Consistency of the Single Calculus Chain Optical Products with Archived Measurements from an EARLINET Lidar Station

Voudouri, Kalliopi Artemis; Σιώμος, Νικόλαος; Michailidis, Konstantinos; D’Amico, Giuseppe; Mattis, Ina; Balis, D.

doi:10.3390/rs12233969

Cited by 7 publications

(3 citation statements)

References 35 publications

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“…The main and basic aerosol optical properties, derivable from the lidar observations, are the particle backscatter coefficient profiles (355, 532, 1064 nm), the particle extinction coefficient profiles (355, 532 nm), the respective extinction-to-backscatter ratio (lidar ratio) at 355 and 532 nm, and the particle linear depolarization ratio (PLDR) at 532 nm. A detailed description of the THELISYS technical characteristics can be found in Siomos et al [32], whilst a detailed description of the signal processing and the applied algorithms are provided in Voudouri et al [33]. The THELISYS dataset is regularly analyzed and quality assured (following all the Q/A procedures within EARLINET) and is publicly available at https://www.earlinet.org/, accessed on 15 November 2023.…”

Section: Instrumentation and Data Products 21 Thessaloniki Lidar Syst...mentioning

confidence: 99%

Investigating a Persistent Stratospheric Aerosol Layer Observed over Southern Europe during 2019

Voudouri,

Michailidis,

Koukouli

et al. 2023

Remote Sensing

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A persistent stratospheric aerosol layer first appeared during July 2019 above Thessaloniki, Greece (40.5°N, 22.9°E). It was initially at 12 km and, during August 2019, was even up to 20 km, with increased thickness and reduced attenuated backscatter levels till the end of the year. In this study, we analyze the geometrical and optical properties of this stratospheric layer, using ground-based Lidar measurements, CALIOP/CALIPSO & OMPS-LP space-borne observations, as well as CAMS/ECMWF assimilation experiments. The main aim of the paper is to present an overview of this atmospheric feature and to identify any temporal changes in the aerosol properties that would signify substantial changes in the composition of this long-lasting stratospheric plume over Thessaloniki. This aim is further enhanced by emphasizing the importance of the combined information based on active ground- and space-borne lidars, passive remote sensing, and models during the complex stratospheric aerosol conditions as those encountered during 2019. The layer’s origin is linked to the Raikoke volcanic eruption in the Kuril Islands in June 2019, yielding a particle linear depolarization ratio less than 0.05, while some indications exist that the intense forest fires at mid and high northern latitudes throughout the summer of 2019 also contributed to the persistent layer. We report that in July, mainly volcanic sulphate aerosol layers with a 1–3 km vertical extent were identified in the stratosphere at ~15 km over Thessaloniki, while after August and until the end of 2019, the plume heights showed a significant month-to-month variability and a broadening (with thickness greater than 3 km) towards lower altitudes. The aerosol optical thickness was found to be in the range between 0.004 and 0.125 (visible) and 0.001 and 0.095 (infrared) and the particle depolarization of the detected stratospheric plume was found to be 0.03 ± 0.04, indicative of spherical particles, such as sulphate aerosols.

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Section: Instrumentation and Data Products 21 Thessaloniki Lidar Syst...mentioning

confidence: 99%

Investigating a Persistent Stratospheric Aerosol Layer Observed over Southern Europe during 2019

Voudouri,

Michailidis,

Koukouli

et al. 2023

Remote Sensing

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“…The full overlap height is almost 800m a.s.l. A detailed description of THELISIS can be found in Siomos et al (2018) and Voudouri et al (2020).…”

Section: Thessalonikimentioning

confidence: 99%

First assessment of Aeolus L2A particle backscatter coefficient retrievals in the Eastern Mediterranean

