Publications

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Taguchi, B, Xie SP, Mitsudera H, Kubokawa A.  2005.  Response of the Kuroshio Extension to Rossby waves associated with the 1970s climate regime shift in a high-resolution ocean model. Journal of Climate. 18:2979-2995. Abstract
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Taguchi, B, Qiu B, Nonaka M, Sasaki H, Xie S-P, Schneider N.  2010.  Decadal variability of the Kuroshio Extension: mesoscale eddies and recirculations. Ocean Dynamics. 60:673-691.   10.1007/s10236-010-0295-1   Abstract
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Taguchi, B, Xie SP, Schneider N, Nonaka M, Sasaki H, Sasai Y.  2007.  Decadal variability of the Kuroshio Extension: Observations and an eddy-resolving model hindcast. Journal of Climate. 20:2357-2377.   10.1175/jcli4142.1   Abstract
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Takahashi, H, Su H, Jiang JH, Luo ZJ, Xie SP, Hafner J.  2013.  Tropical water vapor variations during the 2006-2007 and 2009-2010 El Ninos: Satellite observation and GFDL AM2.1 simulation. Journal of Geophysical Research-Atmospheres. 118:8910-8920. AbstractWebsite

Water vapor measurements from Aura Microwave Limb Sounder (MLS, above 300 hPa) and Aqua Atmospheric Infrared Sounder (AIRS, below 300 hPa) are analyzed to study the variations of moisture during the 2006-2007 and 2009-2010 El Ninos. The 2006-2007 El Nino is an East Pacific (EP) El Nino, while the 2009-2010 El Nino is a Central Pacific (CP) El Nino or El Nino Modoki. Results show that these two types of El Nino events produce different patterns of water vapor anomalies over the tropical ocean, approximately resembling the cloud anomalies shown in Su and Jiang (2013). Regression of water vapor anomalies onto the Nino-3.4 SST for the A-Train period shows a clear upper tropospheric amplification of the fractional water vapor change, i.e., the ratio of the change in specific humidity to the layer-averaged specific humidity. Furthermore, tropical water vapor anomalies in different circulation regimes are examined. It is shown that the variations of water vapor during the 2006-2007 El Nino are mainly controlled by the thermodynamic component, whereas both dynamic and thermodynamic components control the water vapor anomalies during the 2009-2010 El Nino. GFDL AM2.1 model simulations of water vapor and cloud anomalies for the two El Ninos are compared with the satellite observations. In general, the model approximately reproduces the water vapor anomalies on both zonal and meridional planes but it produces too strong a cloud response in the mid- and lower troposphere. The model fails to capture the dynamic component of water vapor anomalies, particularly over the Indian Ocean.

Tanimoto, Y, Xie SP.  1999.  Ocean-atmosphere variability over the Pan-Atlantic basin. Journal of the Meteorological Society of Japan. 77:31-46. Abstract
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Tanimoto, Y, Xie SP, Kai K, Okajima H, Tokinaga H, Murayama T, Nonaka M, Nakamura H.  2009.  Observations of Marine Atmospheric Boundary Layer Transitions across the Summer Kuroshio Extension. Journal of Climate. 22:1360-1374.   10.1175/2008jcli2420.1   Abstract
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Tanimoto, Y, Kanenari T, Tokinaga H, Xie S-P.  2011.  Sea Level Pressure Minimum along the Kuroshio and Its Extension. Journal of Climate. 24:4419-4434.   10.1175/2011jcli4062.1   Abstract
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Tanimoto, Y, Xie SP.  2002.  Inter-hemispheric decadal variations in SST, surface wind, heat flux and cloud cover over the Atlantic Ocean. Journal of the Meteorological Society of Japan. 80:1199-1219. Abstract
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Tanimoto, Y, Kajitani T, Okajima H, Xie S-P.  2010.  A Peculiar Feature of the Seasonal Migration of the South American Rain Band. Journal of the Meteorological Society of Japan. 88:79-90.   10.2151/jmsj.2010-106   Abstract
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Timmermann, A, Lorenz SJ, An SI, Clement A, Xie SP.  2007.  The effect of orbital forcing on the mean climate and variability of the tropical Pacific. Journal of Climate. 20:4147-4159.   10.1175/jcli4240.1   Abstract
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Timmermann, A, Okumura Y, An SI, Clement A, Dong B, Guilyardi E, Hu A, Jungclaus JH, Renold M, Stocker TF, Stouffer RJ, Sutton R, Xie SP, Yin J.  2007.  The influence of a weakening of the Atlantic meridional overturning circulation on ENSO. Journal of Climate. 20:4899-4919.   10.1175/jcli4283.1   Abstract
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Tokinaga, H, Xie SP, Mukougawa H.  2017.  Early 20th-century Arctic warming intensified by Pacific and Atlantic multidecadal variability. Proceedings of the National Academy of Sciences of the United States of America. 114:6227-6232.   10.1073/pnas.1615880114   AbstractWebsite

With amplified warming and record sea ice loss, the Arctic is the canary of global warming. The historical Arctic warming is poorly understood, limiting our confidence in model projections. Specifically, Arctic surface air temperature increased rapidly over the early 20th century, at rates comparable to those of recent decades despite much weaker greenhouse gas forcing. Here, we show that the concurrent phase shift of Pacific and Atlantic interdecadal variability modes is the major driver for the rapid early 20th-century Arctic warming. Atmospheric model simulations successfully reproduce the early Arctic warming when the interdecadal variability of sea surface temperature (SST) is properly prescribed. The early 20th-century Arctic warming is associated with positive SST anomalies over the tropical and North Atlantic and a Pacific SST pattern reminiscent of the positive phase of the Pacific decadal oscillation. Atmospheric circulation changes are important for the early 20th-century Arctic warming. The equatorial Pacific warming deepens the Aleutian low, advecting warm air into the North American Arctic. The extratropical North Atlantic and North Pacific SST warming strengthens surface westerly winds over northern Eurasia, intensifying the warming there. Coupled ocean-atmosphere simulations support the constructive intensification of Arctic warming by a concurrent, negative-to-positive phase shift of the Pacific and Atlantic interdecadal modes. Our results aid attributing the historical Arctic warming and thereby constrain the amplified warming projected for this important region.

