Pacific Decadal Oscillation and its Role in Alaska’s Climate

The Pacific Decadal Oscillation (PDO) plays a crucial role in shaping long-term climate variability in Alaska. Persistent positive PDO phases may be associated with warmer winters and increased precipitation, while negative PDO phases often bring colder temperatures and drier conditions. The PDO influences both seasonal shifts and long-term trends in Alaska's climate. This study examines the relationship between Alaska’s climate and the positive and negative phases of the PDO index. Specifically, it analyzes the monthly correlations between PDO phases and statewide weather variables—precipitation and temperature—using approximately 100 years of data. Periods of distinctly positive and negative PDO phases were selected to assess their impacts. Correlations between the PDO index and temperature and precipitation were evaluated for all climate divisions in Alaska, with results visualized through maps.The study also applies the Self-Organizing Map (SOM) algorithm to decompose the data into nodes, enabling an assessment of PDO influence on extreme temperature and precipitation across climate divisions. Climate division data was further used to generate node matrices for a more detailed analysis. The findings indicate that the correlation between the Pacific Decadal Oscillation (PDO) and temperature in Alaska is generally weak but positive, decreased temperatures are more pronounced in negative PDO phase with the highest correlation of 0.35 observed in February. Increasing temperatures are more observed in positive PDO Phase. The relationship is more pronounced in specific regions, with the highest correlation (0.526) in Cook Inlet. Correlations between precipitation and the PDO index are weak or nonexistent, with the highest negative correlation (-0.3043) occurring in the Central Interior in December. Overall, the connection between PDO and Alaska’s climate is complex.