Stratospheric AOD after the 2011 eruption of Nabro volcano measured by lidars over the Northern Hemisphere
University of Maryland, Baltimore County1, Langley Research Center2, National Oceanic and Atmospheric Administration3, Goddard Space Flight Center4, University of Granada5, Polytechnic University of Catalonia6, Centre national de la recherche scientifique7, Chinese Academy of Sciences8, Indian Institute of Technology Kanpur9
TL;DR: In this article, the authors report on ground-based lidar observations of the same event from every continent in the Northern Hemisphere, taking advantage of the synergy between global lidar networks such as EARLINET, MPLNET and NDACC with independent lidar groups and satellite CALIPSO.
Abstract: Nabro volcano (13.37°N, 41.70°E) in Eritrea erupted on 13 June 2011 generating a layer of sulfate aerosols that persisted in the stratosphere for months. For the first time we report on ground-based lidar observations of the same event from every continent in the Northern Hemisphere, taking advantage of the synergy between global lidar networks such as EARLINET, MPLNET and NDACC with independent lidar groups and satellite CALIPSO to track the evolution of the stratospheric aerosol layer in various parts of the globe. The globally averaged aerosol optical depth (AOD) due to the stratospheric volcanic aerosol layers was of the order of 0.018 ± 0.009 at 532 nm, ranging from 0.003 to 0.04. Compared to the total column AOD from the available collocated AERONET stations, the stratospheric contribution varied from 2% to 23% at 532 nm.
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TL;DR: The European Aerosol Research Lidar Network (EARLINET) as mentioned in this paper was founded as a research project for establishing a quantitative, comprehensive, and statistically significant database for the horizontal, vertical, and tempo-ral distribution of aerosols on a continental scale.
Abstract: The European Aerosol Research Lidar Network, EARLINET, was founded in 2000 as a research project for establishing a quantitative, comprehensive, and statistically significant database for the horizontal, vertical, and tempo- ral distribution of aerosols on a continental scale. Since then EARLINET has continued to provide the most extensive col- lection of ground-based data for the aerosol vertical distribu- tion over Europe. This paper gives an overview of the network's main de- velopments since 2000 and introduces the dedicated EAR- LINET special issue, which reports on the present innova- tive and comprehensive technical solutions and scientific re- sults related to the use of advanced lidar remote sensing tech- niques for the study of aerosol properties as developed within the network in the last 13 years. Since 2000, EARLINET has developed greatly in terms of number of stations and spatial distribution: from 17 sta- tions in 10 countries in 2000 to 27 stations in 16 countries in 2013. EARLINET has developed greatly also in terms of technological advances with the spread of advanced multi- wavelength Raman lidar stations in Europe. The develop- ments for the quality assurance strategy, the optimization of instruments and data processing, and the dissemination of data have contributed to a significant improvement of the net- work towards a more sustainable observing system, with an increase in the observing capability and a reduction of oper- ational costs. Consequently, EARLINET data have already been ex- tensively used for many climatological studies, long-range transport events, Saharan dust outbreaks, plumes from vol- canic eruptions, and for model evaluation and satellite data validation and integration. Future plans are aimed at continuous measurements and near-real-time data delivery in close cooperation with other ground-based networks, such as in the ACTRIS (Aerosols, Clouds, and Trace gases Research InfraStructure Network) www.actris.net, and with the modeling and satellite commu- nity, linking the research community with the operational world, with the aim of establishing of the atmospheric part of the European component of the integrated global observ- ing system.
417 citations
TL;DR: Preliminary validation studies show that the AOD discrepancies between CALIOP and AERONET/MODIS (ocean) are reduced in V4 compared to V3, and the lidar ratio revisions are the most influential factor for AOD changes from V3 to V4, especially for cloud-free skies.
