ACTRIS Aerosol Remote Sensing in support ofEarthCARE Cal/Val
Doina Nicolae – ACTRIS Centre for Aerosol Remote Sensing
Lucia Mona – Aerosl Remote Sensing unit @ ACTRIS Data Centre
2nd ESA EarthCARE Validation Workshop

25-28 May 2021 (online)
ESA UNCLASSIFIED – For ESA Official Use Only

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What is ACTRIS Aerosol Remote Sensing
The chain from data collection to QA/QC data products for aerosol remote sensing measurements•EARLINET•

Lidar stations•

Lidar Calibration Centre••Single Calculus Chain•

AERONET-EU
AERONET-Europe Calibration Service
AEROET-EU processing•Synergy:
GRASP/GARRLIC

Photometer stations•

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Attenuated backscatter profile
Volume depolarization profile
Particle backscatter coefficient profile
Particle extinction coefficient profile
Lidar ratio profile
Angstrom exponent profile
Backscatter related angstrom exponent profile
Particle depolarization ratio profile
Particle layer geometrical properties
Column integrated extinction
Column integrated extinction
Spectral Downward Sky Radiances
Direct Sun/Lunar Aerosol Optical Depth (column)
Aerosol columnar properties: fine and coarse
modes volume concentrations, size distribution,refractive index
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Aerosol remote sensing in ACTRIS
ARES
Aerosol Remote Sensing Unit at the ACTRIS Data Centre

ARES
Centralized dataprocessing

CARS
Centre for Aerosol Remote Sensing

CARS
Centralized support forQA/QC

ARS National Facilities
Stations operating co-located aerosol lidars andphotometers

ARS National Facilities
Aerosol lidar
Sun/sky/lunar photometer3

Aerosol remote sensing in ACTRIS
2021
Total: 30

2025
Total: 51

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Aerosol remote sensing data workflow
Before ACTRIS

Mainly based on the expertise of the PI
Long process
Differences in data treatment (the use of the SCC not mandatory)

Many rejected datasets (QC at the EARLINET db side)
Inhomogeneity of the datasets

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Aerosol remote sensing data workflow
Now in ACTRISCARS provides• Guidelines for instrument design and setup• Standard Operation Procedures• Standard Quality Assurance tests• Software tools for controlling the status of theinstrument at its location• Check of the photometer data

ARES ensures• Centralized processing of lidar raw datafiles –Single Calculus Chain (SCC)••• Aerosol profile and columnar data products:
various levels: partially (level 1) or fully (level 2)
quality assured•

CARS organizes• Annual calibration of photometers• Continuous QC of the photometer level 1 data
• Annual expert analysis of the lidar QA/QC tests• Occasionally (~ each 5 years) directcomparisons with reference lidars (funding!)

Blocking of configuration of the centralized sofware
Centralized automatic quality control of the data•••

High and low resolution total attenuated backscatter andvolume depolarization ratio time series
Aerosol extinction, backscatter, lidar ratio, angstromexponent and depolarization ratio vertical profiles
Columnar information and aerosol microphysical properties
profilesSynergistic lidar/photometer products as vertical profiles ofaerosol microphysical properties.

• Statistical analysis (including seasonality andannuality) of the most important aerosol opticalparameters (level 3)• Traceability of the data

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Aerosol remote sensing data workflow
Now in ACTRIS

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Previous experience (as a network)••

CALIPSO•EARLINET started correlative measurements for CALIPSO on 14 June 2006, i.e. at the beginning of theCALIPSO operation.

•NASA provides weekly forecast of CALIOP track with 1sec resolution•Overpasses distributed centrally to all the stations (100 km)•Data centrally flagged as CALIPSO overpasses relatedFollow-ups••

EARLINET worked on CALIPSO validation and exploitation even under ESA contract (like ESA-CALIPSOand LIVAS)AEOLUS•EARLINET & CLOUDNET (ACTRIS) are now working for Aeolus Cal/Val
Lessons learned from the validation of Aeolus L2A product with EARLINET, Nikos Siomos - NOA8

Attenuated backscattercomparison

Examples from CALIPSO Cal/Val
Level 1Methodology for Attenuated Backscattercomparison was developed and applied to
the network observations [Mona et al.,2009; Pappalardo et al., 2010]
Comparison of optical properties for feedback on
the methods/algorithms [e.g. Wandinger etal., 2010]
Evaluation of climatological products andinvestigation of potential improvements atclimatological scale in terms of typing/lidar
ratio assumptions [Papagiannopoulos etal., 2016]
Many studies combining CALIPSO andEARLINET data for a better understandingof 4d aerosol field characteristics[Pappalardo et al., 2010] and taking themost of high quality EARLINET data andCALIPSO coverage [Amiridis et al., 2015]

Optical properties comparison

Level 2
Level 2

Representativenessinvestigation

Climatological products

Level 3

Synergy CALIPSO-EARLINETaerosol model (LIVAS-AOD
climatology)

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Testing of the new workflow: ACTRIS/EARLINET COVID-19
campaign•Intensive observation campaign May 2020•••

21 participating stations
NRT processing  fast analysis  SCC server, notpublic
QA tests + measured meteorological fields  reanalysis  EARLINET/ACTRIS database, public
693 datasets collected3473 data products calculated> 2500 data products in the ACTRIS Data Portal•Fast processing and analysis of the existingmeasurements Jan. Apr. 2020

•CARS-ARES workshop, online, 6-8 July 2020••••

Coordinated studies
Technical aspects
Studies at individual stations
Publications
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Testing of the new workflow: ACTRIS/EARLINET COVID-19
campaign

Dust up
to 8 km

Marinepollutedup to 2km

Separation of dust andnon-dust backscatter@Antikythera; courtesyof Eleni Marinou et al.,NOA

Pollen as seen by thephotometer @Kuopio;
courtesy of Mika Komppulaet al., FMI

Preliminary findings••••

Slightly decreased AOD (photometer)
Slightly increased Angstrom (photometer and lidar), especially inthe low troposphere (lidar)
Less absorbing particles (lidar and photometer)
More non-spherical particles (lidar)

Detailed analysis on-going for several publications
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Work for EarthCARE
Use of a similar approach as for Calipso and Aeolus, but:
New workflows
More automatic data tagging and transfer is under development
New QA/QC procedures
Kind request:• Forecast of 1-sec resolution track of the lidar sensor → direct transfer to ARES (for the involved aerosol
remote sensing stations) → automatic tag “EarthCARE correlative”• Fast access to X-MET product (ARES) → NRT level 2 data products (correlative)• Fast access to ECMWF forecasted meteorological fields (ARES) → NRT level 2 data products (all)Advanced products based on QC EARLINET data and EarthCARE observations• Differences of correlated observations as a function of the interesting parameters (e.g. locations, day/night
conditions, aerosol type, observed ext/backscatter), annual release
Other specific needs for the Cal/Val?
• Please formulate them: higher frequency for dataset released, other parameters of interest, etc.?
• Can be accommodated through agreements and making use of access to virtual services of ACTRIS
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Thank you for your time.
https://www.actris.eu/

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