scholarly journals Pacific Sea Surface Temperatures in the Twentieth Century: An Evolution-Centric Analysis of Variability and Trend

2008 ◽  
Vol 21 (12) ◽  
pp. 2790-2809 ◽  
Author(s):  
Bin Guan ◽  
Sumant Nigam
Keyword(s):  
Twentieth Century ◽  
North Pacific ◽  
Decadal Variability ◽  
Secular Trend ◽  
Surface Air Temperature ◽  
Natural Variability ◽  
Equatorial Pacific ◽  
Climate Shift ◽  
The North ◽  
The North Pacific

Abstract A consistent analysis of natural variability and secular trend in Pacific SSTs in the twentieth century is presented. By focusing on spatial and temporal recurrence, but without imposition of periodicity constraints, this single analysis discriminates between biennial, ENSO, and decadal variabilities, leading to refined evolutionary descriptions, and between these natural variability modes and secular trend, all without advance filtering (and potential aliasing) of the SST record. SST anomalies of all four seasons are analyzed together using the extended-EOF technique. Canonical ENSO variability is encapsulated in two modes that depict the growth (east-to-west along the equator) and decay (near-simultaneous amplitude loss across the basin) phases. Another interannual mode, energetic in recent decades, is shown linked to the west-to-east SST development seen in post–climate shift ENSOs: the noncanonical ENSO mode. The mode is closely related to Chiang and Vimont’s meridional mode, and leads to some reduction in canonical ENSO’s oscillatory tendency. Pacific decadal variability is characterized by two modes: the Pan-Pacific mode has a horseshoe structure with the closed end skirting the North American coast, and a quiescent eastern equatorial Pacific. The mode exhibits surprising connections to the tropical/subtropical Atlantic, with correlations there resembling the Atlantic multidecadal oscillation. The second decadal mode—the North Pacific mode—captures the 1976/77 climate shift and is closer to Mantua’s Pacific decadal oscillation. This analysis shows, perhaps for the first time, the striking links of the North Pacific mode to the western tropical Pacific and Indian Ocean SSTs. The physicality of both modes is assessed from correlations with the Pacific biological time series. Finally, the secular trend is characterized: implicit accommodation of natural variability leads to a nonstationary SST trend, including midcentury cooling. The SST trend is remarkably similar to the global surface air temperature trend. Geographically, a sliver of cooling is found in the central equatorial Pacific in the midst of widespread but nonuniform warming in all basins. An extensive suite of sensitivity tests, including counts of the number of observational analogs of the modes in test analyses, supports the robustness of this analysis.

North Pacific Decadal Variability and Climate Change in the IPCC AR4 Models

2011 ◽  
Vol 24 (12) ◽  
pp. 3049-3067 ◽  
Author(s):  
Jason C. Furtado ◽  
Emanuele Di Lorenzo ◽  
Niklas Schneider ◽  
Nicholas A. Bond
Keyword(s):  
Twentieth Century ◽  
El Niño ◽  
North Pacific ◽  
Climate Models ◽  
Decadal Variability ◽  
El Nino ◽  
North Pacific Ocean ◽  
Coupled Mode ◽  
The North ◽  
The North Pacific

