Simulated sensitivity of the tropical climate to extratropical thermal forcing: tropical SSTs and African land surface

Talento, Stefanie; Barreiro, Marcelo

doi:10.1007/s00382-015-2890-9

Cited by 8 publications

(12 citation statements)

References 33 publications

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“…This may indicate a more southerly mean position of the ITCZ. Factors that could influence the mean position of the ITCZ include changes in insolation (e.g., Haug et al, 2001;Wang et al, 2005;Cruz et al, 2005;Fleitmann et al, 2003Fleitmann et al, , 2007Schefuß et al, 2005;Suziki, 2011;Kutzbach and Liu, 1997;Partridge et al, 1997;Verschuren et al, 2009;Voarintsoa et al, 2017a) and difference in temperature between the two hemispheres (e.g., Chiang and Bitz, 2005;Broccoli et al, 2006;Chiang and Friedman, 2012;Kang et al, 2008;McGee et al, 2014;Talento and Barreiro, 2016). In contrast, the depositional hiatuses during the MMHI could suggest overall drier conditions, and thus a northward migration of the mean ITCZ.…”

Section: Holocene Climate In Nw Madagascar: Implications For Itcz Dynmentioning

confidence: 99%

“…This uneven distribution of data hinders our understanding of the spatiotemporal characteristics of Holocene climate change and the forcings involved. For example, some forcings would have influenced the behavior of the Intertropical Convergence Zone (ITCZ) as well as monsoonal responses in low-to midlatitude regions (e.g., Wanner et al, 2015;Talento and Barreiro, 2016). In fact, Madagascar is ideally located to provide data on SH Holocene climate changes because of its location (St-Ours, 1959;Middleton and Middleton, 2002), with approximate location for sample collection (red dots).…”

Section: Introductionmentioning

confidence: 99%

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Three distinct Holocene intervals of stalagmite deposition and nondeposition revealed in NW Madagascar, and their paleoclimate implications

et al. 2017

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Abstract. Petrographic features, mineralogy, and stable isotopes from two stalagmites, ANJB-2 and MAJ-5, respectively from Anjohibe and Anjokipoty caves, allow distinction of three intervals of the Holocene in NW Madagascar. The Malagasy early Holocene (between ca. 9.8 and 7.8 ka) and late Holocene (after ca. 1.6 ka) intervals (MEHI and MLHI, respectively) record evidence of stalagmite deposition. The Malagasy middle Holocene interval (MMHI, between ca. 7.8 and 1.6 ka) is marked by a depositional hiatus of ca. 6500 years.Deposition of these stalagmites indicates that the two caves were sufficiently supplied with water to allow stalagmite formation. This suggests that the MEHI and MLHI intervals may have been comparatively wet in NW Madagascar. In contrast, the long-term depositional hiatus during the MMHI implies it was relatively drier than the MEHI and the MLHI.The alternating wet-dry-wet conditions during the Holocene may have been linked to the long-term migrations of the Intertropical Convergence Zone (ITCZ). When the ITCZ's mean position is farther south, NW Madagascar experiences wetter conditions, such as during the MEHI and MLHI, and when it moves north, NW Madagascar climate becomes drier, such as during the MMHI. A similar wetdry-wet succession during the Holocene has been reported in neighboring locations, such as southeastern Africa. Beyond these three subdivisions, the records also suggest wet conditions around the cold 8.2 ka event, suggesting a causal relationship. However, additional Southern Hemisphere highresolution data will be needed to confirm this.

