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Paper title Alpha-lidar: Continuous Daytime Raman Depolarization Lidar for ESA Cal/Val
Authors
  1. Livio Belegante National Institute of Research & Development for Optoelectronics, INOE, Magurele, Romania Speaker
  2. Doina Nicolae National Institute of R&D for Optoelectronics INOE
  3. George Giorgoussis Raymetrics
  4. Dragoș Ene National Institute of Research and Development for Optoelectronics INOE
  5. Alexandru Dandocsi European Space Agency
  6. Cristian Radu National Institute of Research and Development for Optoelectronics INOE
Form of presentation Poster
Topics
  • A1. Atmosphere
    • A1.09 EarthCARE: Preparing for the Scientific Mission Exploitation to Quantify the Impact of Clouds and Aerosols on Radiation
Abstract text Validation and calibration techniques for advanced space borne Earth observation instruments usually relies on ground based reference instruments to provide reference measurements able to assess the performance of the corresponding space instrument. The newly developed A-lidar instrument is one of the reference lidar instrument designed to meet all recommended requirements of the European Research Infrastructure for Short-lived Atmospheric Constituents - ACTRIS (actris.eu). The instrument aims to provide continuous data and will provide data to a wide range of users in order to facilitate high-quality Earth climate research.
The Alpha-lidar is designed to provide daytime backscatter, one daytime extinction, nighttime extinction and three depolarization products (3β, 1α-daytime + 1hsrl, 6α-nighttime, 3δ, 1 water vapour). To achieve these specifications, the instrument makes use of the rotational and vibrational Raman lines at 355, 532 and 1064nm. The instrument is designed to achieve full overlap around 200m for the primary lidar products like the raw and backscatter profiles and can go to lower altitudes for products where signal ratios are used (like the depolarization products).
The Alpha-lidar is split in an operational and an experimental part. The operational part is made up from three lasers and three telescopes, each emitter/receiver pair focusing on a different atmospheric property. The first receiver covers the elastic and Raman channels, the second is dedicated to the 532 and 355nm depolarization channels and the third receiver is dedicated to the 1064nm depolarization channels. In addition to the main lidar units, the instrument is also equipped with an experimental HSRL unit based on the Iodine filtering technique for 532nm. The entire instrument is enclosed in a custom container designed to accommodate the instrument for continuous operation in all weather conditions – see Figure 1.
The data retrieved with the instrument indicates good operation for both daytime and night-time setup. Once all quality assurance tests will be finalized, the instrument will be set for operational use and will be included in the operational programme of the Actris-RI as one of the reference instruments of the CARS central facility (Centre for Aerosol Remote Sensing).
The instrument could be one of the tools used in the EarthCARE and other similar mission in the validation programme. During the conference, several lidar derived products and associated errors, highlighting different atmospheric features will be presented. Product examples retrieved using the ACTRIS Single Calculus Chain are presented in Fig.2.

Acknowledgements:
The work performed for this study was funded by the Ministry of Research and Innovation through the Romanian National Core Program Contract No.18N/2019 and by the European Regional Development Fund through Competitiveness Operational Programme 2014–2020, POC-A.1-A.1.1.1- F- 2015, project Research Centre for environment and Earth Observation CEO-Terra.The research leading to these results has received funding from the European Union H2020, ACTRIS IMP grant no. 871115.