Lessons learned from the Aeolus DISC and Cal/Val
Oliver Reitebuch (DLR) with contribution from the Aeolus DISC and ESA colleagues
2nd ESA EarthCARE Validation Workshop
25-28 May 2021 (online)
ESA UNCLASSIFIED – For ESA Official Use Only1

Lessons learned from the Aeolus DISC and Cal/Val

Oliver Reitebuch1, Isabell Krisch1, Christian Lemmerz1, Oliver Lux1, Uwe Marksteiner1, Nafiseh Masoumzadeh1, Fabian Weiler1, Benjamin Witschas1,Fabio Bracci2, Markus Meringer2, Karsten Schmidt2, Dorit Huber3, Ines Nikolaus4, Frédéric Fabre5, Phil McGoldrick5, Michael Vaughan6, Katja Reissig7,Alain Dabas8, Thomas Flament8, Adrien Lacour8, J.-F. Mahfouf8, M. Savli8, Dimitri Trapon8, Vivien Pourret8, Saleh Abdalla9, Lars Isaksen9, Michael Rennie9,
Angela Benedetti9, Julie Letertre-Danczak9, Dave Donovan10, Jos de Kloe10, Gert-Jan Marseille10, Ad Stoffelen10, Gerd-Jan van Zadelhoff10, Ping Wang10,
Gaetan Perron11, Sebastian Jupin-Langlois11, Joost Smeets12, Bas Pijnacker Hordijk12, Simone Bucci13, Giacomo Gostinicchi13, Sebastian Bley14, FrithjofEhlers15, Thomas Kanitz15, Anne-Grete Straume15, Denny Wernham15, Emilio Alvarez15, Jonas von Bismarck16, Peggy Fischer16, Marta De Laurentis16,Tommaso Parrinello16
1DLR, Institute of Atmospheric Physics, Germany 2DLR, Remote Sensing Technology Institute, Germany 3DoRIT, Germany 4Physics Solutions, Munich University of Applied

Sciences, Germany 5 Les Myriades, France 6OLA, UK 7IB Reissig, Germany 8Météo-France, France 9ECMWF, UK, 10KNMI, The Netherlands 11ABB, Canada 12S&T, The
15ESA-ESTEC, The Netherlands 16ESA-ESRIN, Italy
Netherlands
13serco,Italy 14 TROPOS,Germany
Aeolus
CAL/VAL andScience Workshop,2-6 November20202

Outline of the talk Aeolus mission, highlights andperformance Aeolus processor and productevolution

 Validation of Aeolus products,communication and tools
ESA UNCLASSIFIED - For Official Use

2nd ESA EarthCARE Validation Workshop | 25-28/05/2021 | Slide 3

Aeolus Data Innovation and Science Cluster (DISC)DISC Kick-OFF at DLR, February 2019

Reprocessing

Funded by

ESA UNCLASSIFIED - For Official Use

2nd ESA EarthCARE Validation Workshop | 25-28/05/2021 | Slide 4

Aeolus wind and aerosol observations
polar orbit, sun-synchronous7 day repeat cycle with 111 orbits≈ 16 orbits / dayaltitude 320 km

6200 wind profiles of
1 wind component
per day : 5-6 times
more than radiosondes

altitude up to 30 km
resolution 0.25 – 2 km
24 range bins

Level 1B: calibration, signal levels
Level 2A: aerosol product: ATB, β, α, S
Level 2B: HLOS wind speed
Level 2C: ECMWF model winds along track

requirements:
random error 1 – 2.5 m/s
systematic error <0.7 m/s

Fig. ESA / ATG-medialab

5

Aeolus highlights during first 33 months in orbit

Commissioning Phase
E1 Review
January 2019

Publicrelease ofL2A productin June 2021

Hot-Pixel fix operational on 14/06/19
Rayleigh HLOS wind in m/s

Data release
to Cal/Valteams on
18/12/2018

First wind on 12 Sept 2018

Altitude in m

Launch on
22/08/2018

June 2019

9 January 2020

May/June 2020:

Preparation of
Aeolus Follow-On
started in 2020

Aeolus winds are used bynational weather services(DWD, Météo France) for
daily weather forecasts(also caused by thedecline in aircraft data)

20 April 2020:
12 May 2020:
Public release of wind products

M1 temperature correctionactivated in Aeolus processor

Wind bias before and after implementation of theM1 temperature correction © ECMWF
Reduction in meteorological observations
from aircraft in Europe © DWD

ESA UNCLASSIFIED - For Official UseAeolus SAG – ESRIN – 28 Jan 2020

2nd ESA EarthCARE Validation Workshop | 25-28/05/2021 | Slide 6

Fig. compiled by I. Krisch (DLR)

Monitoring of wind data quality at ECMWF
ECMWF operational monitoring of Aeolus Rayleigh and Mie winds
Rayleigh clear

