Inter-hemispheric Decadal Variations in SST, Surface Wind, Heat Flux and Cloud Cover over the Atlantic Ocean.

Tanimoto, Youichi; Xie, Shang‐Ping

doi:10.2151/jmsj.80.1199

Cited by 78 publications

(78 citation statements)

References 69 publications

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“…3, 4, and 5, we suggest that an oceanic memory of the strongly negative wintertime AO may have influenced the strongly positive summertime AO. A negative wintertime NAO would cause warm SST anomalies in high-and low-latitude regions of the Atlantic, as suggested by Xie and Tanimoto (1998) and Tanimoto and Xie (2002). Because the horizontal structures of the NAO and the AO in the Atlantic sector in winter 2009/2010 are similar (See Fig.…”

Section: Discussionmentioning

confidence: 79%

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A possible cause of the AO polarity reversal from winter to summer in 2010 and its relation to hemispheric extreme summer weather

2012

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In 2010, the Northern Hemisphere, in particular Russia and Japan, experienced an abnormally hot summer characterized by record-breaking warm temperatures and associated with a strongly positive Arctic Oscillation (AO), that is, low pressure in the Arctic and high pressure in the midlatitudes. In contrast, the AO index the previous winter and spring (2009/2010) was record-breaking negative. The AO polarity reversal that began in summer 2010 can explain the abnormally hot summer. The winter sea surface temperatures (SST) in the North Atlantic Ocean showed a tripolar anomaly pattern-warm SST anomalies over the tropics and high latitudes and cold SST anomalies over the midlatitudes-under the influence of the negative AO. The warm SST anomalies continued into summer 2010 because of the large oceanic heat capacity. A model simulation strongly suggested that the AO-related summertime North Atlantic oceanic warm temperature anomalies remotely caused blocking highs to form over Europe, which amplified the positive summertime AO. Thus, a possible cause of the AO polarity reversal might be the ''memory'' of the negative winter AO in the North Atlantic Ocean, suggesting an interseasonal linkage of the AO in which the oceanic memory of a wintertime negative AO induces a positive AO in the following summer. Understanding of this interseasonal linkage may aid in the longterm prediction of such abnormal summer events.

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Section: Discussionmentioning

confidence: 79%

“…3). This tripolar pattern is typical of a negative wintertime NAO (e.g., Rodwell et al 1999;Tanimoto and Xie 2002). In fact, the geopotential height anomaly field at 500 hPa in winter (DJF) 2009/2010 showed the typical pattern for the negative phase of the NAO (Fig.…”

Section: Oceanic Footprint Left By the Previous Winter's Negative Aomentioning

confidence: 80%

A possible cause of the AO polarity reversal from winter to summer in 2010 and its relation to hemispheric extreme summer weather

2012

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“…This dataset contains some missing values in the equatorial and South Pacific regions since satellite observations and spatial interpolation were not used. Details of the calculation procedure are described in Tanimoto and Xie (2002) and Tanimoto et al (2003). We calculate the monthly climatological means based on a 21-or 22-year period from December 1981 to December 2002 for NCEP2 and OISST datasets and for a 46-year period from January 1950 to December 1995 for COADS.…”

Section: Datasetsmentioning

confidence: 99%

Subtropical Paciﬁc SST Variability Related to the Local Hadley Circulation during the Premature Stage of ENSO

Chikamoto

Tanimoto

Mukougawa

et al. 2010

Journal of the Meteorological Society of Japan

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Formation processes of negative (positive) sea surface temperature anomalies (SSTAs) in the subtropical North and South Pacific associated with the ENSO warm (cold) events are examined using reanalysis and in-situ observational datasets. During the premature stage of the ENSO warm events, negative SSTAs appear over the subtropical North Pacific in the February-March period and over the subtropical South Pacific after April, and vice versa in the ENSO cold events. One month prior to the formation of these subtropical negative SSTAs, the negative air humidity anomaly and anomalous downward motion appear at the same location in either the Northern or Southern hemisphere. Associated with these atmospheric anomalies, the strengthened descending branch of local Hadley circulation is observed during the January-February period in the Northern hemisphere and after March in the Southern hemisphere, which coincides with the seasonal transition of the climatological local Hadley circulation from the Northern to Southern hemisphere. Our linear decomposition analysis of surface heat flux anomalies indicates that the negative air humidity anomaly, as well as anomalies in wind speed, contributes to the formation of the subtropical negative SSTAs through the enhanced latent heat flux induced by the anomalous air-sea humidity di¤erence. These results suggest that the anomalous downward motion associated with the changes in local Hadley circulation can induce the subtropical negative SSTAs through the surface humidity variability. A possible mechanism for the subtropical air-sea interaction associated with the local Hadley circulation is discussed.

