ALPHA reference lidar
24 Feb 2023

ACTRIS Centre for Aerosol Remote Sensing (CARS) organized on 12-30 September 2022 first intercomparison campaign of reference high-power lidar systems operated by the CARS Units in Romania and Germany, at MARS - Măgurele centre for Atmosphere and Radiation Studies, Romania. MARS hosts one of three lidar calibration laboratories in ACTRIS, being responsible for ensuring the quality of the data measured by the 42 ACTRIS lidar stations. The goal of the intercomparison campaign was to optimize the automatic procedure for being further implemented at all lidar stations.

Aerial view of the MARS observation site

Experts from the Ludwig Maximillian University, Munich with POLIS reference lidar joined specialists from Romania with RALI and ALPHA reference lidars in order to measure side-by-side and assess the performances of each of the systems. Moreover, experts from the University of Warsaw joined the campaign starting 19 September with the European Space Agency's EMORAL reference system. Quality Assurance tests were performed before sunrise and at noon, when weather permitted. Data was analyzed in parallel by experts (manual analysis) and with the automatic software newly developed at CARS – Centre for Aerosol Remote Sensing. 

CARS reference lidars intercomparison campaign results (selection)

Signal comparison at 355nm between POLIS and ALPHA for far range telescope AN

Results: Good agreement - AN 1.3 km – 12 km; PC 3 km – 20 km; Overlap around 1.3 km ALPHA; Lower overlap for POLIS


Signal comparison at 355nm between POLIS and RALI for far range telescope ANSignal comparison at 355nm between POLIS and RALI for far range telescope PC

Results: Comparison offset 500 m – 4 km, IFF – incidence angle; Good agreement PC4 km – 20 km
Noisier than 532 nm (daytime); Overlap around 500 m RALI; Lower overlap for POLIS