Regional Oceanography of the Northeast Pacific

Overview

The Environmental Research Division has a strong tradition of research in ocean dynamics, climate variability, and fisheries oceanography. Although global in scope, a research emphasis is placed on the Northeast Pacific Ocean (NEP), and on the California Current System (CCS) in particular. Recent research efforts have focused on the following topics:

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Objectives

The principal objectives of this research are to:

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Methods

A number of research methods are used to examine environmental variability in the CCS:

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Recent Results

Seasonality of Physical-Biological Coupling in the CCS

Motivation:  Life cycles of many marine organisms are closely tied to seasonal processes.

Objectives:

Maps of (a,b) surface temperature and (c,d) fluorescence

Maps of (a,b) surface temperature and (c,d) fluorescence off the California coast just prior to (March) and after (April) the 1995 spring transition. Large changes in physical structure and biological response are evident over the course of a few weeks. From Lynn et al. (2003).


Interannual Variability in the CCS

Motivation: Living marine resources are greatly impacted by interannual variability in environmental conditions and processes.

Objectives:

Hovmoller diagrams

Hovmoller diagrams of nitracline depth (top), vertically-integrated chlorophyll-a (middle), and macrozooplankton biomass (bottom) for CalCOFI Lines 80 (left) and 90 (right), for the period January 1996 – October 1999. This was a period of transition from a strong El Nino event in 1997-98 (deep nitracline, low chlorophyll and zooplankton) to a strong La Nina event in 1998-99 (shallow nitracline and enhanced productivity). From Bograd and Lynn (2001).

 

Time series sections of temperature

Time series sections of temperature and vertical temperature gradient for an offshore (left) and coastal (right) location in the central CCS. Bottom time series show varying long-term trends in the strength of stratification (increasing at coast) and depth of the thermocline (increasing at coast) over the period 1950-93. From Palacios et al. (2004).

 

North Pacific Climate Change and Ecosystem Response

Motivation: Major ecosystem fluctuations are associated with decadal-scale shifts in environmental conditions and forcing.

Objectives:

Winter maps of SST

Winter maps of SST anomalies (top) and SLP + vector wind anomalies (bottom) averaged over three periods: 1970-76, 1977-83, and 1999-2002. There appears to have been a transition to a new climate regime following the 1997-98 El Ni?o event. From Peterson and Schwing (2003).

Taken together, these results demonstrate the importance of evaluating temporal and spatial variability over the entire spectrum, and of independently considering changes in seasonal patterns and long-term trends. Evidence suggests that the ecosystem can respond in less than one growing season to a new regime and may return rapidly to a former state associated with a previous regime. Our research indicates that we may be able to characterize ocean regimes in terms of their carrying capacity or suitability for specific stocks.

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