Stratospheric aerosol enhancement and decay after Raikoke eruption in July 2019 as observed from Tbilisi, Georgia and Halle, Belgium using ground-based twilight sky brightness spectral measurements.

2021 ◽  
Author(s):  
Nina Mateshvili ◽  
Didier Fussen ◽  
Iuri Mateshvili ◽  
Filip Vanhellemont ◽  
Christine Bingen ◽  
...  
Keyword(s):  
Western Europe ◽  
Stratospheric Aerosol ◽  
Kuril Islands ◽  
Spectral Measurements ◽  
South Caucasus ◽  
Layer Maximum ◽  
Volcanic Cloud ◽  
Sky Brightness ◽  
In The Beginning ◽  
Stratospheric Aerosols

<p>Twilight sky brightness spectral measurements are an inexpensive and effective way to observe enhancements of stratospheric aerosols. In this work, we present our observations of the volcanic cloud produced by the eruption of Raikoke volcano (Kuril Islands, 48°N, 153°E) above two distinct sites in South Caucasus and Western Europe, respectively: Tbilisi, Georgia (41° 43’ N, 44° 47° E) and Halle, Belgium (50° 44′ N, 4° 14′ E).</p><p>We present our dataset, which describes the evolution of the stratospheric aerosol in the period July 2019-December 2020. Stratospheric aerosol vertical extinction profiles were retrieved at 780 nm from spectral measurements of twilight sky brightness above both sites.</p><p>The first aerosols originating from Raikoke  were observed in the beginning of July above Halle and in August above Georgia. The layer maximum was mostly observed at 17 km above Georgia and at 10-17 km above Belgium until April-May 2020. Later, the volcanic cloud was observed sporadically until the end of 2020.</p>

scholarly journals Nabro volcano aerosol in the stratosphere over Georgia, South Caucasus from ground-based spectrometry of twilight sky brightness

2013 ◽  
Vol 6 (10) ◽  
pp. 2563-2576 ◽  
Author(s):  
N. Mateshvili ◽  
D. Fussen ◽  
G. Mateshvili ◽  
I. Mateshvili ◽  
F. Vanhellemont ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Multiple Scattering ◽  
Optical Depth ◽  
Stratospheric Aerosol ◽  
Aerosol Layer ◽  
Aerosol Extinction ◽  
Spectral Measurements ◽  
South Caucasus ◽  
Tropospheric Aerosol ◽  
Sky Brightness

Abstract. Ground-based spectral measurements of twilight sky brightness were carried out between September 2009 and August 2011 in Georgia, South Caucasus. The algorithm which allowed to retrieve the lower stratospheric and upper tropospheric aerosol extinction profiles was developed. The Monte-Carlo technique was used to correctly represent multiple scattering in a spherical atmosphere. The estimated stratospheric aerosol optical depths at a wavelength of 780 nm were: 6 × 10−3 ± 2 × 10−3 (31 August 2009–29 November 2009), 2.5 × 10−3 ± 7 × 10−4 (20 March 2010–15 January 2011) and 8 × 10−3 ± 3 × 10−3 (18 July 2011–3 August 2011). The optical depth values correspond to the moderately elevated stratospheric aerosol level after the Sarychev eruption in 2009, background stratospheric aerosol layer, and the volcanically disturbed stratospheric aerosol layer after the Nabro eruption in June 2011.

scholarly journals Nabro volcano aerosol in the stratosphere over Georgia, South Caucasus from ground-based spectrometry of twilight sky brightness

2013 ◽  
Vol 6 (3) ◽  
pp. 4401-4444
Author(s):  
N. Mateshvili ◽  
D. Fussen ◽  
G. Mateshvili ◽  
I. Mateshvili ◽  
F. Vanhellemont ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Multiple Scattering ◽  
Stratospheric Aerosol ◽  
Aerosol Layer ◽  
Spectral Measurements ◽  
South Caucasus ◽  
Noctilucent Cloud ◽  
Optical Extinction ◽  
Tropospheric Aerosol ◽  
Sky Brightness

