WP2 - Athens Campaign - NTUA / Level 3 - June 2023

WP2 – ATHENS CAMPAIGN – NTUA 21GRD02 BIOSPHERE. Project: 21GRD02 BIOSPHERE The project (21GRD02 BIOSPHERE) has received funding from the European Partnership on Metrology, co-financed by the European Union’s Horizon Europe Research and Innovation Programme and by the Participating States. Funded by the European Union. README.txt: o Instrument description and calibration status Two lidar systems were used to retrieve aerosol optical properties: the DEPOLarization lidar systEm (DEPOLE) and the elastic-Raman lidar system aErosol and Ozone Lidar system (EOLE). DEPOLE is based on a pulsed Nd: YAG laser emitting at 355 and 532 nm with linear polarization purity more than 99.5%, achieved using a polarizing filter. The elastically backscattered lidar signals are collected at both wavelengths by a 200 mm diameter Dall-Kirkham (f/4) Cassegrainian telescope and are separated into parallel and cross-polarization components using polarizing beam splitter cubes. DEPOLE achieves full overlap at approximately 500 m a.s.l. (Papayannis et al., 2020). DEPOLE provides vertical profiles of the aerosol elastic backscatter coefficient and volume and particle linear depolarization ratios VLDR and PLDR, respectively, at 355 and 532 nm, as well as the aerosol Ångström exponent between these two wavelengths (AE355/532). During BIOSPHERE Campaign we focused on 532 nm measurements from DEPOLE and also, aerosol mass concentration profiles for dust and non-dust components were estimated using the POLIPHON algorithm (Ansmann et al., 2012; Mamouri and Ansmann, 2014; Tesche et al., 2009), which combines depolarization lidar and sun photometer data. Depolarization lidar distinguishes dust from nondust aerosols from aerosol backscatter and depolarization profiles, while sun photometry provides fine/coarse-mode AODs and microphysical properties (volume and surface area). Mass concentrations were calculated using aerosol-specific properties like PLDR, lidar ratio, density, and volume-to-AOD ratios. To this end we used a coarse-mode density of 2.6 g cm−3 (dust) (Hess et al., 1998; Proestakis et al., 2024) and a fine-mode density of 1.35 g/cm−3 (smoke) (Engelhart et al., 2012; Reid et al., 2005). The method remains effective even when lidar and photometer data are not strictly collocated, especially for stable dust events. Total uncertainty in retrieved mass concentrations is ~36-40% and assumed mass densities (±20%). Volumeto-AOD ratios may vary by up to 10% for dust and 20% for smoke (Ansmann et al., 2012, 2019). The EOLE lidar system is based on a pulsed Nd: YAG laser emitting simultaneously at 355, 532, and 1064 nm. The receiving unit includes a 300 mm diameter (f/2) Cassegrainian telescope, which collects both the elastically backscattered signals and the vibrational-rotational Raman signals generated by atmospheric N₂ at 387 and 607 nm, and H₂O at 407 nm. EOLE provides vertical profiles of the aerosol backscatter coefficients at 355, 532, and 1064 nm, and extinction coefficients at 355 and 532 nm, as well as the water vapor mixing ratio in the troposphere. Additionally, EOLE provides vertical profiles of intensive aerosol parameters, including the lidar ratio (LR) at 355 and 532 nm, and aerosol Ångström exponents derived from extinction (AEe355/532) and backscatter (AEb355/532, AEb532/1064) coefficients. The