Fronts, Jet Streams and the Tropopause

Shapiro, M. A.; Keyser, Daniel

doi:10.1007/978-1-944970-33-8_10

Cited by 335 publications

(235 citation statements)

References 82 publications

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“…A cloud head and dry slot are well-known features of the satellite imagery from rapidly deepening extra-tropical cyclones (Böttger et al 1975;Browning & Roberts 1994); they are characteristic of cyclones that follow the evolution described in the model of Shapiro & Keyser (1990). A distinct mesoscale phenomenon referred to as the sting jet is thought to be responsible for the damaging winds in the dry slot: Clark & Browning (2004) have carried out a high-resolution numerical-weatherprediction modelling study of the Great October Storm to show that the sting jet originates within the cloud head at mid-tropospheric levels and that it accelerates rapidly over a 3-hour period, reaching about 50 m s −1 as it descends towards the boundary layer.…”

Section: Introductionmentioning

confidence: 99%

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

Browning

Field

2004

Meteorol. Appl.

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Section: Introductionmentioning

confidence: 99%

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

Browning

Field

2004

Meteorol. Appl.

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“…With this in mind a pre-existing, well-known conceptual model of cyclone development was adopted (Shapiro and Keyser, 1990). This was then modified, by appending stages to the start and the end, to try to capture the full life-cycles of cyclonic features in the extra-tropics.…”

Section: Detectionmentioning

confidence: 99%

“…More recently, Hewson (2009a) extended this conceptual life cycle even further back, to the earliest imaginable point, introducing the term 'diminutive wave' to represent, primarily, this incipient stage. In parallel, the frontal wave and diminutive wave stages were also appended to the start of the familiar Shapiro and Keyser (1990) conceptual model, as illustrated in Figure 1. This depicts the idealized life-cycles of two cyclones, one starting out on a cold front (top, from Hewson, 2009a) the other on a warm front (bottom, new).…”

Section: Introductionmentioning

confidence: 99%

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Objective identification, typing and tracking of the complete life-cycles of cyclonic features at high spatial resolution

Hewson

Titley

2010

Met. Apps

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Synoptic-scale cyclonic features provide an inescapable focal point for operational forecasting, whilst the merits of tracking such features are increasingly being recognized in the climate change field. Close association with adverse and extreme weather is the main motivator. Here a new and highly sophisticated set of techniques to detect, classify and track the full range is developed. A revised conceptual model of cyclone development provided the initial framework, ensuring a solid bond with forecasting practice, whilst also connecting closely to baroclinic life-cycle concepts. Building on this, cyclones are detected using a hybrid of geopotential minimum/vorticity maximum techniques, whilst incorporating important extensions to ensure that vorticity can be used at high resolution (∼50 km) and that features on fronts take priority. To track the features across time, at intervals of 12 h or less, feature attributes in the association process are used. Additionally, an upper-tropospheric steering wind is employed to estimate future and past positions. This facilitates 'half-time tracking', a new approach that has clear-cut advantages over 'full-time tracking' employed elsewhere.In detection tests, comparing with subjectively-drawn charts, the feature hit rate was 84%, and the false alarm ratio 17%, whilst in a simple tracking test the association failure rate was just 2%. These values compare very favourably with previous studies.One key application is discussed. This involves processing ensemble output to provide wide-ranging real-time products tailor-made to forecasters' needs. Products include track-following plume diagrams, for various cyclone attributes, and storm-track strike probability plots for different thresholds of severity.

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“…Bjerknes, 1919;Bjerknes and Solberg, 1922) is characterized by a meridionallyoriented cyclone, a relatively strong cold front, and the formation of an occluded front by the narrowing of the warm sector as the cold front approaches the warm front (Figure 1(a)). In contrast, the Shapiro-Keyser cyclone model (Shapiro and Keyser, 1990) is characterized by a zonally-oriented cyclone, a relatively strong warm front, and the formation of a frontal fracture (weaker baroclinicity along the poleward part of the cold front), a frontal T-bone structure (cold and warm fronts nearly perpendicular), a bent-back warm front (enhanced baroclinicity in the equatorward flow to the west of the cyclone centre), and warm seclusion (Figure 1(b)). …”

Section: Introductionmentioning

confidence: 99%

Baroclinic development within zonally‐varying flows

Schultz

Zhang

2007

Quart J Royal Meteoro Soc

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Previous idealized-modelling studies have shown the importance of across-jet barotropic shear to the resulting evolution of cyclones, anticyclones, surface-based fronts, and upper-level fronts. Meanwhile, many observational studies of cyclones have shown the importance of along-jet variations in the horizontal wind speed (i.e. confluence and diffluence). This study investigates the importance of these along-jet (zonal, for zonally-oriented jets) variations in the horizontal wind speed to the resulting structures and evolutions of baroclinic waves, using idealized models of growing baroclinic waves. An idealized primitive-equation channel model is configured with growing baroclinic perturbations embedded within confluent and diffluent background flows. When the baroclinic perturbations are placed in background confluence, the lower-tropospheric frontal structure and evolution initially resemble the Shapiro-Keyser cyclone model, with a zonallyoriented cyclone, strong warm front, and bent-back warm front. Later, as the baroclinic wave is amplified in the stronger downstream baroclinicity, the warm sector of the cyclone narrows, becoming more reminiscent of the Norwegian cyclone model. The upper-level frontal structure develops with a southwest-northeast orientation, and becomes strongest at the base of the trough, where geostrophic cold advection is occurring. In contrast, when the baroclinic perturbations are placed in background diffluence, the lower-tropospheric frontal structure and evolution resemble the Norwegian cyclone model, with a meridionally-oriented cyclone, strong cold front, and occluded front. The upper-level frontal structure is initially oriented northwest-southeast on the western side of the trough, before becoming zonally oriented. Weak geostrophic temperature advection occurs along its length. These results are compared to those from previous observational and idealized-modelling studies.

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Fronts, Jet Streams and the Tropopause

Cited by 335 publications

References 82 publications

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

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

Objective identification, typing and tracking of the complete life-cycles of cyclonic features at high spatial resolution

Baroclinic development within zonally‐varying flows

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