Sensitivity of the 2012 Arctic Cyclone to Sea Ice and Atmospheric Initial Conditions

Arctic meteorology plays a large role in subseasonal to seasonal (S2S) range predictability, as degradation of forecast skill can often be traced back to processes in polar regions. We hypothesize that one such process derives from tropopause polar vortices (TPV), and their associated interactions with Arctic cyclones (AC) and sea ice. Observational evidence suggests that Arctic cyclones significantly contribute to sea ice loss, and Arctic cyclone development is often facilitated by TPVs in the upper troposphere. TPVs furthermore can potentially impede on the midlatitude jet stream and initiate Rossby wave growth. Knowledge of the dynamics of these features and their interactions with each other and the midlatitude waveguide is thus important for understanding extended forecast range predictability limits.

In order to quantify these interactions and assess their impact on longer term forecasts, the atmospheric component of the Model for Prediction Across Scales (MPAS) model coupled with the Community Earth System Model (CESM) is used in the case of the Great Arctic Cyclone of 2012. This anomalously intense Arctic cyclone with a 12-day lifetime was associated with a large and very rapid loss in sea ice. Experiments show the atmospheric evolution depends strongly on the initial sea ice state. Sensitivity of the cyclone to the initial sea ice state using 1980, 2012 and projected 2050 Arctic Ocean sea ice, as well as its sensitivity to the initial atmospheric state, will be discussed.