Abstract: . The Cloud-Aerosol Lidar with Orthogonal Polarization
(CALIOP) version 4.10 (V4) level 2 aerosol data products, released in
November 2016, include substantial improvements to the aerosol subtyping and
lidar ratio selection algorithms. These improvements are described along
with resulting changes in aerosol optical depth (AOD). The most fundamental
change in the V4 level 2 aerosol products is a new algorithm to identify aerosol
subtypes in the stratosphere. Four aerosol subtypes are introduced for
stratospheric aerosols: polar stratospheric aerosol (PSA), volcanic ash,
sulfate/other, and smoke. The tropospheric aerosol subtyping algorithm was
also improved by adding the following enhancements: (1) all aerosol subtypes
are now allowed over polar regions, whereas the version 3 (V3) algorithm
allowed only clean continental and polluted continental aerosols; (2) a new
“dusty marine” aerosol subtype is introduced, representing mixtures of
dust and marine aerosols near the ocean surface; and (3) the “polluted
continental” and “smoke” subtypes have been renamed “polluted
continental/smoke” and “elevated smoke”, respectively. V4 also revises
the lidar ratios for clean marine, dust, clean continental, and elevated
smoke subtypes. As a consequence of the V4 updates, the mean 532 nm AOD
retrieved by CALIOP has increased by 0.044 (0.036) or 52 % (40 %) for
nighttime (daytime). Lidar ratio revisions are the most influential factor
for AOD changes from V3 to V4, especially for cloud-free skies. Preliminary
validation studies show that the AOD discrepancies between CALIOP and
AERONET–MODIS (ocean) are reduced in V4 compared to V3.
307 citations
TL;DR: In this article, the authors examined the temporal and latitudinal distribution of volcanic SO 2 emissions and reassess the relationship between eruptive SO 2 discharge and eruption magnitude, finding a first-order correlation between SO 2 emission and volcanic explosivity index (VEI), but with significant scatter.
243 citations
TL;DR: In this article, a new and fast SO2 height retrieval algorithm for observations of the Infrared Atmospheric Sounding Interferometer (IASI) is presented which indicates an accuracy better than 2 km for plumes below 20 km and SO2 columns up to the 1 DU level.
Abstract: . In the wake of the June 2011 Nabro eruption, large stratospheric plumes were observed by several instruments up to altitudes of 21 km, much higher than initial reported injection heights. It has been debated whether deep convection associated with the Asian Summer Monsoon anticyclone played a vital role in the vertical transport of the plume. Here we present a new and fast SO2 height retrieval algorithm for observations of the Infrared Atmospheric Sounding Interferometer (IASI). A comprehensive validation with forward trajectories and coincident CALIOP measurements is presented which indicates an accuracy better than 2 km for plumes below 20 km and SO2 columns up to the 1 DU level. We use this new product to analyse the Nabro eruption. Our findings indicate an initial plume located mainly between 15 and 17 km for which the lower parts underwent in succession rapid descent and uplift, within the Asian Monsoon anticyclone circulation, up to the stable thermal tropopause between 16 and 18 km, from where it slowly ascended further into the stratosphere. Evidence is presented that emissions in the first week of the eruption also contributed to the stratospheric sulfur input. This includes a second eruption between 15 and 17 km on the 16th and continuous emissions in the mid-troposphere of which some were also entrained and lifted within the anticyclonic circulation.
98 citations
Leibniz Institute for Neurobiology1, Royal Netherlands Meteorological Institute2, University of Granada3, National Academy of Sciences of Belarus4, Polytechnic University of Catalonia5, Pierre-and-Marie-Curie University6, Paris Diderot University7, Ludwig Maximilian University of Munich8, Finnish Meteorological Institute9, Karlsruhe Institute of Technology10, Bulgarian Academy of Sciences11, German Aerospace Center12, University of L'Aquila13, Max Planck Society14, Deutscher Wetterdienst15, National Technical University of Athens16, University College Cork17, Polish Academy of Sciences18, University of Évora19, École Polytechnique Fédérale de Lausanne20, Norwegian Institute for Air Research21, Stockholm University22
TL;DR: In this article, the authors show the four-dimensional (4-D) distribution of the Eyjafjallajokull volcanic cloud in the troposphere over Europe as observed by EARLINET during the entire volcanic event (15 April-26 May 2010).
