ACCROSS Project: Investigating the impacts of circulation changes on stratospheric tracers

The ACCROSS project (Atmospheric Composition and Circulation investigated with meteorological Reanalyses, Observational datasets and models for the Study of the Stratosphere and its changes) aims to improve our understanding of the circulation changes in the stratosphere during the past three decades. To achieve this objective, miscellaneous observational datasets and model simulations are used. Here are presented the main aspects and the first preliminary results of the project.
In the framework of the recent studies demonstrating the influence of stratospheric circulation changes on the trend of long-lived tracers (e.g. hydrogen chlorine), we decided to investigate the impact of these circulation changes on hydrogen fluoride (HF). Fourier-Transform infrared spectroscopy data produced at the Jungfraujoch NDACC site and satellite data (HALOE and ACE) are used to evaluate the HF trends. Moreover, to support our data interpretation, chemistry-transport model BASCOE simulations are also included.
These early investigations show a modulation in HF time series at Jungfraujoch occurring around 2007. At the time being, it seems that BASCOE driven by ERA-Interim reanalysis cannot capture this modulation.