Data off the south shore of Oahu, Hawaii, show that salinity has increased by 0.7 over the past 35 years. We will use the Wave Glider to reoccupy a portion of the Hawaii-Tahiti Shuttle Experiment and study the causes of this salinity increase. Dramatic water changes, like this increase in salinity, affect ocean circulation, weather and the global climate system. An example of the repercussions of dramatic/large water mass changes is the warm water “blob” off the western coast of North America. This anomaly spans 1000 km by 1000 km and is 4.5 F warmer than average for the region. It is believed that this “blob” is the cause of California’s ongoing massive drought.
The causes and ramifications of increased salt content in the Hawaiian Islands region are currently poorly understood. A similar project looking at increased salinity in the Atlantic indicates that changes in salinity can be attributed to changes in evaporation-precipitation and ocean circulation. Both would cause changes in global climate and fisheries. Station ALOHA, the site of the world’s longest oceanographic time series, is located north of the Hawaiian islands. Data from 1988-present show an increase in salinity at the subsurface salinity maximum?. Because this water is formed at the evaporation maximum and is the most saline water in the region, this is indicates evaporation has increased over time.
To put the Wave Glider data into context, 7 years of Seaglider data from 2008-present will provide a picture of local seasonal and physical variations around the Hawaiian Islands. These data will help isolate long-term changes in the dataset from the background climatology.