Preprints
https://doi.org/10.5194/egusphere-2022-438
https://doi.org/10.5194/egusphere-2022-438
 
31 Aug 2022
31 Aug 2022
Status: this preprint is open for discussion.

Incorporation of aerosols into the COSPv2 satellite lidar simulator for climate model evaluation

Marine Bonazzola1, Hélène Chepfer1, Po-Lun Ma2, Johannes Quaas3, David M. Winker4, Artem Feofilov1, and Nick Schutgens5 Marine Bonazzola et al.
  • 1Laboratoire de Météorologie Dynamique, École Polytechnique, Palaiseau, France
  • 2Pacific Northwest National Laboratory, Richland, WA, USA
  • 3Institute for Meteorology, Universität Leipzig, Leipzig, Germany
  • 4Nasa Langley Research center, Hampton, Virginia, USA
  • 5Vrije Universiteit, Amsterdam, Netherlands

Abstract. Aerosols have a large impact on climate, air quality, and biogeochemical cycles. Their concentrations are highly variable in space and time, and a key variability is in their vertical distribution, because it influences atmospheric heating profiles, aerosols life-time and, as a result, surface concentrations, and because it has an impact on aerosol-cloud interactions. On the side of model-oriented aerosols research, using a lidar aerosol simulator ensures consistent comparisons between the modeled aerosols and the observed aerosols. In the current study, we present the lidar aerosol simulator implemented within the COSPv2 satellite lidar simulator. We estimate the total attenuated backscattered signal (ATB) and the scattering ratios (SR) that would be observed at 532 nm by the lidar CALIOP overflying the atmosphere predicted by the E3SMv1 climate model. The simulator performs the computations at the same vertical resolution as the CALIOP lidar, making use of aerosol optics from the E3SMv1 model as inputs, and assuming that aerosols are uniformly distributed horizontally within each model grid-box. It applies a cloud masking and an aerosol detection threshold, to get the ATB and SR profiles that would be observed above clouds by CALIOP with its actual aerosol detection capability. Our comparison shows that the aerosol distribution simulated at a seasonal timescale is generally in good agreement with observations, with however a discrepancy in the Southern Hemisphere, as the observed SR maximum is not reproduced in simulations there. Comparison between cloud-screened and non cloud-screened computed SRs shows little differences, indicating that the cloud screening by potentially incorrect model clouds does not affect the mean aerosol signal averaged over a season. Consequently, the differences between observed and simulated SR values are not due to sampling errors, and allow to point out some weaknesses in the aerosol representation in models. The use of lidar observations at several wavelengths can give further indication on the nature of the aerosols that need to be improved.

Marine Bonazzola et al.

Status: open (until 26 Oct 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CEC1: 'Comment on egusphere-2022-438', Juan Antonio Añel, 21 Sep 2022 reply
    • AC1: 'Reply on CEC1', Marine Bonazzola, 23 Sep 2022 reply
      • CEC2: 'Reply on AC1', Juan Antonio Añel, 26 Sep 2022 reply
  • RC1: 'Comment on egusphere-2022-438', Duncan Watson-Parris, 03 Oct 2022 reply

Marine Bonazzola et al.

Data sets

CALIOP lidar level L1.5 profiles NASA Langley Atmospheric Science Data Center DAAC https://doi.org/10.5067/CALIOP/CALIPSO/LID_L15-STANDARD-V1-00

CALIOP SR profiles Marine Bonazzola https://doi.org/10.13140/RG.2.2.32924.97929

CALIOP ATB profiles Marine Bonazzola https://doi.org/10.13140/RG.2.2.27891.81442

Model code and software

COSPv2 simulator Rodrigo Guzman, Hélène Chepfer https://github.com/CFMIP/COSPv2.0

Marine Bonazzola et al.

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Short summary
Aerosols have a large impact on climate. Using a lidar aerosol simulator ensures consistent comparisons between modeled and observed aerosols. In the current study, we present a lidar aerosol simulator that applies a cloud masking and an aerosol detection threshold. We estimate the lidar signals that would be observed at 532 nm by the lidar CALIOP overflying the atmosphere predicted by a climate model. Our comparison at the seasonal timescale shows a discrepancy in the Southern Hemisphere.