Mie cloudy+1 m/s in 12 months
minor trend: dominated by βcloud

Laser FM-ALaser FM-A
Laser FM-B
Relaxed QC:••−> 15/ rejected

Laser FM-B
QC:−> 10/ rejected

O-B: Difference
random error is currently in the order of 5.5-6.5 m/s for Rayleigh winds and 3.5-4.5 m/s for Mie winds (mostly clouds):
between Aeolus
observation andrandom errors in both channels increased since launch and show some decrease due to L2B processor improvements
ECMWF forecasted
systematic errors (bias) for both Mie and Rayleigh winds (several m/s) showed strong slow drifts, orbital variations,
HLOS winddifferences for ascending and descending orbits, and occurrence in some range-gates
Data quality reports available online:
https://earth.esa.int/eogateway/instruments/
 Since 20 April 2020 global mean bias for both channels around 0 m/s
aladin/quality-control-reports
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2nd ESA EarthCARE Validation Workshop | 25-28/05/2021 | Slide 7

Figures M. Rennie (ECMWF) et al., 2021, QJRMS, revisedEvolution of ALADIN laser energy and signal levels> 70 mJUV laser energy

65 mJ

internal path signalatmosphericpath signal

Fig. O. Lux (DLR) andLux et al. (2020), Opt. Lett.: laser

SIOP-02 – 11 May 2021

8 / 16

Hot pixel correction implemented on 14-06-2019

4 major causes for wind bias
identified and corrected
Combination of several unexpected error sources withdifferent temporal characteristics
1. Higher dark current rates for some “hot pixels”
 Corrected on 14 June 2019

Weiler et al., AMTD 2020

90°N

11.95

75°N

3. Slow drifts in the illumination of the Rayleigh/Miespectrometers causing a slowly, linear drifting constantbias
 Corrected with Baseline 09 (20 April 2020)

60°N

4. Thermal variations of the M1 telescope mirror
 Corrected with Baseline 09 (20 April 2020)
2 remaining causes for Rayleigh/Mie winds identified

30°S

ESA UNCLASSIFIED - For Official Use

Mean telescope M1 mirror temperatures

11.90

45°N
30°N
11.85

15°N
0°
15°S

11.80

M1 Temp. / °C

2. Error in the on-board software in calculation of residual
projection of the satellite ground speed on the line-ofsight LOS
 Corrected with Baseline 11 (08 October 2020)

45°S
11.75

60°S
75°S
90°S

July 1 – Oct 25, 201911.70

2nd ESA EarthCARE Validation Workshop | 25-28/05/2021 | Slide 9Figures by F. Weiler (DLR) et al., 2020, AMTD, Weiler et al (2021), under preparation

FSOI (Forecast
Sensitivity Observation Impact)
for period 3 July to27 Sept 2019 by
instrument type
Aeolus has second
highest impact ofany satellite
instrument – after
NOAA 20 ATMS
radiances; ≈Metop-B IASI

Aeolus mission objective
to demonstrate positive
impact on NWP is achieved

 For this period with good atmospheric signal withreprocessed L2B, Aeolus provides 4.8% relative FSOIAeolus ≈ radiosondes, > scatterometer & GPSRO Shows the importance of wind profile observations
in NWP even with higher random errors thanrequirements => impact could be even significantly
higher for mission requirements

Aeolus L2B
Fig. M. Rennie (ECMWF) et al., 2021, QJRMS, revised
ESA UNCLASSIFIED - For Official Use

2nd ESA EarthCARE Validation Workshop | 25-28/05/2021 | Slide 10

Outline of the talk Aeolus mission, highlights andperformance Aeolus processor and productevolution

 Validation of Aeolus products,communication and tools
ESA UNCLASSIFIED - For Official Use

2nd ESA EarthCARE Validation Workshop | 25-28/05/2021 | Slide 11Aeolus operational processors and data productbaseline updates every 6 months
Baseline 12New processor versions from DISC and baseline
update for NRT and reprocessing every 6months with improvements in data quality for
all products from L0-L1A-L1B-L2A-L2B andcalibration processors

Next baseline update to baseline 12 product's
will take place on May 26, 2021 => public datarelease of L2A aerosol products in June 2021

First re-processed data set FM-B period 2019was made publicly available in October 2020

Currently second re-processing campaign is ongoing covering FM-B period until October 2020:
will be available in September 2021

ESA UNCLASSIFIED - For Official Use

L2C Wind processor:
ECMWF model
analysis, background

Reprocessing further enhances data quality
Oct. 2020
FM-B 2019
dataFall 2021
FM-B 2019 –Oct 2020

Spring 2022

End 2022

FM-A dataCompleteMission

L1B+L2A processor by D. Huber (DoRIT)
L2B processor by J. de Kloe (KNMI)
ACMF calibration processors by ABB+S&T
2nd ESA EarthCARE Validation Workshop | 25-28/05/2021 | Slide 12

Exploitation of synergies between Aeolus and EarthCARE
for the first High-Spectral Resolution Lidars in SpaceATLID (Heliere et al. 2012)

range-bin number

ALADIN (ESA 2008)# of measurement
ESA UNCLASSIFIED - For Official UseEarthCARE Feature Mask wasadapted and refined by KNMI
(DD, GJvZ) to Aeolus needs
using and re-coded for
operational L2A processor
V. 3.12 by DoRIT/Reissig(February 2021); is available inL2A products for baseline 12

