The influence of Svalbard orography and sea ice on polar low development

The life cycles of intense high-latitude mesoscale cyclones — polar lows — are uniquely shaped by their background environment. Our research focuses on the influence of the orography of Svalbard and of sea ice cover in the Norwegian and Barents Seas on polar low generation. Several cyclones that were observed near Svalbard are selected from the Sea Surface Temperature and Altimeter Synergy for Improved Forecasting of Polar Lows (STARS) database. In addition, a polar low from the ACCACIA field campaign is included in our study. Each case is simulated using Met Office Unified Model with horizontal grid spacing of 2.2 km. Compared to satellite cloud imagery and wind estimates, control runs capture the key features of the mesoscale vortices with reasonable accuracy. Preliminary results of backward trajectory modelling show that air streams spawning the polar lows more often flow from the ice-covered area in the north-west, so sea ice tends to be more important than Svalbard mountains. To prove this, we conduct a series of sensitivity runs with artificially changed land mask, orography, and sea ice cover. In the majority of cases, experiments with altered sea-ice or flattened orography only slightly modify cyclogenesis, but in some cases the polar low is structurally different or not developed at all.