Analysis of SST Anomalies in the North Pacific and their Relation to 500mb Height Anomalies Over the Northern Hemisphere During 1969-1979

Iwasaka, Naoto; Hanawa, Kimio; Toba, Yoshiaki

doi:10.2151/jmsj1965.65.1_103

Cited by 35 publications

(20 citation statements)

References 48 publications

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“…Jiang et al (1995) have recently shown that nonlinear ocean models of the steadily wind-driven double-gyre circulation can oscillate with a periodicity of approximately 3 years. Recent analyses of North Pacific SST and boundary-current geometries have, indeed, identified oscillations with periods near 3.3 years (Iwasaka et al, 1987;Qiu and Joyce, 1992;Speich et al, 1994). Perhaps the localization of the 3.3-year component of United States temperature variability within the western states is a symptom that the driving force is in the North Pacific, immediately to the west.…”

Section: Interannual Oscillationsmentioning

confidence: 98%

Interannual and interdecadal variability in United States surface-air temperatures, 1910-87

1995

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Abstract. Monthly mean surface-air temperatures at 870 sites in the contiguous United States were analyzed for interannual and interdecadal variability over the time interval 1910-87. The temperatures were analyzed spatially by empirical-orthogonal-function analysis and temporally by singularspectrum analysis (SSA). The dominant modes of spatio-temporal variability are trends and nonperiodic variations with time scales longer than 15 years, decadal-scale oscillations with periods of roughly 7 and 10 years, and interannual oscillations of 2.2 and 3.3 years. Together, these modes contribute about 18% of the slower-than-annual United States temperature variance. Two leading components roughly capture the mean hemispheric temperature trend and represent a long-term warming, largest in the southwest, accompanied by cooling of the domain's southeastern quadrant. The extremes of the 2.2-year interannual oscillation characterize temperature differences between the Northeastern and Southwestern States, whereas the 3.3-year cycle is present mostly in the Western States. The 7-to 10-year oscillations are rauch less regular and persistent than the interannual oscillations and characterize temperature differences between the western and interior sectors of the United States. These continental-or regionat-scale temperature variations may be related to climatic variations with similar periodicities, either global or centered in other regions; such variations include quasi-biennial oscillations over the tropical Pacific or North Atlantic and quasi-triennial oscillations of North Pacific sea-surface temperatures.

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Section: Interannual Oscillationsmentioning

confidence: 98%

Interannual and interdecadal variability in United States surface-air temperatures, 1910-87

1995

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“…In this scenario the Pacific/North American (PNA) pattern of the troposphere (Wallace and Gutzler, 1981) was the essential part as the atmospheric bridge from the tropics to the extratropics that could be excited by the cumulus heating as the heat engine for the global atmosphere, which was well correlated with Southern Oscillation Index. In fact, observational studies showed that the wintertime SST variability in the extratropical North Pacific was closely related to the PNA and the strength of the Aleutian Low (Davis, 1976;Iwasaka et al, 1987;Wallace and Jiang, 1987). Numerical experiments (Kitoh, 1991;Alexander, 1992a, b;Luksch and von Storch, 1992;Lau and Nath, 1994) support the conclusion that SST anomalies in the extratropics are formed by wintertime atmospheric forcing that is excited in the tropical air-sea interaction.…”

Section: Introductionmentioning

confidence: 99%

Relationships between Sea Surface Temperature, the Atmospheric Circulation and Air-sea Fluxes on Multiple Time Scales

