EarthCARE Validation Workshop
Session on “Radiation” - 28 May 2021
Covered products:
MSI L1 (M-NOM)
BBR L1 (B-NOM, B-SNG)
BBR L2 (BM-RAD, BMA-FLX)
Note : surface radiation in “Model” session !
ESA UNCLASSIFIED – For ESA Official Use Only

2nd ESA EarthCARE Validation Workshop
25-28 May 2021 (online)
1Session’s Agenda – Proposals related to “Radiation”
MSI L1
discussion here
in the middle
BBR discussion
at the end
ECVT 03 : German Initiative for the Validation of EarthCARE (GIVE), Dr Ulla Wandingen

MSI L1 + BBR L2

ECVT 29: Monitoring MSI/EarthCARE L1 Performances using concomitant intercalibrationand stand-alone approaches (MMP) – Dr Noelle ScottMSI L1

ECVT 20 : Validation of EarthCARE products in China - Dr Hu

MSI L1 + BBR L2

ECVT 23: Validation of EarthCARE products towards their homogenization with CALIPSO forconsolidating the 3D long-term ESA-LIVAS climatology of aerosols, clouds and radiation(ACROSS) - Dr Vassilis Amiridis

BBR L2

ECVT 06 : Evaluation of EarthCARE Radiances and Fluxes with CERES Data Products – DrNorman Loeb

BBR L2

ECVT 01: EarthCARE BBR L1 and L2 Products Assessment – Dr Nicolas Clerbaux

BBR L1 + BBR L22

MSI part of the “Radiation”
session (chaired by J. Fischer)3

BBR part of the “Radiation” session• Introduction of proposals and feedbacks received (N.
Clerbaux, RMIB)• Lessons Learned from CERES (K. Priestley, NASA Langley)• Lessons learned from GERB (Jacqui Russell, Imperial CollegeLondon)• Discussions

4Overview and feedback - German Initiative for theValidation of EarthCARE (GIVE) – Ulla Wandingen
Summary(…) The proposed activities will allow the validation of the entire
chain of EarthCARE L1 and L2 products as well as the evaluation ofrelated algorithms and instrument calibrations. The approaches
include EarthCARE-to-ground, EarthCARE-to-aircraft andEarthCARE-to-satellite comparisons, supported by cloud, aerosol
and radiative-transfer modelling. (…) Cross-satellite validation
activities will enable the global assessment of EarthCARE products.
These experiments will make use of data from SEVIRI, MODIS,OLCI, SLSTR, AVHRR, MHS and other sensors to validate
EarthCARE aerosol, cloud and radiation flux products. (…) It isenvisaged to synergistically explore ground-based, airborne andsatellite-based Principal Investigator measurements in order tovalidate the EarthCARE product chain and the radiation closure
concept as a whole. These activities will be supported by aerosol,
cloud and radiation modelling aiming at the connection ofobservations and the investigation of spatial and temporal variancesof the measured parameters.(…) The team is composed of wellexperienced scientists from 11 German institutions with expertise insatellite, airborne and ground-based remote sensing as well ascloud, aerosol and radiation modelling.

Specific activities regarding TOA radiation :•MSI-like radiances wrt MODIS (Fischer, FUB)•BBR radiances wrt CERES, GERB and ScaRaB (Fischer, FUB)•MSI L1 and BBR L2 radiances wrt SEVIRI (Luca Bugliaro,DLR)

Validation approaches(…)•Satellite: Geostationary observations to validate imager products(…)

5Overview and feedback - Validation of EarthCARE products
in China - Dr HuSummary

The primary objectives of this proposal are to use the China ground-based or Chinese FengYun polar-orbiting satellite
data to validate the corresponding EarthCare L1/L2 products. Main content includes: (1) Validation of ATLID L1 return
signals and extinction coefficient vertical profiles by using ground-based lidar systems; (2) Validation of ATLID L2
integrated aerosol optical depth product using China ground-based sunphotometer network; (3) Radiometriccalibration and validation of MSI visible and near infrared bands using Dunhuang China Radiometric Calibration Sites(CRCS) site; (4) Inter-comparison and mutual evaluation of EarthCARE with FY-3 satellite L1/L2 products. After this study,
we hope to get some anticipated results: (1) The uncertainties of ATLID L1 products in the region of dust aerosols andpolluted city aerosols in China; (2) The uncertainties of ATLID L2 aerosol products over China, which are validated using
ground-based sunphotometer instruments; (3) inter-comparison results between MSI, BBR L2, and combined science
products (including aerosol, cloud and radiation) and China FengYun-3 corresponding products in globe; (4) During thisprogram, the research results of both sides will be published as papers of academic journals, abstract or papers ofconference and workshop, posters of meetings, and short articles of newsletters.
The research team is composed of National Satellite Meteorological Center, China Meteorological Administration(NSMC/CMA), Beijing Research Institute of Telemetry, Italian National Research Council (CNR), and University of Naples“Federico II”.

