Oceanographic Monitoring

Waves

To understand oceanographic conditions along the U.S. West Coast, PISCO is conducting studies of nearshore ocean circulation. These studies employ a suite of advanced oceanographic tools, including Acoustic Doppler Current Profilers (ADCPs), oceanographic radars for mapping surface currents, satellite imagery, towed profilers to collect measurements through the water column, remotely-sensed surface chlorophyll by satellite, and oceanographic sensors mounted on moorings.

Motivation

PISCO’s physical oceanographic research focuses on how physical processes in the marine environment, such as ocean currents, waves and winds, affect ecological dynamics in the coastal zone. We are particularly interested in the nearshore region, also known as the inner-shelf (the area approximately 5-10 km from shore), which is home to most of the communities we study.

The physical environment has both immediate and long-term effects on many organisms and populations. For example, many species grow faster in warmer waters, waves from winter storms can remove entire kelp beds, and fish can be retained or removed from favorable habitat by ocean currents. These are some examples of immediate physical effects at the level of the organism. But the ocean's physical processes also have more subtle and long-term effects on entire marine populations.

Most shallow-water, rocky-shore organisms have open-water larvae that disperse well beyond their near-shore birthing areas, but later return to settle into far away adult habitats. A principal hypothesis of the PISCO project is that ocean temperatures and coastal currents (in addition to larval behavior and planktonic duration) help to control larval transport, settlement, and retention, as well as species range boundaries. These influences structure many coastal marine populations. We are particularly interested in the role of coastal circulation processes, which differ greatly along the coast.

Research Questions

PISCO's physical oceanography program is designed to answer the following two fundamental questions:

  1. What are the nearshore (or inner-shelf) oceanographic patterns and processes along the U.S. West Coast?
  2. How do inner-shelf oceanographic conditions affect the dynamics of shallow subtidal and rocky intertidal communities? 

For example, the intensity of large surface waves created by severe winter storms may control the geographic extent of kelp forests. Or, a predominant direction in ocean currents may limit the extent of a fish population by inhibiting larval transport in one direction, and enhancing it in another.

Approach

All of the PISCO institutions use similar methods to observe the physical processes important to maintaining nearshore communities and controlling larval transport and settlement. These processes include winds, coastal currents, eddies, water mass variability, surface waves, and internal waves. We use moored instruments, small-boat operations and land-based oceanographic radars to study nearshore physical oceanography.

We have dozens of semi-permanent stations (see maps) along the inner shelf of the U.S. West Coast, where we measure ocean temperatures and other physical variables, such as ocean currents. Our physical oceanographic stations are clustered about the OSU, UCSC and UCSB campuses and span a broad portion of the CCLME. Sites are located  along the Oregon coast, in Monterey Bay and the central California, and in the Channel Islands and the Southern California Bight.

Typically located in water depths of 10-20 meters, the stations consist of a mooring with temperature sensors called thermistors (see photo at left). The stations are often supplemented with other instruments, such as nearby, bottom-mounted ADCPs (Acoustic Doppler Current Profilers), which measure water velocities throughout the water column (see photo at right).

Most of our moorings have a similar design. A subsurface float is attached to a mooring line which in turn is anchored to the bottom. The float's buoyancy provides enough tension on the mooring line to keep it vertical even is strong currents. Thermistors are mounted on the taught line, measuring temperatures at typically three depths. Many moorings also have a surface float and thermistor which allow us to measure the temperature just below the sea surface.

ADCPs are mounted to the bottom near the mooring using hard or soft-bottom mounts, depending on the bottom-type. They look upward through the water column and measure two components of current velocity every 1 meter. The moorings are serviced approximately every three-months, when the instruments are swapped with replacements. Most instruments sampling every two minutes to resolve important high-frequency phenomena such as internal waves propagating in the thermocline.

 Our moored observations are supplemented by vertical profiles of water properties (temperature, salinity, and density) taken during small-boat surveys with instruments called CTDs (Conductivity, Temperature, Depth profilers).

Field Sites

PISCO has dozens of physical oceanographic stations spaced along the inner shelf of the US West Coast. Use the clickable map at right to see closer views of most of our sites. For more detailed information on sites and available data click here to be taken to our physical oceanographic data search page.

In 2004, PISCO partnered with the National Marine Sanctuary Program to expand our physical oceanographic research and monitoring. We now have many partnership PISCO/NMSP stations. 

Data from these stations are also available online though a NOAA Website at the following address, http://portal.ncddc.noaa.gov/wco/

We also partner with the following regional ocean observing systems:

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