system reaches full overlap at approximately 800 m a.s.l.. Based on these observations and using well-known methodologies, we can separate the lidar signals between aerosols and clouds, spherical and non-spherical particles in mixed aerosol layers (Ansmann et al., 2012, 2019; Tesche et al., 2009). EOLE (1) and DEPOLE (3) lidar systems along with their telescopes (2 and 4, respectively) are presented in Fig. 1. WP2 – ATHENS CAMPAIGN – NTUA 21GRD02 BIOSPHERE. o Calibration status The last calibration of the DEPOLE lidar system was performed on 17 July 2023, while the EOLE lidar was calibrated on 17 August 2023, during the campaign. A subsequent calibration was carried out for EOLE on 15 November 2023, following the QA/QC calibration standards of ACTRIS – Center for Aerosol Remote Sensing. Prior to the campaign, both lidar systems had been calibrated on 10 November 2022. o Measurement period and time standard The measurement period extends from 1 June 2023 till 30 August 2023. Each Level 2 file, which contains the non-smoothed lidar data, is name as: atyyyymmdd_starttime_stoptime_lvl2.nc (e.g. at20230601_1843_1935_lv2.nc) Similarly, each Level 3, which contains the smoothed lidar data, follows the format: atyyyymmdd_starttime_stoptime_lvl3.nc (e.g. at20230601_1843_1935_lv3.nc) Figure 1. EOLE (1) and DEPOLE (3) lidar systems along with their telescopes (2 and 4, respectively) in the Laser Remote Sensing Unit (LRSU) in the National Technical University of Athens (NTUA). (1) (3) (2) (4) WP2 – ATHENS CAMPAIGN – NTUA 21GRD02 BIOSPHERE. o Column names and units Both Level 2 and Level 3 .nc files follow a specific format with standardized column names and units, as described below: -DEPOLE Lidar System – Depolarization Variable Variable Description Units Height_amsl Height above mean sea level m Backscatter_532_dust Dust backscatter at 532 nm Mm-1 sr-1 Backscatter_532_non_dust Non-dust backscatter at 532 nm Mm-1 sr-1 Backscatter_532_total Total backscatter at 532 nm Mm-1 sr-1 Dust_mass_concentration Dust mass concentration μg m-3 Non_dust_mass_concentration Non-dust mass concentration μg m-3 Mass_concentration_total Total mass concentration μg m-3 PLDR_532 Particle Linear Depolarization Ratio at 532 nm dimensionless - EOLE Lidar System Variable Description Units Angstroem_backscatter_355_1064 Ångström exponent (backscatter 355/1064 nm) – Angstroem_backscatter_355_532 Ångström exponent (backscatter 355/532 nm) – Angstroem_backscatter_532_1064 Ångström exponent (backscatter 532/1064 nm) – Angstroem_extinction_355_1064 Ångström exponent (extinction 355/1064 nm) – Atmospheric_density Atmospheric density cm⁻³ Backscatter_1064 Backscatter at 1064 nm Mm⁻¹ sr⁻¹ Backscatter_532 Backscatter at 532 nm Mm⁻¹ sr⁻¹ Backscatter_355 Backscatter at 355 nm Mm⁻¹ sr⁻¹ Backscatter_532_dust Dust backscatter at 532 nm Mm⁻¹ sr⁻¹ Backscatter_532_non_dust Non-dust backscatter at 532 nm Mm⁻¹ sr⁻¹ Backscatter_532_total Total backscatter at 532 nm Mm⁻¹ sr⁻¹ Extinction_355 Extinction at 355 nm Mm⁻¹ Extinction_532 Extinction at 532 nm Mm⁻¹ Height_amsl_(b1064) Height (a.m.s.l.) for backscatter at 1064 nm m Height_amsl_(b532) Height (a.m.s.l.) for backscatter at 532 nm m Height_amsl_(b355) Height (a.m.s.l.) for backscatter at 355 nm m Height_amsl_(e532) Height (a.m.s.l.) for extinction at 532 nm m Height_amsl_(e355) Height (a.m.s.l.) for extinction at 