npgo: NPGO - North Pacific Gyre Oscillation

In pbs-assess/PACea: An R package of Pacific ecosystem information to help facilitate an ecosystem approach to fisheries management

NPGO – North Pacific Gyre Oscillation

Description

The North Pacific Gyre Oscillation (NPGO) is a climate pattern that is significantly correlated with fluctuations of salinity, nutrients, and chlorophyll-a in long-term observations in the California Current (CalCOFI) and Gulf of Alaska (Line P).

Usage

npgo

Format

A tibble also of class 'pacea_index' with columns:

year:

year of value

month:

month (1 to 12) of value

anomaly:

calculated as the second dominant mode of sea-surface height anomaly over the Northeast Pacific (180 deg W to 100 deg W, 25 deg N to 62 deg N), and then maybe converted to standard deviation units as in Figure 1 of Di Lorenzo et al. (2008), though the numbers do not exactly match that figure (and come from Di Lorenzo's website, which notes that values after 2004 were updated. This might be why numbers do not seem to quite agree.

Details

Adapted from http://www.o3d.org/npgo/ The NPGO emerges as the second dominant mode of sea-surface height variability in the Northeast Pacific. The term NPGO is used because fluctuations reflect changes in the intensity of the central and eastern branches of the North Pacific gyre circulations as evident from the NPGO sea-surface height anomalies. Fluctuations in the NPGO are driven by regional and basin-scale variations in wind-driven upwelling and horizontal advection – the fundamental processes controlling salinity and nutrient concentrations. Nutrient fluctuations drive concomitant changes in phytoplankton concentrations, and may force similar variability in higher trophic levels. The NPGO thus provides a strong indicator of fluctuations in the mechanisms driving planktonic ecosystem dynamics.

Key reference is Di Lorenzo et al. (2008): North Pacific Gyre Oscillation links ocean climate and ecosystem change. Geophysical Research Letters, 35: L08607. doi:10.1029/2007GL032838

Associated code adapted from code generously shared by Chris Rooper.

Author(s)

Andrew Edwards

Source

Generated from running 'data-raw/coastwide-indices/coastwide-indices.R'.

Examples

## Not run: 
npgo
plot(npgo)

## End(Not run)

pbs-assess/PACea documentation built on April 17, 2025, 11:36 p.m.