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

Ohneiser, Kevin; Ansmann, Albert; Engelmann, Ronny; Ritter, Christoph; Chudnovsky, Alexandra; Veselovskii, Igor; Baars, Holger; Gebauer, Henriette; Griesche, Hannes; Radenz, Martin; Hofer, Julian; Althausen, Dietrich; Dahlke, Sandro; Maturilli, Marion

doi:10.5194/acp-2021-117

Cited by 5 publications

(1 citation statement)

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“…The stratospheric sulfur aerosol and cirrus reflectance show a strong inverse correlation in 2001-2011 from Moderate Resolution Imaging Spectroradiometer (MODIS) observations (Friberg et al, 2015). From MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate), Ohneiser et al (2021) observed 30 km high aerosol and cloud layers over high altitudes in the northern hemisphere from October 2019 to May 2020 and found out that those cloud layers were generated by the major wildfire events in July and August 2019. Atmospheric aerosol show an impact on the occurrence and variability of ice clouds, while the influence of aerosol on their microphysical properties remains highly uncertain.…”

Section: Introductionmentioning

confidence: 99%

A global view on stratospheric ice clouds: assessment of processes related to their occurrence based on satellite observations

Zou¹,

Grießbach²,

Hoffmann³

et al. 2022

Preprint

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Abstract. Ice clouds play an important role in regulating water vapor and influencing the radiative budget in the atmosphere. In this study, stratospheric ice clouds (SICs) and stratospheric aerosols from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), deep convection and gravity waves from Atmospheric Infrared Sounder (AIRS) observations and tropopause temperature from ERA5 are analyzed to investigate their long-term variation and processes potentially related to the formation of SICs on the global scale. SICs with cloud top heights 0.25 km above the first tropopause are mainly detected over the tropical continents. SICs associated with the double tropopause events, where the cloud top is between the first and second thermal tropopause, are mostly located in midlatitudes (between 25°–60°). The seasonal cycle and the inter-annual variability of SIC frequencies from 2007 to 2019 show that high SIC frequencies are mainly observed south of the equator from November to March, and at 10° N–20° N from July to September. At mid- and high latitudes, more SICs are observed from December to May in the northern hemisphere and in the southern hemisphere during May to October. Relations between SICs and first tropopause temperature, deep convection, gravity waves, and stratospheric aerosol were analyzed, respectively, on a global scale. Positive correlations between SIC frequencies and deep convection, gravity waves, and stratospheric aerosol and an inverse correlation between SIC frequency and tropopause temperature were observed worldwide. Overlaps of high correlations/anti-correlations were detected over tropical continents, i.e., tropical South America, equatorial Africa, and western Pacific, suggesting a combined effect of tropopause temperature, deep convection, gravity waves, and stratospheric aerosol on SIC occurrence in these regions. Over Central America, North America, the Asian Monsoon, and mid- and high latitudes deep convection and gravity waves present a strong correlation with the occurrence of SICs, individually or interdependently. Regional analyses demonstrated specific relations of tropopause temperature, deep convection, gravity waves, and stratospheric aerosol with SICs at a finer scale. Low tropopause temperature and high occurrence frequency of stratospheric aerosol show strong correlations with high frequencies of SICs over the Indo-Pacific Warm Pool, tropical South America, and equatorial Africa. Deep convection and gravity waves have the strongest correlation with the occurrence frequency of SICs over the Asian Monsoon and the North American Monsoon. Gravity waves and tropopause temperature are highly correlated with SIC occurrence over South America and the northern Atlantic. Moreover, the El Niño phenomenon in 2009–2010 and 2015–2016 coincides with low SIC occurrences over the Indo-Pacific Warm Pool. High stratospheric aerosol loads related to volcanic eruptions (Puyehue-Cordón Caulle and Nabro in 2011) and wildfires (over the United States and Canada in 2017) are closely related to high occurrence frequencies of SICs. We investigated the global distribution and long-term variation of SICs and present a global view of relations between SIC occurrence and tropopause temperature, deep convection, gravity wave activity, and stratospheric aerosol. This work provides a better understanding of the physical processes and climate variability of SICs.

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Section: Introductionmentioning

confidence: 99%

A global view on stratospheric ice clouds: assessment of processes related to their occurrence based on satellite observations

Zou¹,

Grießbach²,

Hoffmann³

et al. 2022

Preprint

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

et al. 2021

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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.

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Tropospheric and stratospheric wildfire smoke profiling with lidar: mass, surface area, CCN, and INP retrieval

et al. 2021

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Abstract. We present retrievals of tropospheric and stratospheric height profiles of particle mass, volume, surface area, and number concentrations in the case of wildfire smoke layers as well as estimates of smoke-related cloud condensation nuclei (CCN) and ice-nucleating particle (INP) concentrations from backscatter lidar measurements on the ground and in space. Conversion factors used to convert the optical measurements into microphysical properties play a central role in the data analysis, in addition to estimates of the smoke extinction-to-backscatter ratios required to obtain smoke extinction coefficients. The set of needed conversion parameters for wildfire smoke is derived from AERONET observations of major smoke events, e.g., in western Canada in August 2017, California in September 2020, and southeastern Australia in January–February 2020 as well as from AERONET long-term observations of smoke in the Amazon region, southern Africa, and Southeast Asia. The new smoke analysis scheme is applied to CALIPSO observations of tropospheric smoke plumes over the United States in September 2020 and to ground-based lidar observation in Punta Arenas, in southern Chile, in aged Australian smoke layers in the stratosphere in January 2020. These case studies show the potential of spaceborne and ground-based lidars to document large-scale and long-lasting wildfire smoke events in detail and thus to provide valuable information for climate, cloud, and air chemistry modeling efforts performed to investigate the role of wildfire smoke in the atmospheric system.

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

Cited by 5 publications

References 0 publications

A global view on stratospheric ice clouds: assessment of processes related to their occurrence based on satellite observations

A global view on stratospheric ice clouds: assessment of processes related to their occurrence based on satellite observations

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

Tropospheric and stratospheric wildfire smoke profiling with lidar: mass, surface area, CCN, and INP retrieval

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