scholarly journals Siberian fire smoke in the High-Arctic winter stratosphere observed during MOSAiC 2019–2020

2021 ◽  
Author(s):  
Kevin Ohneiser ◽  
Albert Ansmann ◽  
Ronny Engelmann ◽  
Christoph Ritter ◽  
Alexandra Chudnovsky ◽  
...  
Keyword(s):  
Polar Vortex ◽  
High Arctic ◽  
The Arctic ◽  
Mean Values ◽  
Wildfire Smoke ◽  
Microphysical Properties ◽  
Winter Half ◽  
Smoke Layer ◽  
Lidar Ratio ◽  
532 Nm

Abstract. During the one-year MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate) expedition the German icebreaker Polarstern drifted through the Arctic Ocean ice from October 2019 to May 2020, mainly at latitudes between 85° N and 88.5° N. A multiwavelength polarization Raman lidar was operated aboard the research vessel and continuously monitored aerosol and cloud layers up to 30 km height. The highlight of the lidar measurements was the detection of a persistent, 10 km deep wildfire smoke layer in the upper troposphere and lower stratosphere (UTLS) from about 7–8 km to 17–18 km height. The smoke layer was present throughout the winter half year until the polar vortex, the strongest of the last 40 years, collapsed in late April 2020. The smoke originated from major fire events, especially from extraordinarily intense and long-lasting Siberian fires in July and August 2019. In this article, we summarize the main findings of our seven-month smoke observations and characterize the aerosol properties and decay of the stratospheric perturbation in terms of geometrical, optical, and microphysical properties. The UTLS aerosol optical thickness (AOT) at 532 nm ranged from 0.05–0.12 in October–November 2019 and was of the order of 0.03–0.06 during the central winter months (December–February). As an unambiguous sign of the dominance of smoke, the particle extinction-to-backscatter ratio (lidar ratio) at 355 nm was found to be much lower than the respective 532 nm lidar ratio. Mean values were 55 sr (355 nm) and 85 sr (532 nm). We further present a review of previous height resolved Arctic aerosol observations (remote sensing) in our study. For the first time, a coherent and representative view on the aerosol layering features in the Central Arctic from the surface up to 27 km height during the winter half year is presented. Finally, a potential impact of the wildfire smoke aerosol on the record-breaking ozone depletion over the Arctic in the spring of 2020 is discussed based on smoke, ozone, and polar stratospheric cloud observations.

scholarly journals The unexpected smoke layer in the High Arctic winter stratosphere during MOSAiC 2019–2020

2021 ◽  
Vol 21 (20) ◽  
pp. 15783-15808
Author(s):  
Kevin Ohneiser ◽  
Albert Ansmann ◽  
Alexandra Chudnovsky ◽  
Ronny Engelmann ◽  
Christoph Ritter ◽  
...  
Keyword(s):  
Ozone Depletion ◽  
Winter Season ◽  
High Arctic ◽  
The Arctic ◽  
Aerosol Layer ◽  
Volcanic Aerosol ◽  
Wildfire Smoke ◽  
Winter Half ◽  
Smoke Layer ◽  
532 Nm

