CALIPSO Aerosol-Typing Scheme Misclassified Stratospheric Fire Smoke: Case Study From the 2019 Siberian Wildfire Season

In August 2019, a 4-km thick wildfire smoke layer was observed in the lower stratosphere over Leipzig, Germany, with a ground-based multiwavelength Raman lidar. The smoke was identified by the smoke-specific spectral dependence of the extinction-to-backscatter ratio (lidar ratio) measured with the Raman lidar. The spaceborne CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) lidar CALIOP (Cloud–Aerosol Lidar with Orthogonal Polarization) detected the smoke and classified it as sulfate aerosol layer (originating from the Raikoke volcanic eruption). In this article, we discuss the reason for this misclassification. Two major sources for stratospheric air pollution were active in the summer of 2019 and complicated the CALIPSO aerosol typing effort. Besides intense forest fires at mid and high northern latitudes, the Raikoke volcano erupted in the Kuril Islands. We present two cases observed at Leipzig, one from July 2019 and one from August 2019. In July, pure volcanic sulfate aerosol layers were found in the lower stratosphere, while in August, wildfire smoke dominated in the height range up to 4–5 km above the local tropopause. In both cases, the CALIPSO aerosol typing scheme classified the layers as sulfate aerosol layers. The aerosol identification algorithm assumes non-spherical smoke particles in the stratosphere as consequence of fast lifting by pyrocumulonimbus convection. However, we hypothesize (based on presented simulations) that the smoke ascended as a results of self-lifting and reached the tropopause within 2–7 days after emission and finally entered the lower stratosphere as aged spherical smoke particles. These sphercial particles were then classified as liquid sulfate particles by the CALIPSO data analysis scheme. We also present a successful case of smoke identification by the CALIPSO retrieval method.

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Cloud and Aerosol Spectroscopy with Raman Lidar

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-13-00188.1 ◽

2014 ◽

Vol 31 (9) ◽

pp. 1946-1963 ◽

Cited By ~ 15

Author(s):

Jens Reichardt

Keyword(s):

Single Photon ◽

Detection System ◽

Focal Length ◽

Aerosol Layer ◽

Raman Lidar ◽

Backscatter Coefficient ◽

Height Range ◽

Cloud Water Content ◽

New Instrument ◽

Raman Backscatter

Abstract A spectrometer for height-resolved measurements of the Raman backscatter-coefficient spectrum of water in its gaseous and condensed phases is presented. The spectrometer is fiber coupled to the far-range receiver of the Raman Lidar for Atmospheric Moisture Sensing (RAMSES) of the German Meteorological Service and consists of a Czerny–Turner spectrograph (500-mm focal length) and a 32-channel single-photon-counting detection system based on a multianode photomultiplier. During a typical measurement (transmitter wavelength of 355 nm), the spectrum between 385 and 410 nm is recorded with a spectral resolution of 0.79 nm; the vertical resolution is 15 m and the height range is 15 km. The techniques outlined are those that are applied to calibrate the spectrum measurement and to monitor fluorescence by atmospheric aerosols that have the potential to interfere with the water observation. For the first time, Raman spectra of liquid-water, mixed-phase, and cirrus clouds are reported, and their temperature dependence is investigated by means of band decomposition. The spectrum-integrated condensed-water Raman backscatter coefficient strongly depends on cloud particle volume, but it is not tightly correlated with the cloud optical properties (particle extinction and backscatter coefficient), which implies that retrieval of cloud water content from optical proxies is likely impossible. Aerosol measurements are also discussed. Depending on type, aerosols may show no backscattering in the spectrometer range at all, or a featureless spectrum that stems quite likely from fluorescence. Finally, the example of a cloud forming in an aerosol layer demonstrates that the new instrument not only opens up new perspectives in cloud research but also contributes to studies of cloud–aerosol interaction.

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Record-breaking stratospheric smoke and record-breaking ozone depletion events in the Arctic and in Antarctica in 2020! Any link between smoke occurrence and ozone depletion?

10.5194/dach2022-111 ◽

2021 ◽

Author(s):

Kevin Ohneiser ◽

Albert Ansmann ◽

Ronny Engelmann ◽

Boris Barja ◽

Holger Baars ◽

...

