Spatio-temporal structure of the pentadecadal variability over the North Pacific

https://doi.org/10.1016/S0079-6611(00)00042-2Get rights and content

Abstract

Using a Multi-Taper frequency domain-Singular Value Decomposition (MTM–SVD), a pentadecadal oscillation was detected in the winter–spring sea-level pressure (SLP) field over the North Pacific and surface air-temperature in North America which was significant at the 95% confidence level. The MTM–SVD captured the different SLP and air-temperature distributions between the winter and spring seasons in a consistent manner. The pentadecadal SLP signature in the spring season is centered nearer the west coast of North America than in the winter season. This zonal displacement is consistent with the prominent springtime pentadecadal air-temperature variability in mid-latitude western North America.

A wavelet analysis of the Pacific Decadal Oscillation Index (PDOI) showed that the regime shifts in the 1920s, 1940s and 1970s involved simultaneous phase reversals of the bidecadal and pentadecadal variations. The two interdecadal variations are synchronized with one another such that a half period of the pentadecadal oscillation (one epoch of an individual regime) corresponds to one and half periods of the bidecadal oscillation. These results are consistent with the wavelet analysis of the North Pacific Index (NPI). Similar resonance between the bidecadal and pentadecadal variations is evident in air-temperatures over Alaska. The bidecadal and pentadecadal signals have different seasonality in these time series, suggesting that although the two interdecadal variations arise from two different physical mechanisms, they interact with each other. The most distinct seasonal difference was observed in mid-latitude western North America, where the bidecadal variation prevails only in the winter season and the pentadecadal variation only in the spring season.

Alaska air-temperatures in the winter and winter–spring of 1999 were the coldest since 1977, as were springtime air-temperatures in mid-latitude western North America, in contrast to the warm anomalies that prevailed in this region during 1977–98. The NPI and PDOI also exhibited an opposite polarity in 1999 to the respective regime mean polarities. These anomalous conditions in winter and spring seasons of 1999 may signify a major regime shift in 1998–1999. In order to verify whether or not a regime shift did occur in 1998–1999, a careful examination of additional data in coming ten or so years will be necessary.

Introduction

A growing body of literature has revealed that there were climatic regime shifts in the 1920s, 1940s and 1970s which had significant influences on the physical and biological environments over and around the North Pacific. Nitta and Yamada (1989) and Trenberth (1990) reported that in the 1970s the Aleutian low abruptly strengthened. This abrupt change has been referred to as a climatic regime shift. A climatic regime shift is defined as a transition from one climatic state to another within a period substantially shorter than the lengths of the individual epochs of each climate states (e.g., Minobe, 1997). A number of analyses have shown the significant changes occurred in the physical environments in association with the 1970s regime shift (e.g., Graham, 1994; Tanimoto, Iwasaka, Hanawa & Toba, 1993; Trenberth & Hurrell, 1994; Miller, Cayan, Barnett, Graham & Oberhuber, 1994; Miller, Cayan, & White, 1998; Polovina, Mitchum & Evans, 1995; Lagerloef, 1995; Nakamura, Lin & Yamagata, 1997; Zhang & Levitus, 1997; Schneider, Miller, Alexander & Deser, 1999; Tourre, Kushnir & White, 1999; Zhang & Liu, 1999; Suga, Kato & Hanawa (2000)).

Several analyses indicate that similar regime shifts also occurred in the 1920s and 1940s with alternating polarities (Kondo, 1988, Hare & Francis, 1995, Dettinger & Cayan, 1995; Zhang, Wallace & Battisti, 1997; Minobe, 1997; Mantua, Hare, Zhang, Wallace & Francis, 1997). Mantua et al. (1997) called the low-frequency variability associated with the regime shifts the Pacific (Inter) Decadal Oscillation (PDO). From the point of view of the representative time scale, Minobe (1999) described the low-frequency variability as a pentadecadal oscillation. All three climatic regime shifts observed in the 20th century have had a significant influence on the marine ecosystems, notably in dramatic changes of several stocks of commercial fish (i.e., Mantua et al., 1997; Kodama, Nagashima & Izumi, 1995; McGowan, Cayan & Dorman, 1998; Yasuda, Sugusaki, Watanabe, Minobe & Oo-zeki, 1999). The pentadecadal variability has also been detected in tree-ring records over the United States and Canada during the 18th and 19th centuries, but with a somewhat longer timescale (from 50–70 years) than the 50 year timescale observed in instrumental data in the present century (Ware, 1995, Minobe, 1997, Shabalova & Weber, 1999, Ware & Thomson, 2000).

The three climatic regime shifts are not only important scientific issues intrinsically, but are also important because of their influence on interannual climate variations. Minobe and Mantua (1999) showed that the interannual variability in the wintertime Aleutian low is strong in a regime with a stronger regime-mean Aleutian low, with coherent signatures in the SLP, 500 hPa geopotential height, SST, and wind fields. Gershunov and Barnett (1998) showed that the influence of El Niño and Southern Oscillation (ENSO) on North America is modulated by the regime shifts. Power, Casey, Folland, Colman and Mehta (1999) also indicated that the ENSO influence on Australian rainfall is dependent on the PDO.