Abstract. During the 1-year MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate) expedition, the German icebreaker Polarstern drifted through Arctic Ocean ice from October 2019 to May 2020, mainly at latitudes between 85 and 88.5∘ N. A multiwavelength polarization Raman lidar was operated on board the research vessel and continuously monitored aerosol and cloud layers up to a height of 30 km. During our mission, we expected to observe a thin residual volcanic aerosol layer in the stratosphere, originating from the Raikoke volcanic eruption in June 2019, with an aerosol optical thickness (AOT) of 0.005–0.01 at 500 nm over the North Pole area during the winter season. However, the highlight of our measurements was the detection of a persistent, 10 km deep aerosol layer in the upper troposphere and lower stratosphere (UTLS), from about 7–8 to 17–18 km height, with clear and unambiguous wildfire smoke signatures up to 12 km and an order of magnitude higher AOT of around 0.1 in the autumn of 2019. Case studies are presented to explain the specific optical fingerprints of aged wildfire smoke in detail. The pronounced aerosol layer was present throughout the winter half-year until the strong polar vortex began to collapse in late April 2020. We hypothesize that the detected smoke originated from extraordinarily intense and long-lasting wildfires in central and eastern Siberia in July and August 2019 and may have reached the tropopause layer by the self-lifting process. In this article, we summarize the main findings of our 7-month smoke observations and characterize the aerosol in terms of geometrical, optical, and microphysical properties. The UTLS AOT at 532 nm ranged from 0.05–0.12 in October–November 2019 and 0.03–0.06 during the main winter season. The Raikoke aerosol fraction was estimated to always be lower than 15 %. We assume that the volcanic aerosol was above the smoke layer (above 13 km height). As an unambiguous sign of the dominance of smoke in the main aerosol layer from 7–13 km height, the particle extinction-to-backscatter ratio (lidar ratio) at 355 nm was found to be much lower than at 532 nm, with mean values of 55 and 85 sr, respectively. The 355–532 nm Ångström exponent of around 0.65 also clearly indicated the presence of smoke aerosol. For the first time, we show a distinct view of the aerosol layering features in the High Arctic from the surface up to 30 km height during the winter half-year. Finally, we provide a vertically resolved view on the late winter and early spring conditions regarding ozone depletion, smoke occurrence, and polar stratospheric cloud formation. The latter will largely stimulate research on a potential impact of the unexpected stratospheric aerosol perturbation on the record-breaking ozone depletion in the Arctic in spring 2020.

scholarly journals Wildfire Smoke in the Stratosphere Over Europe–First Measurements of Depolarization and Lidar Ratios at 355, 532, and 1064 nm

2020 ◽  
Vol 237 ◽  
pp. 02036
Author(s):  
Moritz Haarig ◽  
Holger Baars ◽  
Albert Ansmann ◽  
Ronny Engelmann ◽  
Kevin Ohneiser ◽  
...  
Keyword(s):  
Lower Stratosphere ◽  
Wavelength Dependence ◽  
Depolarization Ratio ◽  
Wildfire Smoke ◽  
Lidar Measurements ◽  
Smoke Layer ◽  
Lidar Ratio ◽  
Linear Depolarization Ratio ◽  
532 Nm

Canadian wildfire smoke was detected in the troposphere and lower stratosphere over Europe in August and September 2017. Lidar measurements from various stations of the European Aerosol Research Lidar Network (EARLINET) observed the stratospheric smoke layer. Triple-wavelength (355, 532, and 1064 nm) lidar measurements of the depolarization and the lidar ratio are reported from Leipzig, Germany. The particle linear depolarization ratio of the wildfire smoke in the stratosphere had an exceptional strong wavelength dependence reaching from 0.22 at 355 nm, to 0.18 at 532 nm, and 0.04 at 1064 nm. The lidar ratio increased with wavelength from 40±16 sr at 355 nm, to 66±12 sr at 532 nm, and 92±27 sr at 1064 nm. The development of the stratospheric smoke plume over several months was studied by long-term lidar measurements in Cyprus. The stratospheric smoke layers increased in altitude up to 24 km height.

scholarly journals Extreme levels of Canadian wildfire smoke in the stratosphere over central Europe – Part 2: Lidar study of depolarization and lidar ratios at 355, 532, and 1064 nm and of microphysical properties

2018 ◽  
Author(s):  
Moritz Haarig ◽  
Albert Ansmann ◽  
Holger Baars ◽  
Cristofer Jimenez ◽  
Igor Veselovskii ◽  
...  
Keyword(s):  
Extinction Coefficients ◽  
Wildfire Smoke ◽  
Microphysical Properties ◽  
High Particle ◽  
Lidar Measurements ◽  
Fire Smoke ◽  
Order Of Magnitude ◽  
Lidar Ratio ◽  
532 Nm ◽  
Tropospheric Layer

