Satellite Data Rescue

Pascal Prunet Bill Bell, Marie Doutriaux-Boucher, Mike Grant, Andrzej Klonecki, Viju John, Jon Mittaz, Joerg Schulz, Carsten Standfuss Climate Change Projects consortium C3S 311b (EUMETSAT) and C3S 311c (SPASCIA, Icare, U. Reading, Météo-France, UKMO, Capital-High-Tech Introduction

Climate Satellite data are extensively used for Numerical Weather Change Prediction (NWP) : Real time measurements constraining the present for the improvement of weather forecasts

• Reanalysis aims at providing a consistent and long term view of the past climate • ERA5 - reanalysis currently run for the period 1950-present (see presentation by Hans) • ERA6 – the next generation global reanalysis, scheduled for 2023 start

• Strong need of past data for constraint and validation : Early satellite data are critical to complement sparse in-situ data • First satellite image in April 1960 • Operational satellites since 1979

Satellite data rescue is an on-going effort aiming at going back in time as far as possible, identifying and preparing satellite data of best quality for reanalysis Radiances assimilated in ERA5 Geostationary radiances Climate Change Not used in ERA-Int, but used in ERA5 Reprocessed data, or change in processing since ERA-Int Same as ERA-Int Hyperspectral Infrared Not used in ERA5, but used in ERA-Int Multi-spectral Infrared

Satellite radiances (L1) are increasingly assimilated in reanalyse +VTPR in 1970’s Microwave Imagers - New instruments - improved and more consistent (reprocessed) datasets Microwave Sounders But less data before 2000 Basically no satellite radiances used before 1979 (except VTPR)

Credit to Dinand Schepers Early Satellite Data Rescue (pre-2000 : to be completed (inventory activity))

EARLY SATELLITE ERA (pre-1979) Research satellites (NIMBUS 1-7, MODERN ERA (1979-2000) NOAA) operational Satellites (NOAA, DMSP, GOES, 1979 METEOSAT)

THIR /N4-7 Infrared Imagers

HRIR/N1-3 SSU/TIROS_N/NOAA 6-14 MRIR /N2-3

SCR/N4-5 HIRS/2- HIRS/1/N 4 6 Infrared Sounders SIRS/N3-4 PMR/N 6 IRIS/N3-4 VTPR/NOAA2-5 IMG/ADEO SSH/DMSP F1-F4 S ITPR/N5 SMMIS/DMSP F16-19

NEMS/N5 MSU/TIROS-N-NOAA6-14 SSM/T-2/DMSP F11-15 Microwave Sounders/ SSM/T-1/DMSP F4, F7- SMMR/SEASAT-N7 F15 Imagers SSM/I/DMSP F4, F7-F15 MVIRI+SEVIRI

ATS GMS SMS-1,2

AVHRR/POES Geostationary GOES 1-15 and/or AMV 1960 1970 1980 1990 2000 Data Recovery: reading bands, storing in modern format Legend: Reprocessing (recalibration, navigation, …), Quality assessment Data not yet assimilated Data assimilated in ERA5 Use of satellite data in reanalysis Climate • Early satellite data are valuable for constraining the past states of the Earth Change system. But it is crucial that we have data for which: • Stringent quality control is applied • Radiances have been optimised (in terms of calibration, processing …) • Instrumental characteristics are known • Any instrumental biases and uncertainties are well characterised Drift in bias due to ice deposition on sensor: METEOSAT-9, 13.4µm channel: FGBias –

Obs Sensor decontamination C3S data rescue activities Climate Two on-going projects are focusing on priority datasets, building on Change outcomes of the FP7 ERA-CLIM and ERA-CLIM2 projects which identified the most potentially useful datasets for climate reanalysis : • C3S-311b : satellite data rescue and reprocessing • Aims at going back in time as far as possible, best possible individual instrument correction, error flagging, advanced uncertainty estimates and harmonisation over the time series. • Addresses instruments with highest impact on forecast error reduction • Iterative improvement to operational satellite series • C3S-311c Lot 1 : satellite data rescue • the objective is to recover, assess and bring to a high level of preparation and qualification a selection of early pre-operational satellite data records for use in climate reanalysis • Main focus on Pre-1979 datasets Early Satellite Data Rescue (pre-2000) C3S 311b

EARLY SATELLITE ERA (pre-1979) C3S 311c Research satellites (NIMBUS 1-7, MODERN ERA (1979-2000) NOAA) operational Satellites (NOAA, DMSP, GOES, 1979 METEOSAT)

