74. Decadal Trends of Underway pCO2 Observed from VOS ships in the Tropical Pacific

Catherine E. Cosca (1)*, Richard A. Feely (1), Simone R. Alin (1)

1 National Oceanic and Atmospheric Administration/Pacific Marine Environmental Laboratory, Seattle, WA, 98115, USA

Background
As part of a multi-year effort to quantify the flux of CO2 between the ocean and atmosphere, the Ocean Climate Observation Program of NOAA supports the deployment of underway CO2 systems on NOAA research ships and volunteer observing ships (VOS) in the Atlantic, Pacific and Southern Oceans. For the past decade (2004 – present), PMEL has maintained an underway pCO2 system on 6 different container ships crossing the Pacific Ocean from Long Beach to New Zealand.

Methods
Measurements of pCO2 have been collected from 39 crossings of the Tropical Pacific from Long Beach to New Zealand from 2004 through 2016, capturing data during various ENSO and seasonal conditions. Data are quality controlled locally at PMEL, and globally via the SOCAT community, resulting in a high quality time series of pCO2 and ancillary measurements in the Pacific region.

Findings
A pattern of increased pCO2 distributions across the entire Pacific basin has emerged from the sustained high quality pCO2 measurements PMEL has attained from container ships in the past decade. The decadal difference in pCO2 reaches ~ 36 μatm at the equator, and decreases in the southern latitudes. Of particular note is a dramatic increase of pCO2 in the northern hemisphere due to anomalously high sea surface temperatures known as “The Blob”.

Conclusions
Enhanced carbon distributions in the North Pacific may have strong implications for the oceanic carbon budget for the time frame the anomalously high sea surface temperatures continues to exist, transitioning the region from a CO2 sink to a CO2 source.