Twentieth century North Atlantic climate change. Part II: Understanding the effect of Indian Ocean warming

Hoerling, Martin P.; Hurrell, James W.; Xu, Taiyi; Bates, Gary T.; Phillips, Adam S.

doi:10.1007/s00382-004-0433-x

Cited by 236 publications

(253 citation statements)

References 26 publications

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“…First, random, internal climate variations appear large enough to offer an explanation of the observed NAO trend over the past decades. In agreement with recent studies [Hurrell et al, Hoerling et al, 2004], our results suggest that the NAO trends are caused by precipitation trends over the tropical Indian Ocean. Second, we conclude from our simulations that the CWP is possibly one of the dominant players in future climate change.…”

Section: Conclusion and Discussionsupporting

confidence: 93%

“…These propagate into the Northern hemisphere and within a couple of weeks cause a strengthening of the NAO over the North Atlantic. Simulations with different atmospheric general circulation models (AGCMs) that are forced with the observed tropical sea surface temperature (SST) convincingly demonstrate that the precipitation increase over the Indian Ocean in response to the historical warming trend of the tropical Oceans indeed induces the observed NAO trend Hoerling et al, 2004].…”

Section: Resultsmentioning

confidence: 99%

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Tropical origins for recent and future Northern Hemisphere climate change

Selten

Branstator

Dijkstra

et al. 2004

Geophysical Research Letters

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Results from a large ensemble of climate model simulations over the period 1940–2080 suggest that the observed strengthening of the westerly winds over the North Atlantic during the past decades is not due to the enhanced greenhouse effect but is largely an expression of a random, internal climate variation driven by increased precipitation over the tropical Indian Ocean. Instead, the enhanced greenhouse effect drives a change in the extra‐tropical winter circulation through intensified precipitation over the tropical West Pacific. This change is characterized by a wave train encompassing the whole Northern hemisphere, a pattern known as the Circumglobal Waveguide Pattern.

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Section: Conclusion and Discussionsupporting

confidence: 93%

Section: Resultsmentioning

confidence: 99%

Tropical origins for recent and future Northern Hemisphere climate change

Selten

Branstator

Dijkstra

et al. 2004

Geophysical Research Letters

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“…We explore this idea using a synthesis of globally distributed proxy records and results from new coupled model experiments examining the response to a warmer Indian-West Pacific Ocean. The model results are also discussed in the context of previous experiments bearing on the role of tropical SSTs in driving recent and past climate change (e.g., Rodwell et al 1999;Branstator 2000;Hoerling et al 2001;Bader and Latif 2003;Giannini et al 2003;Hurrell et al 2004;Hoerling et al 2004;Deser and Phillips 2006;Seager et al 2008), and others examining the climate response to changes in irradiance and high latitude temperatures (e.g., Clement et al 1996;Shindell et al 2001;Meehl et al 2003;Sun et al 2004;Mann et al 2005;Pierce et al 2006;Ammann et al 2007;Timmermann et al 2007a, b, Lu et al 2007). …”

Section: Introductionmentioning

confidence: 79%

“…The experimental design was motivated by proxy evidence for medieval climate changes not well explained by a cooler tropical Pacific alone (as discussed above) and model simulations showing that warmer Indian Ocean SSTs produce important features of inferred MCA climate changes (e.g., Bader and Latif 2003;Hurrell et al 2004;Hoerling et al 2004). We used the National Center for Atmospheric Sciences (NCAR) Community Climate System Model (CCSM, v. 3.0.1 beta 14; Collins et al 2006;Kiehl et al 2006) with the atmospheric model configured at triangular-31 spectral truncation (about 3.75°resolution) and 26 vertical levels, and the ocean model with 40 vertical levels, zonal resolution of 1.8°, and meridional resolution varying from 1.8°at higher latitudes to 0.8°in the tropics (Gent et al 2006).…”

