Decadal Variability of the Tropical Atlantic Ocean Surface Temperature in Shipboard Measurements and in a Global Ocean-Atmosphere Model

Mehta, Vikram M.; Delworth, Thomas L.

doi:10.1175/1520-0442(1995)008<0172:dvotta>2.0.co;2

Cited by 108 publications

(73 citation statements)

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“…Ice core analysis suggests a shorter AMO quasi-periodicity (about 20 years) during the Little Ice Age and a longer periodicity in the Medieval Warm Period (Chylek et al 2012). Atmosphere-Ocean coupled climate models (Metha and Delworth 1995;Griffies and Bryan 1997;Delworth and Knutson 2000;Dong and Sutton 2001;Wei and Lohmann 2012;Mahajan et al 2011;Henriksson et al 2012;Yang et al 2013;Escudier et al 2013;Zanchettin et al 2013) as well as simplified conceptual ocean models (Frankcombe and Djikstra 2011), or statistical harmonic models (Humlum et al 2011;Mazzarella and Scafetta 2012;Scafetta 2012) suggest a future persistent AMO like multi-decadal oscillation. Based on this evidence of the past behavior we expect the AMO to retain its cyclic behavior during the twenty-first century with a cycle length of 60-70 years.…”

Section: Discussionmentioning

confidence: 97%

Imprint of the Atlantic multi-decadal oscillation and Pacific decadal oscillation on southwestern US climate: past, present, and future

et al. 2013

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The surface air temperature increase in the southwestern United States was much larger during the last few decades than the increase in the global mean. While the global temperature increased by about 0.5°C from 1975 to 2000, the southwestern US temperature increased by about 2°C. If such an enhanced warming persisted for the next few decades, the southwestern US would suffer devastating consequences. To identify major drivers of southwestern climate change we perform a multiple-linear regression of the past 100 years of the southwestern US temperature and precipitation. We find that in the early twentieth century the warming was dominated by a positive phase of the Atlantic multi-decadal oscillation (AMO) with minor contributions from increasing solar irradiance and concentration of greenhouse gases. The late twentieth century warming was about equally influenced by increasing concentration of atmospheric greenhouse gases (GHGs) and a positive phase of the AMO. The current southwestern US drought is associated with a near maximum AMO index occurring nearly simultaneously with a minimum in the Pacific decadal oscillation (PDO) index. A similar situation occurred in mid-1950s when precipitation reached its minimum within the instrumental records. If future atmospheric concentrations of GHGs increase according to the IPCC scenarios (Solomon et al. in Climate change 2007: working group I. The Physical Science Basis, Cambridge, 996 pp, 2007), climate models project a fast rate of southwestern warming accompanied by devastating droughts (Seager et al. in Science 316:1181-1184, 2007 Williams et al. in Nat Clim Chang, 2012). However, the current climate models have not been able to predict the behavior of the AMO and PDO indices. The regression model does support the climate models (CMIP3 and CMIP5 AOGCMs) projections of a much warmer and drier southwestern US only if the AMO changes its 1,000 years cyclic behavior and instead continues to rise close to its 1975-2000 rate. If the AMO continues its quasi-cyclic behavior the US SW temperature should remain stable and the precipitation should significantly increase during the next few decades.

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Section: Discussionmentioning

confidence: 97%

Imprint of the Atlantic multi-decadal oscillation and Pacific decadal oscillation on southwestern US climate: past, present, and future

et al. 2013

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“…It is characterized by a north-south interhemispheric gradient of SST anomalies. It exhibits interannual to decadal time scales (Moura and Shukla, 1981;Servain, 1991;Mehta and Delworth, 1995; Rajagopalan et al, 1998) and has been referred to as the "dipole mode" During typical dipole episodes (i.e. the simultaneous manifestation of the out-of-phase relationship in the tropical Atlantic SST), anomalies appear with opposite signs on either side of the Intertropical Convergence Zone (ITCZ).…”

Section: Introductionmentioning

confidence: 99%

Relationship between the equatorial and meridional modes of climatic variability in the tropical Atlantic

Servain¹,

Wainer²,

McCreary³

et al. 1999

Geophysical Research Letters

162

124

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Abstract. The tropical Atlantic Ocean exhibits two primary modes of interannual climate variability: an equatorial mode analogous to, but weaker than, the Pacific E1 Nifio phenomenon, and a meridional mode that does not have a Pacific counterpart. The equatorial mode is responsible for warm (and cold) sea surface temperature (SST) events, mainly in the Gulf of Guinea, and is identifiable by abnormal changes in the equatorial thermocline slope resulting from zonal-wind anomalies in the western tropical Atlantic. The meridional mode is characterized by a noah-south interhemispheric gradient of SST anomalies. Here it is shown, using observed surface and subsurface oceanic temperatures, that the meridional mode is linked to the equatorial mode, at both decadal and short-interannual (1-2 years) time scales. Both modes involve noah-south displacements of the ITCZ, as in the annual response.

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“…This mode involves a low-frequency oscillation of SST gradient across the equator, with spatially coherent SST patterns in the subtropics of either hemisphere. Empirical studies indicate that the dipole-like SST variability appears to have a pronounced spectral peak at a period of approximately 12 years, and accounts for about 20% of the total yearly-averaged SST variance in the tropical Atlantic Ocean [Mehta and Delworth, 1995 That an Atlantic dipole variability may be quasi-cyclical due to a regional scale coupled ocean-atmosphere instability occurring at low frequencies raises the possibility that the slowly evolving SST dipole may be predicted by models involving only processes in the tropical Atlantic basin. The predictability follows simply from the fact that a cycle is sequential, and therefore one part of the cycle must follow another.…”

Section: Introductionmentioning

confidence: 99%

Prediction of tropical Atlantic sea surface temperature

Chang

Luo

Hong

et al. 1998

Geophysical Research Letters

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Abstract. The variability of sea surface temperature (SST) in the tropical Atlantic Ocean has a significant influence on the rainfall over Northeast Brazil and the Sahel. The predictability of the SST fluctuations in this region has, therefore, been a central concem for Atlantic climate studies. Here we show that the north tropical Atlantic SST variability has significant predictability using statistical models at short lead times (< 1 year), and using a coupled ocean-atmosphere model for longer-range forecasts (lead times up to about 3 years). While the remote influence of the IndoPacific, primarily due to E1 Nifio, has been fbund to enhance the predictability of SST in the north Atlantic at short lead times, local ocean-atmosphere interactions dominate the predictable dynamics farther south, and at longer time scales.

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Decadal Variability of the Tropical Atlantic Ocean Surface Temperature in Shipboard Measurements and in a Global Ocean-Atmosphere Model

Cited by 108 publications

References 0 publications

Imprint of the Atlantic multi-decadal oscillation and Pacific decadal oscillation on southwestern US climate: past, present, and future

Imprint of the Atlantic multi-decadal oscillation and Pacific decadal oscillation on southwestern US climate: past, present, and future

Relationship between the equatorial and meridional modes of climatic variability in the tropical Atlantic

Prediction of tropical Atlantic sea surface temperature

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