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Mathieu ReverdyHélène Chepfer

Workshop EECLAT21-23 janvier 2013

Implementation of ATLID/Earthcare lidar simulator within

CFMIP–Observation Simulator Package

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• Merge of CALIOP (since 2006) and ATLID (2015) lidar data. => decade cloud dataset for evaluation of cloud description in

climate models within (CFMIP).

• COSP is adapted to ATLID capability.

• With ACTSIM, we diagnose cloud cover in GOCCP that 532 nm spaceborn lidar (such as CALIOP) would have observed from space. We have adapted this lidar simulator to 355 nm, corresponding to ATLID.

• With ECSIM (lidar simulator), we produce “Level 1 like” data for CALIOP and ATLID.

• first stage to build GOECP consistent with CALIPSO-GOCCP.

Introduction

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• COSP package + model LMDZ4 for cloud fractions. • ACTSIM (532 nm and 355 nm) to compare CALIOP/ATLID results.• ECSIM to produce “Level 1 like” CALIOP and ATLID data.

Method

CALIOP ATLID532 nm 355 nmNormal HSRL

FOVAltitude 705 km 393 km

WavelengthResolution

130 μrad 80 μrad

• Effects of Multiple scattering.• Effects of wavelength.• Effects of cloud detection threshold.• Total attenuated backscatter.• etc...

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Effects of Multiple scattering 1/2

High Level Cloud (CLH)> 6.5km

CALIOP ATLID

Differences

• MSC0.7-MSC0.3

• Low differences for CALIOP ~ 1-2%.• Larger differences for ATLID (factor 10: 10-20%) and near Poles ~40-50%.

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Low Level Cloud (CLL)< 3.2km

CALIOP ATLID

Effects of Multiple scattering 2/2

Differences

• MSC0.7-MSC0.3

• Differences comparable between CALIOP and ATLID ~ +/- 10%.

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Effects of wavelength

CALIOP-ATLID

CLH

CLL

• Left: MSC0.7-MSC0.7 / Right: MSC0.3-MSC0.3

• CLH 0.7: Important differences over North Pole and tropical belt (convective spots).• CLH 0.3: Less differences over North Pole. Still important over tropical belt. • CLL 0.7 and 0.3: Differences comparable between CALIOP and ATLID.

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Effects of cloud detection threshold

CLH

CLL

CALIOP-ATLID

• Left: MSC0.7-MSC0.7 / Right: MSC0.3-MSC0.3 • SRCALIOP=5 / SRATLID=2 best threshold•Small differences around convective spots for CLH. Small differences near North Pole for CLL.

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ECSIM

• Medium scene: 150x100 km. Clouds at 5 km and 10km of altitude.• Level 1 CALIOP and ATLID files. => estimation of ATB (total attenuated backscatter) for different profils.• 480m averaging to fit ACTSIM resolution. => Vertical profil correlation >0.83 but for molecular signal only (0.20)

Full Resolution Damaged Resolution

CALIOP

ATLID

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• Molecular ATB profils at 1064nm, 532 nm and 355 nm.• Good agreement between.

• Cloud detection threshold:SR=5 for CALIOPSR=2 for ATLID

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• Adapt the COSP lidar simulator to ATLID.• Sensitivity tests with wavelengths, cloud detection thresholds, etc...• Use ECSIM through different scenes (only one shown).• Compare theory with simulation outputs.

• Next studies:

Use WRF with ECSIMFocus on Signal to Noise Ratio, FOV, altitudes and HSRL resolution.Write GOECP

Conclusions and Outlook