Section: Tropical Warming Simulationsmentioning

confidence: 99%

Support for global climate reorganization during the “Medieval Climate Anomaly”

et al. 2010

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Widely distributed proxy records indicate that the Medieval Climate Anomaly (MCA; *900-1350 AD) was characterized by coherent shifts in large-scale Northern Hemisphere atmospheric circulation patterns. Although cooler sea surface temperatures in the central and eastern equatorial Pacific can explain some aspects of medieval circulation changes, they are not sufficient to account for other notable features, including widespread aridity through the Eurasian sub-tropics, stronger winter westerlies across the North Atlantic and Western Europe, and shifts in monsoon rainfall patterns across Africa and South Asia. We present results from a full-physics coupled climate model showing that a slight warming of the tropical Indian and western Pacific Oceans relative to the other tropical ocean basins can induce a broad range of the medieval circulation and climate changes indicated by proxy data, including many of those not explained by a cooler tropical Pacific alone. Important aspects of the results resemble those from previous simulations examining the climatic response to the rapid Indian Ocean warming during the late twentieth century, and to results from climate warming simulations-especially in indicating an expansion of the Northern Hemisphere Hadley circulation. Notably, the pattern of tropical Indo-Pacific sea surface temperature (SST) change responsible for producing the proxy-model similarity in our results agrees well with MCA-LIA SST differences obtained in a recent proxy-based climate field reconstruction. Though much remains unclear, our results indicate that the MCA was characterized by an enhanced zonal Indo-Pacific SST gradient with resulting changes in Northern Hemisphere tropical and extra-tropical circulation patterns and hydroclimate regimes, linkages that may explain the coherent regional climate shifts indicated by proxy records from across the planet. The findings provide new perspectives on the nature and possible causes of the MCA-a remarkable, yet incompletely understood episode of Late Holocene climatic change.

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“…Usually the teleconnection can be separated into the extratropical responses of the ENSO mode [1][2][3][4][5][6][7][8][9][10], the extratropical responses of monsoon mode [11][12][13][14][15][16][17][18][19], and the downstream responses to the upstream wave sources [17][18][19][20]. The Chinese winter ice storms in 2008 and the worst South China drought in 2010 may also result from local teleconnection responses to the tropical or high latitude anomalies.…”

mentioning

confidence: 99%

A semi-analytical model for the propagation of Rossby waves in slowly varying flow

et al. 2011

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Instead of using complicated general circulation models (GCMs), a simple semi-analytical model based on ray theory has been used to study energy evolution and ray path of Rossby waves in slowly varying mean flows. Our model yields similar results to those calculated from barotropic models, and also provides a chance to study Rossby waves in the slowly varying flows with both vertical and meridional shears. The model results show that upward Rossby waves can only grow in westerlies, and decay when further ascend. The baroclinic Rossky waves are restrained by the β effect in lower latitude. In the westerly jet with meridional and vertical shears, the barotropic Rossby waves originated from south of the westerly jet, and these can grow while propagating upper-northward. The baroclinic Rossby waves originated from north of the westerly jet and can grow while propagating upward and southward. Such a semi-analytical model provides a simple forecasting tool to allow study of the local weather anomalies to the heating/topography forcing associated with the global warming. In fact, it is usually Rossby waves that transport energy in global teleconnection [7,20,21]. In sub-equatorial regions, Rossby waves can propagate in the westerly jet [13,20,22]. Such Rossby wave sources may come from tropical heating coupled with mean vertical shear [23], or higher-latitude topography [24].To understand global teleconnection, it is necessary to study the growth and ray path of Rossby waves under mean flow conditions. This allows prediction of the local weather or climate based on the pre-existent mean flows and wave sources. Earlier theories of Rossby waves identified the theoretical instability criteria [21,[25][26][27][28][29]: (a) consistent with the results of Hoskins and Karoly [7], "great circle" propagation was simulated in a uniform westerly; (b) the "guided" Rossby waves (l/k > 0) develop on the south of the westerly jet, where ∂U/∂y > 0, and the "trailing" Rossby waves (l/k > 0) develop on the north side of the westerly jet, where ∂U/∂y < 0 [21]; (c) in positive (∂U/∂y > 0) sheared mean flow, northward Rossby waves turn back at a turning point, while the southward Rossby waves approach the critical level directly [30,31]; (d) the divergent effect is necessary for the prop-

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Twentieth century North Atlantic climate change. Part II: Understanding the effect of Indian Ocean warming

Cited by 236 publications

References 26 publications

Tropical origins for recent and future Northern Hemisphere climate change

Tropical origins for recent and future Northern Hemisphere climate change

Support for global climate reorganization during the “Medieval Climate Anomaly”

A semi-analytical model for the propagation of Rossby waves in slowly varying flow

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