A solar escalator: Observational evidence of the self‐lifting of smoke and aerosols by absorption of solar radiation in the February 2009 Australian Black Saturday plume

Laat, A. T. J. de; Zweers, Deborah Claire Stein; Boers, R.; Tuinder, O. N. E.

doi:10.1029/2011jd017016

Cited by 87 publications

(110 citation statements)

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“…Thus, due to dilution and the mentioned removal processes in the mid-latitudes there is little chance for a longterm stratospheric impact. Rising farther into the stratosphere would, e.g., require dynamical lifting or absorption of solar radiation by the particles (De Laat et al, 2012).…”

Section: Discussionmentioning

confidence: 99%

35 yr of stratospheric aerosol measurements at Garmisch-Partenkirchen: from Fuego to Eyjafjallajökull, and beyond

et al. 2013

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Lidar measurements at Garmisch-Partenkirchen (Germany) have almost continually delivered backscatter coefficients of stratospheric aerosol since 1976. The time series is dominated by signals from the particles injected into or formed in the stratosphere due to major volcanic eruptions, in particular those of El Chichon (Mexico, 1982) and Mt Pinatubo (Philippines, 1991). Here, we focus more on the long-lasting background period since the late 1990s and 2006, in view of processes maintaining a residual lower-stratospheric aerosol layer in absence of major eruptions, as well as the period of moderate volcanic impact afterwards. During the long background period the stratospheric backscatter coefficients reached a level even below that observed in the late 1970s. This suggests that the predicted potential influence of the strongly growing air traffic on the stratospheric aerosol loading is very low. Some correlation may be found with single strong forest-fire events, but the average influence of biomass burning seems to be quite limited. No positive trend in background aerosol can be resolved over a period as long as that observed by lidar at Mauna Loa. We conclude that the increase of our integrated backscatter coefficients starting in 2008 is mostly due to volcanic eruptions with explosivity index 4, penetrating strongly into the stratosphere. Most of them occurred in the mid-latitudes. A key observation for judging the role of eruptions just reaching the tropopause region was that of the plume from the Icelandic volcano Eyjafjallajökull above Garmisch-Partenkirchen (April 2010) due to the proximity of that source. The top altitude of the ash above the volcano was reported just as 9.3 km, but the lidar measurements revealed enhanced stratospheric aerosol up to 14.3 km. Our analysis suggests for two or three of the four measurement days the presence of a stratospheric contribution from Iceland related to quasi-horizontal transport, differing from the strong descent of the layers entering Central Europe at low altitudes. The backscatter coefficients within the first 2 km above the tropopause exceed the stratospheric background by a factor of four to five. In addition, Asian and Saharan dust layers were identified in the free troposphere, Asian dust most likely even in the stratosphere

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Section: Discussionmentioning

confidence: 99%

35 yr of stratospheric aerosol measurements at Garmisch-Partenkirchen: from Fuego to Eyjafjallajökull, and beyond

et al. 2013

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“…In Table 1, we included the extraordinarily strong pyrocumulonimbus-related Australian wildfire event observed in February 2009 (Siddaway and Petelina, 2011;de Laat et al, 2012). Strong bushfires, very high temperatures, low winds, and thunderstorm evolution on 7 February, 2009, ("Black Saturday") triggered the lifting of enormous amounts of smoke towards the upper troposphere from where the smoke layers ascended by the self-lifting mechanism to a height of 15-20 km (Boers et al, 2010;de Laat et al, 2012).…”

Section: Discussionmentioning

confidence: 99%

“…Strong bushfires, very high temperatures, low winds, and thunderstorm evolution on 7 February, 2009, ("Black Saturday") triggered the lifting of enormous amounts of smoke towards the upper troposphere from where the smoke layers ascended by the self-lifting mechanism to a height of 15-20 km (Boers et al, 2010;de Laat et al, 2012). Similar maximum 532 nm AEC and AOT values as measured over central Europe on 21-22 August 2017, were observed with the CALIPSO lidar in the lower stratosphere over the South Pacific east of Australia at heights above the tropopause and below 20 km a few days after 7 February, 2009, (de Laat et al, 2012. The stratospheric perturbation slowly decreased during the following months (FebruaryJune 2009) (Siddaway and Petelina, 2011).…”

Section: Discussionmentioning

confidence: 99%

“…Fromm et al (2000Fromm et al ( , 2003 and Rosenfeld et al (2007) showed that large amounts of fire smoke can be lifted up to the tropopause within a short time period (less than 1 h) and can partly reach the lower stratosphere via the formation of pyrocumulonimbus clouds that are associated with strong updrafts with vertical wind velocities of 10-30 m s −1 (Fromm et al, 2010;Peterson et al, 2017). Self-lifting effects (Boers et al, 2010;Siddaway and Petelina, 2011;de Laat et al, 2012) and gravito-photophoresis forces (Rohatschek, 1996;Pueschel et al, 2000;Cheremisin et al, 2005;Renard et al, 2008) lead to a further ascent of the soot-containing layers.…”

