On the Roles of Tropical and Midlatitude SSTs in Forcing Interannual to Interdecadal Variability in the Winter Northern Hemisphere Circulation

Graham, Nicholas E.; Barnett, T. P.; Wilde, R.; Ponater, M.; Schubert, Silke

doi:10.1175/1520-0442(1994)007<1416:otrota>2.0.co;2

Cited by 184 publications

(103 citation statements)

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“…How were these changes communicated? Were the effects of rapid changes in tropical Indo-Pacific SSTs transmitted across the planet via circulation changes [as seen in many model results (e.g., Lau 1985;Graham et al 1993;Hoerling et al 2001;Alexander et al 2002;Bader and Latif 2003), including the tropical warming experiments described in Sect. 3.2]?…”

Section: 2)mentioning

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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Section: 2)mentioning

confidence: 99%

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

et al. 2010

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“…Geopotential height decreases over high latitudes and increases over lower latitudes, while westerlies over the mid latitudes strengthen over the past 53 years in all seasons with respect to the associated mode. This abrupt climate change in Northern Hemisphere was also noticed by Graham (1994) and Graham et al (1994). Power spectrum analysis of the EOF1 time series shows that only the trend component reaches the 95% signi®cant level and the remaining components contribute little to the total power ( Figure 6).…”

Section: Relationship Between the Variations Of Global Zonal-mean Atmmentioning

confidence: 99%

Global warming mode of atmospheric circulation

Zhu

Wang

Zhang

2002

Atmospheric Science Letters

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Variations of global zonal-mean atmospheric circulation are studied using the National Center of Environment Prediction/National Center of Atmosphere Research (NCEP/NCAR) reanalysis data set from January 1948 to February 2001 and CCM3.6 (Community Climate Model Version 3.6) simulations for the period 1900±1999. Empirical orthogonal function (EOF) analysis indicates that variations of zonal-mean geopotential height in the tropics are usually opposite to those over the subpolar zone in both hemispheres. The ®rst mode of EOF analysis shows that height is higher than normal in the tropics when it is lower over the subpolar zone in both hemispheres with much stronger westerlies over mid latitudes in both hemispheres, and vice versa. This mode explains about 50% variance and is predominant in the whole troposphere. The time series of EOF1 has a sharp transition near about 1977 and the polarity changes from negative to positive. This mode is closely related to the variations of global mean surface air temperature. The detrended correlation coef®cient between EOF1 time series and the surface air temperature is 0.74 in the boreal winter. Furthermore, the lowest correlation coef®cient among the other three seasons, annual mean, seasonal mean and monthly mean is higher than 0.42 which indicates the fairly good relationship between this mode and the surface air temperature. This result has been veri®ed using CCM3.6 simulations.*

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“…In recent studies, the technique of EOF analysis, canonical correlation analysis (CCA), or singular value decomposition (SVD) analysis have been applied to the results of GCM experiments and observed data, with further evidence of atmospheric responses to SST forcing being reported (Kitoh, 1991a, b;Graham, 1994;Graham et al, 1994;Lau andNath, 1990, 1994;Kawamura et al, 1995a, b, and many others). All these studies have further demonstrated statistically significant atmospheric responses to SST forcing.…”

Section: Introductionmentioning

confidence: 99%

A Study of SST-forced Variability and Potential Predictability of Seasonal Mean Fields using the JMA Global Model

Sugi

Kawamura

Sato

1997

Journal of the Meteorological Society of Japan

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An ensemble climate simulation experiment has been conducted using the Japan Meteorological Agency (JMA) global model to study the SST-forced atmospheric variability and potential predictability of seasonal mean fields. The ensemble consists of three model integrations each for the same 34-year period. The three integrations use the same observed SST for the period 1955-1988 but start from different atmospheric initial states.The variance ratios of the SST-forced variability to the total variability of the seasonal mean fields are computed. The ratios are considered to represent "potential predictability" (possible maximum predictability when SST is perfectly predicted). The variance ratios of pressure fields are generally high (50-90%) in the tropics but low (less than 30%) in the extratropics, suggesting that the potential predictability of the seasonal mean fields is high in the tropics but low in the extratropics. The variance ratios of precipitation take a wide range of values within the tropics from 74% for N.E. Brazil rainfall to 31% for Indian summer monsoon rainfall, indicating large regional differences in the potential predictability of seasonal mean rainfall within the tropics. The variance ratio of globally-averaged global mean land surface air temperature is high (66%) but the ratio is low (less than 30%) for the seasonal mean local surface air temperature over most land area. This suggests that the potential predictability of local land surface air temperature is low.

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On the Roles of Tropical and Midlatitude SSTs in Forcing Interannual to Interdecadal Variability in the Winter Northern Hemisphere Circulation

Cited by 184 publications

References 0 publications

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

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

Global warming mode of atmospheric circulation

A Study of SST-forced Variability and Potential Predictability of Seasonal Mean Fields using the JMA Global Model

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