Keyword(s):

Ozone Depletion ◽

Particle Surface ◽

Chemical Processes ◽

Ozone Hole ◽

The Arctic ◽

Aerosol Layer ◽

Raman Lidar ◽

Smoke Particles ◽

Heterogeneous Chemical ◽

Ozone Profile

The highlight of our multiwavelength polarization Raman lidar measurements during the 1-year MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate) expedition in the Arctic Ocean ice from October 2019 to May 2020 was the detection of a persistent, 10 km deep aerosol layer in the upper troposphere and lower stratosphere (UTLS) with clear and unambiguous wild-fire smoke signatures. The smoke is supposed to originate 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.Temporally almost parallelly, record-breaking wild&#64257;res accompanied by unprecedentedly strong pyroconvection were raging in the south-eastern part of Australia in late December 2019 and early January 2020. These &#64257;res injected huge amounts of biomass-burning smoke into the stratosphere where the smoke particles became distributed over the entire southern hemispheric in the UTLS regime from 10-30 km to even 35 km height. The stratospheric smoke layer was monitored with our Raman lidar in Punta Arenas (53.2&#176;S, 70.9&#176;W, Chile, southern South America) for two years.The fact that these two events in both hemispheres coincided with record-breaking ozone hole events in both hemispheres in the respective spring seasons motivated us to discuss a potential impact of the smoke particles on the strong ozone depletion. The discussion is based on the overlapping height ranges of the smoke particles, polar stratospheric clouds, and the ozone hole regions. It is well known that strong ozone reduction is linked to the development of a strong and long-lasting polar vortex, which favours increased PSC formation. In these clouds, active chlorine components are produced via heterogeneous chemical processes on the surface of the PSC particles. Finally, the chlorine species destroy ozone molecules in the spring season. However, there are two pathways to influence ozone depletion by aerosol pollution. The particles can influence the evolution of PSCs and specifically their microphysical properties (number concentration and size distribution), and on the other hand, the particles can be directly involved in heterogeneous chemical processes by increasing the particle surface area available to convert nonreactive chlorine components into reactive forms. A third (indirect) impact of smoke, when well distributed over large parts of the Northern or Southern hemispheres, is via the influence on large-scale atmospheric dynamics.We will show our long-term smoke lidar observations in the central Arctic and in Punta Arenas as well as ozone profile measurements during the ozone-depletion seasons. Based on these aerosol and ozone profile data we will discuss the potential interaction between smoke and ozone.

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Detection of an enhanced stratospheric aerosol layer above Europe one year after the eruption of the volcano Raikoke

10.5194/egusphere-egu21-14197 ◽

2021 ◽

Author(s):

Laura Tomsche ◽

Andreas Marsing ◽

Tina Jurkat-Witschas ◽

Johannes Lucke ◽

Katharina Kaiser ◽

...

Keyword(s):

Mass Spectrometer ◽

Lower Stratosphere ◽

Volcanic Eruptions ◽

Stratospheric Aerosol ◽

Sulfate Aerosol ◽

Aerosol Layer ◽

Volcanic Aerosol ◽

Aerosol Mass Spectrometer ◽

Aerosol Mass

Extreme volcanic eruptions inject significant amounts of sulfur-containing species into the lower stratosphere and sustain the stratospheric aerosol layer which tends to cool the atmosphere and surface temperatures.During the BLUESKY campaign in May/June 2020, the aerosol composition and its precursor gas SO2 were measured with a time-of-flight aerosol mass spectrometer onboard the research aircraft HALO and with a atmospheric chemical ionization mass spectrometer onboard the DLR Falcon. While SO2 was slightly above background levels in the lower stratosphere above Europe, the aerosol mass spectrometer detected an extended aerosol layer. This sulfate aerosol layer was observed on most of the HALO flights and the sulfate mixing ratio increased significantly between 10 and 14 km altitude. Back trajectory calculations show no recent transport of polluted boundary layer air or ground-based emissions into the lower stratosphere. Therefore, we suggest that the stratospheric sulfate aerosol layer might be attributed to the aged stratospheric plume of the volcano Raikoke in Japan. In June 2019, Raikoke injected huge amounts of SO2 into the lower stratosphere, which were converted to sulfate and contributed to the stratospheric aerosol layer. This decaying volcanic aerosol layer was observed with the aerosol mass spectrometer over Europe a year after the eruption. The long-term volcanic remnants enhance the total stratospheric aerosol surface area, facilitate heterogeneous reactions on these particles and provide additional cloud condensation nuclei in the UTLS. They further offset some of the reduced sulfur burden from aviation that was observed during the COVID-19 lockdown in 2020. The sensitive and highly time resolved airborne measurements of composition and size of stratospheric aerosol from an explosive volcanic eruption help to better constrain sulfur chemistry in the lower stratosphere, validate satellite observations near their detection threshold and can be used to evaluate dispersion and chemistry-climate models on long-term effects of volcanic aerosol.&#160;