Gkikas

Gialitaki

Binietoglou

et al. 2022

Preprint

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Abstract. Since 2018, the Aeolus satellite of the European Space Agency (ESA) acquires wind HLOS (horizontal line-of-sight) profiles throughout the troposphere and up to the lower stratosphere, filling a critical gap of the Global Observing System (GOS). Aeolus, carrying ALADIN, the first UV HSRL Doppler lidar ever placed in space, along with wind HLOS profiles provides also vertically resolved optical properties of particulates (aerosols, hydrometeors). The present study focuses on the assessment of Aeolus L2A particulate backscatter coefficient, retrieved by the Standard Correct Algorithm (SCA), in the Eastern Mediterranean, a region hosting a variety of aerosol species. Ground-based retrievals acquired by lidar instruments operating in Athens (capital of Greece), Thessaloniki (north Greece) and Antikythera (southwest Greece) serve as reference. All lidar stations provide routine measurements to the PANACEA (PANhellenic infrastructure for Atmospheric Composition and climatE chAnge) network. A set of ancillary data including sunphotometric observations (AERONET), reanalysis products (CAMS, MERRA-2), satellite observations (MSG-SEVIRI, MODIS-Aqua) and backward trajectories (FLEXPART) are utilized towards an optimum characterization of the probed atmospheric conditions under the absence of a classification scheme in Aeolus profiles. First, emphasis is given on the assessment of Aeolus L2A backscatter coefficient under different aerosol scenarios over Antikythera island. Due to the misdetection of the cross-polar component of the backscattered lidar signal, Aeolus underestimates backscatter by up to 33 % when non-spherical mineral particles are recorded (10th July 2019). A very good performance is revealed on 3rd July 2019, when homogeneous loads of fine spherical particles are confined below 4 km. The level of agreement between spaceborne and ground-based retrievals varies with altitude when aerosol layers, composed of particles of different origin, are stratified (8th July 2020, 5th August 2020). According to the statistical assessment analysis for 46 identified cases, it is revealed a poor-to-moderate performance for the unfiltered (aerosols plus clouds) Aeolus profiles which improves substantially when cloud contaminated profiles are excluded from the collocated sample. This positive tendency is evident at both Aeolus vertical scales (regular, 24 bins and mid-bin, 23 bins) and it is justified by the drastic reduction of the bias and root-mean-square-error scores. In vertical, Aeolus performance downgrades at the lowermost bins (attributed to either the surface reflectance or the increased noise levels for the Aeolus retrievals and to the overlap issues for the ground-based profiles). Among the three PANACEA stations, the best agreement is found at the remote site of Antikythera with respect to the urban sites of Athens and Thessaloniki. Finally, all key Cal/Val aspects necessary for future relevant studies, the recommendations for a possible Aeolus follow-on mission and an overview of the ongoing related activities are thoroughly discussed.

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“…For lidar observation, the continuous long-term and high spatial resolution data can be achieved at the same time (Liu et al, 2021;Voudouri et al, 2020). Nevertheless, PM concentration retrieval based on lidar extinction coefficient highly depends 40 on aerosol size distribution, aerosol composition, and atmospheric relative humidity assumptions, which are highly uncertain (Tao et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Characteristics of fine particle matters at the top of Shanghai Tower

Yin

Gao

et al. 2022

Preprint

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Abstract. To investigate the physical and chemical processes of fine particle matters at mid-upper planetary boundary layer (PBL), we conducted one-year continuous measurements of fine particle matters (PM), chemical composition of non-refractory submicron aerosol (NR-PM1) and some gas species (including sulfur dioxide, nitrogen oxides and ozone) at an opening observatory (~600 m) at the top of Shanghai Tower (SHT), which is the Chinese 1st and World’s 2nd highest building located in the typical financial central business district of Shanghai, China. This is the first report for the characteristics of fine particles based on continuous and sophisticated online measurements at the mid-upper level of urban PBL. The observed PM2.5 and PM1 mass concentrations at SHT were 25.5±17.7 and 17.3±11.7 μg m-3 respectively. Organics, nitrate (NO3) and sulfate (SO4) occupied the first three leading contributions to NR-PM1 at SHT, accounting for 35.8 %, 28.6 % and 20.8 % respectively. The lower PM2.5 concentration was observed at SHT by 16.4 % compared with that near surface during the observation period. It was attributed to the decreased nighttime PM2.5 concentrations (29.4 % lower than surface) at SHT in all seasons due to the complete isolations from both emissions and gas precursors near surface. However, daytime PM2.5 concentrations at SHT were 12.4–35.1 % higher than those near surface from June to October, resulted from unexpected larger PM2.5 levels during early to middle afternoon at SHT than surface. We suppose the significant chemical production of secondary aerosols existed in mid-upper PBL because strong solar irradiance, adequate gas precursors (e.g., NOx) and lower temperature were observed at SHT favorable for both photochemical production and gas-to-particle partitioning. This was further demonstrated by the significant increasing rate of oxygenated organic aerosols and NO3 observed at SHT during 8:00–12:00 in spring (7.4 % h-1 and 12.9 % h-1), autumn (9.3 % h-1 and 9.1 % h-1) and summer (13.0 % h-1 and 11.4 % h-1), which cannot be fully explained by vertical mixing. It was noting that extremely high NO3 was observed at SHT both in daytime and nighttime in winter, accounting for 37.2 % in NR-PM1, suggesting the efficient pathway from heterogeneous and gas oxidated formation. Therefore, we highlight the priority of NOx reduction in Shanghai for the further improvement of air quality. This study reported greater daytime PM2.5 concentrations at the height of 600 m in urban PBL compared with surface measurement, providing insight into their potential effects on local air quality, radiation forcing, and cloud/fog formations. We propose that the efficient production of secondary aerosol in mid-upper PBL should be cognized and explored more comprehensively by synergetic observations in future.

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Consistency of the Single Calculus Chain Optical Products with Archived Measurements from an EARLINET Lidar Station

Cited by 7 publications

References 35 publications

Investigating a Persistent Stratospheric Aerosol Layer Observed over Southern Europe during 2019

Investigating a Persistent Stratospheric Aerosol Layer Observed over Southern Europe during 2019

First assessment of Aeolus L2A particle backscatter coefficient retrievals in the Eastern Mediterranean

Characteristics of fine particle matters at the top of Shanghai Tower

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