Observations and Biogeochemical Model Results of Dissolved Oxygen off of Central California

A potential threat of climate change is global decrease in dissolved oxygen at depth due to increased stratification. Regionally, the California Current has experienced dissolved oxygen declines since the late 1980s with observations from Oregon and the Southern California Bight. Here, observations of dissolved oxygen were gathered from 1998 to 2013 off of Monterey Bay, California on CalCOFI Line 67, a transect spanning from 20 to 300 km from shore. Preliminary analysis suggests that oxygen declines in the past few decades are greatest at the hypoxic boundary around the 26.7 sigma-theta isopycnal (depth 350-400 m), and that there is a complex spatial structure from onshore to offshore in terms of the rate of decline of dissolved oxygen. The observations along Line 67 were compared with model output from the Pacific basin ROMS-CoSiNE biogeochemical model to first, evaluate the model and second, investigate mechanisms to explain changing oxygen dynamics. The dissolved oxygen dynamics along line 67 are informative of the transition from offshore dynamics in the California Current to nearshore dynamics in Monterey Bay.