Objective fronts

Hewson, Tim

doi:10.1017/s1350482798000553

Cited by 245 publications

(393 citation statements)

References 24 publications

Supporting

Mentioning

373

Contrasting

Unclassified

Order By: Relevance

“…The difference is that the precipitation peaks in the morning (9 : 00-10 : 00 CET). On the basis of a model of synoptic cold front analysis in the free atmosphere, cold air advection follows the cold front (Browning and Monk, 1982;Browning, 1985;Hewson, 1998). The arrival of a cold front would normally also cause a colder spell in the lower troposphere.…”

Section: Relation Between Diurnal Cycle and Precipitation Typementioning

confidence: 99%

Seasonal characteristics of diurnal precipitation variation in Kraków (South Poland)

Twardosz¹

2006

Intl Journal of Climatology

View full text Add to dashboard Cite

Abstract:This paper describes the diurnal cycle of liquid precipitation using the amplitude and phase of two precipitation characteristics: frequency and totals. A uniquely long set of uniform hourly precipitation data from Kraków (South Poland) was used. This vast and reliable basic material was collected by the author using pluviographic data covering the period 1886-2002. The role of precipitation type in forming the general diurnal cycle of precipitation was discussed. Two precipitation types, frontal and air mass, were taken into consideration. The role of particular air masses (polar maritime and polar continental) and atmospheric fronts (warm and cold fronts) in the 24-h precipitation cycle was determined. The frontal and air mass precipitation events were identified using a documentation of synoptic situations by Niedźwiedź over the area of southern Poland for the 1951-2002 period.Depending on the precipitation characteristic (frequency or totals), season of the year and precipitation type, the diurnal precipitation cycle may have one or two modes. The bimodality of the distribution occurs mainly for air mass precipitation. The morning maximum of precipitation frequency in all seasons of the year mimics the diurnal variation of precipitation in maritime polar air masses. Precipitation concentration in the afternoon hours is determined mainly by the intensity of processes in the cold front zone and in the homogeneous polar continental and maritime air masses. Significant differences in precipitation distribution in cold and warm fronts are connected with the time of precipitation concentration within the diurnal period. The type of atmospheric front determines the layout of precipitation clouds, intensity of precipitation formation and the velocity of front movement.

show abstract

Section: Relation Between Diurnal Cycle and Precipitation Typementioning

confidence: 99%

Seasonal characteristics of diurnal precipitation variation in Kraków (South Poland)

Twardosz¹

2006

Intl Journal of Climatology

View full text Add to dashboard Cite

show abstract

“…Sections 2.2 and 2.3 show how simple graphical devices are used to locate such phenomena, and also how point detection constitutes a simple extension of line segment detection. These techniques were first touched on in Hewson (1997), with line segment detection discussed at length in Hewson (1998a).…”

Section: Rationalementioning

confidence: 99%

“…Whilst implementation of the above methodology requires some programming effort, the reward for time invested is a powerful and versatile identification framework, which has numerous possibilities for extension (such as colouring using other variables; see Hewson, 1998a).…”

Section: Masking Wm2mentioning

confidence: 99%

“…This is achieved by first computing, at every grid point, a notional, local, front-normal unit axisŝ front (column 1, Table IA-B), using the 5-point mean axis method of Hewson (1998a). This provides local front-relative coordinates (s, n) because s is simply parallel toŝ front .…”

Section: Diagnostic Listmentioning

confidence: 99%

“…'Front-relative' diagnostics can then be computed across the domain, even in areas remote from fronts: an example is provided later, in Figure 4. In effect, an accurate approximation to frontal orientation prior to computing where the fronts themselves actually are is being provided, meaning that the front-locating process is partly iterative (see Hewson, 1998a). An alternative way of definingŝ front would be via the gradient of the front locating diagnostic itself (i.e.…”

Section: Diagnostic Listmentioning

confidence: 99%

See 2 more Smart Citations

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

Hewson

Titley

2010

Met. Apps

View full text Add to dashboard Cite

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.

show abstract

Atmospheric fronts in current and future climates

Catto

Nicholls

Jakob

et al. 2014

Geophysical Research Letters

View full text Add to dashboard Cite

Key Points:• Objective front ID applied to historical and RCP8.5 CMIP5 simulations • Compared to ERA-Interim, models represent frequency and strength of fronts well • Projections show decrease in front frequency in NH and poleward shift in SH Supporting Information:• Readme • Table S1 • Figure S1 • Figure S2 • Figure S3 • Figure S4 Correspondence to: J. L. Catto, jennifer.catto@monash.edu Abstract Atmospheric fronts are important for the day-to-day variability of weather in the midlatitudes.It is therefore vital to know how their distribution and frequency will change in a projected warmer climate.Here we apply an objective front identification method, based on a thermal front parameter, to 6-hourly data from models participating in Coupled Model Intercomparison Project phase 5. The historical simulations are evaluated against ERA-Interim and found to produce a similar frequency of fronts and with similar front strength. The models show some biases in the location of the front frequency maxima. Future changes are estimated using the high emissions scenario simulations (Representative Concentration Pathway 8.5). Projections show an overall decrease in front frequency in the Northern Hemisphere, with a poleward shift of the maxima of front frequency and a strong decrease at high latitudes where the temperature gradient is decreased. The Southern Hemisphere shows a poleward shift of the frequency maximum, consistent with previous storm track studies.

show abstract

Objective fronts

Cited by 245 publications

References 24 publications

Seasonal characteristics of diurnal precipitation variation in Kraków (South Poland)

Seasonal characteristics of diurnal precipitation variation in Kraków (South Poland)

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

Atmospheric fronts in current and future climates

Contact Info

Product

Resources

About