Abstract The two leading modes of North Pacific sea surface temperature (SST) and sea level pressure (SLP), as well as their connections to tropical variability, are explored in the 24 coupled climate models used in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) to evaluate North Pacific decadal variability (NPDV) in the past [twentieth century; climate of the twentieth century (20C3M) scenario] and future [twenty-first century; Special Report on Emissions Scenarios (SRES) A1B scenario] climate. Results indicate that the two dominant modes of North Pacific oceanic variability, the Pacific decadal oscillation (PDO) and the North Pacific Gyre Oscillation (NPGO), do not exhibit significant changes in their spatial and temporal characteristics under greenhouse warming. However, the ability of the models to capture the dynamics associated with the leading North Pacific oceanic modes, including their link to the corresponding atmospheric forcing patterns and to tropical variability, is questionable. The temporal and spatial statistics of the North Pacific Ocean modes exhibit significant discrepancies from observations in their twentieth-century climate, most visibly for the second mode, which has significantly more low-frequency power and higher variance than in observations. The dynamical coupling between the North Pacific Ocean and atmosphere modes evident in the observations is very strong in the models for the first atmosphere–ocean coupled mode, which represents covariability of the PDO pattern with the Aleutian low (AL). However, the link for the second atmosphere–ocean coupled mode, describing covariability of an NPGO-like SST pattern with the North Pacific Oscillation (NPO), is not as clearly reproduced, with some models showing no relationship between the two. Exploring the tropical Pacific–North Pacific teleconnections reveals more issues with the models. In contrast with observations, the atmospheric teleconnection excited by the El Niño–Southern Oscillation in the models does not project strongly on the AL–PDO coupled mode because of the displacement of the center of action of the AL in most models. Moreover, most models fail to show the observational connection between El Niño Modoki–central Pacific warming and NPO variability in the North Pacific. In fact, the atmospheric teleconnections associated with El Niño Modoki in some models have a significant projection on, and excite the AL–PDO coupled mode instead. Because of the known links between tropical Pacific variability and NPDV, these analyses demonstrate that focus on the North Pacific variability of climate models in isolation from tropical dynamics is likely to lead to an incomplete view, and inadequate prediction, of NPDV.

scholarly journals Interannual-decadal variability of wintertime mixed layer depths in the North Pacific detected by an ensemble of ocean syntheses

2015 ◽  
Vol 49 (3) ◽  
pp. 891-907 ◽  
Author(s):  
Takahiro Toyoda ◽  
Yosuke Fujii ◽  
Tsurane Kuragano ◽  
Naohiro Kosugi ◽  
Daisuke Sasano ◽  
...  
Keyword(s):  
Mixed Layer ◽  
North Pacific ◽  
Decadal Variability ◽  
The North ◽  
The North Pacific

North Hemispheric winter air temperature variability and its linkage to North Pacific and North Atlantic SST modes?

2020 ◽  
Author(s):  
Binhe Luo ◽  
Dehai Luo ◽  
Aiguo Dai ◽  
Lixin Wu
Keyword(s):  
North America ◽  
Air Temperature ◽  
North Atlantic ◽  
North Pacific ◽  
Wave Train ◽  
Surface Air Temperature ◽  
Eastern North America ◽  
The North ◽  
The North Atlantic ◽  
The North Pacific

<p>Winter surface air temperature (SAT) over North America exhibits pronounced variability on sub-seasonal-to-interdecadal timescales, but its causes are not fully understood. Here observational and reanalysis data from 1950-2017 are analyzed to investigate these causes. Detrended daily SAT data reveals a known warm-west/cold-east (WWCE) dipole over midlatitude North America and a cold-north/warm-south (CNWS) dipole over eastern North America. It is found that while the North Pacific blocking (PB) is important for the WWCE and CNWS dipoles, they also depend on the phase of the North Atlantic Oscillation (NAO). When a negative-phase NAO (NAO-) concurs with PB, the WWCE dipole is enhanced (compared with the PB alone case) and it also leads to a warm north/cold south dipole anomaly in eastern North America; but when PB occurs with a positive-phase NAO (NAO<sup>+</sup>), the WWCE dipole weakens and the CNWS dipole is enhanced. In particular, the WWCE dipole is favored by a combination of eastward-displaced PB and NAO<sup>-</sup> that form a negative Arctic Oscillation. Furthermore, a WWCE dipole can form over midlatitude North America when PB occurs together with southward-displaced NAO<sup>+</sup>.The PB events concurring with NAO<sup>-</sup> (NAO<sup>+</sup>) and SAT WWCE (CNWS) dipole are favored by the El Nio-like (La Nia-like) SST mode, though related to the North Atlantic warm-cold-warm (cold-warm-cold) SST tripole pattern. It is also found that the North Pacific mode tends to enhance the WWCE SAT dipole through increasing PB-NAO<sup>-</sup> events and producing the WWCE SAT dipole component related to the PB-NAO<sup>+</sup> events because the PB and NAO<sup>+</sup> form a more zonal wave train in this case.</p>

