Sustained axisymmetric intrusions in a rotating system

Ungarish, Marius; Johnson, Chris; Hogg, Andrew J.

doi:10.1016/j.euromechflu.2015.10.008

Cited by 5 publications

(18 citation statements)

References 19 publications

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“…The fine ash and sulfate aerosols both heat the stratosphere and thereby dynamically influence the resulting processes via circulation changes caused by absorption of near-infrared and LW radiation. This model has already been successfully applied for the simulation of recent and past large volcanic eruptions (e.g., Niemeier et al, 2009Niemeier et al, , 2019Toohey et al, , 2019. However, earlier studies with MAECHAM5-HAM were often performed with a lower horizontal and vertical resolution.…”

Section: Model Descriptionmentioning

confidence: 99%

“…The initial distribution and subsequent evolution of the volcanic cloud depends on the meteorological conditions of the stratosphere at the time of the eruption (Marshall et al, 2019;Toohey et al, 2019). This is particularly pronounced in midlatitude eruptions but also holds true for tropical eruptions (Jones et al, 2016).…”

Section: Eruption Daymentioning

confidence: 99%

“…Sulfate aerosols have a longer lifetime than fine ash and elicit a stronger climate impact. The LSE is an extratropical eruption and could, locally, have led to a stronger impact than a tropical eruption of the same size (Toohey et al, 2019). Following a NH eruption, sulfate is mainly transported within the Brewer-Dobson circulation (BDC) to higher northern latitudes (Fig.…”

Section: Global Distribution Of Sulfur Burdenmentioning

confidence: 99%

“…The volcanic cloud interacts with solar and terrestrial radiation. The ash is heated by absorption of solar radiation, causing an additional vertical updraft (Muser et al, 2020) and may cause the development of a mesocyclone (Baines and Sparks, 2005;Chakraborty et al, 2009;Niemeier et al, 2009;Ungarish et al, 2016). This heating occurs right after the eruption, before the substantial formation of sulfate aerosols.…”

Section: Introductionmentioning

confidence: 99%

“…Considerable advances in the modeling of volcanically induced climatic forcing of NH midlatitude eruptions have recently been made (Toohey et al, 2019), and these warrant renewed attention to the prehistoric LSE's potential influence on NH climate. The rich volcanological detail associated with this Late Pleistocene eruption facilitates a robust understanding of its interaction with the meteorological conditions shaping its ash and aerosol dispersal.…”

Section: Introductionmentioning

confidence: 99%

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Simulation of ash clouds after a Laacher See-type eruption

2021

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Abstract. Dated to approximately 13 000 years ago, the Laacher See (East Eifel volcanic zone) eruption was one of the largest midlatitude Northern Hemisphere volcanic events of the Late Pleistocene. This eruptive event not only impacted local environments and human communities but probably also affected Northern Hemispheric climate. To better understand the impact of a Laacher See-type eruption on NH circulation and climate, we have simulated the evolution of its fine ash and sulfur cloud with an interactive stratospheric aerosol model. Our experiments are based around a central estimate for the Laacher See aerosol cloud of 15 Tg of sulfur dioxide (SO2) and 150 Tg of fine ash, across the main eruptive phases in May and a smaller one in June with 5 Tg SO2 and 50 Tg of fine ash. Additional sensitivity experiments reflect the estimated range of uncertainty of the injection rate and altitude and assess how the solar-absorptive heating from the fine ash emitted in the first eruptive phase changed the volcanic clouds' dispersion. The chosen eruption dates were determined by the stratospheric wind fields to reflect the empirically observed ash lobes as derived from geological, paleoecological and archeological evidence linked directly to the prehistoric Laacher See eruption. Whilst our simulations are based on present-day conditions, and we do not seek to replicate the climate conditions that prevailed 13 000 years ago, we consider our experimental design to be a reasonable approximation of the transport pathways in the midlatitude stratosphere at this time of year. Our simulations suggest that the heating of the ash plays an important role for the transport of ash and sulfate. Depending on the altitude of the injection, the simulated volcanic cloud begins to rotate 1 to 3 d after the eruption. This mesocyclone, as well as the additional radiative heating of the fine ash, then changes the dispersion of the cloud itself to be more southward compared to dispersal estimated without fine ash heating. This ash-cloud-generated southerly migration process may at least partially explain why, as yet, no Laacher See tephra has been found in Greenland ice cores. Sulfate transport is similarly impacted by the heating of the ash, resulting in 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. Our study offers new insights into the dispersion of volcanic clouds in midlatitudes and addresses a likely behavior of the ash cloud of the Laacher See eruption that darkened European skies at the end of the Pleistocene. In turn, this study can also serve as significant input for scenarios that consider the risks associated with re-awakened volcanism in the Eifel.

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Section: Model Descriptionmentioning

confidence: 99%

Section: Eruption Daymentioning

confidence: 99%

Section: Global Distribution Of Sulfur Burdenmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Simulation of ash clouds after a Laacher See-type eruption

2021

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Volcanic lightning reveals umbrella cloud dynamics of the 15 January 2022 Hunga volcano eruption, Tonga

Jarvis,

Caldwell,

Noble

et al. 2024

Bull Volcanol

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Development of supercritical motion and internal jumps within lock-release radial currents and draining flows

2021

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The unsteady radial flow of relatively dense fluid released from an axisymmetric lock is analysed when it freely drains over an edge and when it generates a gravity current propagating over a horizontal surface. In both situations when modelled using the shallow water equations, despite initiation from rest within a lock, the flow thins, accelerates and becomes supercritical in a region close to the symmetry axis. For free-drainage, this alters the outflow, while for radial gravity currents, it leads to the formation of an internal jump connecting rapidly moving fluid to more tranquil flow at the front. Both scenarios share the same supercritical flow structure, which is related to their initiation from lock-release conditions and is a function of axisymmetry; the phenomena is not found in analogous two-dimensional flows. Through analysis and numerical integration of the governing equations, the common onset and consequences of supercriticality are revealed in both flows, and in particular, the progression of the fluid motions to self-similar states that develop at late times.

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Sustained axisymmetric intrusions in a rotating system

Cited by 5 publications

References 19 publications

Simulation of ash clouds after a Laacher See-type eruption

Simulation of ash clouds after a Laacher See-type eruption

Volcanic lightning reveals umbrella cloud dynamics of the 15 January 2022 Hunga volcano eruption, Tonga

Development of supercritical motion and internal jumps within lock-release radial currents and draining flows

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