Attribution of Winter Windstorm Variability in Europe to Anomalous States of the North Atlantic Ocean
Abstract
The number of windstorms is steadily rising in the North Atlantic-European region since 1871. Recent studies in multi-centennial simulations of the ECHAM5-MPIOM model show that increased meridional overturning circulation transport is associated with higher windstorm activity through augmented baroclinicity over the North Atlantic Ocean. This acts as a source of cyclones that drift across the Northern Atlantic-European region. Here, we study these effects on a shorter timescale with an additional focus on variables such as surface latent heat flux and ocean barotropic transport. We use composite maps of an ensemble of results from the MPI-ESM-LR model historical simulations which run from 1961 to 2005. Seasonal windstorm activity is defined as the seasonal (DJF) mean of the storm severity index in Europe. In years of anomalously high windstorm activity, preliminary results show patterns of strongly anomalous sea-surface temperatures (SSTs) and ocean heat content (OHC) along the path of the North Atlantic Current (NAC). Composites of surface latent heat flux and barotropic ocean transport also show anomalies in the same region. Lastly, strong Eady growth rates are also visible along the path of the NAC. Our results suggest that on multi-decadal timescales, changes in surface latent heat flux and North Atlantic barotropic transport in the NAC region induce anomalies in SSTs and/or OHC, which then translate to increased baroclinicity.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.A13E0328M
- Keywords:
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- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSESDE: 1620 Climate dynamics;
- GLOBAL CHANGEDE: 4313 Extreme events;
- NATURAL HAZARDSDE: 4318 Statistical analysis;
- NATURAL HAZARDS