Beyond Cold and Warm Fronts: An Objective Classification for Maritime Mid-Latitude Fronts
Abstract
The distinction between cold and warm fronts is one of the fundamental building blocks for our understanding of extratropical cyclones. The distinction is conceptually well founded and proved extremely insightful in a wealth of contexts. Nevertheless, there are contexts, like the interaction between fronts and orography, in which this distinction alone is insufficient to explain the large range of different interactions that are observed and documented in the literature. As a first step to revisiting the problem of front-orography interactions, we objectively detect three-dimensional front objects in the ERA-Interim data set, and classify them using EOF analysis of the variability between front objects. In addition to the distinction between cold and warm fronts, the EOF analysis exposes several further dimensions of variability: (a) front intensity, (b) surface fluxes and (c) large-scale forcing. These additional dimensions of variability are robust, because they consistently constitute the dominating patterns of variability in a large number of locations in the Atlantic, Pacific and Indian Oceans. We demonstrate the significance of the additional dimensions by lagged composites that illustrate the different temporal evolution for different front types. Finally, we show that the additional front types can be redefined based on simple parameter thresholds, such that our results can easily be applied in other contexts without repeating the (rather involved) EOF analysis.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.A51C0060S
- Keywords:
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- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSESDE: 3319 General circulation;
- ATMOSPHERIC PROCESSESDE: 3354 Precipitation;
- ATMOSPHERIC PROCESSESDE: 1620 Climate dynamics;
- GLOBAL CHANGE