Time
Common time reference for satellite observations.
Crete · GavdosReference infrastructure
Measuring Earth
to trust what we measure from space
How do we know
a satellite is right?
Satellite altimetry observations are independently calibrated and validated through reference infrastructure in Crete and Gavdos.
EO / CAL–VAL / 04Scroll to observe ↓
The measurement chain
From satellite observation to trusted data
01Satellite pass
02Radar altimetry
03Reference site
04Transponder / ground
05Reference measurement
06Calibration & validation
07Trusted data
Crete & Gavdos
Reference infrastructure
Visualized source map · no live status
CDN1Source-identified
GavdosReference area
Satellite altimetryIndependent referenceCal / Val
FIDUCIAL REFERENCE SYSTEMS
One reference. Comparable measurements. Trusted observations.
Fiducial Reference Systems establish common standards for time, coordinates and measurement traceability in satellite altimetry.
Coordinates
Consistent terrestrial and inertial reference frames.
Traceability
Measurements connected to international metrology standards.
Uncertainty
Transparent and comparable uncertainty budgets.
Reference set / 02
Selected references
Fiducial reference systems for time and coordinates in satellite altimetry
Stelios P. Mertikas et al.
Advances in Space Research, 2021
DOI: 10.1016/j.asr.2020.05.014Fiducial Reference Measurements for Satellite Altimetry Calibration: The Constituents
Stelios P. Mertikas et al.
International Association of Geodesy Symposia
DOI: 10.1007/1345_2019_56
ESA documentaryMonitoring sea level change
Watch film ▶
Monitoring sea level change
from a mountain top
Watch film ▶European Space Agency
Technical University of Crete / AORI Films
2018
Missions & Cal/ValEngineering confidence
Engineering confidence
across missions
Ground reference for a new generation of ocean topography.
Explore missionsResearch & publicationsScience that builds
Science that builds
confidence
Schematic interface · not measured data
Data & resourcesOpen data.
Open data.
Open knowledge.
Interface visualization · not an operational dataset
Access resourcesSelected missions & Cal/Val activities
Reference infrastructure across missions
04SWOT Cal/Val
SWOT Ocean & Geodetic Calibration / Validation
Ground reference for a new generation of ocean topography.
Permanent Cal/Val infrastructure in Crete and Gavdos supports SWOT oceanographic and geodetic products.
NASA / JPLSWOTCrete + Gavdos
SWOT · Ocean Cal/Val · Geodetic CalValStelios MertikasProject Investigator · Technical University of Crete
04SWOT Cal/ValSatellite altimetry · Cal/Val reference
ESA films / field stories
Observation in context
Three films from the field and from orbit.
Capability framework
Satellite altimetryCalibration & validationCrete + GavdosReference infrastructureGeodesyReference systemsEarth observationScientific analysis
News & stories
Latest signals
Research & publications
Selected scientific work
Research supporting satellite altimetry, calibration and validation, geodesy and reference infrastructure in Crete and Gavdos.
AllAltimetryCal / ValGeodesyTransponders
012024Remote SensingCal / Val
The ESA Permanent Facility for Altimetry Calibration in Crete: Advanced Services and the Latest Cal/Val Results
Stelios P. Mertikas et al.
022024Remote SensingGeodesy
Local Gravity and Geoid Improvements around the Gavdos Satellite Altimetry Cal/Val Site
Stelios P. Mertikas et al.
032022Advances in Space ResearchTransponders / Cal / Val
Performance evaluation of the CDN1 altimetry Cal/Val transponder to internal and external constituents of uncertainty
Stelios P. Mertikas et al.
042018Remote SensingSatellite Altimetry
Fifteen Years of Cal/Val Service to Reference Altimetry Missions: Calibration of Satellite Altimetry at the Permanent Facilities in Gavdos and Crete, Greece
Stelios P. Mertikas et al.