Abstract: . The eruption of the Icelandic volcano Eyjafjallajokull in April–May 2010 represents a "natural experiment" to study the impact of volcanic emissions on a continental scale. For the first time, quantitative data about the presence, altitude, and layering of the volcanic cloud, in conjunction with optical information, are available for most parts of Europe derived from the observations by the European Aerosol Research Lidar NETwork (EARLINET). Based on multi-wavelength Raman lidar systems, EARLINET is the only instrument worldwide that is able to provide dense time series of high-quality optical data to be used for aerosol typing and for the retrieval of particle microphysical properties as a function of altitude. In this work we show the four-dimensional (4-D) distribution of the Eyjafjallajokull volcanic cloud in the troposphere over Europe as observed by EARLINET during the entire volcanic event (15 April–26 May 2010). All optical properties directly measured (backscatter, extinction, and particle linear depolarization ratio) are stored in the EARLINET database available at http://www.earlinet.org . A specific relational database providing the volcanic mask over Europe, realized ad hoc for this specific event, has been developed and is available on request at http://www.earlinet.org . During the first days after the eruption, volcanic particles were detected over Central Europe within a wide range of altitudes, from the upper troposphere down to the local planetary boundary layer (PBL). After 19 April 2010, volcanic particles were detected over southern and south-eastern Europe. During the first half of May (5–15 May), material emitted by the Eyjafjallajokull volcano was detected over Spain and Portugal and then over the Mediterranean and the Balkans. The last observations of the event were recorded until 25 May in Central Europe and in the Eastern Mediterranean area. The 4-D distribution of volcanic aerosol layering and optical properties on European scale reported here provides an unprecedented data set for evaluating satellite data and aerosol dispersion models for this kind of volcanic events.
91 citations
Cites background from "Stratospheric AOD after the 2011 er..."
...…ten-year period without appreciable volcanic activity, which ended by the end of 2006 when a series of several eruptions injected particles into the stratosphere that were recorded with lidar systems world-wide (Mattis et al., 2010; Kravitz et al., 2011; Sawamura et al., 2012; Trickl et al., 2012)....
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6,535 citations
"Stratospheric AOD after the 2011 er..." refers background in this paper
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2,302 citations
TL;DR: In this article, a new capability to predict the climatic response to a large tropical eruption for the succeeding 2 years will prove valuable to society, as well as to detect and attribute anthropogenic influences on climate, including effects of greenhouse gases, aerosols, and ozone-depleting chemicals.
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2,150 citations
"Stratospheric AOD after the 2011 er..." refers background in this paper
...The injection of SO2 due to volcanic eruptions is the biggest natural source of perturbations in the stratosphere (Robock 2000)....
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TL;DR: A simple analytical method is presented that shows some potential for application to the problem of extracting attenuation and backscatter coefficients in an inhomogeneous atmosphere from the return signal of a monostatic single-wavelength lidar system.
Abstract: A simple analytical method is presented that shows some potential for application to the problem of extracting attenuation and backscatter coefficients in an inhomogeneous atmosphere from the return signal of a monostatic single-wavelength lidar system. The method assumes the validity of the single-scattering lidar equation and a power law relationship between backscatter and attenuation. For optical depths greater than unity the inversion method can be applied in principle using only information contained in the signal itself. In contrast to a well-known related analytical inversion solution, the new solution form is shown to be stable with respect to perturbations in the signal, the postulated relationship between backscatter and attenuation, and the assumed or estimated boundary value of attenuation.
1,364 citations
"Stratospheric AOD after the 2011 er..." refers methods in this paper
...…Lidar (HSRL) techniques, or related to each other by a range-independent extinction-to-backscatter ratio (or lidar ratio, S, in units of steradian—sr) assuming layer homogeneity, e.g. elastic backscatter lidars using Klett–Fernald technique (Klett 1981, Fernald et al 1972) and variations thereof....
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TL;DR: The eruption of Mt Pinatubo in June 1991 caused the largest perturbation this century to the participate content of the stratosphere, which put an end to several years of globally warm surface temperatures as discussed by the authors.
Abstract: The eruption of Mt Pinatubo in June 1991 caused the largest perturbation this century to the participate content of the stratosphere. The radiative influence of the injected particles put an end to several years of globally warm surface temperatures. At the same time, the combined effect of volcanic particles and anthropogenic reactive chlorine has led to record low levels of stratospheric ozone.
857 citations
"Stratospheric AOD after the 2011 er..." refers background in this paper
...Explosive eruptions like Pinatubo in 1991 are the proof of how such events can impact our climate and the global temperature at the surface (McCormick et al 1995)....
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