Tokinaga, H, Xie S-P.  2011.  Weakening of the equatorial Atlantic cold tongue over the past six decades. Nature Geoscience. 4:222-226.   10.1038/ngeo1078   Abstract
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Tokinaga, H, Xie S-P.  2011.  Wave- and Anemometer-Based Sea Surface Wind (WASWind) for Climate Change Analysis. Journal of Climate. 24:267-285.   10.1175/2010jcli3789.1   Abstract
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Tokinaga, H, Xie SP, Deser C, Kosaka Y, Okumura YM.  2012.  Slowdown of the Walker circulation driven by tropical Indo-Pacific warming. Nature. 491:439-+.   10.1038/nature11576   Abstract

Global mean sea surface temperature (SST) has risen steadily over the past century(1,2), but the overall pattern contains extensive and often uncertain spatial variations, with potentially important effects on regional precipitation(3,4). Observations suggest a slowdown of the zonal atmospheric overturning circulation above the tropical Pacific Ocean (the Walker circulation) over the twentieth century(1,5). Although this change has been attributed to a muted hydrological cycle forced by global warming(5,6), the effect of SST warming patterns has not been explored and quantified(1,7,8). Here we perform experiments using an atmospheric model, and find that SST warming patterns are the main cause of the weakened Walker circulation over the past six decades (1950-2009). The SST trend reconstructed from bucket-sampled SST and night-time marine surface air temperature features a reduced zonal gradient in the tropical Indo-Pacific Ocean, a change consistent with subsurface temperature observations(8). Model experiments with this trend pattern robustly simulate the observed changes, including the Walker circulation slowdown and the eastward shift of atmospheric convection from the Indonesian maritime continent to the central tropical Pacific. Our results cannot establish whether the observed changes are due to natural variability or anthropogenic global warming, but they do show that the observed slowdown in the Walker circulation is presumably driven by oceanic rather than atmospheric processes.

Tokinaga, H, Xie S-P.  2009.  Ocean tidal cooling effect on summer sea fog over the Okhotsk Sea. Journal of Geophysical Research-Atmospheres. 114   10.1029/2008jd011477   Abstract
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Tokinaga, H, Tanimoto Y, Nonaka M, Taguchi B, Fukamachi T, Xie SP, Nakamura H, Watanabe T, Yasuda I.  2006.  Atmospheric sounding over the winter Kuroshio Extension: Effect of surface stability on atmospheric boundary layer structure. Geophysical Research Letters. 33   10.1029/2005gl025102   Abstract
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Tokinaga, H, Xie S-P, Timmermann A, McGregor S, Ogata T, Kubota H, Okumura YM.  2012.  Regional Patterns of Tropical Indo-Pacific Climate Change: Evidence of the Walker Circulation Weakening. Journal of Climate. 25:1689-1710.   10.1175/jcli-d-11-00263.1   Abstract
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Tokinaga, H, Tanimoto Y, Xie S-P, Sampe T, Tomita H, Ichikawa H.  2009.  Ocean Frontal Effects on the Vertical Development of Clouds over the Western North Pacific: In Situ and Satellite Observations. Journal of Climate. 22:4241-4260.   10.1175/2009jcli2763.1   Abstract
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Tokinaga, H, Tanimoto Y, Xie SP.  2005.  SST-induced surface wind variations over the Brazil-Malvinas confluence: Satellite and in situ observations. Journal of Climate. 18:3470-3482. Abstract
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Tomita, T, Xie SP, Nonaka M.  2002.  Estimates of surface and subsurface forcing for decadal sea surface temperature variability in the mid-latitude North Pacific. Journal of the Meteorological Society of Japan. 80:1289-1300. Abstract
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Tomita, H, Xie SP, Tokinaga H, Kawai Y.  2013.  Cloud response to the meandering Kuroshio extension front. Journal of Climate. 26:9393-9398.   10.1175/jcli-d-13-00133.1   AbstractWebsite

A unique set of observations on board research vessel (R/V) Mirai in April 2010 captured a striking cloud hole over a cold meander of the Kuroshio Extension (KE) east of Japan as corroborated by atmospheric soundings, ceilometer, shipboard radiation data, and satellite cloud images. Distinct differences were also observed between the warm meander farther to the north and warm water south of the KE. The atmosphere is highly unstable over the warm meander, promoting a well-mixed marine atmospheric boundary layer (MABL) and a layer of solid stratocumulus clouds capped by a strong inversion. Over the warm water south of the KE, MABL deepens and is decoupled from the ocean surface. Scattered cumulus clouds develop as captured by rapid variations in ceilometer-derived cloud base. The results show that the meandering KE front affects the entire MABL and the clouds. Such atmospheric response can potentially intensify the baroclinicity in the lower atmosphere.