Development and Production of the Onboard Radiometric Calibration References for the Next Generation of European Weather Forecasting Space Instruments

Eumetsat’s new generation weather satellites will include improved infrared sounders, the IASI-NG on MetOp Second Generation and the IRS on Meteosat Third Generation. The data collected by the infrared sounders will be used to obtain vertical profiles of temperature and humidity as well as other climate variables (vertical profiles of the concentration of some trace gases, surface temperatures, cloud top height, etc.). That information will then be used in numerical weather prediction models and in support of climate studies. A key feature of those instruments is to embed high end traceable calibration sources in order for the instruments to fulfill their role in producing high quality data that can be used with confidence and can be successfully compared to other instruments (past and future) for long-term climate study trends.

For calibration in the infrared, the radiometric references are essentially quasi-blackbody sources: sources of high emissivity and accurately known temperature emitting energy that can be precisely predicted with Planck’s law of radiation. ABB is currently developing the onboard infrared calibration sources for all the new generation of European infrared weather forecasting space instruments in LEO or GEO orbit. That includes two blackbodies for IASI NG instrument onboard Metop-SG: BB-FTS for the sounder and BB-IIS for the cloud imager and one for the IRS onboard MTG. This paper will present an overview of these projects covering the key features of the different calibration sources, the status of their development and recent test results.