Dynamics of sting‐jet storm <i>Egon</i> over continental Europe: Impact of surface properties and model resolution

Eisenstein, Lea; Pantillon, Florian; Knippertz, Peter

doi:10.1002/qj.3666

Cited by 16 publications

(28 citation statements)

References 44 publications

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“…Five pressure levels (300, 500, 700, 850 and 925 hPa) were available, of which only two were useful to identify the slantwise descent of a sting-jet. The only existing automated method to detect sting-jets in highresolution simulations, known as back-trajectory analysis (Martínez-Alvarado et al, 2014) requires output on many pressure levels at time intervals less than one hour (Eisenstein et al, 2020). Although this is a powerful method, its application is not feasible on a climatological timescale due to its large storage and computational costs.…”

Section: Sting-jet Diagnosticmentioning

confidence: 99%

“…The median RH ice at 500hPa within the positive gradient points should be greater than 80%, indicating the descent originates from within the cloud head. The threshold of 80% is applied as this has been used in previous sting-jet analyses to indicate the location of cloud (Eisenstein et al, 2020;Volonté et al, 2018;Coronel et al, 2016). RH ice at 500hPa was chosen instead of at 700hPa, as the algorithm was found to perform better.…”

Section: Sting-jet Diagnosticmentioning

confidence: 99%

“…And secondly, the sting-jet accelerates during its descent within the free atmosphere unopposed by friction, bringing high momentum air towards the surface (Slater et al, 2015). This descent can then be further accelerated by evaporative cooling (Browning, 2004;Clark et al, 2005;Browning et al, 2015;Rivière et al, 2020) and the release of a slantwise instability, known as conditional symmetric instability (Clark et al, 2005;Gray et al, 2011;Baker et al, 2014;Coronel et al, 2016;Volonté et al, 2018;Eisenstein et al, 2020). As a result, the presence of a stingjet may yield wind speeds that can far exceed those expected when viewing isobars of a synoptic chart.…”

Section: Introductionmentioning

confidence: 99%

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Extreme windstorms and sting-jets in convection-permitting climate simulations over Europe

Manning

Kendon

Fowler

et al. 2021

Preprint

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Extra-tropical windstorms are one of the costliest natural hazards affecting Europe, and windstorms that develop a sting-jet are extremely damaging. A sting-jet is a mesoscale core of very high wind speeds that occurs in Shapiro-Keyser type cyclones, and high-resolution models are required to adequately model sting-jets. Here, we develop a low-cost methodology to automatically detect sting jets, using the characteristic warm seclusion of Shapiro-Keyser cyclones and the slantwise descent of high wind speeds, within pan-European 2.2km convection-permitting climate model (CPM) simulations over Europe. The representation of wind gusts is improved with respect to ERA-Interim reanalysis data compared to observations; this is linked to better representation of cold conveyor belts and sting-jets in the CPM. Our analysis indicates that Shapiro-Keyser cyclones, and those that develop sting-jets, are the most damaging windstorms in present and future climates. The frequency of extreme windstorms is projected to increase by 2100 and a large contribution comes from sting-jet storms. Furthermore, extreme wind speeds and their future changes are underestimated in the GCM compared to the CPM. We conclude that the CPM adds value in the representation of extreme winds and surface wind gusts and can provide improved input for impact models compared to coarser resolution models.

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Section: Sting-jet Diagnosticmentioning

confidence: 99%

Section: Sting-jet Diagnosticmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Extreme windstorms and sting-jets in convection-permitting climate simulations over Europe

Manning

Kendon

Fowler

et al. 2021

Preprint

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“…All fields considered in this study, including conditions for instabilities (see Table 1), are thus on pressure levels. See Volonté et al (2018) and Grams and Archambault (2016) for examples of the use of NDdiag in the literature.…”

Section: Additional Post-processingmentioning

confidence: 99%

Idealised simulations of cyclones with robust symmetrically unstable sting jets

Volonté

Clark

Gray

2020

Weather Clim. Dynam.