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Section: Holocene Climate In Nw Madagascar: Implications For Itcz Dynmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Three distinct Holocene intervals of stalagmite deposition and nondeposition revealed in NW Madagascar, and their paleoclimate implications

et al. 2017

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“…4(a,b). Therefore, in the relative change of that have identified a northward shift of ITCZ (Talento and Barreiro, 2016;Yoshimori and Broccoli, 2008;Kang et al, 2009;Frierson and Hwang, 2012;Schneider et al, 2014). Regarding the red areas in the north Atlantic, in the north Pacific and in the south Pacific, they are consistent with an increase in the occurrence of fronts which cause large daily fluctuations of temperature and thus an increase of Hilbert frequency.…”

Section: Analysis Of Frequency Variationsmentioning

confidence: 58%

Quantifying interdecadal changes in large-scale patterns of surface air temperature variability

Zappalà

Barreiro

Masoller

2017

Preprint

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Abstract. We study daily surface air temperature (SAT) reanalysis in a grid over the Earth surface and identify and quantify changes in SAT variability patterns during the period 1979-2016. By analyzing Hilbert amplitude and frequency we identify the regions where relative variations are most pronounced (larger than ±50% for the amplitude and ±100% for the frequency).Amplitude variations are interpreted as due to changes in precipitation or ice melting; frequency variations, to a northward shift of the inter-tropical convergence zone (ITCZ) and a widening of the rainfall band in the western Pacific Ocean. The ITCZ 5 is the ascending branch of the Hadley cell and thus, by affecting the tropical atmospheric circulation, ITCZ migration has far reaching climatic consequences. As the methodology proposed here can be applied to many other geophysical time series, our work will stimulate new research that will advance the understanding of climate change impacts.Copyright statement.

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“…This pattern is similar to the one used in Kang et al, (2008) and in Talento and Barreiro (2016) and it is intended to represent the asymmetric temperature changes associated with glacial-interglacial and millennial-scale climate variability as well as the .asymmetric SST pattern characteristic of the global warming trend. The forcing pattern is superposed to a background state and is obtained as explained in Talento and Barreiro (2016).…”

Section: Experimental Designmentioning

confidence: 99%

“…In particular, Talento and Barreiro (2016) change, then the ITCZ response strongly weakens although it is not negligible, in particular, over the Atlantic Ocean and Africa. If, in addition, the land surface temperature over Africa is maintained fixed the ITCZ response completely vanishes, indicating that the ITCZ response to the extratropical forcing is not possible just trough purely atmospheric processes, but needs the involvement of either the tropical SST or the continental surface temperatures.…”

Section: Introductionmentioning

confidence: 99%

Sensitivity of the tropical climate to an interhemispheric thermal gradient: the role of tropical ocean dynamics

Talento¹,

Barreiro²

2017

Preprint

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Abstract. This study aims to determine the role of the tropical ocean dynamics in the response of the climate to an extratropical thermal forcing. We analyse and compare the outcomes of coupling an atmospheric general circulation model (AGCM) with two ocean models of different complexity. In the first configuration the AGCM is coupled with a slab ocean model while in the second a Reduced Gravity Ocean (RGO) model is additionally coupled in the tropical region. We find that the imposition of an extratropical thermal forcing (warming in the Northern Hemisphere and cooling in the SouthernHemisphere with zero global mean) produces, in terms of annual means, a weaker response when the RGO is coupled, thus indicating that the tropical ocean dynamics opposes the incoming remote signal. On the other hand, while the slab ocean coupling does not produce significant changes to the equatorial Pacific sea surface temperature (SST) seasonal cycle, the RGO configuration generates a strong warming in the centre-east of the basin from April to August balanced by a cooling during the rest of the year, strengthening the seasonal cycle in the eastern portion of the basin. We hypothesize that such changes are possible via the dynamical effect that zonal wind stress has on the thermocline depth. We also find that the imposed extratropical pattern affects El Niño Southern Oscillation, weakening its amplitude and low-frequency behaviour.

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Simulated sensitivity of the tropical climate to extratropical thermal forcing: tropical SSTs and African land surface

Cited by 8 publications

References 33 publications

Three distinct Holocene intervals of stalagmite deposition and nondeposition revealed in NW Madagascar, and their paleoclimate implications

Three distinct Holocene intervals of stalagmite deposition and nondeposition revealed in NW Madagascar, and their paleoclimate implications

Quantifying interdecadal changes in large-scale patterns of surface air temperature variability

Sensitivity of the tropical climate to an interhemispheric thermal gradient: the role of tropical ocean dynamics

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