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During the Covid-19 lockdown, the automatic CIMEL micro-pulse LiDARs continued profiling the atmosphere! The CIMEL micro-pulse LiDARs do not require supervised operation or human attendance, allowing recording continuous measurements during emergency situations like the Covid-19 lockdown.
An example of continuous measurements performed by the CE376-GPN micro-pulse LiDAR (532 nm polarized and 808 nm unpolarized) along with the CE318-T Sun/Sky/Lunar photometer at Laboratoire d’Optique Atmosphérique (LOA) in Lille, France are presented below (Fig.1).
Figure 1: Measurements by the CE376-GPN micro-pulse LiDAR along with the CE318-T photometer at LOA in Lille
Since the lockdown in France on 16 March 2020, the CIMEL micro-pulse LiDAR continues measurements, providing long time series of LiDAR data which will allow to study the impact of the lockdown on air quality.
On the examples above, two situations are presented during this period: low fine particle loading from urban background pollution and a desert dust intrusion event on 27 March 2020 (Fig.1, left) and low aerosol loading (fine particles from urban background pollution) on 5 April 2020 (Fig.1, right).
The daily mean AOD at 500 nm recorded by the CE318-T sun photometer was 0.35 for the dust event on 27 March 2020 and 0.1 for the “clean” conditions on 5 April 2020.
The desert dust intrusion event captured in CIMEL LiDAR data at Lille on 27 March 2020 is consistent with the Saharan dust intrusion forecasted by the NMMB/BSC-Dust model (See Fig.2 below), showing shallow dust layers in the 3 – 10 km altitude range (the dotted line on the dust forecast figure represents the location of Lille, France).
Figure 2: NMMB/BSC-Dust model
More recently, the CE376-GPNP micro-pulse LIDAR (Fig. 3) is operating at CIMEL in Paris, France, to provide more continuous data for the aerosols and clouds research community.
Figure 3: Measurements by the CE376-GPN micro-pulse LiDAR along with the CE318-T photometer at CIMEL in Paris