Implementation of ATLID/Earthcare
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Implementation of ATLID/Earthcare lidar simulator within CFMIP–Observation Simulator Package. Mathieu Reverdy Hélène Chepfer. Workshop EECLAT 21-23 janvier 2013. Introduction.

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Mathieu Reverdy Hélène Chepfer

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Mathieu reverdy h l ne chepfer

Implementation of ATLID/Earthcare lidar simulator within CFMIP–Observation Simulator Package

Mathieu Reverdy

Hélène Chepfer

Workshop EECLAT

21-23 janvier 2013


Mathieu reverdy h l ne chepfer

Introduction

  • 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.


Mathieu reverdy h l ne chepfer

Method

  • 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.

  • Effects of Multiple scattering.

  • Effects of wavelength.

  • Effects of cloud detection threshold.

  • Total attenuated backscatter.

  • etc...


Mathieu reverdy h l ne chepfer

Effects of Multiple scattering 1/2

CALIOP

ATLID

High Level Cloud (CLH)

> 6.5km

Differences

  • MSC0.7-MSC0.3

  • Low differences for CALIOP ~ 1-2%.

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


Mathieu reverdy h l ne chepfer

Effects of Multiple scattering 2/2

CALIOP

ATLID

Low Level Cloud (CLL)

< 3.2km

Differences

  • MSC0.7-MSC0.3

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


Mathieu reverdy h l ne chepfer

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.


Mathieu reverdy h l ne chepfer

Effects of cloud detection threshold

CALIOP-ATLID

CLH

CLL

  • 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.


Mathieu reverdy h l ne chepfer

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


Mathieu reverdy h l ne chepfer

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

  • Good agreement between.

  • Cloud detection threshold:

    SR=5 for CALIOP

    SR=2 for ATLID


Mathieu reverdy h l ne chepfer

  • Conclusions and Outlook

  • 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 ECSIM

    Focus on Signal to Noise Ratio, FOV, altitudes and HSRL resolution.

    Write GOECP


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