CALIPSO climatological products: evaluation and suggestions from EARLINET
The CALIPSO Level 3 (CL3) product is the most recent data set produced by the observations of the Cloud–Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument onboard the Cloud–Aerosol Lidar and Pathfinder Satellite Observations (CALIPSO) space platform. The European Aerosol Research Li...
| Main Authors: | , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-02-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/16/2341/2016/acp-16-2341-2016.pdf |
| Summary: | The CALIPSO Level 3 (CL3) product is
the most recent data set produced by the observations of the
Cloud–Aerosol Lidar with Orthogonal Polarization (CALIOP)
instrument onboard the Cloud–Aerosol Lidar and Pathfinder Satellite
Observations (CALIPSO) space platform. The European Aerosol Research
Lidar Network (EARLINET), based mainly on multi-wavelength Raman
lidar systems, is the most appropriate ground-based reference for
CALIPSO calibration/validation studies on a continental scale. In
this work, CALIPSO data are compared against EARLINET monthly
averaged profiles obtained by measurements performed during CALIPSO
overpasses. In order to mitigate uncertainties due to spatial and
temporal differences, we reproduce a modified version of CL3 data
starting from CALIPSO Level 2 (CL2) data. The spatial resolution is
finer and nearly 2° × 2°
(latitude × longitude) and only simultaneous measurements are used for ease of
comparison. The CALIPSO monthly mean profiles following this
approach are called CALIPSO Level 3*, CL3*. We find good agreement
on the aerosol extinction coefficient, yet in most of the cases
a small CALIPSO underestimation is observed with an average bias of
0.02 km<sup>−1</sup> up to 4 km and 0.003 km<sup>−1</sup>
higher above. In contrast to CL3 standard product, the CL3* data set
offers the possibility to assess the CALIPSO performance also in
terms of the particle backscatter coefficient keeping the same
quality assurance criteria applied to extinction profiles. The mean
relative difference in the comparison improved from 25 % for
extinction to 18 % for backscatter, showing better
performances of CALIPSO backscatter retrievals. Additionally, the
aerosol typing comparison yielded a robust identification of dust
and polluted dust. Moreover, the CALIPSO aerosol-type-dependent
lidar ratio selection is assessed by means of EARLINET observations,
so as to investigate the performance of the extinction
retrievals. The aerosol types of dust, polluted dust, and clean
continental showed noticeable discrepancy. Finally, the potential
improvements of the lidar ratio assignment have been examined by
adjusting it according to EARLINET-derived values. |
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| ISSN: | 1680-7316 1680-7324 |