Using the ERM instrument on FY-3x?

6

Overview and feedback - Validation of EarthCARE products towards their homogenization
with CALIPSO for consolidating the 3D long-term ESA-LIVAS climatology of aerosols,clouds and radiation (ACROSS)- Dr Vassilis Amiridis
Summary
The overarching objective of ACROSS is to perform thorough cal/val investigations on EarthCARE products
over Greece, a region well-known for its complex atmospheric environment. The experiments will be
designed such as to achieve the following core objectives:(1) to perform a thorough validation of the EarthCARE stand-alone aerosol and cloud products employing
sophisticated ground-based remote sensors and spaceborne observations derived from passive and active
satellite instruments;(2) to utilize the validated aerosol and cloud products in Radiative Transfer Model (RTM) simulations
for depicting radiation and further intercompare with high-quality solar irradiance measurements atsurface (ground-based actinometry) and at TOA (space-borne radiometers, including BBR);(3) to expand ESA-LIVAS for including EarthCARE aerosol, cloud and radiation products, and to utilize theRTM developed in step 2 in order to include CALIPSO-based radiation estimations in the existing ESA-LIVAS
aerosol and cloud climatic dataset. LIVAS will contribute on the evaluation of the EarthCARE performance interms of reproducing well-known climatological patterns at global scale. The validation activities will involve:•a continuous cal/val activity at three monitoring sites in Greece (Thessaloniki, Athens, Finokalia)•3 Intensive Observational Periods (IOPs) of 3-month each, including targeted large-scale field experiments
in Greece•on-demand operation of mobile facilities that will be deployed at EarthCARE orbital crossing points inGreece
The project consortium will use quality-assured instrumentation including (…). For the TOA EarthCARE
product validation, satellite multi-sensor synergies will be utilized, using aerosol and cloud retrievals frompassive sensors in polar (e.g. MODIS, VIIRS) and geostationary (e.g. SEVIRI) orbits but also solar radiation
retrievals acquired by CERES and TOA Radiation GERB/SEVIRI product. In terms of scientificrequirements, (…)

7

Overview and feedback - Evaluation of EarthCARE Radiances andFluxes with CERES Data Products – Dr Norman Loeb (NASA Langley)
Summary

Validation approaches and strategies:(…) The proposed work consists of four parts,

BBR and CERES unfiltered radiance comparisons:
Unfiltered radiances are compared using collocatedfootprints. We will use collocated BBR and CERES Aqua or
S-NPP footprints near 80-degrees North. Similar
comparisons have been made using CERES instruments on
Terra and Aqua.

1) evaluation of broadband radiances observed by the BBR instrument with co-located broadband
radiances observed by CERES instruments,
2) evaluation of broadband top-of-atmosphere (TOA) fluxes derived from BBR radiance observations withco-located CERES- and geostationary-derived TOA fluxes,3) evaluation of EarthCARE computed TOA and surface fluxes with fluxes derived from CERES algorithms andBBR and CERES TOA observed flux computations:surface observations, andInstantaneous shortwave and longwave TOA fluxes derived4) evaluation of EarthCARE cloud properties with cloud properties derived from Moderate Resolution Imaging
from BBR will be compared with CERES values from theSpectroradiometer (MODIS) and geostationary satellites with the CERES cloud algorithm, and evaluation oflevel-2 CERES Ed4 SSF product. In addition, EarthCARE
other input variables such as surface albedos and temperature and humidity profiles used in flux computations.
TOA fluxes derived from angular distribution models will be
The first part directly addresses the calibration of the BBR instrument relative to calibration of CERES
compared with TOA fluxes derived from geostationary
instruments. The second part of the proposal examines how angular distribution model differences lead tosatellite observations.
TOA flux differences. Because EarthCARE uses shortwave and longwave angular distribution models that
Computed TOA and surface flux computations:differ from those used by CERES, TOA flux differences will likely significantly exceed instrument calibration
Instantaneous TOA and surface fluxes from EarthCARE
differences.
products will be compared with CERES computed(…)
instantaneous TOA and surface fluxes using collocated
The above four proposed activities also provide an opportunity to evaluate the CERES radiance and flux
footprints with observation time separation of less than 15
products. The radiance comparisons provide an independent check on CERES calibration. Because BBR
minutes.
provides broadband radiances at three different angles from the same geolocation over its ground track, BBR
Surface flux evaluation with surface observations:observations are unique and provide an ideal dataset to test CERES angular distribution models. In
Currently, the CERES team uses surface flux observations ataddition, BBR-derived TOA fluxes provide an evaluation of TOA fluxes inferred from geostationary satellite
46 buoys and 36 ground sites.
imagers using narrowband to broadband conversions. Comparisons of surface fluxes and inputs used for flux
8computations also enable evaluation of CERES surface fluxes and inputs. (…).

