Trinidad Head Ocean Observing Node (THOON)

The Trinidad Head Ocean Observing Node (THOON) is an ocean acidification and hypoxia (OAH) -focused observation node located near Trinidad Head, at Station TH02 (~75m depth), comprise of two instrument platforms: 

  1. A profiling mooring to measure conditions throughout the water column at high temporal and spatial (vertical) resolution
  2. A benthic platform equipped to support continuous monitoring of conditions near the seafloor and to resolve currents throughout the water column.

Profiling mooring

The profiling mooring is equipped with an RBR sensor package to profile temperature, salinity, chlorophyll, and dissolved oxygen throughout the water column at high temporal resolution (roughly every 8 minutes) and to transmit the data in real-time to shore via cellular communications. To measure pH throughout the water column, a Deep-Sea-DuraFET was integrated into the WireWalker sensor package, building on recent progress towards configuring the sensor for rapid profiling applications.

Bottom Lander

A Deep SeapHOx was also deployed as part of the THOON to collect continuous observations of pH, dissolved oxygen, temperature and salinity near the seafloor, as well as a Sentinel V Acoustic Doppler Current Profiler (ADCP) to profile currents throughout the water column.

Spring - October 2023 THOON Deployments

The THOON WireWalker and Bottom Lander were deployed several times between May - October 2023. These deployments allowed us to observe high-resolution variability in the water column during periods of coastal upwelling. Data from one of these deployments are shown below.

An upwelling event was observed between October 2 - 10 2023, as indicated by positive Coastal Upwelling Transport Index (CUTI) values and upwelling favorable winds. These conditions led to cold, low-dissolved oxygen, low-pH, and nutrient rich water being transported to shallower depths. Full depth temperature profiles from the Wire Walker during this period allowed us to observe the onset and relaxation of this event as it happened.