Ocean Weather Station Papa, located at 50°N 145°W off the western coast of Vancouver, has one of the longest ocean time series, dating from 1949 to 1981, when two ships rotated every six weeks taking oceanic and weather measurements. After the weather ship program ended in 1981, oceanographic monitoring continued through the Line-P Program with Canada’s Department of Fisheries and Ocean, while weather observations resumed in 2007 when the United States’ National Oceanic and Atmospheric Administration (NOAA) deployed a buoy at Station Papa. This study uses Station Papa’s ocean and weather time series data to investigate two hypotheses that might explain the reduction in salt concentration on the ocean surface, also referred to as sea surface salinity, observed at Station Papa over the 70-year period. The first hypothesis states that increased rainfall, either because of more frequent or more intense storms, is causing the salt concentration to decrease. The second hypothesis states evaporation off the ocean surface has decreased, thereby contributing to the reduction in the sea surface salinity. Climatologies, or averages across a long time-period, that were calculated from the buoy and the weather ship data show that the first hypothesis is correct, while the second is not. Rainfall has increased at Station P over the last 70 years, but so has evaporation, although not as much as the increase in rainfall. This long time series allows us to better understand our changing world, especially in the context of air-sea interactions when oceanic observations are so rare.

Annika would like to thank her faculty sponsor Dr. Charles Graves for their support of this project.