P103 The Sensitivity of Orographically Enhanced Extreme

Precipitation Events in Western Norway to Changes in SST

Sandvik, Mari Ingeborg, and Asgeir Sorteberg, Geophysical Institute, University in Bergen, Norway

Studies indicate an increased risk of more frequent precipitation extremes in a warming world, which may result in more frequent flooding, avalanches and landslides. Thus, the ability to understand how processes influence extreme precipitation events could result in a better representation in models used in both research and weather forecasting. The WRF model has been used in 3 case studies where a uniform change in SST (±2°C) was applied to test the sensitivity of both precipitation intensity and distribution to a warmer and colder Atlantic Ocean. As the precipitation events are strongly dependent on the path of the low-pressure systems we apply spectral nudging of the large-scale system in order to keep the synoptic flow similar in the control and sensitivity runs. Preliminary results (10km resolution) suggest that even if the large scale flow is forced to not change the extreme precipitation changes does not follow Clausius-Clapeyron scaling for the individual cases as changes in vertical velocities are very different from case to case. Future work will contain more case studies with similar properties, found by cluster analysis, simulated by the WRF model to look for sensitivity patterns due to changes in SST.