An interesting feature of these regime shifts is the rapidity with which the transition from one regime to another occurs. Analyzing a representative SLP time series, the North Pacific Index (NPI) defined by Trenberth and Hurrell (1994), Minobe (1999) explained that all three climatic regime shifts in the 20th century have involved simultaneous phase reversals between the pentadecadal (a period of about 50 years) and bidecadal (a period of about 17 years) oscillations. An epoch of a regime is equivalent to a half period of the pentadecadal variation, and corresponds to one and half periods of the bidecadal variation. In other words, the pentadecadal and bidecadal oscillations are synchronized with a relative period of three. A wavelet analysis of the NPI revealed that the pentadecadal oscillation prevailed both in the winter and spring, but the bidecadal oscillation occurred only in the winter. From these seasonal differences between the bidecadal and pentadecadal variations, it has been inferred that these two climate oscillations are generated by different mechanisms. The bidecadal variability over the North Pacific has been analyzed from various aspects; Royer (1989) first reported the bidecadal variability from an analysis of air and water-temperatures in Alaska. The upper water temperature, or mixed layer depth, was reported to exhibit the bidecadal signal (Lagerloef, 1995, Polovina et al., 1995, Tourre et al., 1999), and bidecadal variations were also detected in analyses of basin-scale or global surface temperature and/or SLP (Ghil & Vautard, 1991, Kawamura, 1994, Polovina et al., 1995, Mann & Park, 1994, Mann & Park, 1996, White & Cayan, 1998; Zhang, Sheng & Shabbar, 1998; Tourre et al., 1999).

In these previous studies, however, the seasonality and regionality of the pentadecadal variability or regime shifts have not been fully clarified. The pentadecadal signature was evident in the SLP in both the winter and spring seasons (Minobe, 1999), whereas the signature in the air-temperature in mid-latitude western North America is only found in spring (Minobe, 1997). Why there is this different seasonality between the SLP and air-temperature has not yet been explained. In this paper, in order to examine the seasonal and regional dependency more closely, we analyze the SLP and air-temperature by using a MTM–SVD. It is also interesting to examine whether the resonance between the bidecadal and pentadecadal variations shown for the NPI by Minobe (1999) is common to other large scale climate indices, such as the PDO index (PDOI) proposed by Zhang et al. (1997). The PDOI also captures the three climatic regime shifts in the present century (Mantua et al., 1997). So, we have performed a series of the wavelet analyses for the PDOI and area averages for several air-temperatures time series.

Section snippets

Data

We analyze the following monthly 5°×5° gridded SLP and land air-temperature. The SLP data from January 1899 to June 1999 was provided from NCAR, as the updated version of the SLP data of Trenberth and Paolino (1980). The air-temperature data from January 1880 to June 1999 are the gridded version of the Global Historical Climate Network (Vose et al., 1992), the gridding method described by Baker, Eischeid, Karl and Diaz (1995).

As representative climate proxies, the North Pacific Index (NPI) and

Winter–spring MTM–SVD

Fig. 1 shows the LFV spectra of the winter–spring combined MTM–SVD for the SLP over the North Pacific and western North America. A significant peak on interdecadal timescale occurs at 0.030 cycle yr−1 (33-year period). As noted in the Appendix, the frequency at the LFV peak does not necessarily give a representative timescale, which can be obtained from the reconstruction of a representative time series. The reconstructed time series has about two cycles in a one-hundred year record suggesting

Discussion

From the point of view of the superposition of the bidecadal and pentadecadal variations, only the three previously noted climatic regime shifts were accompanied by the simultaneous phase reversals of bidecadal and pentadecadal variations in the present century. Several papers documented that a series of atmospheric and oceanographic changes occurred over the North Pacific in 1988/89, and a certain portion of the changes was opposite to the changes which occurred in 1976/77 (Tachibana, Honda &

Conclusions

This paper examines aspects of the spatio-temporal structure of the atmospheric and oceanic variability over the North Pacific. The structure of the pentadecadal variability was analyzed by using a winter–spring combined MTM–SVD. The pentadecadal SLP variability in winter is distributed over the entire zonal extent of the Pacific basin, but the springtime SLP pattern is shifted toward the east with the strong zonal SLP gradient only within 10° longitude from the west coast of North America.

Acknowledgements

I thank Y. Kushnir, M. Scheledinger, and M. Shabalova for invaluable discussions, R.-H. Zhang, N. Schneider, L. D. Talley and D.M. Ware for preprints and reprints, N. Mantua for Pacific Decadal Oscillation Index, M.E. Mann for source code of the MTM–SVD. Insightful advises by N. Mantua and an anonymous reviewer are helpful to improve the present paper. Some figures are produced with the GrADS developed by B. Doty. This study is supported by grants from the Japanese Ministry of Education,

References (63)

  • M. Ghil et al.