Abstract. Ground-based spectral measurements of twilight sky brightness were carried out between October 2009 and August 2011 in Georgia, South Caucasus. The algorithm which allowed to retrieve the lower stratospheric and upper tropospheric aerosol extinction profiles was developed. The Monte-Carlo technique was used to correctly represent multiple scattering in a spherical atmosphere. The estimated stratospheric aerosol optical depths at a wavelength of 780 nm were: 3.0 × 10−3 ± 1 × 10 −3 (31 August 2009–15 January 2011) and 1.1 × 10−2 ± 3 × 10−3 (18 July 2011–03 August 2011, 10 observations). The first optical depth value corresponds to the background stratospheric aerosol level, the last one to the volcanically disturbed one after the Nabro eruption in June 2011. Reconsideration of measurements acquired soon after the Pinatubo eruption in 1991 allowed to model the phenomenon of the "second purple light", a twilight sky brightness enhancement at large solar zenith angles (97–102°). Monte-Carlo modeling reveals that the second purple light is caused by multiple scattering in the stratospheric aerosol layer. The modeling also shows that, assuming a hypothetical mesospheric aerosol layer with optical extinction comparable to typical noctilucent cloud values, a measurable twilight sky brightness increase at wavelength 440 nm follows at solar zenith angles 98–99&deg.

scholarly journals Simulation of ash clouds after a Laacher See-type eruption

2021 ◽  
Author(s):  
Ulrike Niemeier ◽  
Felix Riede ◽  
Claudia Timmreck
Keyword(s):  
Explosive Volcanism ◽  
Stratospheric Aerosol ◽  
Radiative Heating ◽  
The Arctic ◽  
Current Evidence ◽  
Aerosol Model ◽  
Model Experiments ◽  
North East ◽  
Volcanic Cloud ◽  
The Impact

<p>The large explosive eruption of the Laacher See volcano c. 12,900 yrs BP marked the end of explosive volcanism in the East Eifel volcanic zone (Germany). We have reviewed the current evidence for the impact of the Laacher See Eruption (LSE) on the immediate and wider environment as recorded in a range of proxies with a series of interactive stratospheric aerosol model experiments. Recent studies about the climate impact of NH extratropical eruptions and new insights about the dating of the LSE warrant a return to this cataclysmic eruption and its potential influence on Northern Hemisphere climate. Rather detailed reconstructions of its eruption dynamics have been proposed. The eruption might have lasted several weeks or even months, most likely with an initial (~10h) intense early phase resulting in deposits over north-east Germany and the Baltic Sea, and a slightly later and weaker phase leaving deposits south of the volcano towards the Alps.</p><p>Our interactive stratospheric aerosol model experiments are based on a reference LSE experiment with emission estimates of 20 Tg of sulfur dioxide (SO<sub>2</sub>) and 200 Tg of fine-ash, across two eruptive phases in May and June. Additional sensitivity experiments reflect the estimated range of uncertainty of the injection rate and altitude and, assess how the solar-absorptive heating from the 150 Tg of sub-micron ash emitted in the first eruptive phase changed the LSE cloud’s dispersion. Our simulations reveal that the heating of the ash likely played an important role in the transport of ash and sulfate. Depending on the altitude of the injection, our simulated volcanic cloud begins to rotate shortly after the eruption. This meso-cyclone, as well as the additional radiative heating of the fine ash then changes the dispersion of the cloud to be more southerly compared to dispersal estimated without fine-ash heating. Sulfate transport is similarly impacted by the heating of the ash, resulting in a stronger transport to low-latitudes, later arrival of the volcanic cloud in the Arctic regions and a longer lifetime compared to cases without injection of fine ash.</p>

scholarly journals Quasi-biennial oscillation of the tropical stratospheric aerosol layer