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“…The absence of a signature in the tropical Pacific also indicates that the El Ni no-Southern Oscillation (ENSO) is not related to the snow in Tokyo. Over the North Atlantic, a significant tripole pattern, which interacts with the North Atlantic Oscillation (e.g., Rodwell et al 1999;Tanimoto and Xie 2002), has been associated with the EU pattern. Also the PDO may be related to longterm multi-decadal variations of the snow in Tokyo.…”

Section: Relationship To Sstsmentioning

confidence: 99%

Interannual Variation in Snow-accumulation Events in Tokyo and its Relationship to the Eurasian Pattern

Tachibana

Nakamura

Tazou

2007

SOLA

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We examined interannual variation in snowaccumulation events in Tokyo and the relationship of this variation to large-scale atmospheric patterns. Years when snow-accumulation events occurred tended to coincide with a west-to-east wavetrain pattern in the middle and upper troposphere over Eurasia. The pattern, which includes cyclonic anomalies over Europe and East Asia and anticyclonic anomalies over Siberia, is identical to the negative phase of the Eurasian (EU) pattern, which is the leading mode of an empirical orthogonal function (EOF) analysis applied for the Eastern Hemisphere in the 500-hPa height field. Anomalous cold air associated with the negative EU pattern widely covers East Asia and Japan in the lower troposphere. No significant relation to storm-track activities around Japan was found except for extremely deep snowfall years. The cold atmospheric anomaly associated with the negative EU pattern possibly lowers the surface air temperature over Tokyo, creating an environment favorable to snowfall and snow accumulation. In the extremely deep snow years, the signature of the EU pattern was weak, and storm tracks over the ocean to the south of Japan were significantly active. No clear long-term trend in snow-accumulation events was found, although a downward trend due to anthropogenic effects was expected. IntroductionEven a few centimeters of snow accumulation in Tokyo can cause massive traffic congestion and railservice delays. As Tokyo is a key center of global and national economic and political activities, disruptions caused by snowfall can negatively affect the Japanese economy. Thus, the ability to provide long-term forecasts of snowfall in Tokyo is important. However, many previous meteorological studies have focused on shortterm forecasts or on events such as the relationship between snowfall in Tokyo and the location and path of cyclones (e.g., Ito 1956;Yamamoto 1984). Furthermore, while numerous past studies have examined snowfall in Tokyo and synoptic-scale conditions (e.g., Ito 1956;Yamamoto 1984;Yasuda and Tomine 1998), the lack of research from a global-scale perspective has prevented long-term forecasting.Large-scale atmospheric modes that may be related to the winter climate of Japan include the Arctic Oscillation (AO), Western Pacific (WP) pattern, and Eurasian (EU) pattern. The WP pattern is a north-south dipole pattern around Japan that is related to snowfall in regions along the Sea of Japan (Tachibana et al. 2007). The EU pattern is a west-east wavetrain pattern that originates over western Europe and moves toward Japan (Wallace and Gutzlar 1981). The EU pattern is connected to amplification of AO (Ohashi and Yamazaki 1999). Thompson and Wallace (2000) examined the link between the AO and extreme meteorological events around the world, briefly mentioning the association of AO with snowfall in Tokyo. However, no previous studies have considered in detail the interannual variation in snowfall in Tokyo and its relationship to largescale atmospheric teleconnection patterns, whic...

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Inter-hemispheric Decadal Variations in SST, Surface Wind, Heat Flux and Cloud Cover over the Atlantic Ocean.

Cited by 78 publications

References 69 publications

A possible cause of the AO polarity reversal from winter to summer in 2010 and its relation to hemispheric extreme summer weather

A possible cause of the AO polarity reversal from winter to summer in 2010 and its relation to hemispheric extreme summer weather

Subtropical Paciﬁc SST Variability Related to the Local Hadley Circulation during the Premature Stage of ENSO

Interannual Variation in Snow-accumulation Events in Tokyo and its Relationship to the Eurasian Pattern

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