THIR /N4-7 Infrared Imagers

HRIR/N1-3 SSU/TIROS_N/NOAA 6-14 MRIR /N2-3

SCR/N4-5 HIRS/2- HIRS/1/N 4 6 Infrared Sounders SIRS/N3-4 PMR/N 6 IRIS/N3-4 VTPR/NOAA2-5 IMG/ADEOS SSH/DMSP F1-F4 HIRS/METOP ITPR/N5 SMMIS/DMSP F16-19 MHS, ATMS, MWHS, MWHS-2, ATMS NEMS/N5 MSU/TIROS-N-NOAA6-14 SSM/T-2/DMSP F11-15 SCAMS/N SSM/T-1/DMSP F4, F7- Microwave Sounders/ 6 SMMR/SEASAT-N7 F15 SSM/I/DMSP F4, F7-F15 Imagers

MVIRI+SEVIRI

ATS GMS SMS-1,2

Climate Iterative improvement of datasets and algorithms Change • Validation and quality analysis • Feedback from users

radiosonde

FCDR [L1] TCDR [L2] Scientific Approach for satellite data rescue

Climate DATA REANALYSIS MODEL FIELDS Change

Analysis of available ERA5 information on instruments

UNCERTAINTY TREE (FIDUCEO approach) Radiative Transfer Simulated Observed organizing the information Model (RTTOV) (Background) radiances about the different sources of uncertainty radiances ensure that nothing is missed at a higher level

Instrument and error characterisation feedback When possible, Satellite data reprocessing O-B (Observation - Background) analysis of O-B patterns

min N bpj = ∑ βi ij ‖𝑦𝑦 − i𝐻𝐻=1 𝑥𝑥𝑎𝑎 −𝑏𝑏‖ Parameterisation of observational See C3S 311c poster for more details bias for use in assimilation could serve as an important early reference linking the period up to the current high-precision atmospheric Climate sounding interferometers (IMG, AIRS, Change IASI, CrIS) Can be used as a calibration reference for TIR imagers in orbit at the same time (SIRS, THIR)

IASI / Metop

AIRS / Aqua CrIS / SNPP and JPSS

Example : data rescue of IRIS (1970) • InfraRed Spectrometer that provides high spectral resolution atmospheric spectra. • Precursor of interferometry-based space borne IR atmospheric sounding missions such as IASI or CrIS • Accurate information on Temperature and Water vapour • Measurements of Trace gases : Ozone, CO2, … Example of recovery activities: IRIS

Climate IRIS initiated the history of IR sounders, supports their use, and provides useful past information Change 1970 1996 - 2005 - 2007 - 2012 2016 2020

IRIS IMG AIRS IASI CrIS Poli and Brunel, 2016: C3S 311c: “Obs-Obs” analysis First “O-B” (ERA40) IRIS Rescue approach : Short duration of the  Systematic instrument Harries et al. 2001 : Bantges et al., 2016: dataset.  Use accurate RT analysis (FIDUCEO-like) IRIS / IMG IRIS/IMG/IASI No accurate Radiative  Instrument model transfer Confirms the interest of  Up-to-date RT Prove the interest of IRIS (climate signal) No instrument model IRIS, and the need to  Improved O-B (wrt ERA5) better understand But studies suggest incomplete Current challenges: instrument and processing understanding of instrument and processing Only NIMBUS-4 data were recovered from ageing magnetic bands by NASA

Only L1 data available

Incomplete documentation Example of recovery activities: IRIS

Climate Change 1970 1996 - 2005 - 2007 - 2012 2016 2020

IRIS IMG AIRS IASI CrIS Poli and Brunel C3S 311c

O-B (observation – Background)

Poli and Brunel : First objective evaluation of O-B

Instrument model : Better understanding of IRIS-1 (Spectral Response), improved RT, first uncertainty estimate

ERA5 : Improved B

Feedbacks from “Rescue” approach : better understanding of L1, improved RT (or post-processing), consolidated error characterisation Bias correction model 2016 2020 2022 Approach for satellite data rescue

Climate DATA REANALYSIS MODEL FIELDS Change

Analysis of available ERA5 information on instruments

UNCERTAINTY TREE (FIDUCEO approach) Radiative Transfer Simulated Observed organizing the information Model (RTTOV) about the different sources radiances radiances of uncertainty ensure that nothing is missed at a higher level

Instrument and error characterisation

When possible, Satellite data reprocessing feedback O-B (observation - Background) analysis of O-B patterns

Observation community Data assimilation community

Parameterisation of observational bias for tests in assimilation Climate Change Future work and perspective Objective : Readiness for ERA6

 Bringing priority datasets to a high level of readiness:  Quality assessment, instrument and error characterisation IMG/ADEOS  Data reprocessing when possible IASI / Metop CrIS / SNPP and JPSS  Updating the radiative transfer capabilities for studied sensors (RTTOV coefficients)  Assessing bias correction model  Major additional effort needed to maximize the use of early satellite record  The early (pre-2000) satellite inventory will serve as a resource for defining next priorities and performing future work