The 18.6‐year lunar nodal cycle and surface temperature variability in the northeast Pacific

Abstract

The 18.6‐year lunar nodal cycle (LNC) is a significant feature of winter (January) air and sea temperatures along the North American west coast over a 400‐year period. Yet much of the recent temperature variation can also be explained by wind patterns associated with the PNA teleconnection. At Sitka, Alaska, (57°N) and nearby stations in northern British Columbia, the January PNA index accounts for over 70% of average January air temperatures in lengthy meteorological records. It appears that the LNC signal in January air temperatures in this region is not independent of the PNA, but is a component of it. The Sitka air temperature record, along with SSTs along the British Columbia coast and the PNA index have significant cross‐correlations with the LNC that appear at a 2‐year lag, LNC leading. The influence of the PNA pattern declines in winter with decreasing latitude but the LNC component does not. It appears as a significant feature of long‐term SST variation at Scripps Pier and the California Current System. The LNC also appears over centennial‐scales in proxy temperatures along western North America. The linkage of LNC‐moderated surface temperatures to processes involving basin‐scale teleconnections expands the possibility that the proximate mechanism may be located remotely from its expression in the northeast Pacific. Some of the largest potential sources of a diurnal tidal signal in the atmosphere are located in the western Pacific; the Sea of Okhotsk and the Indonesian archipelago.