no data, never as normal conditions

Clouds, revisit gaps and mixed pixels limit what can be observed. Changes in sensors and processing can create artificial trends.

09Stewardship

Who maintains the method.

Space and Earth Observation stewards earth observation and remote sensing for the Consortium and reviews how it is applied across platforms.

11Questions

Questions and answers.

What are the limits of earth observation and remote sensing in this field?
Clouds, revisit gaps and mixed pixels limit what can be observed. Changes in sensors and processing can create artificial trends.
How are results checked?
Products are assessed against ground reference data using accuracy matrices and independent samples. Cross-calibration between sensors checks consistency over time.
Are the values on this page real?
The data names, roles and checks are real descriptions of practice. The canvas shows a design of the method's use, not a run; no result is reported here.
Where else is this method applied?
The canonical method page lists every platform that applies it.
Food Nexus

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