Inter-calibration of Geostationary Satellites' Imager Observations

1. SCM-06: Status Report to SEP-14 Inter-calibration of imager observations from time-series of geostationary satellites (IOGEO) 7 and 8 February 2019, Geneva, Switzerland Rob Roebeling (EUM) on behalf of the project participants

2. Project purpose at start Phase II 

3. SCM-06 IOGEO* Towards a GEO ring Fundamental Climate Data Record (FCDR) of inter-calibrated Infrared, Water vapourand Visible radiances European Organisation for the Exploitation of Meteorological Satellites (Rob Roebeling, Tim Hewison) Japanese Meteorological Agency (Masaya Takahashi) National Oceanic and Atmospheric Administration (Kenneth Knapp, Anand Inamdar) Deutscher Wetterdienst (Marc Schroeder) China Meteorological Administration (Peng Zhang, Xiuqing Hu) Indian Meteorological Department (A.K. Sharma, Ashim Mitra) Korea Meteorological Administration (Dohyeong Kim, Hyesook Lee) *Inter-calibration of imager observations from time-series of geostationary satellites (IOGEO)

4. Objective: Re-calibrate (harmonized) and Inter-calibrate Meteosat First Generation (MFG) and Meteosat Second Generation (MSG) IR, WV, and VIS radiances from 1982 till date. Project Activities: to share common re-calibration methods between the participating agencies; to re-calibrate geostationary data from all heritage instruments; to compare re-calibrated geostationary data in overlap regions; to prepare an FCDR of re-gridded radiances normalized to a reference instrument; SCM-06 IOGEO - Introduction

5. Phase II Key findings, advances and developments

6. Introduction – Harmonization(sensor equivalent calibration) Harmonisation: A harmonized satellite series is one where all the calibrations of the sensors have been done consistently relative to reference datasets which can be traced back to known reference sources, in an ideal case back to SI. Each sensor is calibrated to the reference in a way that maintains the characteristics of that individual sensor such that the calibration radiances represent the unique nature of each sensor. This means that two sensors which have been harmonized may see different signals when looking at the same location at the same time where the difference is related to known differences in the responses of each sensor such as differences in the sensors spectral response functions etc.

7. Introduction - Homogenization (reference sensor normalized calibration) Homogenization: Unlike harmonization, homogenization is where all satellites are forced to look the same such that when looking at the same location at the same time they would (in theory) give the same signal. In reality the signals from different sensors would be different and homogenization is adding in corrective terms to each satellite to make them look the same. It is likely that these corrective terms will not be 100% effective and that the process of homogenization will add in scene dependent errors to the uncertainty budget which may be difficult to assess.

8. Sharing re-calibration methods Generating Fundamental Climate Data Records (FCDRs) • During phase-II three new partners joint IOGEO, i.e.: CMA, IMD, and KMA. • [IR and WV calibration] JMA, EUMETSAT, CMA, and NOAA use similar re-calibration methods for their heritage geostationary IR/WV channels, taking infrared sounder (HIRS/2/AIRS/IASI) observations as reference; • [IR and WV calibration] IMD and KMA are planning to adopt HIRS based re-calibration methods as well; • [IR and WV calibration] EUMETSAT and JMA generated, in close collaboration, a 30 years+ FCDRs for their heritage IR/WV channels; • [VIS calibration] NOAA uses MODIS observations as a reference for the re-calibration of the their geostationary VIS channel; • [VIS calibration] EUMETSAT uses vicarious calibration techniques to reconstruct the spectral response and to re-calibrate VIS channel on Meteosat First Generation (MFG) satellites; • [VIS calibration] EUMETSAT generated a 30 years+ FCDR for their VIS channel.