Currently Aeolus version of theATLID Optimal Estimation
Operationalalgorithm (DD) is implemented
L2A Aeolus
in operational code for summerFeature Mask
delivery of L2A V3.13: will be
FM probabilities
available for baseline 13 in
Sept. 2021
Figure by D. Huber(DoRIT)
2nd ESA EarthCARE Validation Workshop | 25-28/05/2021 | Slide 13

L2A
SCA

available in
Sept 2021
in L2Aproducts

MLEAELPRO
Level 2B
wind
processor
opticalproperties
code

Range bin index

available in
L2A productBackscatter coefficient Mm-1sr-1Aeolus Level 2a product backscatter coefficient

Orbit 6142
(Sept 2019)

L2B
OPC

ESA UNCLASSIFIED - For Official Use

100200BRC

300400

2nd ESA EarthCARE Validation Workshop | 25-28/05/2021 | Slide 14

Figure F. Ehlers (ESA), Ehlers et al., AMTD, in preparation
Th. Flament (Météo-France) et al. AMTD, in preparation

Outline of the talk Aeolus mission, highlights andperformance Aeolus processor and productevolution

 Validation of Aeolus products,communication and tools
ESA UNCLASSIFIED - For Official Use

2nd ESA EarthCARE Validation Workshop | 25-28/05/2021 | Slide 15

Validation of Aeolus aerosol product with ground based lidar

 Ground-based lidars measuring backscatterand extinction coefficient and depolarization at 355 nm are key for the validationof the Aeolus aerosol products L2A
 Ground-truth needed for assessment ofAeolus radiometric performance („photonbudget“) for Mie channel (on-going) Routine observatations over longer period(>1 yr) needed due to only few colocations
 Active Cal/Val teams (funding!) withexpertise in data product quality
ESA UNCLASSIFIED - For Official Use

Figure H. Baars (TROPOS) et al., 2021, GRL

2nd ESA EarthCARE Validation Workshop | 25-28/05/2021 | Slide 16

Airborne validation with 2 wind lidars on DLR Falcon
AVATARI example: North Atlantic Jet Stream
east of Greenland on 16/09/19

Flight direction

AVATARI 201909/09 – 01/10

WindVal-III 201817/11 – 05/12
AVATARE 201924/05 – 05/06
AVATARTAeolus orbits
September 2021

ESA UNCLASSIFIED - For Official Use Three campaigns since Aeolus
launch: 34 research flights; >15000
km along the satellite track;different locations, seasons andAeolus mission phases• Validation of wind errors and their occurence analyzed withnominal and reprocessed Aeolus data  recommendations for
Aeolus processor evolutions; QC advice for the Cal/Val community
Witschas et al. (2020), AMT, Lux et al. (2020), AMT
2nd ESA EarthCARE Validation Workshop | 25-28/05/2021 | Slide 17

Figure: Ch. Lemmerz (DLR)

Balloon campaigns for wind validation in stratosphere

TAPAPA/
Stratéole2
Fig. A. Hertzog (LMD) et al., 2020, Cal/Val workshop

GoogleLoon
Fig. S. Bley (ESA, TROPOS)ESA UNCLASSIFIED - For Official Use

2nd ESA EarthCARE Validation Workshop | 25-28/05/2021 | Slide 18

Interactive exploitation of Aeolus via VirES
https://aeolus.services

Currently interface to Python
under development (VirtualResearch Environment) to support
Cal/Val teams and automatedprocessing
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2nd ESA EarthCARE Validation Workshop | 25-28/05/2021 | Slide 19

Communication
Aeolus Cal/Val ––Communication
WIKI, workshops, papers
Cal/Val Workshop ESRIN, March 2019

Aeolus
Cal/ValWiki
8 accepted, 23 under review

ESA UNCLASSIFIED - For Official Use

https://www.aeolus.esa.int/
confluence/pages/
2nd ESA EarthCARE Validation Workshop | 25-28/05/2021 | Slide20

Summary of some lessons learned

Monitoring tools for instrument parameters (laser,temperatures, satellite), and product Level 1 and 2
are essential after launch; NRT monitoring using
model output from ECMWF was key for bias correction

Aeolus performance showed expected and unexpectedbehavior: laser, lidar signals, satellite, detector, thermal=> we are in continuous “commissioning” phaseStrong team of engineers/scientist with laser/lidarexpertise, algorithm, operational processor development,
NWP monitoring and impact within Aeolus DISC

Strong support of cal/val teams is essential for mission
success, e.g. ground, airborne, balloon, model => join
Aeolus validation in preparation of EarthCARE

Enhance cooperation between Aeolus and EarthCARE
teams for the benefit of both missions and in supportof an operational follow-on mission for Aeolus

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2nd ESA EarthCARE Validation Workshop | 25-28/05/2021 | Slide 21