Abstract. Extremely high particle extinction coefficients, an order of magnitude higher than after the Mt. Pinatubo eruption in 1991, were measured in the stratosphere over Leipzig, Germany, on 22 August 2017. In a series of two articles, we present our observations of this record-breaking smoke event. In part 1 (Ansmann et al., 2018), we provide an overview of the smoke situation. The particle extinction coefficients reached 500 Mm−1 at 532 nm in the lower stratosphere around 15 km height and the smoke-related aerosol optical thickness (AOT) was close to 1.0 around noon. In part 2, we present the optical and microphysical properties of the fire smoke observed in a tropospheric layer from 5–6.5 km height and in a stratospheric layer from 15–16 km height. Three Raman lidars were run at Leipzig after sunset on 22 August. As a highlight, triple-wavelength polarization/Raman lidar measurements of the particle depolarization ratio and extinction-to-backscatter ratio (lidar ratio) at all three important lidar wavelengths of 355, 532, and 1064 nm could be performed. Very different particle depolarization ratios were found in the troposphere and in the stratosphere. The obviously compact and spherical tropospheric smoke particles caused almost no depolarization of backscattered laser radiation at all three wavelength (

scholarly journals Extreme levels of Canadian wildfire smoke in the stratosphere over central Europe – Part 1: AERONET, MODIS and lidar observations

2018 ◽  
Author(s):  
Albert Ansmann ◽  
Holger Baars ◽  
Alexandra Chudnovsky ◽  
Moritz Haarig ◽  
Igor Veselovskii ◽  
...  
Keyword(s):  
Central Europe ◽  
Volcanic Eruptions ◽  
Light Extinction ◽  
Extinction Coefficients ◽  
Wildfire Smoke ◽  
Microphysical Properties ◽  
High Particle ◽  
Smoke Layer ◽  
Lidar Observations ◽  
532 Nm

Abstract. Light extinction coefficients of 500 Mm−1, about 20 times higher than after the Pinatubo volcanic eruptions in 1991, were observed with lidar in the stratosphere over Leipzig, Germany, on 22 August 2017. A pronounced smoke layer extended from 14–16 km height and was 3–4 km above the local tropopause. Optically dense layers of Canadian wildfire smoke reached central Europe 10 days after injection into the lower stratosphere caused by rather strong pyrocumulonimbus activity over western Canada. The smoke-related aerosol optical thickness (AOT) was close to 1.0 at 532 nm over Leipzig during the noon hours. We present detailed observations of this record-breaking smoke event in a series of two articles. In part 1, we provide an overview of Aerosol Robotic Network (AERONET) sun photometer observations and Moderate Resolution Imaging Spectroradiometer (MODIS) retrievals of AOT and show lidar measurements documenting the aerosol layering and the very high particle extinction coefficients. In part 2 (Haarig et al., 2018), observations with three polarization/Raman lidars are presented, performed at Leipzig after sunset on 22 August to elucidate the optical and microphysical properties of the aged smoke. As shown in this part 1, smoke particles were found throughout the free troposphere (532 nm AOT of 0.3). A pronounced 2-km thick stratospheric smoke layer occurred from 14–16 km height (AOT of 0.6). AERONET and lidar observations indicate peak mass concentrations of 70–100 μg m−3 in the stratosphere around noon and a well-defined (accumulation mode) smoke particle size distribution characterized by a large effective radius of 0.3–0.4 μm and the absence of a particle coarse mode.

scholarly journals Wildfire smoke, Arctic haze, and aerosol effects on mixed-phase and cirrus clouds over the North Pole region during MOSAiC: an introduction

