Long-term Vicarious Adjustment of Ocean Colour Sensors

Background and Rationale

Timeliness for this Working Group

There are currently seven ocean colour sensors in orbit, operated by various space agencies or national organisations, with another ten new missions planned for launch between 2017 and 2022. The abundance of satellite ocean colour datasets  represents a great opportunity for global monitoring of the Earth environment, but the challenge remains to ensure that these data meet ocean colour radiometry uncertainty budget requirements.

We rely on a complementary calibration using ground-truth measurements, i.e., “system vicarious calibration” (SVC) to meet the requirements for climate quality data. System vicarious calibration is therefore a fundamental and intrinsic part of a satellite ocean colour mission and acquisition of in situ data should be of the highest possible standard of precision and accuracy. This working group will foster a wide-ranging debate with international participants,  the main objective of which is to provide guidelines on the best practices for system vicarious calibration of ocean colour sensors from various missions.

Relation with Exiting Activities

The working group will build on the following projects:

• ESA project FRM4SOC Project  (June 2016 to June 2018) and ;
• EUMETSAT project OC-VCAL (October 2016 to October 2018).

One element of the FRM4SOC project was to organise a workshop on vicarious infrastructure (21 – 23 February 2017, ESA/ESRIN, Frascati, Italy)  which brought together the international community to open the discussions. View the report of the workshop for further information.

Members

• Christophe Lerebourg, ACRI-ST, France (Co-chair)
• Ewa Kwiatkowska, EUMETSAT, Germany (Co-chair)
• Carol Johnson,  NIST, USA (Co-chair)
• David Antoine,  LOV, France
• Ken Voss, University of Miami, USA
• Constant Mazeran, Solvo, France
• Nigel Fox, NPL, UK
• Andrew Banks, NPL, UK
• Marlon Lewis, Dalhousie University, Canada
• Emmanuel Boss, University of Maine, USA
• Bryan Franz, NASA, GSFC, USA
• Hiroshi Murakami, JAXA , Japan
• Sean Bailey, NASA GSFC, USA
• Craig Donlon, ESA/ESTEC, Netherlands,

Terms of Reference

The prime objective of the working group is to define the best practices to reach a high standard of precision and accuracy for in situ OCR measurements necessary to fulfill the SVC requirements. To achieve this, the working group will address the following tasks:

• Review of historical and contemporary approaches to SVC;
• Document lessons learned from international teams;
• Review the strengths and weaknesses of alternative methods and approaches to OCR satellite SVC;
• Review and define justified and traceable requirements for measurements to be appropriate for SVC of satellite OCR;
• Review the costs to implement, operate and maintain satellite OCR SVC infrastructure;
• The working group shall conclude with a consensus on the way forward to deliver the best scientific outcomes to support long-term ocean colour SVC.

A second objective is:

• To assess the procedures used to derive SVC gains and in particular the impact of in situ data uncertainty

The workshop organized as part of the FRM4SOC project will end-up with a conference proceeding and a monograph. The latest to be reviewed by the working group members shall serve as a baseline for the IOCCG monograph.