A new characterization of the North Atlantic eddy-driven jet using 2-dimensional moment analysis

• Main Authors: Perez, Jacob, Maycock, Amanda, Griffiths, Stephen, Hardiman, Steven, McKenna, Christine
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2024
• Subjects: article; Verlagsveröffentlichung; North Atlantic
• Online Access: https://doi.org/10.5194/egusphere-2024-318; https://noa.gwlb.de/receive/cop_mods_00071792; https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00070051/egusphere-2024-318.pdf; https://egusphere.copernicus.org/preprints/2024/egusphere-2024-318/egusphere-2024-318.pdf

We develop a novel technique for characterising the latitude, tilt and intensity of the North Atlantic eddy-driven jet using a feature identification method and two-dimensional moment analysis. Applying this technique to the ERA5 reanalysis, the distribution of daily winter jet latitude is unimodal with a mean of 46° N and a negative skew of -0.07. This is in contrast with the trimodal distribution of the daily Jet Latitude Index (JLI) . We show that our method exhibits less noise than the JLI, casting doubt on the previous interpretations of the trimodal distribution as evidence for regime behaviour of the North Atlantic jet. It also explicitly and straightforwardly handles days where the jet is split. Though climatologically the jet is tilted south-west to north-east, around a fifth of winter days show an opposite tilted jet. Our method is simple, requiring only daily 850 hPa zonal wind data, and diagnoses the jet in a more informative and robust way than previous methods.