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Lofted aerosol layers over the North Pole during the winter period 2019-2020 measured during MOSAiC

10.5194/egusphere-egu21-2677 ◽

2021 ◽

Author(s):

Kevin Ohneiser ◽

Ronny Engelmann ◽

Albert Ansmann ◽

Martin Radenz ◽

Hannes Griesche ◽

...

Keyword(s):

Mineral Dust ◽

Mixed Phase ◽

North Pole ◽

The Arctic ◽

Aerosol Layer ◽

Raman Lidar ◽

Wildfire Smoke ◽

The North ◽

Arctic Haze ◽

The Impact

The MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate) expedition, lasting from September 2019 to October 2020, was the largest Arctic research initiative in history. The goal of the expedition was to take the closest look ever at the Arctic as the epicenter of global warming and to gain fundamental insights that are key to better understand global climate change. We continuously operated a multiwavelength aerosol/cloud Raman lidar aboard the icebreaker Polarstern, drifting through the Arctic Ocean trapped in the ice from October to May, and monitored aerosol and cloud layers in the Central Arctic up to 30 km height at latitudes mostly > 85&#176;N. The lidar was integrated in a complex remote sensing infrastructure aboard Polarstern. A polarization Raman lidar is designed to separate the main continental aerosol components (mineral dust, wildfire smoke, anthropogenic haze, volcanic aerosol). Furthermore, the Polarstern lidar enabled us to study the impact of these different basic aerosol types on the evolution of Arctic mixed-phase and ice clouds. &#160;The most impressive and unprecedented observation was the detection of a persistent, 10 km deep aerosol layer of aged wildfire smoke over the North Pole region between 8 and 18 km height from October 2019 until the beginning of May 2020. The wildfire smoke layers originated from severe and huge fires in Siberia, Alaska, and western North America in 2019 and may have contained mineral dust injected into the atmosphere over the hot fire places together with the smoke. We will present the main MOSAiC findings including a study of a long-lasting mixed-phase cloud layer evolving in Arctic haze (at heights below 6 km) and the role of mineral dust in the Arctic haze mixture to trigger heterogeneous ice formation. Furthermore, we present a case study developing in the smoke-dominated layer around 10 km height.

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Lidar observations of Nabro volcano aerosol layers in the stratosphere over Gwangju, Korea

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-1171-2015 ◽

2015 ◽

Vol 15 (1) ◽

pp. 1171-1191 ◽

Cited By ~ 4

Author(s):

D. Shin ◽

D. Müller ◽

K. Lee ◽

S. Shin ◽

Y. J. Kim ◽

...

Keyword(s):

Lower Stratosphere ◽

Stratospheric Aerosol ◽

Aerosol Layer ◽

Raman Lidar ◽

Backscatter Coefficient ◽

Upper Troposphere ◽

Lidar Measurements ◽

Volcanic Aerosols ◽

Lidar Observations ◽

532 Nm

Abstract. We report on the first Raman lidar measurements of stratospheric aerosol layers in the upper troposphere and lower stratosphere over Korea. The data were taken with the multiwavelength aerosol Raman lidar at Gwangju (35.10° N, 126.53° E), Korea. The volcanic ash particles and gases were released around 12 June 2011 during the eruption of the Nabro volcano (13.37° N, 41.7° E) in Eritrea, east Africa. Forward trajectory computations show that the volcanic aerosols were advected from North Africa to East Asia. The first observation of the stratospheric aerosol layers over Korea was on 19 June 2011. The stratospheric aerosol layers appeared between 15 and 17 km height a.s.l. The aerosol layers' maximum value of the backscatter coefficient and the linear particle depolarization ratio at 532 nm were 1.5 ± 0.3 Mm−1 sr−1 and 2.2%, respectively. We found these values at 16.4 km height a.s.l. 44 days after this first observation, we observed the stratospheric aerosol layer again. We continuously probed the upper troposphere and lower stratosphere for this aerosol layer during the following 5 months, until December 2011. The aerosol layers typically occurred between 10 and 20 km height a.s.l. The stratospheric aerosol optical depth and the maximum backscatter coefficient at 532 nm decreased during these 5 months.