    Interdecadal oscillations and the warming trend in global temperature time series

    Nature, London

    (1991)
  • N.E. Graham

    Decadal scale variability in the 1970s and 1980s: observations and model results

    Climate Dynamics

    (1994)
  • D.F. Gu et al.

    Interdecadal climate fluctuations that depend on exchanges between the tropics and extratropics

    Science

    (1997)
  • S.R. Hare et al.

    Climate change and salmon production in the Northeast Pacific Ocean

  • F.-F. Jin

    A theory of interdecadal climate variability of the North Pacific ocean–atmosphere system

    Journal of Climate

    (1997)
  • R. Kawamura

    A rotated EOF analysis of global sea surface temperature variability with interannual and interdecadal scales

    Journal of Physical Oceanography

    (1994)
  • J. Kodama et al.

    Long-term variations in the ‘mongoku herring’ clupea pallasi valenciennes resources in relation to the ocean environments in the waters off sanrikua and Joban

    Bulletin of Miyagi Prefecture Fishery Research Division Center

    (1995)
  • J. Kondo

    Volcanic eruptions, cool summers and famines in the northeastern part of Japan

    Journal of Climate

    (1988)
  • Y. Kushnir

    Interdecadal variations in North Atlantic sea surface temperature and associated atmospheric conditions

    Journal of Climate

    (1994)
  • G.S.E. Lagerloef

    Interdecadal variations in the Alaska gyre

    Journal of Physical Oceanography

    (1995)
  • M. Latif et al.

    Causes of decadal climate variability over the North Pacific and North America

    Science

    (1994)
  • M. Latif et al.

    Decadal climate variability over the North Pacific and North America: dynamics and predictability

    Journal of Climate

    (1996)
  • K.-M. Lau et al.

    Climate signal detection using wavelet transform: how to make a time series sing

    Bulletin of the American Meteorological Society

    (1995)
  • M.E. Mann et al.

    Global-scale modes of surface temperature variability on interannual to century timescale

    Journal of Geophysical Research

    (1994)
  • M.E. Mann et al.

    Joint spatiotemporal modes of surface temperature and sea level pressure variability in the Northern Hemisphere during the last century

    Journal of Climate

    (1996)
  • N.J. Mantua et al.

    A Pacific interdecadal climate oscillation with impacts on salmon production

    Bulletin of American Meteorological Society

    (1997)
  • J.A. McGowan et al.

    Climate–ocean variability and ecosystem response in the Northeast Pacific

    Science

    (1998)
  • A.J. Miller et al.

    The 1976–1977 climate shift of the Pacific Ocean

    Oceanography

    (1994)
  • A.J. Miller et al.

    A westward-intensified decadal change in the North Pacific thermocline and gyre-scale circulation

    Journal of Climate

    (1998)
  • S. Minobe

    A 50–70 year climatic oscillation over the North Pacific and North America

    Geophysical Research Letters

    (1997)
  • S. Minobe

    Resonance in bidecadal and pentadecadal climate oscillations over the North Pacific: role in climatic regime shifts

    Geophysical Research Letters

    (1999)
  • Cited by (177)

    • Interdecadal variability of the Western Subarctic Gyre in the North Pacific Ocean

      2021, Deep-Sea Research Part I: Oceanographic Research Papers
      Citation Excerpt :

      That weakening was related to the recent slowdown of global surface warming (Yan et al., 2016), which was tightly linked with La Niña–like cooling at the sea surface in the equatorial Pacific (Kosaka and Xie, 2013). It should be remembered that a regime shift occurred in the North Pacific in 1998/1999 (Hare and Mantua, 2000; Minobe, 2000, 2002; Bond et al., 2003; Jo et al., 2013). Moreover, the North Pacific Gyre Oscillation (NPGO), the second most important mode of the empirical orthogonal function (EOF) with respect to Sea Level Anomaly (SLA), tended to frequently exhibit positive values after the regime shift of 1998/1999, except during 2005–2006 and after 2014 (Fig. 2a) (Di Lorenzo et al., 2008).

    • Concurrent reductions in sinking particle flux and its ratios of opal and organic carbon to CaCO <inf>3</inf> in the oligotrophic western North Pacific Ocean during 2007–2014

      2019, Deep-Sea Research Part I: Oceanographic Research Papers
      Citation Excerpt :

      The trends were attributed to the enhanced water column CaCO3 dissolution and reduced calcifier productivity caused by weakened ventilation and ocean acidification resulting from surface water warming and atmospheric CO2 invasion, respectively. This study also indicated that biogenic particle fluxes were correlated with the North Pacific Index (Minobe, 2000; Watanabe et al., 2008). In the North Pacific subtropical gyre (22.75°N, 158°W; Station ALOHA of the Hawaiian Ocean Time-Series), where the marine ecosystem is largely supported by N2 fixation, phytoplankton productivity increased by 50% from 1989 to 2004 (Corno et al., 2007; Karl et al., 1997).

    View all citing articles on Scopus
    View full text