Paper on Long Term Trends in North Pacific Frontal Structure

Current Status of Accomplishment or Milestone: Work on this manuscript is still in progress.

Background: Recent satellite studies have demonstrated the biological significance of large-scale frontal features in the North Pacific Ocean. The Transition Zone Chlorophyll Front (TZCF), for example, is a key forage habitat for many marine animals, and serves as a migratory corridor for some species of turtles, fish, marine mammals, and seabirds. This work explores the interannual variability in the position of this and other large-scale frontal features in the North Pacific by analyzing wind- and temperature-derived proxies of frontal position. Variability in frontal structure is being compared to historical estimates of various marine populations.

Purpose of Activity/Goal of Project: This work seeks to provide an evaluation of interannual to decadal fluctuations in frontal structure and position, which are not attainable from satellite data alone.

Description of Accomplishment and Significant Results: Wind-derived proxies of TZCF position compare well with the standard chlorophyll-derived position estimates from satellite ocean color. Historical wind data is subsequently being used to provide frontal position estimates from the 1950s to present. These results will be presented in a peer-reviewed scientific journal.

Significance of Accomplishment (e.g., to the Center, to Management, and to NMFS Strategic plan Goals): Historical estimates of large-scale North Pacific frontal positions can be used to interpret trends in biological populations that are known to utilize North Pacific fronts. Knowledge of how frontal position varies temporally can lead to better protection and management of relevant marine species.

Problems: Several more urgent projects during the first two quarters of FY03 delayed completion of this manuscript. These included the completion of two manuscripts on anomalous Subarctic influences in the California Current for a special section of Geophysical Research Letters; the editing of a special volume of Deep-Sea Research II on CalCOFI; and leading the completion of the California Current chapter for the PICES Ecosystem Status Report. It is expected that the manuscript will be submitted to Fisheries Oceanography in 4th quarter, FY03.

Key Contact: Steven Bograd (831-648-8314, sbograd@pfeg.noaa.gov)