2015 ◽  
Vol 15 (10) ◽  
pp. 5557-5584 ◽  
Author(s):  
R. Hommel ◽  
C. Timmreck ◽  
M. A. Giorgetta ◽  
H. F. Graf
Keyword(s):  
Seasonal Variations ◽  
Stratospheric Aerosol ◽  
Static Balance ◽  
Aerosol Layer ◽  
Mixing Ratio ◽  
Quasi Biennial Oscillation ◽  
Mixing Ratios ◽  
Vertical Extent ◽  
Biennial Oscillation ◽  
Stratospheric Aerosols

Abstract. This study describes how aerosol in an aerosol-coupled climate model of the middle atmosphere is influenced by the quasi-biennial oscillation (QBO) during times when the stratosphere is largely unperturbed by volcanic material. In accordance with satellite observations, the vertical extent of the stratospheric aerosol layer in the tropics is modulated by the QBO by up to 6 km, or ~ 35% of its mean vertical extent between 100–7 hPa (about 16–33 km). Its largest vertical extent lags behind the occurrence of strongest QBO westerlies. The largest reduction lags behind maximum QBO easterlies. Strongest QBO signals in the aerosol surface area (30 %) and number densities (up to 100% e.g. in the Aitken mode) are found in regions where aerosol evaporates, that is above the 10 hPa pressure level (~ 31 km). Positive modulations are found in the QBO easterly shear, negative modulations in the westerly shear. Below 10 hPa, in regions where the aerosol mixing ratio is largest (50–20 hPa, or ~ 20–26 km), in most of the analysed parameters only moderate statistically significant QBO signatures (< 10%) have been found. QBO signatures in the model prognostic aerosol mixing ratio are significant at the 95% confidence level throughout the tropical stratosphere where modelled mixing ratios exceed 0.1 ppbm. In some regions of the tropical lower stratosphere the QBO signatures in other analysed parameters are partly not statistically significant. Peak-to-peak amplitudes of the QBO signature in the prognostic mixing ratios are up to twice as large as seasonal variations in the region where aerosols evaporate and between 70–30 hPa. Between the tropical tropopause and 70 hPa the QBO signature is relatively weak and seasonal variations dominate the variability of the simulated Junge layer. QBO effects on the upper lid of the tropical aerosol layer turn the quasi-static balance between processes maintaining the layer's vertical extent into a cyclic balance when considering this dominant mode of atmospheric variability. Global aerosol-interactive models without a QBO are only able to simulate the quasi-static balance state. To assess the global impact of stratospheric aerosols on climate processes, those partly nonlinear relationships between the QBO and stratospheric aerosols have to be taken into account.

Lidar observations of volcanic aerosol over the UK since June 2019

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

&lt;p&gt;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&amp;#176;N, 4.1&amp;#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.&lt;/p&gt;

МЕЖДУНАРОДНЫЙКОНТЕКСТРЕВОЛЮЦИОННОЙИДЕОЛОГИИВРОССИИНАЧАЛАXXВ.

2019 ◽  
pp. 192-209
Author(s):  
G.N. Lanskoy
Keyword(s):  
Political Development ◽  
Western Europe ◽  
Comparative Method ◽  
Historical Experience ◽  
Revolutionary Movement ◽  
Political Ideas ◽  
Russian State ◽  
Basic Ideas ◽  
In The Beginning ◽  
Parallel Evaluation