2021 ◽  
Vol 21 (17) ◽  
pp. 13397-13423 ◽  
Author(s):  
Ronny Engelmann ◽  
Albert Ansmann ◽  
Kevin Ohneiser ◽  
Hannes Griesche ◽  
Martin Radenz ◽  
...  
Keyword(s):  
Mixed Phase ◽  
North Pole ◽  
Raman Lidar ◽  
Upper Troposphere ◽  
Wildfire Smoke ◽  
The North ◽  
Microphysical Properties ◽  
Arctic Haze ◽  
Smoke Layer ◽  
532 Nm

Abstract. An advanced multiwavelength polarization Raman lidar was operated aboard the icebreaker Polarstern during the MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate) expedition to continuously monitor aerosol and cloud layers in the central Arctic up to 30 km height. The expedition lasted from September 2019 to October 2020 and measurements were mostly taken between 85 and 88.5∘ N. The lidar was integrated into a complex remote-sensing infrastructure aboard the Polarstern. In this article, novel lidar techniques, innovative concepts to study aerosol–cloud interaction in the Arctic, and unique MOSAiC findings will be presented. The highlight of the lidar measurements was the detection of a 10 km deep wildfire smoke layer over the North Pole region between 7–8 km and 17–18 km height with an aerosol optical thickness (AOT) at 532 nm of around 0.1 (in October–November 2019) and 0.05 from December to March. The dual-wavelength Raman lidar technique allowed us to unambiguously identify smoke as the dominating aerosol type in the aerosol layer in the upper troposphere and lower stratosphere (UTLS). An additional contribution to the 532 nm AOT by volcanic sulfate aerosol (Raikoke eruption) was estimated to always be lower than 15 %. The optical and microphysical properties of the UTLS smoke layer are presented in an accompanying paper (Ohneiser et al., 2021). This smoke event offered the unique opportunity to study the influence of organic aerosol particles (serving as ice-nucleating particles, INPs) on cirrus formation in the upper troposphere. An example of a closure study is presented to explain our concept of investigating aerosol–cloud interaction in this field. The smoke particles were obviously able to control the evolution of the cirrus system and caused low ice crystal number concentration. After the discussion of two typical Arctic haze events, we present a case study of the evolution of a long-lasting mixed-phase cloud layer embedded in Arctic haze in the free troposphere. The recently introduced dual-field-of-view polarization lidar technique was applied, for the first time, to mixed-phase cloud observations in order to determine the microphysical properties of the water droplets. The mixed-phase cloud closure experiment (based on combined lidar and radar observations) indicated that the observed aerosol levels controlled the number concentrations of nucleated droplets and ice crystals.

scholarly journals Lidar Measuremnt on Dust Transport from the Saharan Desert to the Iran Plateau

2020 ◽  
Vol 237 ◽  
pp. 02020
Author(s):  
Hossein Panahifar ◽  
Ruhollah Moradhaseli ◽  
Hadi Bourzoie ◽  
Mahdi Gholami ◽  
Hamid Reza Khalesifard
Keyword(s):  
Trajectory Analysis ◽  
Saharan Dust ◽  
Dust Particles ◽  
Raman Lidar ◽  
Dust Layer ◽  
Mean Values ◽  
Dust Transport ◽  
Lidar Ratio ◽  
532 Nm ◽  
Iran Plateau

Optical properties of long-range Saharan dust particles transported to the Iran Plateau have been investigated. The results were derived from the measurements of a dual-wavelength Depolarized backscatter/Raman lidar and a Cimel CE318-2 sunphotometer. Observations were performed in Zanjan, Northwest Iran. The backward trajectory analysis show that the lofted dust plumes come from the Saharan desert and travel along Mediterranean Sea and Turkey toward Iran. The lidar ratio within the lofted dust layer has been found with mean values of 50 sr at 532 nm. For the depolarization ratio, mean values of 25% have been found.

scholarly journals Multiyear Typology of Long-Range Transported Aerosols over Europe

