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Frm4alt International Review Workshop

“International Review Workshop On Satellite Altimetry Cal/Val Activities and Applications"

23-26 April 2018,
Chania, Crete, Greece.

Workshop url



Transponder calibration

Transponder calibration at the CDN1 ESA Altimeter Calibration Site:

  • CryoSat-2 on 5-Feb-2018 18:41:47 UTC (Previous Cal/Val 5-Jan-2018 at 8:04:26 UTC),
  • Tandem mission of Jason-2 and Jason-3, March-October 2016,
  • Jason-3 continuously every 10 days after its launch,
  • Sentinel-3A every 27 days at 20:00:12 UTC continuously after its launch.



What is FRM for Altimetry?
Why need FRM now?
How to implement it?

Download: Webstory 2

Accurate determination and monitoring of sea-level changes are of fundamental value and crucial in understanding the ocean’s influence on our weather patterns and long-term climate change of our planet. For more than 30 years, satellite altimetry has been monitoring changes in sea level and climate, unequivocally, over regional to global scales with [mm/yr] accuracy and reliably, with respect to the center of mass of the Earth.

  • Fiducial Reference Measurements for Altimetry (FRM4ALT) are essential so that monitoring of the ocean and its changes is maintained:
  • Objective, continuous, homogeneous and reliable;
  • Free of errors and biases for any mission;
  • Uninterrupted and tied from one mission to the next.


ESA logo  IAG logo 2016 


 GeoMatLab Logo  DTU Space 2017 Space Logo

frm4alt logo 6 Dec 2017


SeRAC: Sentinel-3 Radar Altimeter Calibration Site in Crete

Serac crete eu


FRM4ALT is continued in the Sentinel-3 Radar Altimeter Calibration in Crete (SeRAC) activity with Operational Support, now in place. The objective of this SeRAC project is to ensure the routine operations and maintenance of the CDN1 transponder Cal/Val site for Sentinel-3A but also for Sentinel-3B Commissioning and Routine Operational Phase. The transponder Cal/Val operations shall be further supported by the sea-surface Cal/val sites established at the Permanent Facility for Altimetry Calibration in west Crete, Greece.

url: www.serac-crete.eu