EARLINET Single Calculus Chain – overview on methodology and strategy

D’Amico, Giuseppe; Amodeo, Aldo; Baars, Holger; Binietoglou, Ioannis; Freudenthaler, Volker; Mattis, Ina; Wandinger, Ulla; Pappalardo, Gelsomina

doi:10.5194/amt-8-4891-2015

Cited by 96 publications

(87 citation statements)

References 37 publications

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“…Future activities should also be undertaken in the direction of harmonization of lidar observations and data. In this sense, the effort to develop standardized tools for aerosol lidar analysis, as realized in the case of ACTRIS/EARLINET in form of the single-calculus-chain (SCC) software (D'Amico et al, 2015(D'Amico et al, , 2016Mattis et al, 2016), and to open its use to non-EARLINET lidar stations and teams is another step forward on the long way of global lidar data harmonization.…”

Section: Discussionmentioning

confidence: 99%

The unprecedented 2017–2018 stratospheric smoke event: Decay phase and aerosol properties observed with EARLINET

Baars¹,

Ansmann²,

Ohneiser³

et al. 2019

Preprint

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Abstract. Six months of stratospheric aerosol observations with the European Aerosol Research Lidar Network (EARLINET) from August 2017 to January 2018 are presented. The decay phase of an unprecedented, record-breaking stratospheric perturbation caused by wild fire smoke is reported and discussed in terms of geometrical, optical, and microphysical aerosol properties. Enormous amounts of smoke (mainly soot particles) were injected into the upper troposphere and lower stratosphere over fire areas in western Canada on 12 August 2017 during strong thunderstorm-pyrocumulonimbus activity. The stratospheric smoke plumes spread over the entire northern hemisphere in the following weeks and months. Twenty-eight European lidar stations from northern Norway to southern Portugal and the Eastern Mediterranean monitored the strong stratospheric perturbation on a continental scale. The main smoke layer (over central, western, southern, and eastern Europe) was found between 15 and 20&#8201;km height since September 2017 (about two weeks after entering the stratosphere). Thin layers of smoke were detected to ascent to 22&#8211;24 km height. The stratospheric aerosol optical thickness at 532&#8201;nm decreased from values >&#8201;0.25 on 21&#8211;23 August 2017 to 0.005&#8211;0.03 until 5&#8211;10 September, and was mainly 0.003&#8211;0.004 from October to December 2017, and thus still significantly above the stratospheric background (0.001&#8211;0.002). Stratospheric particle extinction coefficients (532&#8201;nm) were as high as 50&#8211;200&#8201;Mm&#8722;1 until the beginning of September and of the order of 1&#8201;Mm&#8722;1 (0.5&#8211;5&#8201;Mm&#8722;1) from October 2017 until the end of January 2018. The corresponding layer mean particle mass concentration was of the order of 0.05&#8211;0.5&#8201;&#956;g&#8201;cm&#8722;3 over the months. Soot is an efficient ice-nucleating particle (INP) at upper tropospheric (cirrus) temperatures and available to influence cirrus formation when entering the tropopause from above. We estimated INP concentrations of 50&#8211;500&#8201;L&#8722;1 until the first days in September and afterwards 5&#8211;50&#8201;L&#8722;1 until the end of the year 2018 in the lower stratosphere for typical cirrus formation temperatures of &#8722;55&#8201;&#176;C and ice supersaturation values of 1.15. The measured profiles of the particle linear depolarization rato indicated the predominance of non-spherical soot particles. The 532&#8201;nm depolarization ratio decreased with time in the main smoke layer from values of 0.15&#8211;0.25 (August&#8211;September) to values of 0.05&#8211;0.10 (October&#8211;November) and <&#8201;0.05 (December&#8211;January). The decrease of the depolarization ratio is consistent with the steady removal of the larger smoke particles by gravitational settling and changes in the particle shape with time towards a spherical form. An ascending layer with a vertical depth of 500&#8211;1000&#8201;m was detected (over the Eastern Mediterranean at 32&#8211;35&#176;&#8201;N) that ascended from about 18&#8211;19&#8201;km to 22&#8211;23&#8201;km height from the beginning of October to the beginning of December 2017 (about 2&#8201;km per month) and may be related to the increasing build up of the winter-hemispheric Brewer&#8211;Dobson circulation system.