Section: Introductionmentioning

confidence: 99%

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Extreme levels of Canadian wildfire smoke in the stratosphere over central Europe on 21–22 August 2017

et al. 2018

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Abstract. Light extinction coefficients of 500 Mm −1 , about 20 times higher than after the Pinatubo volcanic eruptions in 1991, were observed by European Aerosol Research Lidar Network (EARLINET) lidars in the stratosphere over central Europe on 21-22 August 2017. Pronounced smoke layers with a 1-2 km vertical extent were found 2-5 km above the local tropopause. Optically dense layers of Canadian wildfire smoke reached central Europe 10 days after their injection into the upper troposphere and lower stratosphere which was caused by rather strong pyrocumulonimbus activity over western Canada. The smoke-related aerosol optical thickness (AOT) identified by lidar was close to 1.0 at 532 nm over Leipzig during the noon hours on 22 August 2017. Smoke particles were found throughout the free troposphere (AOT of 0.3) and in the pronounced 2 km thick stratospheric smoke layer at an altitude of 14-16 km (AOT of 0.6). The lidar observations indicated peak mass concentrations of 70-100 µg m −3 in the stratosphere. In addition to the lidar profiles, we analyzed Moderate Resolution Imaging Spectroradiometer (MODIS) fire radiative power (FRP) over Canada, and the distribution of MODIS AOT and Ozone Monitoring Instrument (OMI) aerosol index across the North Atlantic. These instruments showed a similar pattern and a clear link between the western Canadian fires and the aerosol load over Europe. In this paper, we also present Aerosol Robotic Network (AERONET) sun photometer observations, compare photometer and lidar-derived AOT, and discuss an obvious bias (the smoke AOT is too low) in the photometer observations. Finally, we compare the strength of this recordbreaking smoke event (in terms of the particle extinction coefficient and AOT) with major and moderate volcanic events observed over the northern midlatitudes.

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“…Pyro-convection, a combination of extreme convection and forest fires that manifests within pyro-cumulonimbus (pyroCb) clouds (Fromm et al, 2006), has the potential to uplift aerosols directly into the stratosphere. Another mechanism that can potentially cause stratospheric injection into the UTLS is through isentropic transport caused by solar radiation absorption of aerosols (de Laat et al, 2012). Explosive volcanic eruptions can also inject polluted material -including ash, sulphur dioxide (SO 2 ), carbon dioxide (CO 2 ) and water vapour (H 2 O) -directly into the UTLS with resulting plumes being transported across the globe (Prata et al, 2007;Clarisse et al, 2008).…”

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confidence: 99%

MIPAS detection of cloud and aerosol particle occurrence in the UTLS with comparison to HIRDLS and CALIOP

et al. 2012

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Abstract. Satellite infrared emission instruments require efficient systems that can separate and flag observations which are affected by clouds and aerosols. This paper investigates the identification of cloud and aerosols from infrared, limb sounding spectra that were recorded by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), a high spectral resolution Fourier transform spectrometer on the European Space Agency's (ESA) ENVISAT (Now inoperative since April 2012 due to loss of contact). Specifically, the performance of an existing cloud and aerosol particle detection method is simulated with a radiative transfer model in order to establish, for the first time, confident detection limits for particle presence in the atmosphere from MIPAS data. The newly established thresholds improve confidence in the ability to detect particle injection events, plume transport in the upper troposphere and lower stratosphere (UTLS) and better characterise cloud distributions utilising MIPAS spectra. The method also provides a fast front-end detection system for the MIPClouds processor; a processor designed for the retrieval of macro-and microphysical cloud properties from the MIPAS data.It is shown that across much of the stratosphere, the threshold for the standard cloud index in band A is 5.0 although threshold values of over 6.0 occur in restricted regimes. Polar regions show a surprising degree of uncertainty at altitudes above 20 km, potentially due to changing stratospheric trace gas concentrations in polar vortex conditions and poor signal-to-noise due to cold atmospheric temperatures. The optimised thresholds of this study can be used for much of the time, but time/composition-dependent thresholds are recommended for MIPAS data for the strongly perturbed polar stratosphere. In the UT, a threshold of 5.0 applies at 12 km and above but decreases rapidly at lower altitudes. The new thresholds are shown to allow much more sensitive detection of particle distributions in the UTLS, with extinction detection limits above 13 km often better than 10 −4 km −1 , with values approaching 10 −5 km −1 in some cases.Comparisons of the new MIPAS results with cloud data from HIRDLS and CALIOP, outside of the poles, establish a good agreement in distributions (cloud and aerosol top heights and occurrence frequencies) with an offset between MIPAS and the other instruments of 0.5 km to 1 km between 12 km and 20 km, consistent with vertical oversampling of extended cloud layers within the MIPAS field of view. We conclude that infrared limb sounders provide a very consistent picture of particles in the UTLS, allowing detection limits which are consistent with the lidar observations. Investigations of MIPAS data for the Mount Kasatochi volcanic eruption on the Aleutian Islands and the Black Saturday fires in Australia are used to exemplify how useful MIPAS limb sounding data were for monitoring aerosol injections into the UTLS. It is shown that the new thresholds allowed such events to be much more effectively derived fro...

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A solar escalator: Observational evidence of the self‐lifting of smoke and aerosols by absorption of solar radiation in the February 2009 Australian Black Saturday plume

Cited by 87 publications

References 70 publications

35 yr of stratospheric aerosol measurements at Garmisch-Partenkirchen: from Fuego to Eyjafjallajökull, and beyond

35 yr of stratospheric aerosol measurements at Garmisch-Partenkirchen: from Fuego to Eyjafjallajökull, and beyond

Extreme levels of Canadian wildfire smoke in the stratosphere over central Europe on 21–22 August 2017

MIPAS detection of cloud and aerosol particle occurrence in the UTLS with comparison to HIRDLS and CALIOP

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