Tanimoto

Iwasaka²,

Hanawa

1997

Journal of the Meteorological Society of Japan

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The relationships of sea surface temperature (SST) anomalies with atmospheric general circulation and with momentum and heat fluxes are investigated in order to show the dominant structures in the North Pacific in the ENSO cycle (ES: 2-5 years) and decadal (DC: longer than 5 years) time scales, using newly computed monthly 5ox5o (longitude x latitude) gridded datasets for SST, wind stress, and net surface heating fields and National Meteorological Center (NMC) geopotential height data for the 40-year period of The Pacific/North American (PNA) like pattern that has three centers in the 150oW-170oW longitudinal band in the wintertime 500hPa height field is prominent in the decadal changes of wintertime SST anomalies. Stronger (weaker) westerlies are located south (north) of the normal jet stream position during periods of below-normal (above-normal) SST anomalies in most of the entire extratropical North Pacific. Those SST anomalies are caused by the enhanced (suppressed) heat release along the Kuroshio and its extension, and by stronger (weaker) southward Ekman transport. However the dominant pattern of the wind field on the ES time scale is quite different from that on the DC time scale. The westerly jet in the central North Pacific is stronger than normal, but shifts northward of its mean position in years of ENSO warm episodes. On the other hand, the northwesterly wind is weaker, hence heat release is suppressed in the western North Pacific. A Western Pacific (WP) like pattern then appears in the atmospheric geopotential height field over the ocean with a below-normal center in the Bering Sea and an above-normal center south of Japan. The situation is reversed in the years of ENSO cold episodes.The differences in the spatial patterns of SST anomalies on the DC and ES time scales are associated with differences in the atmospheric circulation, such as the predominance of PNA-like versus WP-like patterns. The corresponding change in the wind system then brings about a change of heat release and Ekman transport that form the SST anomalies. It appears that the distinctions between these two atmospheric patterns are responsible for the differences in the spatial structure of tropical SST anomalies on the DC and ES time scales.

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“…As to the direct relation between winter climate in Japan and the global SSTAs, several groups have undertaken an analysis of the observational data (e.g., Kawamura, 1984Kawamura, , 1986Iwasaka et al, 1987). The winter climate in Japan tends to be mild in El Nino years.…”

Section: Introductionmentioning

confidence: 99%

“…The surface air temperature in central Japan is shown to have high temporal correlation with warm SSTA over the equatorial central Pacific Ocean, but also with warm SSTA over south and east off Japan, the South China Sea and the Indian Ocean. On the other hand it is reported that SSTA in the North Pacific Ocean is caused by an atmospheric fluctuation (Kawamura, 1984;Iwasaka et al, 1987). Kawamura (1984) claims that warm SSTA off Japan is a result of the weaker cold surge than normal…”

Section: Introductionmentioning

confidence: 99%

A Numerical Experiment on Sea Surface Temperature Anomalies and Warm Winter in Japan

Kitoh

1988

Journal of the Meteorological Society of Japan

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Impact of the sea surface temperature anomalies (SSTAs) on atmospheric circulations are studied with emphasis on the winter climate in Japan with the use of an atmospheric general circulation model.The empirical orthogonal function analyses are performed for precipitation, geopotential height at 500mb and surface air temperature. It is shown that leading eigenvectors of precipitation are zonally elongated in the tropics and that the distribution of positive and negative precipitation anomalies is dependent on the SST and precipitation field in the control run. Surface air temperature in East Asia is mostly governed by the temperature contrast between Japan-East China region and the Sea of Okhotsk. This is associated with high pressure anomalies in the North Pacific Ocean, which weakens the cold surge from Siberia. This circulation is found in the first eigenvector in the present experiment El(Z500) and is dominant in the run which uses the composited January SSTA observed during warm winter in Japan. The simulated anomalies in mid-latitude circulation correspond well with the observations.An additional run with the SSTA over the equator east of the dateline gives the largest anticyclonic circulation response over the North Pacific Ocean and the warmest surface air temperature anomalies in East Asia. The pattern relevant to warm winter in Japan is not a simple atmospheric response to tropical heating. It is conceivable that inherently there is a dominant circulation mode like El(Z500) and that this mode can be activated either by a direct and/or an indirect orographic effect or by anomalous heating induced by the SSTA.This pattern can be understood as a response to subtropical mass source/sink distribution under the framework of a linear theory.

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Analysis of SST Anomalies in the North Pacific and their Relation to 500mb Height Anomalies Over the Northern Hemisphere During 1969-1979

Cited by 35 publications

References 48 publications

Interannual and interdecadal variability in United States surface-air temperatures, 1910-87

Interannual and interdecadal variability in United States surface-air temperatures, 1910-87

Relationships between Sea Surface Temperature, the Atmospheric Circulation and Air-sea Fluxes on Multiple Time Scales

A Numerical Experiment on Sea Surface Temperature Anomalies and Warm Winter in Japan

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