Overview and feedback - EarthCARE BBR L1 and L2 Products
Assessment – Dr Nicolas Clerbaux (RMIB)
Summary

Proposal updates

BRR instrument performance and product quality will be thoroughly assessed by a seriesof validation activities. These will establish the quality of the level 1 instrument radiances atboth the nominal 10x10km² spatially integrated scale (B-NOM) and at detector level (BSNG). Assessment will address spatial and radiometric accuracy, consistency, stability,
noise and anomalous behaviour. Both level 1 and level 2 product assessment will useEarth reference targets including deep convective clouds and coastlines and co-incident
MSI observations to inform the analysis. The evaluation of the level 2 products (BM-RAD andBMA-FLX) will also involve comparisons against independent broadband measurementsfrom CERES, GERB or ScaRaB. Level 2 evaluation will provide assessment of both thelevel 2 processing and the quality of the underlying level 1 data.

•(…)

Drift of Terra and Aqua will be investigated to improved collocation

Common practices applied to QA/QC•

Simultaneous Nadir Overpass(SNO) ( NOAA/NESDIS )•Deep Convective Clouds•

Statistical analysis of BBR detector signals•

Comparison of BBR with MSI Narrowband-to-Broadband

Validation approaches and strategies:•CERES and BBR have different Spectral Responses. If errors in thecomparison of unfiltered radiances are found, comparisons between filteredradiances will be considered after wavelength differences compensation.

Assessment during the 6 months commissioning phase will put primary focus on the level 1
data to establish basic data integrity, noise characteristics, gain stability and the effect ofchopper drum speed on the science products. Results will inform discussions on theoptimum operating configuration and provide recommendations for the lifetime of themission. A preliminary BBR validation report will document the results for the Commissioning
Phase review.

•Matching of observations in place and time → ~NOAA-20 (CERESFM6) DN 12:40 and BBR DN 14:00 Aqua AN 13:30 (drift in 2023?), Terra
AN 10:30 (drift in 2021?),

Over the 3 year mission, products will be further evaluated and monitored, with changes toinstrument response regularly assessed. Dedicated analysis of level 2 products may result
in recommendations for updates to the level 2 processing (e.g. BBR radiance unfiltering orradiance to flux conversions). All findings will be consolidated in a BBR validation reportprovided to ESA at end of the project, 3 years after commissioning.

•A priori CERES SSF will be used. EBAF-like corrections to beinvestigated with the CERES team.

(…)•CERES PSF size is bigger than BBR swath (maximum 18 km nadir) :Need to use MSI to improve matching•Statistical validation analysis according to scene type•
Selection of geophysical scenes for validation: Deep Convective
Clouds, snow, desert, VAS site (Spain)
9

BBR part of the “Radiation” session• Introduction of proposals and feedbacks received (N.
Clerbaux, RMIB)• Lessons Learned from CERES (K. Priestley, NASALangley)• Lessons learned from GERB (Jacqui Russell, Imperial CollegeLondon)• Discussions

10

BBR part of the “Radiation” session• Introduction of proposals and feedbacks received (N.
Clerbaux, RMIB)• Lessons Learned from CERES (K. Priestley, NASA Langley)• Lessons learned from GERB (Jacqui Russell, ImperialCollege London)• Discussions

11

BBR part of the “Radiation” session• Introduction of proposals and feedbacks received (N.
Clerbaux, RMIB)• Lessons Learned from CERES (K. Priestley, NASA Langley)• Lessons learned from GERB (Jacqui Russell, Imperial CollegeLondon)• Discussions

12

BBR L1 & L2 Validation : Discussion Topics•

IOCV : adequacy of IOCV for BBR L1 (see presentation of Kostka Wallace). Are all the planned activities are sufficient ?
Adequate? Why not to operate BBR during the first 2 months of commissioning? What about acquisition at different chopper
drum mechanism speed?

•BBR L1 / L2 Cal/Val approaches : which reference instrument will be available? collocation, spatial-temporal matching? Driftof Terra and Aqua : problem or opportunity ?

•Synergies with MSI? Excellent for nadir view but quid off-nadir views?

•Ground Sites / Campaigns ( Satellite overpass over Validation Sites): “the injection orbit will be established in September
2021 but nevertheless further details will be decided in a later state. Even once established the orbit will vary by +/- 25 km.
Detailed orbit predictions can only be given several days in advance”. Is it okay for Univ. Valencia and Dr. Hu?

•CERES campaign in PAPS? Is it possible with the limited swath of BBR?