355 nm m WP2 – ATHENS CAMPAIGN – NTUA 21GRD02 BIOSPHERE. Height_amsl_(density) Height (a.m.s.l.) for atmospheric density m Height_amsl_(LR,Angstroem) Height (a.m.s.l.) for Lidar Ratio and Ångström exponent m LidarRatio_355 Lidar ratio at 355 nm sr LidarRatio_532 Lidar ratio at 532 nm sr Dust_mass_concentration Dust mass concentration μg m⁻³ Non_dust_mass_concentration Non-dust mass concentration μg m⁻³ Mass_concentration_total Total mass concentration μg m⁻³ PLDR_532 Particle Linear Depolarization Ratio at 532 nm dimensionless o Contact person (name, email, institute) Marilena Gidarakou, [email protected] , NTUA, Athens, Greece Alexandros Papayannis, [email protected]ua.gr, NTUA ,Athens, Greece References Ansmann, A., Seifert, P., Tesche, M., and Wandinger, U.: Profiling of fine and coarse particle mass: case studies of Saharan dust and Eyjafjallajökull/Grimsvötn volcanic plumes, Atmospheric Chem. Phys., 12, 9399–9415, https://doi.org/10.5194/acp-12-9399-2012, 2012. Ansmann, A., Mamouri, R.-E., Hofer, J., Baars, H., Althausen, D., and Abdullaev, S. F.: Dust mass, cloud condensation nuclei, and ice-nucleating particle profiling with polarization lidar: updated POLIPHON conversion factors from global AERONET analysis, Atmospheric Meas. Tech., 12, 4849–4865, https://doi.org/10.5194/amt-12-4849-2019, 2019. Engelhart, G. J., Hennigan, C. J., Miracolo, M. A., Robinson, A. L., and Pandis, S. N.: Cloud condensation nuclei activity of fresh primary and aged biomass burning aerosol, Atmospheric Chem. Phys., 12, 7285– 7293, https://doi.org/10.5194/acp-12-7285-2012, 2012. Hess, M., Koepke, P., and Schult, I.: Optical Properties of Aerosols and Clouds: The Software Package OPAC, Bull. Am. Meteorol. Soc., 79, 831–844, https://doi.org/10.1175/15200477(1998)079%253C0831:OPOAAC%253E2.0.CO;2, 1998. Mamouri, R. E. and Ansmann, A.: Fine and coarse dust separation with polarization lidar, Atmospheric Meas. Tech., 7, 3717–3735, https://doi.org/10.5194/amt-7-3717-2014, 2014. Papayannis, A., Kokkalis, P., Mylonaki, M., Soupiona, R., Papanikolaou, C. A., Foskinis, R., and Giakoumaki, A.: Recent Upgrades of the EOLE and AIAS Lidar Systems of the National Technical University of Athens Operating Since 2000 in Athens, Greece, EPJ Web Conf., 237, 02030, https://doi.org/10.1051/epjconf/202023702030, 2020. Proestakis, E., Gkikas, A., Georgiou, T., Kampouri, A., Drakaki, E., Ryder, C., Marenco, F., Marinou, E., and Amiridis, V.: A near-global multiyear climate data record of the fine-mode and coarse-mode components of atmospheric pure-dust, Aerosols/Remote Sensing/Data Processing and Information Retrieval, https://doi.org/10.5194/amt-2023-262, 2024. WP2 – ATHENS CAMPAIGN – NTUA 21GRD02 BIOSPHERE. Reid, J. S., Eck, T. F., Christopher, S. A., Koppmann, R., Dubovik, O., Eleuterio, D. P., Holben, B. N., Reid, E. A., and Zhang, J.: A review of biomass burning emissions part III: intensive optical properties of biomass burning particles, Atmospheric Chem. Phys., 5, 827–849, https://doi.org/10.5194/acp-5-827-2005, 2005. Tesche, M., Ansmann, A., Müller, D., Althausen, D., Engelmann, R., Freudenthaler, V., and Groß, S.: Vertically resolved separation of dust and smoke over Cape Verde using multiwavelength Raman and polarization lidars during Saharan Mineral Dust Experiment 2008, J. Geophys. Res. Atmospheres, 114, https://doi.org/10.1029/2009JD011862, 2009.