Paper is devoted to origins and to content of ideological conceptions which had influence to preparation of revolutions in Russia in the beginning of XX century. These conceptions are examined from viewpoint of their appearance in countries of Western Europe and partly in Russia and of their future transformation to practice of social and political development of Russia. In text are analyzed objective conditions for diversification of conceptions of liberalism, Marxism and revolutionary anarchism on territory of Russian Empire. For decision of indicated researching tasks were used retrospective and logical methods which gave possibility to show connection between historical experience of development of Russian state and perception of oppositional political ideas by its citizens. In context of conceptions of foreign minders were also studied basic ideas of theoreticians of Russian revolutionary movement of end of XIX beginning of XX century V.I. Lenin, G.V. Plekhanov, L.D. Trotsky and some other authors. In paper was used comparative method with aim of parallel evaluation of viewpoints of foreign and Russian scientists on specifities of diversification of revolutionary ideas in Russia in the beginning of XX century. In the end of paper are determined the alternative forms of revolutionary development in Russia in the beginning of XX century connected with diversity of revolutionary ideologies actual for this period.Статья посвящена истокам и содержанию идеологических концепций, оказавших влияние на подготовку революций в России в начале XX века. Эти концепции рассматриваются с точки зрения их появления в странах Западной Европы и отчасти в России и их дальнейшей трансформации в практику социальнополитического развития России. В тексте анализируются объективные условия диверсификации концепций либерализма, марксизма и революционного анархизма на территории Российской Империи. Для решения указанных исследовательских задач были использованы ретроспективные и логические методы, которые позволили показать связь между историческим опытом развития российского государства и восприятием оппозиционных политических идей его гражданами. В контексте концепций зарубежных мыслителей были также изучены основные идеи теоретиков русского революционного движения конца XIXначала XX века В. И. Ленина, Г. В. Плеханова, Л. Д. Троцкого и некоторых других авторов. В работе использован сравнительный метод с целью параллельной оценки точек зрения зарубежных и российских ученых на особенности диверсификации революционных идей в России в начале XX века. В конце статьи определяются альтернативные формы революционного развития в России в начале XX века, связанные с многообразием актуальных для этого периода революционных идеологий.

scholarly journals Sulphur dioxide as a volcanic ash proxy during the April–May 2010 eruption of Eyjafjallajökull Volcano, Iceland

2011 ◽  
Vol 11 (14) ◽  
pp. 6871-6880 ◽  
Author(s):  
H. E. Thomas ◽  
A. J. Prata
Keyword(s):  
Western Europe ◽  
Volcanic Ash ◽  
Final Phase ◽  
Middle Phase ◽  
Eruption Style ◽  
Infrared Imager ◽  
Cloud Monitoring ◽  
Volcanic Ash Cloud ◽  
Volcanic Cloud ◽  
Financial Losses

Abstract. The volcanic ash cloud from the eruption of Eyjafjallajökull volcano in April and May 2010 resulted in unprecedented disruption to air traffic in Western Europe causing significant financial losses and highlighting the importance of efficient volcanic cloud monitoring. The feasibility of using SO2 as a tracer for the ash released during the eruption is investigated here through comparison of ash retrievals from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) with SO2 measurements from a number of infrared and ultraviolet satellite-based sensors. Results demonstrate that the eruption can be divided into an initial ash-rich phase, a lower intensity middle phase and a final phase where considerably greater quantities both ash and SO2 were released. Comparisons of ash-SO2 dispersion indicate that despite frequent collocation of the two species, there are a number of instances throughout the eruption where separation is observed. This separation occurs vertically due to the more rapid settling rate of ash compared to SO2, horizontally through wind shear and temporally through volcanological controls on eruption style. The potential for the two species to be dispersed independently has consequences in terms of aircraft hazard mitigation and highlights the importance of monitoring both species concurrently.

scholarly journals Past Evolution and Recent Changes in Western Europe Large-scale Circulation

2021 ◽  
Author(s):  
Antoine Blanc ◽  
Juliette Blanchet ◽  
Jean-Dominique Creutin
Keyword(s):  
Large Scale ◽  
Western Europe ◽  
Weather Conditions ◽  
Large Scale Circulation ◽  
Zonal Flows ◽  
Important Challenge ◽  
Key Driver ◽  
Height Fields ◽  
In The Beginning ◽  
Local Weather