Atmosphere ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 482 ◽  
Author(s):  
Victor Nicolae ◽  
Camelia Talianu ◽  
Simona Andrei ◽  
Bogdan Antonescu ◽  
Dragoș Ene ◽  
...  
Keyword(s):  
Mean Values ◽  
Continental Scale ◽  
Angstrom Exponent ◽  
Circulation Types ◽  
Ångström Exponent ◽  
Lidar Ratio ◽  
The One ◽  
Aerosol Types ◽  
532 Nm ◽  
Ångstrom Exponent

In this study, AERONET (Aerosol Robotic Network) and EARLINET (European Aerosol Research Lidar Network) data from 17 collocated lidar and sun photometer stations were used to characterize the optical properties of aerosol and their types for the 2008–2018 period in various regions of Europe. The analysis was done on six cluster domains defined using circulation types around each station and their common circulation features. As concluded from the lidar photometer measurements, the typical aerosol particles observed during 2008–2018 over Europe were medium-sized, medium absorbing particles with low spectral dependence. The highest mean values for the lidar ratio at 532 nm were recorded over Northeastern Europe and were associated with Smoke particles, while the lowest mean values for the Angstrom exponent were identified over the Southwest cluster and were associated with Dust and Marine particles. Smoke (37%) and Continental (25%) aerosol types were the predominant aerosol types in Europe, followed by Continental Polluted (17%), Dust (10%), and Marine/Cloud (10%) types. The seasonal variability was insignificant at the continental scale, showing a small increase in the percentage of Smoke during spring and a small increase of Dust during autumn. The aerosol optical depth (AOD) slightly decreased with time, while the Angstrom exponent oscillated between “hot and smoky” years (2011–2015) on the one hand and “dusty” years (2008–2010) and “wet” years (2017–2018) on the other hand. The high variability from year to year showed that aerosol transport in the troposphere became more and more important in the overall balance of the columnar aerosol load.

scholarly journals Depolarization and lidar ratios at 355, 532, and 1064 nm and microphysical properties of aged tropospheric and stratospheric Canadian wildfire smoke

2018 ◽  
Vol 18 (16) ◽  
pp. 11847-11861 ◽  
Author(s):  
Moritz Haarig ◽  
Albert Ansmann ◽  
Holger Baars ◽  
Cristofer Jimenez ◽  
Igor Veselovskii ◽  
...  
Keyword(s):  
Wavelength Dependence ◽  
Particle Radius ◽  
Depolarization Ratio ◽  
Particle Volume ◽  
Wildfire Smoke ◽  
Smoke Particles ◽  
Microphysical Properties ◽  
532 Nm ◽  
Tropospheric Layer ◽  
Depolarization Ratios

Abstract. We present spectrally resolved optical and microphysical properties of western Canadian wildfire smoke observed in a tropospheric layer from 5–6.5 km height and in a stratospheric layer from 15–16 km height during a record-breaking smoke event on 22 August 2017. Three polarization/Raman lidars were run at the European Aerosol Research Lidar Network (EARLINET) station of Leipzig, Germany, after sunset on 22 August. For the first time, the linear depolarization ratio and extinction-to-backscatter ratio (lidar ratio) of aged smoke particles were measured at all three important lidar wavelengths of 355, 532, and 1064 nm. Very different particle depolarization ratios were found in the troposphere and in the stratosphere. The obviously compact and spherical tropospheric smoke particles caused almost no depolarization of backscattered laser radiation at all three wavelengths (<3 %), whereas the dry irregularly shaped soot particles in the stratosphere lead to high depolarization ratios of 22 % at 355 nm and 18 % at 532 nm and a comparably low value of 4 % at 1064 nm. The lidar ratios were 40–45 sr (355 nm), 65–80 sr (532 nm), and 80–95 sr (1064 nm) in both the tropospheric and stratospheric smoke layers indicating similar scattering and absorption properties. The strong wavelength dependence of the stratospheric depolarization ratio was probably caused by the absence of a particle coarse mode (particle mode consisting of particles with radius >500 nm). The stratospheric smoke particles formed a pronounced accumulation mode (in terms of particle volume or mass) centered at a particle radius of 350–400 nm. The effective particle radius was 0.32 µm. The tropospheric smoke particles were much smaller (effective radius of 0.17 µm). Mass concentrations were of the order of 5.5 µg m−3 (tropospheric layer) and 40 µg m−3 (stratospheric layer) in the night of 22 August 2017. The single scattering albedo of the stratospheric particles was estimated to be 0.74, 0.8, and 0.83 at 355, 532, and 1064 nm, respectively.