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One year of Raman lidar observations of free-tropospheric aerosol layers over South Africa

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-5429-2015 ◽

2015 ◽

Vol 15 (10) ◽

pp. 5429-5442 ◽

Cited By ~ 16

Author(s):

E. Giannakaki ◽

A. Pfüller ◽

K. Korhonen ◽

T. Mielonen ◽

L. Laakso ◽

...

Keyword(s):

South Africa ◽

Optical Properties ◽

Biomass Burning ◽

Mean Value ◽

Aerosol Layer ◽

Raman Lidar ◽

Tropospheric Aerosol ◽

Wide Range ◽

Significant Difference ◽

532 Nm

Abstract. Raman lidar data obtained over a 1 year period has been analysed in relation to aerosol layers in the free troposphere over the Highveld in South Africa. In total, 375 layers were observed above the boundary layer during the period 30 January 2010 to 31 January 2011. The seasonal behaviour of aerosol layer geometrical characteristics, as well as intensive and extensive optical properties were studied. The highest centre heights of free-tropospheric layers were observed during the South African spring (2520 ± 970 m a.g.l., also elsewhere). The geometrical layer depth was found to be maximum during spring, while it did not show any significant difference for the rest of the seasons. The variability of the analysed intensive and extensive optical properties was high during all seasons. Layers were observed at a mean centre height of 2100 ± 1000 m with an average lidar ratio of 67 ± 25 sr (mean value with 1 standard deviation) at 355 nm and a mean extinction-related Ångström exponent of 1.9 ± 0.8 between 355 and 532 nm during the period under study. Except for the intensive biomass burning period from August to October, the lidar ratios and Ångström exponents are within the range of previous observations for urban/industrial aerosols. During Southern Hemispheric spring, the biomass burning activity is clearly reflected in the optical properties of the observed free-tropospheric layers. Specifically, lidar ratios at 355 nm were 89 ± 21, 57 ± 20, 59 ± 22 and 65 ± 23 sr during spring (September–November), summer (December–February), autumn (March–May) and winter (June–August), respectively. The extinction-related Ångström exponents between 355 and 532 nm measured during spring, summer, autumn and winter were 1.8 ± 0.6, 2.4 ± 0.9, 1.8 ± 0.9 and 1.8 ± 0.6, respectively. The mean columnar aerosol optical depth (AOD) obtained from lidar measurements was found to be 0.46 ± 0.35 at 355 nm and 0.25 ± 0.2 at 532 nm. The contribution of free-tropospheric aerosols on the AOD had a wide range of values with a mean contribution of 46%.

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Nascent RNA sequencing defines dynamic aryl hydrocarbon receptor signaling responses to wood smoke particles

10.1101/2021.02.23.432311 ◽

2021 ◽

Author(s):

Arnav Gupta ◽

Sarah K. Sasse ◽

Lynn Sanford ◽

Margaret A. Gruca ◽

Robin D. Dowell ◽

...

Keyword(s):

Gene Expression ◽

Aryl Hydrocarbon Receptor ◽

Airway Epithelial Cells ◽

Wood Smoke ◽

Primary Role ◽

Airway Epithelial ◽

Transcriptional Responses ◽

Wildfire Smoke ◽

Smoke Particles ◽

Aryl Hydrocarbon

AbstractTranscriptional responses to wildfire smoke, an increasingly important cause of human morbidity, are poorly understood. Here, using a combination of precision nuclear run-on sequencing (PRO-seq) and the assay for transposase-accessible chromatin using sequencing (ATAC-seq), we identify rapid and dynamic changes in transcription and chromatin structure in Beas-2B airway epithelial cells after exposure to wood smoke particles (WSP). By comparing 30 and 120 minutes of WSP exposure, we defined three distinct temporal patterns of transcriptional induction and chromatin responses to WSP. Whereas transcription of canonical targets of the aryl hydrocarbon receptor (AHR), such as CYP1A1 and AHRR, was robustly increased after 30 minutes of WSP exposure, transcription of these genes and associated enhancers returned to near baseline at 120 minutes. ChIP-qPCR assays and AHR knockdown confirmed a role for AHR in regulating these transcriptional responses, and we applied bioinformatics approaches to identify novel AHR-regulated pathways and targets including the DNA methyltransferase, DNMT3L, and its interacting factor, SPOCD1. Our analysis also defined a role for NFkB as a primary transcriptional effector of WSP-induced changes in gene expression. The kinetics of AHR- and NFkB-regulated responses to WSP were distinguishable based on the timing of both transcriptional responses and chromatin remodeling, with induction of several cytokines implicated in maintaining the NFkB response. In aggregate, our data establish a direct and primary role for AHR in mediating airway epithelial responses to WSP and identify crosstalk between AHR and NFkB signaling in controlling pro-inflammatory gene expression.