Different Impacts of the East Asian Winter Monsoon on the Surface Air Temperature in North America during ENSO and Neutral ENSO Years

2020 ◽  
Vol 33 (24) ◽  
pp. 10671-10690
Author(s):  
Tianjiao Ma ◽  
Wen Chen ◽  
Hans-F. Graf ◽  
Shuoyi Ding ◽  
Peiqiang Xu ◽  
...  
Keyword(s):  
Wave Packet ◽  
North Pacific ◽  
East Asian Winter Monsoon ◽  
East Asian ◽  
Surface Air Temperature ◽  
Winter Monsoon ◽  
Asian Winter Monsoon ◽  
The North ◽  
The North Pacific ◽  
Central North Pacific

AbstractThe present study investigates different impacts of the East Asian winter monsoon (EAWM) on surface air temperature (Ts) in North America (NA) during ENSO and neutral ENSO episodes. In neutral ENSO years, the EAWM shows a direct impact on the Ts anomalies in NA on an interannual time scale. Two Rossby wave packets appear over the Eurasian–western Pacific (upstream) and North Pacific–NA (downstream) regions associated with a strong EAWM. Further analysis suggests that the downstream wave packet is caused by reflection of the upstream wave packet over the subtropical western Pacific and amplified over the North Pacific. Also, the East Asian subtropical westerly jet stream (EAJS) is intensified in the central and downstream region over the central North Pacific. Hence, increased barotropic kinetic energy conversion and the interaction between transient eddies and the EAJS tend to maintain the circulation anomaly over the North Pacific. Therefore, a strong EAWM tends to result in warm Ts anomalies in northwestern NA via the downstream wave packet emanating from the central North Pacific toward NA. A weak EAWM tends to induce cold Ts anomalies in western-central NA with a smaller magnitude. However, in ENSO years, an anomalous EAJS is mainly confined over East Asia and does not extend into the central North Pacific. The results confirm that the EAWM has an indirect impact on the Ts anomalies in NA via a modulation of the tropical convection anomalies associated with ENSO. Our results indicate that, for seasonal prediction of Ts anomalies in NA, the influence of the EAWM should be taken into account. It produces different responses in neutral ENSO and in ENSO years.

scholarly journals Multidecadal Fluctuation of the Wintertime Arctic Oscillation Pattern and Its Implication

2018 ◽  
Vol 31 (14) ◽  
pp. 5595-5608 ◽  
Author(s):  
Hainan Gong ◽  
Lin Wang ◽  
Wen Chen ◽  
Debashis Nath
Keyword(s):  
North Atlantic ◽  
North Pacific ◽  
Arctic Oscillation ◽  
Surface Air Temperature ◽  
Western North America ◽  
Oscillation Pattern ◽  
The North ◽  
The Pacific ◽  
The North Atlantic ◽  
The North Pacific

The multidecadal fluctuations in the patterns and teleconnections of the winter mean Arctic Oscillation (AO) are investigated based on observational and reanalysis datasets. Results show that the Atlantic center of the AO pattern remains unchanged throughout the period 1920–2010, whereas the Pacific center of the AO is strong during 1920–59 and 1986–2010 and weak during 1960–85. Consequently, the link between the AO and the surface air temperature over western North America is strong during 1920–59 and 1986–2010 and weak during 1960–85. The time-varying Pacific center of the AO motivates a revisit to the nature of the AO from the perspective of decadal change. It reveals that the North Pacific mode (NPM) and North Atlantic Oscillation (NAO) are the inherent regional atmospheric modes over the North Pacific and North Atlantic, respectively. Their patterns over the North Pacific and North Atlantic remain stable and change little with time during 1920–2010. The Atlantic center of the AO always resembles the NAO over the North Atlantic, but the Pacific center of the AO only resembles the NPM over the North Pacific when the NPM–NAO coupling is strong. These results suggest that the AO seems to be fundamentally rooted in the variability over the North Atlantic and that the annular structure of the AO very likely arises from the coupling of the atmospheric modes between the North Pacific and North Atlantic.

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