9. Homogenized (Reference Sensor Normalized) time-series of EUMETSAT and JMA IR and WV channels MFG Series Radiances- homogenized to the 6 micron channel of Meteosat-5 JMA Series Radiances- homogenized to 7 micron channel of MTSAT-2 MFG Series Radiances- homogenized to the 11 micron channel of Meteosat-5 JMA Series Radiances- homogenized to 11 micron channel of MTSAT-2 1977 1985 1993 2001 2009 2017 1982 1986 1990 1994 1998 2002 2006 2010 2014 Figure: Time-series of EUMETSAT (MFG) and JMA (GMS, GOES-9, MTSAT) homogenised IR and WV FCDRs

10. Homogenized (Reference Sensor Normalized) time-series of EUMETSAT VIS channel Figure: Time-series of EUMETSAT (MFG) homogenised VIS FCDR over an Algerian, Nile, and Ocean target

11. Joint IOGEO and GSICS inter-comparison of harmonised (re-calibrated) WV, IR (and VIS) radiances

12. GSICS and IOGEO partners initiated a joint study to compare harmonized (or re-calibrated) radiances from the water vapor (WV), infrared (IR),(andvisible (VIS))channels on heritage geostationary satellites. A common repository (FTP site) has been set-up where GSICS and IOGEO partners uploaded their recalibrated data for two test days. Under the lead of GSICS, GSICS and IOGEO are now searching for resources for doing the inter-comparison work, including: To inter-compare re-calibrated data in overlapping regions; To compare re-calibrated data against IASI observations; To compare re-calibrated data against simulated radiances from ECMWF. IOGEO and GSICS inter-comparison

13. IOGEO and GSICS inter-comparison – Status Data Uploads : Ready and uploaded to the common FTP site : Ready but not yet uploaded to the common FTP site  : Not ready  : Current status needs to be checked

14. Project status at end Phase II Lessons Learnt Potential for future Activities

15. EUMETSAT produced FCDR of MVIRI and SEVIRI recalibrated radiances for the IR and WV channels covering the period 1982 – 2017, using HIRS/2, IASI and AIRS observations as a reference (common recalibration method developed at EUMETSAT). EUMETSAT and JMA produced FCDR of GMS/GOES/MTSAT recalibrated radiances for the IR and WV channels covering the period 1978-2017, using EUMETSATs recalibration method. EUMETSAT produced FCDR of MVIRI recalibrated radiances for the VIS channel covering the period 1982 – 2017, using reconstructed spectral response functions from the FIDUCEO project. Prepared common repository for joint GSICS and IOGEO comparison of recalibrated VIS/IR/WV radiances. Project Status at end of Phase-II

16. Lessons Learnt Much work has been done at the individual space agencies on improving the time-series of their sensors; Great progress has been made on using one method on another agencies data (EUMETSAT’s for JMA satellites); Long-term Visiting Scientist stays as practised with JMA at EUMETSAT help to achieve the use of a common calibration method; It is challenging to take the next step, and bring the data from the individual space agencies together and provide a geo-ring FCDR in a common quality and common format; Main challenge for the future is to enable more intense collaboration of space agencies working towards a common goal which should be the geo-ring FCDR employing the same scientific methodology and technical specification to produce outputs; The latter would ideally require funding at all sides at the same time.

17. Potential for Continuation ALL: To agree on the common goal, technical specifications and secure funding; ALL: To seek beta users for FCDRs including gridded representation; ALL: To perform inter-comparison IOGEO and GSICS recalibrated IR/WV/VIS radiances from all GEOs for common test period; DWD: To utilize pre- release of IR/WV inter-calibrated FCDR and re-compute FTH; NOAA, IMD, CMA, KMA: To produce IR/WV inter-calibrated FCDR (or cal. coefficients); NOAA, IMD, CMA, JMA, KMA: To produce VIS inter-calibrated FCDR (or cal. coefficients); ALL: to set up a plan for collaborative activities among the participants (e.g. longer-term visiting scientist plan) that helps accomplishing recalibration of GEO satellitesas it has been done for EUMETSAT and JMA satellites; ALL: Generation of a combined product of gridded inter-calibrated radiances that is based on re-calibrated radiances from as many geostationary satellite data as possible.

18. Thank You