Long-term Variability in Pacific Decadal Oscillation Teleconnections to Climate in Alaska: From "In a Relationship" to "It’s Complicated"

Abstract:

Since the Pacific Decadal Oscillation's (PDO) identification in 1997, it has been widely used as a seasonal-forecasting and decision-making tool in Alaska. Gulf of Alaska sea surface temperatures have oscillated every few decades between warmer (positive PDO) and colder (negative PDO). In the historical record, there are two negative phases and two positive phases, but since 2000, the PDO has vacillated between warm and cold states annually. Recent inconsistencies in the phase of the PDO as well as its influence on climate have warranted further study of this climate phenomenon. Previous work found that strength and importance of the PDO teleconnections to temperature and precipitation varied widely over time in the Twentieth Century Reanalysis (v2) data and in CRU TS3.2.1. In light of the inherent problems with reanalyses and with gridded products in data-poor areas, it is necessary to examine individual station data to further understand the relationship of the PDO with climate in Alaska. This study examines temperature and precipitation data for individual stations across Alaska to determine the stability of PDO teleconnections. Individual station data were downloaded from the NOAA National Centers for Environmental Information GHCN-D database. For the months of January, February and March, stations with at least 90% complete data for all three months were selected. Using stations grouped according to the recently developed Alaska climate divisions, the stability of PDO teleconnections was analyzed in terms of station anomalies from the PRISM climatology. In many parts of the state, the relationship between the PDO and local climate was not as stable as expected. Even at individual stations, the strength and influence of the PDO was often inconsistent over time.