Evidence from Meteosat imagery of the interaction of sting jets with the boundary layer

Browning, K. A.; Field, Michael

doi:10.1017/s1350482704001379

Cited by 29 publications

(39 citation statements)

References 6 publications

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“…after 0700 UTC) the SJ reaches the top of the boundary layer and interacts with it. The speed on trajectories rapidly decreases, while θ w increases abruptly by a few K. Shallow convection is visible in the simulated satellite imagery at this time, in the form of an arc‐chevron cloud which may be related to the cloud patterns discussed by Browning and Field (). Of course, it is difficult to rely on the properties of trajectories undergoing such marked turbulent mixing, as they no longer represent a coherent airstream.…”

Section: Resultssupporting

confidence: 94%

The role of mesoscale instabilities in the sting‐jet dynamics of windstorm Tini

Volonté

Clark

Gray

2018

Quart J Royal Meteoro Soc

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Sting jets (SJs) occur as an additional region of low‐level strong winds in some Shapiro–Keyser‐type extratropical cyclones. While SJs are widely accepted as being distinct from the warm and cold conveyor belts, the mechanisms responsible for their occurrence are still not fully understood. Here we determine the relative importance of the release of mesoscale instabilities and synoptic‐scale cyclone dynamics, so addressing an area of current debate. Numerical weather prediction simulations of a SJ‐containing windstorm are analysed and Lagrangian trajectories used to assess the evolution of, and mesoscale atmospheric instabilities (e.g. symmetric and inertial instabilities) in, the descending airstream. The SJ undergoes a two‐stage descent: cooling via sublimation followed by a large acceleration accompanied by instability release. Combined tilting and stretching of vorticity play a major role in the local onset of instability on the airstream. Vorticity and frontogenesis fields have a narrow slantwise banded structure in the cloud head and around the SJ; the descending SJ modifies the widespread frontolysis expected from the large‐scale dynamics alone in the frontal‐fracture region. A coarser‐resolution simulation also generates strong winds in the frontal‐fracture region, although these are significantly weaker than in the higher‐resolution simulation. The SJ airstream in the coarser‐resolution simulation undergoes a weaker descent without instability generation and descends in a widespread frontolytic region. Hence, while the SJ undergoes a process of destabilisation that enhances its descent and acceleration in the higher‐resolution simulation, enhancing the strong winds already generated by the synoptic‐scale cyclone dynamics, this destabilisation does not occur in the SJ produced by a coarser‐resolution simulation, resulting in weaker winds. This analysis reveals the synergy between the paradigms of SJ occurrence through the release of mesoscale instabilities and synoptic‐scale cyclone dynamics and demonstrates that the current debate may in part be a consequence of the model resolutions used by different studies.

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Section: Resultssupporting

confidence: 94%

The role of mesoscale instabilities in the sting‐jet dynamics of windstorm Tini

Volonté

Clark

Gray

2018

Quart J Royal Meteoro Soc

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“…4. Were these flows associated with multiple cloud heads within the parent systems akin to the system with six stacked cloud heads reported by Dixon et al ( 2000), while Browning and Field (2004) and Roberts and Forbes (2004) give details of two other systems with two, discontinuous cloud heads. By comparison of the wind roses for the classified events it is clear that strong wind events fall into three groups: the warm sector events and cold frontal events from the south-west; tropopause folds from the northwest, and sting jets from the west.…”

Section: Placing the Events In Their Synoptic Contextmentioning

confidence: 99%

A climatology of mid-tropospheric mesoscale strong wind events as observed by the MST radar, Aberystwyth

Parton¹,

Dore²,

Vaughan³

2010

Met. Apps

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Continuous sounding of the troposphere by the NERC Mesosphere-Stratosphere-Troposphere (MST) wind profiling radar, mid-Wales, since late 1997 provides a unique dataset with which to study the mesoscale wind field of the mid-troposphere over the United Kingdom. A wind speed probability density function (PDF) generated from 7 years of data is used to design a feature-finding algorithm to identify mesoscale strong wind events in the radar dataset. The resulting 117 events form a climatology of mesoscale strong wind features at mid-tropospheric heights over the British Isles, defined as peak wind speeds at or above the top 1% of the PDF, wind speeds exceeding the top 5% for at least 1 h, and extending over at least 1 km in depth. Plotting the location of the peak winds of these features on schematic charts of the Norwegian and Shapiro-Keyser models of cyclogenesis show these to be mainly warm sector and cold frontal in nature, with smaller numbers of tropopause folds and sting jets. Wind roses indicate a prevailing westerly direction for mid-tropospheric winds generally, but the strong wind events are distinctly different: cold frontal and warm sector events prevail from the south to southwest, tropopause folds from the northwest and sting jets from the west. The wider applicability of the results to the British Isles is established through comparison with radiosonde data from five sites covering the British Isles.

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“…The ''streaky'' nature of the damage suggested the existence of large-scale structures within the main cyclonic depression. These have been described by Browning (2003) and Browning and Field (2004) and given the name ''Sting Jets'' because of the characteristic ''scorpion tale'' pattern of clouds that are associated with them. Gust speeds of around 40-45 m/s were recorded in the south of England, with gusts of up to 50 m/s near the coast and over open sea.…”

Section: The Modern Period 1980-mentioning

confidence: 99%