Relationships Between Polar Highs Activity and Air Temperature Anomalies in the North Pacific Region

Because of thermal deficit in the Arctic Basin region which reign throughout the year and especially during the winter season, polar air masses break out from the North Pole equatorward as polar highs. Polar highs which circulate across the North Pacific region descend from North Eastern Siberia. They travel the Pacific Ocean by Bering, Okhotsk, Japan and East China seas, then adopt zonal trajectories with a meridional component. Around 40 percent of them continue their trajectories to North Western America. Along their paths, polar highs affect atmospheric characteristics and especially air temperature. This study establishes relationships between space-time variability of polar highs and air temperature at 2 meters in North Pacific aerological space. Initially, from daily sea level pressure data for the region 80° E to 110° W and 90° N to 0° , we have developed an automated method to track the paths and record features for each polar high track during the period 1950-1999. Next, we have analyzed the seasonal cycle of these features: frequency, maximum pressure, velocity and type of trajectory. With this information we have computed an index which characterizes the inter-annual variability of polar highs activity. Finally we have calculated temporal correlations between the polar highs activity index and air temperature anomalies at 2 meters for each season. The strongest correlations are found in winter with positive correlations in the inter-tropical zone and negative correlations in North Eastern Siberia and Central North Pacific. The large-scale physics governing these relationships will be elucidated.