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Abstract. Idealised simulations of Shapiro–Keyser cyclones developing a sting jet (SJ) are presented. Thanks to an improved and accurate implementation of thermal wind balance in the initial state, it was possible to use more realistic environments than in previous idealised studies. As a consequence, this study provides further insight into SJ evolution and dynamics and explores SJ robustness to different environmental conditions, assessed via a wide range of sensitivity experiments. The control simulation contains a cyclone that fits the Shapiro–Keyser conceptual model and develops a SJ whose dynamics are associated with the evolution of mesoscale instabilities along the airstream, including symmetric instability (SI). The SJ undergoes a strong descent while leaving the cloud-head banded tip and markedly accelerating towards the frontal-fracture region, revealed as an area of buckling of the already-sloped moist isentropes. Dry instabilities, generated by vorticity tilting via slantwise frontal motions in the cloud head, exist in similar proportions to moist instabilities at the start of the SJ descent and are then released along the SJ. The observed evolution supports the role of SI in the airstream’s dynamics proposed in a conceptual model outlined in a previous study. Sensitivity experiments illustrate that the SJ is a robust feature of intense Shapiro–Keyser cyclones, highlighting a range of different environmental conditions in which SI contributes to the evolution of this airstream, conditional on the model having adequate resolution. The results reveal that several environmental factors can modulate the strength of the SJ. However, a positive relationship between the strength of the SJ, both in terms of peak speed and amount of descent, and the amount of instability occurring along it can still be identified. In summary, the idealised simulations presented in this study show the robustness of SJ occurrence in intense Shapiro–Keyser cyclones and support and clarify the role of dry instabilities in SJ dynamics.

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“…Doppler lidar measurements are challenging in extratropical cyclones due to the low aerosol load, which hinders observations after the passage of fronts. This was the case during the extreme windstorm ''Egon'' on 12-13 January 2017, which involved an unprecedented sting jet over continental Europe (Eisenstein et al 2019) but could not be sampled satisfactorily. Data quality was much better during other WASTEX case studies including the intense windstorm ''Thomas'' on 23 February 2017, which is the focus of the paper.…”

Section: Introductionmentioning

confidence: 99%

Formation of Wind Gusts in an Extratropical Cyclone in Light of Doppler Lidar Observations and Large-Eddy Simulations

Pantillon

Adler

Corsmeier

et al. 2019

Monthly Weather Review

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Damaging gusts in windstorms are represented by crude subgrid-scale parameterizations in today’s weather and climate models. This limitation motivated the Wind and Storms Experiment (WASTEX) in winter 2016–17 in the Upper Rhine Valley over southwestern Germany. Gusts recorded at an instrumented tower during the passage of extratropical cyclone “Thomas” on 23 February 2017 are investigated based on measurements of radial wind with ≈70-m along-beam spacing from a fast-scanning Doppler lidar and realistic large-eddy simulations with grid spacings down to 78 m using the Icosahedral Nonhydrostatic model. Four wind peaks occur due to the storm onset, the cold front, a precipitation line, and isolated showers. The first peak is related to a sudden drop in dewpoint and results from the downward mixing of a low-level jet and a dry layer within the warm sector characterized by extremely high temperatures for the season. While operational convection-permitting forecasts poorly predict the storm onset overall, a successful ensemble member highlights the role of upstream orography. Lidar observations reveal the presence of long-lasting wind structures that result from a combination of convection- and shear-driven instability. Large-eddy simulations contain structures elongated in the wind direction that are qualitatively similar but too coarse compared to the observed ones. Their size is found to exceed the effective model resolution by one order of magnitude due to their elongation. These results emphasize the need for subkilometer-scale measuring and modeling systems to improve the representation of gusts in windstorms.

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Dynamics of sting‐jet storm Egon over continental Europe: Impact of surface properties and model resolution

Cited by 16 publications

References 44 publications

Extreme windstorms and sting-jets in convection-permitting climate simulations over Europe

Extreme windstorms and sting-jets in convection-permitting climate simulations over Europe

Idealised simulations of cyclones with robust symmetrically unstable sting jets

Formation of Wind Gusts in an Extratropical Cyclone in Light of Doppler Lidar Observations and Large-Eddy Simulations

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