scholarly journals Airborne high spectral resolution lidar observation of pollution aerosol during EUCAARI-LONGREX

2012 ◽  
Vol 12 (10) ◽  
pp. 26843-26869
Author(s):  
S. Groß ◽  
M. Esselborn ◽  
F. Abicht ◽  
M. Wirth ◽  
A. Fix ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Spectral Resolution ◽  
High Spectral Resolution ◽  
Mean Values ◽  
Lidar Observation ◽  
Depolarisation Ratio ◽  
Lidar Ratio ◽  
High Spectral Resolution Lidar ◽  
Lidar Observations ◽  
532 Nm

Abstract. Airborne high spectral resolution lidar observations over Europe during the EUCAARI field experiment in May 2008 are analysed with respect to spatial distribution and optical properties of continental pollution aerosol. Continental aerosol is characterized by its depolarisation and lidar ratio. Mean values of 6%±1% for the particle linear depolarisation ratio, and 56 sr±6 sr for the lidar ratio were found for pollution aerosol. Both, lidar ratio and depolarisation ratio at 532 nm show virtually no variations for all analysed days during the measurement campaign.

scholarly journals Characterization of smoke/dust episode over West Africa: comparison of MERRA-2 modeling with multiwavelength Mie-Raman lidar observations

2017 ◽  
Author(s):  
Igor Veselovskii ◽  
Philippe Goloub ◽  
Thierry Podvin ◽  
Didier Tanre ◽  
Arlindo da Silva ◽  
...  
Keyword(s):  
West Africa ◽  
Dust Particles ◽  
Raman Lidar ◽  
Near Surface ◽  
Smoke Layer ◽  
Correct Location ◽  
Fine Mode ◽  
Lidar Ratio ◽  
Aerosol Parameters ◽  
532 Nm

Abstract. Observations of multiwavelength Mie-Raman lidar taken during the SHADOW field campaign are used to analyze a smoke/dust episode over West Africa on 24–27 December 2015. For the case considered, the dust layer extended from the ground up to approximately 2000 m while the elevated smoke layer occurred in the 2500 m–4000 m range. The profiles of lidar measured backscattering, extinction coefficients and depolarization ratios are compared with the vertical distribution of aerosol parameters provided by the Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2). The MERRA-2 model simulated the correct location of the near–surface dust and elevated smoke layers. The values of modeled and observed extinctions at both 355 nm and 532 nm are also rather close. Good coherence between measured and modeled extinction profiles provides an opportunity to test how well the model reproduces backscattering of dust particles at different wavelengths. The comparison shows good agreement of modeled and measured backscattering coefficients at 355 nm, meaning that the modeled dust lidar ratio of 65 sr in the near-surface layer is close to the observed value. At 532 nm however, the simulated lidar ratio is lower than measurements (about 40 sr and 50 sr respectively). The reason for this disagreement could be that the assumed imaginary part of the refractive index for dust (0.0025 at 532 nm) is too low, or that the particle size distribution in the model is too much weighted toward fine mode dust. The model predicts significant concentration of dust particles inside the smoke layer. This is supported by a high depolarization ratio of 15 % observed in the center of this layer. The backscattering Ångström exponent at 355/532 nm as well as both lidar ratios have a minimum in the center of the elevated layer, which can also be explained by the presence of dust.

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