•Foster collaboration : seek for possible synergies between the different ECVTs. (eg comparisons CERES – EarthCAREBBR). Define responsibilities? Working groups? Visiting scientist? Develop and share common tools (collocation, etc...)?
Technical aspects: programming language, format, …

•Are there missing expertize ? Aluminum mirror degradation (expertize in ScaRaB?), aging of the forward view?

•BBR L2 “domains” : are they sufficient/adequate? Are there new requests/requirements for the BM-RAD JSG product?

•(…)

13

BBR IOCV slides from Kostka Wallace

14

BBR calibration concept
LW and SW data from 3 telescopes; LW data retrieved via subtraction of SW from TW channel.
•Requires knowledge of the instrument and scene spectral response.
Unfiltering can be enhanced with use of MSI data to improved the scene spectral correction factor

BBR calibration approach:• TW: Two point calibration using hot & cold blackbodies•

Performed on-board automatically, every 90 s, for removal of
signals offset (instrument self emission) & gain determination.

• SW: SW aging data from solar illuminated diffusor.
•Collected over 30 orbits, every 2 months.

•Monitor Photo Diodes in the telescope baffles assess aging of thediffuser and filter.

•L1B products used to plot SW gain ratio, LW spectral correction
factor and filter transmission for expert assessment of any needto update CCDB parameters (review every 6 months)
15

BBR IOCV concept
During Commissioning:•Switch on, decontamination (12 hr), health status check (telemetry in limits), functional check (mode changes,mechanism movements etc.)•Detector raw data check (comparison of raw mode and processed output in the instrument ISP to verify onboard DSP.)•LW performance check from standard L1b data product (gain, LW radiance noise, gain stability).
Possible updates to blackbody power, calibration interval.

•SW calibration collects data for in-flight reference and any update of calibration parameters
Performance check compares data against Visible Calibration (VisCal) system on-ground reference
characterization and calibration 2 months later (MPD noise and collection of in-flight aging reference SW
gain ratio, LW spectral correction factor and filter transmission)•

Detector linearity check via swap of powers to hot and cold BBs over several hours with instrument continuous
operation
Repeated 6 monthly, although no linearity change is expected
16

BBR key calibration parameters
measuredpre-flightmeasured
in-flight

applied in-flight

Data frequency

SW gain ratio, BüDerived fromBBR_SOL_1B

ü CCDB

Collect 2 mo,assess 6 mo

LW spectral correction factor, Aü

Derived from
BBR_SOL_1B

ü CCDB

Collect 2 mo,assess 6 mo

SW filter transmission, <𝜏 > 𝑆𝑊ü

Derived from
BBR_SOL_1B

ü CCDB

Collect 2 mo,assess 6 mo

BBR_LIN_1B

ü CCDB

6 mo

Detector linearity

ü

Detector gain, GLWüDerived from
BBR_LIN_1B

ü CCDB

90 s

TW calibration intervalüDerived from
BBR_LIN_1B

On-board

90 s

Offset and gain stability

üDerived from
BBR_LIN_1B

ü CCDB

90 s

MPD noiseüBBR_SOL_1B

ü CCDB

Collect 2 mo,assess 6 mo
17

10 km along-track integration

Integration areas (PSF)
On BBR grid:• 10 km x 10km : Standard resolution• 5 km x 10km : Small resolution• Full swath x 10km : Full resolution, nocombined flux
resolutions sampled @1km
On Joint Standard Grid (JSG):• 5 JSG x 21 JSG : Assessment Domain(configurable)• JSG pixel: only SW and LW radiances
Resolutions sampled @ 1JSG

AD PSF
definition

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BM-RAD product: spatial resolutions
X-JSG

BM-RAD
B-NOM(B-SGN)
M-NOM
M-CM
X-MET

SW
MSI-based(JSG)

SW/LW
stand-alone(JSG)

BM-RAD-JSG
JSG pixel

BM-RAD-FULL
17/28 (nadir/oblique) x 10 km

BM-RAD-STD
10 x 10 km

SW/LW
stand-alone(BBR grid)

SW
MSI-based(BBR grid)

SW/LW
stand-alone(BBR grid)

SW
MSI-based(BBR grid)

SW (nadir)
MSI-based(JSG)

BM-RAD-JSG-PSFcorrected
JSG pixel

BM-RAD-SMALL
5 x 10 km

SW/LW
stand-alone(BBR grid)

SW/LW(nadir)stand-alone(JSG)

BM-RAD-Assessment
5x21 JSG pixels

SW
MSI-based(BBR grid)

SW/LW
stand-alone(JSG)SW
MSI-based(JSG)

BM-RAD radiances at AD(5x21 km) will be used in BMA-FLX
and ACMB-DF

1919