ICAROHS
using E3SIM for the creation of realistic scenes
This talk has been motivated by requests from people wanting to know
if/how E3SIM could be used in support of ECARE Cal/Val.
GJ van Zadelhoff, D. Donovan (Bernadett Weinzierl, Andreas Petzold & ICAROHS team)
2nd ESA EarthCARE Validation Workshop
25-28 May 2021 (online)
ESA UNCLASSIFIED – For ESA Official Use Only

1ICAROHS Project (2009-2011; Andreas Petzold)§ Provide recommendations for future single and multi-λ HSRL instruments whichmeet the accuracy requirements of current aerosol-climate interactionmodeling.
§ Within ICAROHS a prototype spaceborne multi-λ capable HSRL forward models
was being developed within the EarthCARE Simulator§ For this realistic scenes were needed based on campaign data to ensure thatrealistic properties were forward modelled§ Realistic scenes can be used to perform:
1. Evaluation of HSRL lidar (ATLID) L1 data
2. Evaluation of retrieval algorithms
3. Sensitivity studies using the forward simulations and satellite instrument(ATLID) modes
4. Sensitivity studies determining retrieval uncertainties due to instrument
parameters and atmospheric assumptions (etc.)
5. The formulation of requirements for future airborne campaigns

Scene Creation Approach
DefineDefine field data sets (HSRL, aerosol insitu) for instrument model validation.

Build

Build E3SIM scenes from field data; treat
aircraft as low-flying satellite. One canalso use a ground-based station.

Evaluate

Evaluate E3SIM output against themeasured HSRL data; determine
accuracy.

AssessAssess E3SIM ATLID forward modelled
signals

real HSRL data

ECSIM sceneAs a reminder:
the E3SIM route would look like..
Retrievalofbeta,alpha,depol

Aux data(3D) field of
Scatteringtype andSize
Distribution
parameters !

L1 Validation +Radiometric assessment
Possible iterations
with different
instrument model
settings/adjustments

E3SIM UFF file

Check ?

Apply ECSIM
RT code(s) in
satellite mode
Apply ATLID
instrument
model

Apply ECSIM
RT code(s) interrestrial
mode
ApplyGround-based
lidar
instrument
model

Field data base used within ICAROHS
aerosol inlet

meteorologicalmeasurements

55
50

LACE

EUCAARI

45

latitude / deg

40

HSR Lidar
PCASP

35

FSSP-300DLR Falcon 20-E5max. altitude: 42.000 ft
max. endurance:
4h30

SAMUM-125• Mineral dust
§ Aged dust
§ Biomass burning aerosol
boreal fires
grassland fires§ Anthropogenic pollution§ Marine aerosol§ Volcanic ash

2015
10SAMUM-2

5-30

-25

-20-15-10-50

longitude / deg

5

1015

20

Particle size spectrum
Aerosol absorption
Mixing state
Backscatter
Extinction, lidar ratio
Depolarisation ratio@532, 1064
@532
@532, 1064

E3SIM scene creation input requirements
1. Extinction for every aerosol or cloud pointà Extinction from Rayleigh channel and Backscatter Ratio
2. Aerosol (cloud) particle size distribution, morphology, and phaseà In-situ measured PSD & mask
3. Cloud, aerosol, molecular mask

à Mask using Depolarization and lidar Ratio
4. Atmospheric conditions (T, P, RH, gases):à Radiosondes/ECMWF/in-situ
5. Instrument lidar (freq, fov etc) & flight information (height, speed etc.)

à Flight InfoSAMUM 1
19-05-2006

HSRL measurements

Icarohs final meeting: 27-01-2011

7

SAMUM 1
19-05-2006

HSRL measurements

Icarohs final meeting: 27-01-2011

Retrieval artifact8

For useful forward signals there is a need for higher resolution
extinction and layer boundaries
à Using backscatter ratio to update the retrieved Rayleigh based extinctionb mie + b ray Pmie + Pray
R==b rayPraya = b mie × SP( z )b ray = CairT ( z)For regions which consistsof the same aerosol type(masked using S and d)
and which have a similar
PSD: S is roughly constant.

P( z )
a = b mie × S = Cst × ( R - 1) ×T ( z)The mean lidar ratio for each aerosol region (S) is estimated by shifting
the lidar ratio distribution to match the Rayleigh retrieved extinction peak.
9Extinction from shifted backscatter ratio

Rayleigh extinction
Shifted R distribution
ECSIM scene
extinction
Extinction from Rayleigh channel

Icarohs final meeting: 27-01-201110

SAMUM 1
19-05-2006

Linking microphysics
and extinction•At each point the aerosol psd is scaled to match the local extinction•Aerosol-molecular separation is masked using the b-ratio (aerosols: R>1.3)

In-situ datameasured bythe DLR-Falcon

We used one PSD throughout the scene.
11

saharan dust layer - 4 june 2006

Height[km]Forward modeled Mie Co-polar signals

Height[km]

Measured Mie Co-polar signals

saharan dust layer - 4 june 2006

Height[km]Forward modeled Mie Co-polar signals

Height[km]

Measured Mie Co-polar signals

Mie co-polar signal (blue: calculated , black measured)Statistical comparison of ECSIM forward modelledand measured signals
Co-polar Mie 04-06-2006

Cross-polar Mie 04-06-2006

14

EUCAARI Example

13-05-2008
Extinction from the Rayleigh channel

Extinction
Ratio (3x)
Mask:
ICE, fromDust,BackscatterIndustrial pollution

Icarohs final meeting: 27-01-2011

15

EUCAARI Validation

13-05-2008
Measured Mie Co-polar signals

Modeled Mie Co-polar signals

Correlation

Aerosol TypeECSIM scattering type

0.79
0.87
0.66

Industrial pollution
Dust
Ice

H2SO4-25%
Spheroids
Ice

16

Forward modeling signals for Satellite instruments

Height [km]Mie EarthCARE

Height [km]Height [km]Mie Falcon

532nm Calipso

Lunchpraatje RK

17

Conclusion• Simulations (loosely defined) will play an important role in ATLID L1
validations.
• If simple approaches are not sufficient sophisticated approaches arepossible.

• The E3SIM(and like) approaches as shown is potentially powerful but very labor
intensive!
• It is not a direct validation!
• Scenes can be defined and evaluated in detail using active instruments and in-situ
observations.
• This may enable the use of a 532nm HSRL data for evaluation of EarthCARE data
• A single collocation (underflight) event can be extended for statistical analysis/error
analysis/representativity by modeling the entire flight as if it was seen by EarthCARE.
• At the same time E3SIM is far from a Plug-and-Play tool (and likely, practicallyspeaking, could never be made into one without significant resources andcommitment) !