Department of Signal Processing and Acoustics

MetEOC3 project (2017-2020)

European Metrology Programme for Innovation and Research (EMPIR) project MetEOC3 - "Metrology for Earth Observation and Climate".

European Metrology Programme for Innovation and Research (EMPIR) project MetEOC3 - "Metrology for Earth Observation and Climate".

 

The overall aim of the project was to contribute to the establishment of the necessary metrology infrastructure for climate observing systems. This project was the follow-up of the EMRP MetEOC2 where Metrology Research Institute was contributing to collection of set of empirical data to support the building of bidirectional reflectance distribution function (BRDF) models for non-instrumented PICS as calibrations test sites and, in particular, for other than nadir observations.

In this project, Metrology Research Institute's main task was to measure BRDF of sand from Gobabeb test site that is one of the Radiometric Calibration Network (RadCalNet). This would produce a set of SI-traceable empirical data required to decrease the uncertainty of in-flight climate satellite calibrations.

meteoc3
Figure 1. Photograph of the gonioreflectometer used to perform BRDF measurements.

For this purpose, Metrology Research Institute developed a 3D goniometer capable of in- and out-of-plane BRDF measurements of horizontally aligned samples. Coupling with a supercontinuum laser, three different detectors (Si, InGaAs and extended InGaAs) allow to operate the new instrument in the wavelength range from 400 to 2070 nm. SI-traceability of the 3D goniometer was achieved by measuring a spectralon PTFE sample, the BRDF of which had been characterised by an absolute reference goniometer with an uncertainty of 0.2%. Correction factors were derived from the ratio  between absolute and relative spectralon BRDF measurements, giving an estimate of the BRDF of Gobabeb test site ground samples with an uncertainty of less than 1 %.

References

[1] Lanevski, D., Manoocheri, F. & Ikonen, E., “Gonioreflectometer for measuring 3D spectral BRDF of horizontally aligned samples with traceability to SI”, 1 Apr 2022, Metrologia. 59, 2, 13 p.

Contact persons: Farshid Manoocheri and Robin Aschan

More information can be found at the project website:

http://www.meteoc.org/

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