Ocean Indices

Variations in marine survival of salmon and steelhead are linked to large-scale changes in North Pacific oceanic and atmospheric conditions, as well as to local physical and biological conditions off the Oregon and Washington coasts. Ocean data can further the understanding of trends in salmon abundance as well as provide input to the development of salmon forecasts.

This web page provides access to large-scale ecosystem indicators, including the Pacific Decadal Oscillation (PDO) and the Multivariate El Niño/Southern Oscillation Index (MEI), and regional and local indices. Columbia Basin Research maintains the Pacific Northwest Index (PNI) and the Spring Transition Dates and Fall Transition Dates web pages. The Columbia River DART database includes the Air/Ocean Moored Buoy Data and Ocean Coastal Upwelling Index (CUI) daily datasets provided by Pacific Fisheries Environmental Laboratory, NMFS, NOAA.

  • Pacific Northwest Index (PNI), Columbia Basin Research (CBR), School of Aquatic and Fishery Sciences, University of Washington

    The PNI, developed by Ebbesmeyer and Strickland (1995), is a terrestrial climate index useful for studying climate effects on salmon productivity trends. The PNI is an annual climate index based on the average of three normalized variables: average annual air temperature at Olga in the San Juan Islands, total precipitation at Cedar Lake in the Cascade Mountains, and snowpack depth at Paradise on Mount Rainier on March 15 of each year. The index is available for the years 1891 to the present. In addition, a five-year running average is calculated. Years with positive values of the PNI are warmer and drier than average and those with negative values are cooler and wetter than average. Currently, CBR updates the index annually.

    Ebbesmeyer, C.C. and R.M. Strickland. 1995. Oyster Condition and Climate: Evidence from Willapa Bay. Publication WSG-MR 95-02, Washington Sea Grant Program, University of Washington, Seattle, WA.

  • Spring Transition Dates and Fall Transition Dates, Columbia Basin Research (CBR), School of Aquatic and Fishery Sciences, University of Washington

    The spring transition is the most critical time of the seasonal plankton production cycle and marks the day when the Pacific Ocean off the Oregon and Washington coasts transitions from a winter downwelling state to a summer upwelling state. It has been found that the earlier in the year that upwelling begins, the greater ecosystem productivity will be in that year. Several time series of the annual spring transition date are available, including the following estimation methods: Ocean Current Simulator (OSCURS) model, the Logerwell method, and a biological spring transition keyed to the arrival of dominant winter copepod populations. The OSCURS time series is available for the years 1946-1994 and is no longer updated. Spring transition dates based on the Logerwell method, which are derived from coastal upwelling and sea level data, are provided courtesy of Elizabeth Logerwell, NWFSC. The series starts with 1969 and is updated annually. The biological spring transition date is also updated annually and begins with 1996, along with values for several earlier years. The biological spring transition data are provided by Dr. William Peterson, NWFSC, Newport Field Station.

    The fall transition initiates the winter downwelling season when nutrient-depleted warmer water is transported shoreward. This date establishes the beginning of a period of lower secondary productivity. Several time series of the annual fall transition date are available, including the following three methods: OSCURS model, a method developed by Elizabeth Logerwell, NWFSC, and a biological fall transition date. The OSCURS model fall transition dates are available for the years 1946-1994 and are no longer being updated. The series using the Logerwell method has been computed by CBR personnel starting with 1969 and is updated on an annual basis. The biological fall transition data are also updated annually starting with the year 1996, and are provided by Dr. William Peterson, NWFSC, Newport Field Station.

  • Air/Ocean Data from NOAA Moored Buoys, Environmental Research Division (ERD), Pacific Fisheries Environmental Laboratory, NMFS, NOAA

    The ERD processes raw hourly data from 22 NOAA National Data Buoy Center (NDBC) moored buoys along the North American west coast. As part of their auxiliary data holdings, the ERD provides the processed buoy data sets in both hourly values and daily mean values of air temperature, sea temperature, surface atmospheric pressure, wind speed, and wind direction. The processed buoy data are updated semi-annually by ERD.

    Additional Resources:

  • Multivariate ENSO Index (MEI), Physical Sciences Division, Earth System Research Laboratory, NOAA

    The MEI is a leading indicator for the El Niño/Southern Oscillation (ENSO) phenomenon and is calculated as the first unrotated Principal Component of six observed variables over the tropical Pacific Ocean. These six variables are: sea level pressure, zonal and meridional components of the surface wind, sea surface temperature, surface air temperature, and total cloudiness fraction of the sky. The MEI is computed for each of twelve sliding bimonthly seasons (Dec/Jan, Jan/Feb,..., Nov/Dec). Negative values of the MEI represent the cold ENSO phase (La Niña), while positive MEI values represent the warm ENSO phase (El Niño). El Niño events are often accompanied by declines in adult salmon returns. ESRL updates the index on a monthly basis.

  • Ocean Coastal Upwelling Index (CUI), Environmental Research Division (ERD), Pacific Fisheries Environmental Laboratory, NMFS, NOAA

    Upwelling is an important process affecting plankton production off the Pacific Northwest. The CUI is a measure of the volume of water that upwells along the coast; it identifies the amount of offshore transport of surface waters due to geostrophic wind fields. Indices are in units of cubic meters per second along each 100 meters of coastline. Positive numbers indicate offshore transport for the upwelling index product and southward transport for the along-shore product. The CUI was developed by Dr. Andrew Bakun (Bakun 1973) and is provided by the Pacific Fisheries Environmental Lab (PFEL) of NOAA National Marine Fisheries Service (NMFS). The ERD Live Access Server provides access to the updated 6-hourly, daily, and monthly data sets (select: Environmental Data Server New Version → ERD Derived Environmental Indices → Upwelling Index, 15 NA Locations).

    Bakun, A. 1973. Coastal upwelling indices, west coast of North America, 1946-71. U.S. Dept. of Commerce, NOAA Tech. Rep., NMFS SSRF-671.

    Additional Resources:

  • Informational web site based on the annual report of how physical and biological ocean conditions may affect the growth and survival of juvenile salmon in the northern California Current off Oregon and Washington. A number of physical, biological, and ecosystem indicators are presented. In addition, the indicators may be useful in examining variations in ocean conditions and the affects on recruitment of fish stocks, seabirds, and other marine animals.

    Peterson, W.T., R.C. Hooff, C.A. Morgan, K.L. Hunter, E. Casillas, and J.W. Ferguson. 2006. Ocean Conditions and Salmon Survival in the Northwen California Current. Northwest Fisheries Science Center, Seattle, WA.

  • Pacific Decadal Oscillation (PDO), Joint Institute for the Study of Atmosphere and Ocean (JISAO), UW/ NOAA

    The PDO is a climate index based upon patterns of variation in sea surface temperature in the North Pacific from 1900 to the present (Mantua et al. 1997). The PDO is defined as the leading principal component of North Pacific monthly sea surface temperature variability (poleward of 20N for the 1900-1993 period) and is correlated with commercial salmon landings from Washington, Oregon, and California. The index is updated every two or three months by JISAO, a joint institute of the University of Washington and NOAA.

    Mantua, N. J., S. R. Hare, Y. Zhang, J. M. Wallace, and R. C. Francis. 1997. A Pacific decadal climate oscillation with impacts on salmon. Bulletin of the American Meteorological Society 78:1069-1079.