Abstract. Detecting trends in regional large-scale circulation (LSC) is an important challenge as LSC is a key driver of local weather conditions. In this work, we investigate the past evolution of Western Europe LSC based on the 500 hPa geopotential height fields from 20CRv2c (1851–2010), ERA20C (1900–2010) and ERA5 (1950–2010) reanalyses. We focus on the evolution of large-scale circulation characteristics using three atmospheric descriptors that are based on analogy – characterizing the geopotential shape stationarity and how well a geopotential shape is reproduced in the climatology – together with a non-analogy descriptor accounting for the intensity of the centers of action. These descriptors were shown relevant to study precipitation extremes and variability in the Northwestern Alps in previous studies. Even though LSC characteristics and trends are consistent among the three reanalyses after 1950, we find major differences between 20CRv2c and ERA20C from 1900 to 1950 in accordance with previous studies. Notably, ERA20C produces flatter geopotential shapes in the beginning of the 20th century and shows a reinforcement of the meridional pressure gradient that is not observed in 20CRv2c. We then focus on the recent changes in LSC from 1950 to 2019 using ERA5. We combine the four atmospheric descriptors with an existing weather pattern classification to study the recent changes in the main atmospheric influences over France and Western Europe (Atlantic, Mediterranean, Northeast, Anticyclonic). We show that little changes are found in Northeast circulations. However, we show that Atlantic circulations (zonal flows) tend to become more similar to known Atlantic circulations in winter. Anticyclonic conditions tend to become more stationary in summer – a change that can potentially affect summer heatwaves. Furthermore, Mediterranean circulations tend to become more stationary, more similar to known Mediterranean circulations and associated with stronger centers of action in autumn, which could have implications for autumn extreme precipitation in the Mediterranean-influenced regions of the Southwestern Alps.

scholarly journals Measurement Report: Lidar measurements of stratospheric aerosol following the 2019 Raikoke and Ulawun volcanic eruptions

2021 ◽  
Vol 21 (7) ◽  
pp. 5597-5604
Author(s):  
Geraint Vaughan ◽  
David Wareing ◽  
Hugo Ricketts
Keyword(s):  
Initial Period ◽  
Volcanic Eruptions ◽  
Stratospheric Aerosol ◽  
Elastic Channel ◽  
Aerosol Cloud ◽  
Maximum Value ◽  
Lidar Measurements ◽  
Volcanic Cloud ◽  
Lidar Ratio ◽  
The Uk

Abstract. At 18:00 UTC on 21 June 2019 the Raikoke volcano in the Kuril islands began a large-magnitude explosive eruption, sending a plume of ash and sulfur dioxide into the stratosphere. A Raman lidar system at Capel Dewi Atmospheric Observatory, UK, was deployed to measure the vertical extent and optical depth of the volcanic aerosol cloud following the eruption. The elastic channel at 355 nm allowed measurements up to 25 km, but the Raman channel was only sensitive to the troposphere. Therefore, retrievals of backscatter ratio profiles from the raw backscatter measurements required aerosol-free profiles derived from nearby radiosondes and allowance for aerosol extinction using a lidar ratio of 40–50 sr. Small amounts of aerosol were measured prior to the arrival of the volcanic cloud (27 June–5 July 2019), from pyroconvection over Canada. Model simulations by de Leeuw et al. (2020) and Kloss et al. (2020) show that volcanic ash may have reached Europe from 1 July onwards and was certainly present over the UK after 10 July. The lidar detected a thin layer at an altitude of 14 km late on 3 July, with the first detection of the main aerosol cloud on 13 July. In this initial period the aerosol was confined below 16 km, but eventually the cloud extended to 20.5 km. A sustained period of clearly enhanced stratospheric aerosol optical depths began in early August, with a maximum value (at 355 nm) around 0.05 in mid-August and remaining above 0.02 until early November. Thereafter, optical depths decayed to around 0.01 by the end of 2019 and remained around that level until May 2020. The altitude of peak backscatter varied considerably (between 14 and 18 km) but was generally around 15 km. However, on one notable occasion on 25 August 2019, a layer around 300 m thick with peak lidar backscatter ratio around 1.5 was observed as high as 21 km.

Sign in / Sign up

Export Citation Format

Share Document