Problems and solutions for drawing fronts objectively

McCann, Donald W.; Whistler, James P

doi:10.1017/s1350482701002079

Cited by 21 publications

(20 citation statements)

References 9 publications

(29 reference statements)

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“…Note that the TFP does not need any non-thermal parameters as input. In particular, it is independent from the horizontal wind which, for example, does not hold for the operator used in McCann and Whistler (2001).…”

Section: Discussion Of the Methodologymentioning

confidence: 99%

“…Nowadays, the TFP is confronted with more sophisticated operators (e.g. Hewson, 1998;McCann and Whistler, 2001) which provide promising results in coarse resolutions. Nevertheless, it turns out that the TFP is still competitive to other locating functions in high resolutions, if the gradient minimum is avoided (Equation (4)).…”

Section: Discussion Of the Methodologymentioning

confidence: 99%

“…In particular, the TFP benefits from the comparative smoothness of its low-order derivatives. McCann and Whistler (2001) find fault with the TFP, because it does not detect all significant fronts in their applications. Contrary to their experience, a high sensitivity of the TFP is observed in the high-resolution fields, sometimes even yielding spurious or insignificant fronts.…”

Section: Discussion Of the Methodologymentioning

confidence: 99%

“…There are several schemes which operate on a two-dimensional thermal field at a predefined height (e.g. Huber-Pock and Kress, 1989;Steinacker, 1992;Hewson, 1998;McCann and Whistler, 2001). All the approaches originally are developed for global numerical weather prediction (NWP) models with resolutions between 100 and 400 km.…”

Section: J Jenkner Et Almentioning

confidence: 99%

“…HuberPock and Kress, 1989) or 700-1000 hPa (e.g. McCann and Whistler, 2001). In general, the thickness exhibits the merit of being a more robust measure than locally defined parameters, because it corresponds to a vertically averaged temperature.…”

Section: The Thermal Parametermentioning

confidence: 99%

See 4 more Smart Citations

Detection and climatology of fronts in a high‐resolution model reanalysis over the Alps

Jenkner

Sprenger

Schwenk

et al. 2009

Meteorological Applications

103

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The identification of low-level thermal fronts is particularly challenging in high-resolution model fields over complex terrain. Firstly, direct model output often contains numerical noise which spuriously influences the highfrequency variability of thermal parameters. Secondly, the boundary layer interferes via convection and consequently leaves its thermal marks on low levels. Here, an automated objective method for the detection of frontal lines is introduced which is designed to be insusceptible to consequences of small grid spacings. To this end, existing algorithms are readopted and combined in a novel way. The overall technique subdivides into a basic detection of fronts and a supplemental division into local fronts and synoptic fronts. The fundamental parts of the detection are: (1) a smoothing of the initial fields, (2) a definition of the frontal strength, and, (3) a localisation with the thermal front parameter. The local fronts are identified by means of a classification of open and closed thermal contours. The resulting data comprise the spatial outline of the frontal structures in a binary field as well as their type and movement. The novel methodology is applied to a 3 year high-resolution reanalysis over central Europe computed with the COSMO model using a grid spacing of 7 km. Grid-point based climatologies are derived for the Alpine region. Frequencies of occurrence and characteristics of motion are analysed for different frontal types. The novel climatology also provides quantitative evidence of dynamical properties such as the retardation of cold fronts ahead of mountains and the dissolution of warm fronts over mountains.

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Section: Discussion Of the Methodologymentioning

confidence: 99%

Section: Discussion Of the Methodologymentioning

confidence: 99%

Section: Discussion Of the Methodologymentioning

confidence: 99%

Section: J Jenkner Et Almentioning

confidence: 99%

Section: The Thermal Parametermentioning

confidence: 99%

See 3 more Smart Citations

Detection and climatology of fronts in a high‐resolution model reanalysis over the Alps

Jenkner

Sprenger

Schwenk

et al. 2009

Meteorological Applications

103

View full text Add to dashboard Cite

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Climatological characteristics of fronts in the western North Pacific based on surface weather charts

et al. 2014

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Composite front climatology in the western North Pacific is determined using a newly developed 1.0°gridded data set. Here we propose a research strategy for determining the spatiotemporal distribution of fronts using weather chart images published by the Japan Meteorological Agency, one of the major data providers in the region. A preliminarily investigation of the internal data characteristics for the period of 2000-2010 is undertaken, and the final 4 years of data are used for an analysis of front climatology to avoid the effect of any spurious trends. This enables in-depth analyses to be conducted, which have not previously been possible in the region, including the composites of cross-sectional patterns for the thermal fields and precipitation near fronts, front length seasonality, and the significance of the thermal gradient near the fronts, in addition to determining the frontal frequency and spatial distribution of frontal precipitation. Pixel-wise analysis reveals that 56% of the local precipitation maximum is located on the warm side of a cold front caused by less tilted upward motion on the warm side, with the intrusion of the upper level cold dry air into the warm side. This new data set also enables a further analysis of the occluded fronts, which are not correctly distinguished in the existing objective detection method.

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Increase in the number of extremely strong fronts over Europe? A study based on ERA‐Interim reanalysis (1979–2014)

Schemm

Sprenger

Martius

et al. 2017

Geophysical Research Letters

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Evidence is presented that the frequency of extremely strong fronts, which occur mainly in summer, has increased over Europe in ERA‐Interim reanalyses data (1979–2014). Fronts are defined using a common detection scheme based on gradients of equivalent potential temperature (θe) at 850 hPa. The frequency increase is due to increasing atmospheric humidity, which in turn is reported as statistically significant over Europe in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR5). There is no trend in the frequency of extremely strong fronts in North America where humidity trends are, according to the IPCC AR5, close to zero. Because frontal precipitation increases with frontal strength, measured by the θe gradient, the increase in the number of extremely strong fronts may help explain regional patterns of longer‐term trends in strong precipitation events.

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Problems and solutions for drawing fronts objectively

Cited by 21 publications

References 9 publications

Detection and climatology of fronts in a high‐resolution model reanalysis over the Alps

Detection and climatology of fronts in a high‐resolution model reanalysis over the Alps

Climatological characteristics of fronts in the western North Pacific based on surface weather charts

Increase in the number of extremely strong fronts over Europe? A study based on ERA‐Interim reanalysis (1979–2014)

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