A novel method for objective identification of 3-D potential vorticity anomalies

Fischer, Christoph; Fink, Andreas H.; Schömer, Elmar; Linden, Roderick van der; Maier-Gerber, Michael; Rautenhaus, Marc; Riemer, Michael

doi:10.5194/gmd-15-4447-2022

Cited by 3 publications

(1 citation statement)

References 52 publications

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“…Such techniques are not yet widely used in weather forecasting and research, with reasons including a lack of suitable software tools and a lack of literature demonstrating the benefit of 3-D visual analysis (Rautenhaus et al, 2018). An overview of the current state of the art in visualization in meteorology has recently been provided by Rautenhaus et al (2018); recent examples of 3-D visual analysis being applied to meteorological research include the studies by Rautenhaus et al (2015b), Orf et al (2017), Kern et al (2018Kern et al ( , 2019, Bader et al (2020), Meyer et al (2021), Bösiger et al (2022), and Fischer et al (2022).…”

Section: Introductionmentioning

confidence: 99%

The three-dimensional structure of fronts in mid-latitude weather systems in numerical weather prediction models

Beckert¹,

Eisenstein²,

Oertel³

et al. 2023

Geosci. Model Dev.

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Abstract. Atmospheric fronts are a widely used conceptual model in meteorology, most encountered as two-dimensional (2-D) front lines on surface analysis charts. The three-dimensional (3-D) dynamical structure of fronts has been studied in the literature by means of “standard” 2-D maps and cross-sections and is commonly sketched in 3-D illustrations of idealized weather systems in atmospheric science textbooks. However, only recently has the feasibility of the objective detection and visual analysis of 3-D frontal structures and their dynamics within numerical weather prediction (NWP) data been proposed, and such approaches are not yet widely known in the atmospheric science community. In this article, we investigate the benefit of objective 3-D front detection for case studies of extra-tropical cyclones and for comparison of frontal structures between different NWP models. We build on a recent gradient-based detection approach, combined with modern 3-D interactive visual analysis techniques, and adapt it to handle data from state-of-the-art NWP models including those run at convection-permitting kilometre-scale resolution. The parameters of the detection method (including data smoothing and threshold parameters) are evaluated to yield physically meaningful structures. We illustrate the benefit of the method by presenting two case studies of frontal dynamics within mid-latitude cyclones. Examples include joint interactive visual analysis of 3-D fronts and warm conveyor belt (WCB) trajectories, as well as identification of the 3-D frontal structures characterizing the different stages of a Shapiro–Keyser cyclogenesis event. The 3-D frontal structures show agreement with 2-D fronts from surface analysis charts and augment the surface charts by providing additional pertinent information in the vertical dimension. A second application illustrates the relation between convection and 3-D cold-front structure by comparing data from simulations with parameterized and explicit convection. Finally, we consider “secondary fronts” that commonly appear in UK Met Office surface analysis charts. Examination of a case study shows that for this event the secondary front is not a temperature-dominated but a humidity-dominated feature. We argue that the presented approach has great potential to be beneficial for more complex studies of atmospheric dynamics and for operational weather forecasting.

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Section: Introductionmentioning

confidence: 99%

The three-dimensional structure of fronts in mid-latitude weather systems in numerical weather prediction models

Beckert¹,

Eisenstein²,

Oertel³

et al. 2023

Geosci. Model Dev.

Self Cite

View full text Add to dashboard Cite

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An objective identification technique for potential vorticity structures associated with African easterly waves

Fischer,

Fink,

Schömer

et al. 2024

Geosci. Model Dev.

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Abstract. Tropical Africa and the North Atlantic Ocean are significantly influenced by African easterly waves (AEWs), which play a fundamental role in tropical rainfall and cyclogenesis in that region. The dynamics of AEWs can be described in a potential vorticity (PV) framework. The important impact of latent heat release by cloud processes is captured in this framework by the diabatic generation of PV anomalies. This paper introduces an innovative approach for the identification and tracking of PV structures within AEWs. By employing AEW tracking and computing the wave phase of each point within the AEW domain using a Hilbert transform, we are able to effectively identify and collect 3-D PV structures associated with specific AEWs. To facilitate a climatological analysis, performed here over the months of June to October from 2002 to 2022, these structures are subsequently characterized by low-dimensional descriptors, including their location, intensity, and orientation. Our climatological analysis reveals the seasonal evolution and the structural attributes of PV anomalies within AEWs over the study domain. PV feature locations closely align with the African easterly jet's latitudinal shift during the summer season. Analysis of the mean pressure level of the 3-D PV structures shows a remarkable shift during their life cycle, indicating deep moist convection characteristics over land and more shallow convection characteristics over the ocean. On average, PV features identified within AEW troughs tilt downshear over land and equatorward over the ocean. The trough-centered analysis reveals distinct differences between satellite-estimated and model-predicted rainfall. Agreement between the results of a more traditional composite analysis and our new feature analysis provides confidence in our feature approach as a novel diagnostic tool. The feature framework provides a low-dimensional representation of the PV structure of AEWs, which facilitates future statistical analyses of the relation of this structure to, for example, tropical cyclogenesis or the predictability of tropical rainfall.

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The three-dimensional structure of fronts in mid-latitude weather systems as represented by numerical weather prediction models

Beckert¹,

Eisenstein

Oertel

et al. 2023

Preprint

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Abstract. Atmospheric fronts are a widely used conceptual model in meteorology, most encountered as two-dimensional (2-D) front lines on surface analysis charts. The three-dimensional (3-D) dynamical structure of fronts has been studied in the literature by means of “standard” 2-D maps and cross-sections and is commonly sketched in 3-D illustrations of idealized weather systems in atmospheric science textbooks. However, only recently the feasibility of objective detection and visual analysis of 3-D frontal structures and their dynamics within numerical weather prediction (NWP) data has been proposed, and such approaches are not yet widely known in the atmospheric science community. In this article, we investigate the benefit of objective 3-D front detection for case studies of extratropical cyclones and for comparison of frontal structures between different NWP models. We build on a recent gradient-based detection approach, combined with modern 3-D interactive visual analysis techniques, and adapt it to handle data from state-of-the-art NWP models including those run at convection-permitting kilometer-scale resolution. The parameters of the detection method (including data smoothing and threshold parameters) are evaluated to yield physically meaningful structures. We illustrate the benefit of the method by presenting two case studies of frontal dynamics within mid-latitude cyclones. Examples include joint interactive visual analysis of 3-D fronts and warm conveyor belt (WCB) trajectories, and identification of the 3-D frontal structures characterising the different stages of a Shapiro-Keyser cyclogenesis event. The 3-D frontal structures show agreement with 2-D fronts from surface analysis charts and augment the surface charts by providing additional pertinent information in the vertical dimension. A second application illustrates the relation between convection and 3-D cold front structure by comparing data from simulations with parameterised and explicit convection. Finally, we consider “secondary fronts” that commonly appear in UK Met Office surface analysis charts. Examination of a case study shows that for this event the secondary front is not a temperature-dominated but a humidity-dominated feature. We argue that the presented approach has great potential to be beneficial for more complex studies of atmospheric dynamics and for operational weather forecasting.

show abstract

A novel method for objective identification of 3-D potential vorticity anomalies

Cited by 3 publications

References 52 publications

The three-dimensional structure of fronts in mid-latitude weather systems in numerical weather prediction models

The three-dimensional structure of fronts in mid-latitude weather systems in numerical weather prediction models

An objective identification technique for potential vorticity structures associated with African easterly waves

The three-dimensional structure of fronts in mid-latitude weather systems as represented by numerical weather prediction models

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