Beyond cold and warm: an objective classification for maritime midlatitude fronts. (9th January 2018)

• Record Type: Journal Article
• Authors: Spensberger, C.; Sprenger, M.
• Is Part Of: Quarterly journal of the Royal Meteorological Society. Volume 144:Number 710(2018)
• Page Start: 261
• Page End: 277
• Publication Date: 2018-01-09
• Subjects: fronts -- front classification -- feature detection; Meteorology -- Periodicals; 551.5
• DOI: 10.1002/qj.3199
• Languages: English
• ISSNs: 0035-9009

Abstract

Abstract : This study introduces a detailed and objective classification for midlatitude maritime fronts. The classification is based on a principal component analysis (PCA) to determine the dominant patterns of variability between fronts. Here, fronts are defined as three‐dimensional frontal volumes, which are detected in the ERA‐Interim dataset for a large number of locations in the Atlantic, Pacific and Indian oceans during both winter and summer. In addition to the well‐established distinction between warm and cold fronts, the PCA exposes several new dimensions of variability: (i) front intensity, (ii) surface fluxes and (iii) along‐front transports, linked to the intensity of the associated conveyor belts. These new dimensions of variability are regionally and seasonally robust and a lagged composite analysis demonstrates that each of the new front types evolves in a dynamically characteristic way. Further, the new front types can be related to established ones like katafronts and anafronts. The new front types are finally redefined based on simple parameter thresholds to simplify their application in future studies. Abstract : Based on 3D frontal volumes detected in the ERA‐Interim dataset, we propose a new detailed classification of midlatitude fronts. In addition to the distinction between cold and warm fronts, our analysis suggests that (i) front intensity, (ii) surface fluxes and (iii) along‐front transports capture physical differences between fronts consistently. The image illustrates how the front type based on surface fluxes varies along the fronts in an example synoptic situation from 27 January 1984, 0000 UTC.