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Section: Discussionmentioning

confidence: 99%

The unprecedented 2017–2018 stratospheric smoke event: Decay phase and aerosol properties observed with EARLINET

Baars¹,

Ansmann²,

Ohneiser³

et al. 2019

Preprint

Self Cite

View full text Add to dashboard Cite

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“…This quantity provides information about the aerosol size and, in contrast to the extinction coefficient, is associated with smaller uncertainty. This is attributed mainly to the derivative in the inversion algorithm (e.g., Ansmann et al, 2002;Freudenthaler et al, 2009), which produces larger uncertainties, while the backscatter coefficient calculated from the combination of Raman elastic channels is less sensitive. The ratio of the aerosol extinction to backscatter coefficient is called the lidar ratio -LRλ 1 -and changes largely for aerosols with different chemical and physical properties.…”

Section: Aerosol Typing Methodsmentioning

confidence: 99%

Comparison of two automated aerosol typing methods and their application to an EARLINET station

et al. 2019

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Abstract. In this study we apply and compare two algorithms for the automated aerosol-type characterization of the aerosol layers derived from Raman lidar measurements over the EARLINET station of Thessaloniki, Greece. Both automated aerosol-type characterization methods base their typing on lidar-derived aerosol-intensive properties. The methodologies are briefly described and their application to three distinct cases is demonstrated and evaluated. Then the two classification schemes were applied in the automatic mode to a more extensive dataset. The dataset analyzed corresponds to ACTRIS/EARLINET (European Aerosol Research Lidar NETwork) Thessaloniki data acquired during the period 2012–2015. Seventy-one layers out of 110 (percentage of 65 %) were typed by both techniques, and 56 of these 71 layers (percentage of 79 %) were attributed to the same aerosol type. However, as shown, the identification rate of both typing algorithms can be changed regarding the selection of appropriate threshold criteria. Four major types of aerosols are considered in this study: Dust, Maritime, PollutedSmoke and CleanContinental. The analysis showed that the two algorithms, when applied to real atmospheric conditions, provide typing results that are in good agreement regarding the automatic characterization of PollutedSmoke, while there are some differences between the two methods regarding the characterization of Dust and CleanContinental. These disagreements are mainly attributed to differences in the definitions of the aerosol types between the two methods, regarding the intensive properties used and their range.

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“…The EAR-LINET backscatter coefficient profiles used in this study are calculated with the SCC version 4 algorithm (for the stations that are not part of PollyNET) and with the methodology described in Haarig et al (2017; for the stations that are part of PollyNET). The SCC algorithm (D'Amico et al, 2015(D'Amico et al, , 2016Mattis et al, 2016) is developed with the concept of sustaining the homogeneity of aerosol products derived from different EARLINET lidar systems while satisfying the need for coordinated, quality-assured measurements. It consists of five different modules, including one for handling the pre-processing of raw lidar data by applying all the necessary instrumental corrections to the signal and a module for providing the final aerosol optical products, namely the particle backscatter and extinction coefficient.…”

Section: Particle Backscatter Coefficient Retrievals From Ground-basementioning

confidence: 99%

EARLINET evaluation of the CATS Level 2 aerosol backscatter coefficient product

et al. 2019

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Abstract. We present the evaluation activity of the European Aerosol Research Lidar Network (EARLINET) for the quantitative assessment of the Level 2 aerosol backscatter coefficient product derived by the Cloud-Aerosol Transport System (CATS) aboard the International Space Station (ISS; Rodier et al., 2015). The study employs correlative CATS and EARLINET backscatter measurements within a 50 km distance between the ground station and the ISS overpass and as close in time as possible, typically with the starting time or stopping time of the EARLINET performed measurement time window within 90 min of the ISS overpass, for the period from February 2015 to September 2016. The results demonstrate the good agreement of the CATS Level 2 backscatter coefficient and EARLINET. Three ISS overpasses close to the EARLINET stations of Leipzig, Germany; Évora, Portugal; and Dushanbe, Tajikistan, are analyzed here to demonstrate the performance of the CATS lidar system under different conditions. The results show that under cloud-free, relative homogeneous aerosol conditions, CATS is in good agreement with EARLINET, independent of daytime and nighttime conditions. CATS low negative biases are observed, partially attributed to the deficiency of lidar systems to detect tenuous aerosol layers of backscatter signal below the minimum detection thresholds; these are biases which may lead to systematic deviations and slight underestimations of the total aerosol optical depth (AOD) in climate studies. In addition, CATS misclassification of aerosol layers as clouds, and vice versa, in cases of coexistent and/or adjacent aerosol and cloud features, occasionally leads to non-representative, unrealistic, and cloud-contaminated aerosol profiles. Regarding solar illumination conditions, low negative biases in CATS backscatter coefficient profiles, of the order of 6.1 %, indicate the good nighttime performance of CATS. During daytime, a reduced signal-to-noise ratio by solar background illumination prevents retrievals of weakly scattering atmospheric layers that would otherwise be detectable during nighttime, leading to higher negative biases, of the order of 22.3 %.

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EARLINET Single Calculus Chain – overview on methodology and strategy

Cited by 96 publications

References 37 publications

The unprecedented 2017–2018 stratospheric smoke event: Decay phase and aerosol properties observed with EARLINET

The unprecedented 2017–2018 stratospheric smoke event: Decay phase and aerosol properties observed with EARLINET

Comparison of two automated aerosol typing methods and their application to an EARLINET station

EARLINET evaluation of the CATS Level 2 aerosol backscatter coefficient product

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