Decadal water‐property trends in the California Undercurrent, with implications for ocean acidification. Issue 12 (11th December 2013)

• Record Type: Journal Article
• Authors: Meinvielle, M.; Johnson, Gregory C.
• Is Part Of: Journal of geophysical research. Volume 118:Issue 12(2013:Dec.)
• Page Start: 6687
• Page End: 6703
• Publication Date: 2013-12-11
• Subjects: California Undercurrent -- ocean acidification -- dissolved oxygen -- spiciness -- potential vorticity; Oceanography -- Periodicals; 551.4605
• DOI: 10.1002/2013JC009299
• Languages: English
• ISSNs: 2169-9275

Abstract

Abstract : [1] This study uses data along the West Coast of North America to analyze the spatial and temporal evolution of water properties to around 500 m depth. The analysis uses potential density ( σ θ ) as the vertical coordinate and bottom depth and latitude as the horizontal coordinates. The study uses historical data from the World Ocean Database 2009 from 25°N to 50°N and 1950–2012 for a large‐scale analysis of water‐property spatial structure and temporal trends in the California Current System (CCS), finding significant trends from 1980 to 2012 along density surfaces near the core of the California Undercurrent (CUC), including decreasing dissolved oxygen (DO) concentration, increasing warmth and salinity, and decreasing potential vorticity. All these changes are consistent with an increasing influence of Pacific equatorial waters with time. Mixing characteristics along the core of the CUC ( σ θ = 26.5 kg m − 3 ) reveal that the 1980–2012 trends in the water‐mass properties in the CUC are mostly consistent with a northward shift of these properties, with additional decreases in DO concentration. These modifications are associated with the shoaling and strengthening of the CUC. The changes also imply increased ocean total (natural and anthropogenic) acidification, as the trend in the DO concentration is consistent with a natural decrease in pH all along the CUC, suggesting that significantly more acidic waters are feeding upwelling onto the shelf around 2012 than around 1980. Key Points: Post‐1980, water‐mass property trends were estimated in the California Undercurrent Increased spiciness, decreased oxygen, and potential vorticity were found with time More or stronger Pacific equatorial water was supplying the California Undercurrent