Global climatologies of Eulerian and Lagrangian flow features based on ERA-Interim reanalyses

Abstract

his paper introduces a newly compiled set of feature-based climatologies identified from ERA-Interim reanalyses (1979?2014). Two categories of flow features are considered: (i) Eulerian climatologies of jet streams, tropopause folds, surface fronts, cyclones and anticyclones, blocks, and potential vorticity (PV) streamers and cutoffs, and (ii) Lagrangian climatologies, based on a large ensemble of air-parcel trajectories, of stratosphere-troposphere exchange (STE), warm conveyor belts (WCB), and tropical moisture exports (TME). Monthly means of these feature climatologies are openly available at the ETH Zurich webpage http://eraiclim.ethz.ch and annually updated. Datasets at higher resolution can be obtained from the authors on request.These feature climatologies allow studying the frequency, variability, and trend of atmospheric phenomena and their inter-relationships across temporal scales. In order to illustrate the potential of this dataset, boreal winter climatologies of selected features are presented and, as a first application, the very unusual Northern Hemispheric winter of 2009/2010 is identified as the season when most of the considered features show maximum deviations from climatology. The second application considers dry winters in the western U.S. and reveals fairly localized anomalies in the eastern North Pacific of enhanced blocking and surface anticyclones, and reduced cyclones.