Analysis of marine stratus surges in the Pacific Northwest

This study examines the long-term trends of marine stratus surges in the Pacific Northwest and corresponding temperature changes across a local study area. Temperature change data for the Seattle Tacoma International Airport was used to assemble a dataset of marine stratus surge events from 1948-2012. The surge count data was then compared to the Pacific Decadal Oscillation Index and the Northern Oscillation Index using a Zero-Inflated Poisson regression model to analyze any relationships between the decadal climate patterns and the occurrence of surges. While there is no correlation between either the PDO or NOI and surge counts, there is a statistically significant correlation between zero counts in the surge data and the NOI monthly index value. A subset of -10°C temperature drops at SeaTac for 2003-2012 was used to compare temperature change on these surge dates with temperature change at various weather stations across a local study area. Descriptive statistics on the area temperature changes were calculated, and a bubble chart and kriging maps were generated to show how this temperature change is experienced across the study area. Analysis of this data shows that a temperature change associated with SeaTac surge events is varied across the study area, and previously stated definition of a marine stratus surge is not appropriate for use at stations other than SeaTac.