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Observational evidence of particle hygroscopic growth in the upper troposphere–lower stratosphere (UTLS) over the Tibetan Plateau

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-8399-2019 ◽

2019 ◽

Vol 19 (13) ◽

pp. 8399-8406 ◽

Cited By ~ 2

Author(s):

Qianshan He ◽

Jianzhong Ma ◽

Xiangdong Zheng ◽

Xiaolu Yan ◽

Holger Vömel ◽

...

Keyword(s):

Relative Humidity ◽

Tibetan Plateau ◽

Lower Stratosphere ◽

Fine Particles ◽

Asian Summer Monsoon ◽

Radiative Properties ◽

Aerosol Layer ◽

The Tibetan Plateau ◽

Hygroscopic Growth ◽

Upper Troposphere

Abstract. We measured the vertical profiles of backscatter ratio (BSR) using the balloon-borne, lightweight Compact Optical Backscatter AerosoL Detector (COBALD) instruments above Linzhi, located in the southeastern Tibetan Plateau, in the summer of 2014. An enhanced aerosol layer in the upper troposphere–lower stratosphere (UTLS), with BSR (455 nm) > 1.1 and BSR (940 nm) > 1.4, was observed. The color index (CI) of the enhanced aerosol layer, defined as the ratio of aerosol backscatter ratios (ABSRs) at wavelengths of 940 and 455 nm, varied from 4 to 8, indicating the prevalence of fine particles with a mode radius of less than 0.1 µm. We find that unlike the very small particles (mode radius smaller than 0.04 µm) at low relative humidity (RHi < 40 %), the relatively large particles in the aerosol layer were generally very hydrophilic as their size increased dramatically with relative humidity. This result indicates that water vapor can play a very important role in increasing the size of fine particles in the UTLS over the Tibetan Plateau. Our observations provide observation-based evidence supporting the idea that aerosol particle hygroscopic growth is an important factor influencing the radiative properties of the Asian Tropopause Aerosol Layer (ATAL) during the Asian summer monsoon.

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Lidar observations of volcanic aerosol over the UK since June 2019

10.5194/egusphere-egu2020-5653 ◽

2020 ◽

Author(s):

Geraint Vaughan ◽

David Wareing ◽

Hugo Ricketts

Keyword(s):

Volcanic Ash ◽

Stratospheric Aerosol ◽

Aerosol Layer ◽

Raman Lidar ◽

Lidar System ◽

Elastic Channel ◽

Enhanced Sensitivity ◽

Volcanic Cloud ◽

The Uk ◽

Lidar Observations

On 22 June 2019, the Raikoke volcano in the Kuril Islands erupted, sending a plume of ask and sulphur dioxide into the stratosphere. A Raman lidar system at Capel Dewi, UK (52.4&#176;N, 4.1&#176;W) has been used to measure the extent and optical depth of the stratospheric aerosol layer following the eruption. The lidar was modified to give it much enhanced sensitivity in the elastic channel, allowing measurements up to 25 km, but the Raman channel is only sensitive to the troposphere. Therefore, backscatter ratio profiles were derived by comparison with aerosol-free profiles derived from nearby radiosondes, corrected for aerosol extinction. Small amounts of stratospheric aerosol were measured prior to the arrival of the volcanic cloud, probably from pyroconvection over Canada. Volcanic ash began to arrive as a thin layer at 14 km late on 3 July, extending over the following month to fill the stratosphere below around 19 km. Aerosol optical depths reached around 0.03 by mid-August and continued at this level for the remainder of the year. The location of peak backscatter varied considerably but was generally around 15 km. However, on one notable occasion on August 25, a layer around 300 m thick with peak lidar backscatter ratio around 1.5 was observed as high as 21 km.

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