Project WHOTS - WHOI Hawaii Ocean Time-series Station

Sponsors

Principal funding is provided by (NOAA) Office of Climate Observations (OCO).

Research

The Hawaii Ocean Timeseries (HOT) site, 100 km north of Oahu, Hawaii, has been occupied since 1988 as a part of the World Ocean Circulation Experiment (WOCE) and the Joint Global Ocean Flux Study (JGOFS). WOCE investigators sought to document and understand seasonal and interannual variability of water masses, relate water mass variations to gyre fluctuations, and develop a climatology of high-frequency physical variability. JGOFS investigators sought to use information about primary production, new production, and particle export from the surface ocean as part of an interdisciplinary research program. The present HOT program includes comprehensive, interdisciplinary upper ocean observations, but does not include continuous surface forcing observations. Thus, the primary intent of the WHOTS mooring is to provide long-term, high-quality air-sea fluxes as a coordinated part of the HOT program and contribute to the goals of observing heat, fresh water and chemical fluxes at a site representative of the oligotrophic North Pacific Ocean.

Moorings

The surface mooring will be maintained for several years to obtain and examine in-situ records of surface meteorology, air-sea fluxes, and upper ocean variability. A Surlyn foam surface buoy is equipped with meteorological instrumentation including two complete Air-Sea Interaction Meteorological (ASIMET) systems, measuring air and sea surface temperatures, relative humidity, barometric pressure, wind speed and direction, incoming shortwave and longwave radiation, and precipitation. Complete surface meteorological time series is recorded every minute, as necessary to compute air-sea fluxes of heat, freshwater and momentum. Each ASIMET system also transmits hourly averages of the surface meteorological variables via the Argos satellite system.

The mooring line is instrumented in order to collect accurate time series of upper ocean temperatures, velocities, and salinities co-incident with the surface forcing record. Subsurface instrumentation is being supplied by the University of Hawaii. This includes vector measuring current meters, conductivity, salinity and temperature recorders, and an Acoustic Doppler current profiler (ADCP).

Field Work

The first WHOI Hawaii Ocean Time Series Station buoy was set in August, 2004 at about 22° 45´ North, 158° West, and recovered on July 25, 2005. The second deployment was made on July 28, 2005 from the RV Melville, and recovered on 24 June 2006 from the RV Revelle. WHOTS 3 was set on June 26 2006 on the Revelle and recovered on June 28 2007 on the KM. WHOTS 4 was set on June 25 2007 on the KM and recovered on June 6 2008 on the KM. WHOTS 5 was set on June 5 2008 on the KM.