Variations in tropical convection as an amplifier of global climate change at the millennial scale

Ivanochko, Tara; Ganeshram, Raja S.; Brummer, Geert-Jan A; Ganssen, G.M.; Jung, Simon; Moreton, Steven G.; Kroon, Dick

doi:10.1016/j.epsl.2005.04.002

Cited by 192 publications

(231 citation statements)

References 58 publications

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“…2; see also Supplementary Information). The data reported here, in concert with existing data 1,2,3,20,21,27 , suggest that these ITCZ migrations extended across the Pacific.…”

supporting

confidence: 55%

“…Palaeoclimate records can provide additional insights into monsoon dynamics, as the past includes larger amplitudes of climate change that may reveal more robust linkages. Previous palaeoclimate reconstructions generally agree that the Asian summer monsoon was weaker during cold phases in the Northern Hemisphere 1,2,3,9,10,11,12,13,14,15 , when the intertropical convergence zone (ITCZ) tends to move southward 16,17,18 , as it does during El Niño years 19,20,21 .…”

mentioning

confidence: 99%

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Influence of the intertropical convergence zone on the East Asian monsoon

Yancheva

Nowaczyk

Mingram

et al. 2007

Nature

805

575

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The Asian-Australian monsoon is an important component of the Earth's climate system that influences the societal and economic activity of roughly half the world's population. The past strength of the rain-bearing East Asian summer monsoon can be reconstructed with archives such as cave deposits 1, 2, 3 , but the winter monsoon has no such signature in the hydrological cycle and has thus proved difficult to reconstruct. Here we present high-resolution records of the magnetic properties and the titanium content of the sediments of Lake Huguang Maar in coastal southeast China over the past 16,000 years, which we use as proxies for the strength of the winter monsoon winds. We find evidence for stronger winter monsoon winds before the Bølling-Allerød warming, during the Younger Dryas episode and during the middle and late Holocene, when cave stalagmites suggest weaker summer monsoons 1, 2, 3 . We conclude that this anticorrelation is best explained by migrations in the intertropical convergence zone. Similar migrations of the intertropical convergence zone have been observed in Central America for the period ad 700 to 900 (refs 4-6), suggesting global climatic changes at that time. From the coincidence in timing, we suggest that these migrations in the tropical rain belt could have contributed to the declines of both the Tang dynasty in China and the Classic Maya in Central America.

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“…2; see also Supplementary Information). The data reported here, in concert with existing data 1,2,3,20,21,27 , suggest that these ITCZ migrations extended across the Pacific.…”

supporting

confidence: 55%

mentioning

confidence: 99%

Influence of the intertropical convergence zone on the East Asian monsoon

Yancheva

Nowaczyk

Mingram

et al. 2007

Nature

805

575

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“…Secondly, the Nd isotopic compositions of surface waters appear to be more easily changed by dust input (Bayon et al, 2002b;Tachikawa et al, 1999b) than those of bottom waters (Jones et al, 1994). Models of regional dustiness also suggest greater dust input to the Indian Ocean during the last glacial (Mahowald et al, 2006), which is supported by the higher aluminium content of glacial detrital sediments from Somali margin cores, interpreted as a proxy of dustiness indicating higher dust contact during glacials than interglacials (Ivanochko et al, 2005). The nearest sources of dust to SK129−CR2 are India and Persia, which have a ε Nd of −13.5 and −9, respectively (Sirocko, 1995;Stoll et al, 2007), which is more negative than Indian Ocean seawater.…”

Section: Proxy Records Of Deep Indian Ocean Paleocirculationmentioning

confidence: 58%

Indian Ocean circulation and productivity during the last glacial cycle

Piotrowski

Banakar

Scrivner

et al. 2009

Earth and Planetary Science Letters

102

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The Indian Ocean is an important part of the global thermohaline circulation system, receiving deep waters sourced from the Southern Ocean and being the location of upwelling and surface-ocean current flow, which returns warm and salty waters to the Atlantic. It is also an ideal location to reconstruct the link between thermohaline circulation and deep-water nutrient contents. No mixing occurs between major deep-water masses along flow paths within the Indian Ocean, so changes in water-mass provenance reflect changes in deep-ocean circulation while nutrient contents reflect addition and dissolution of organic matter. We present neodymium (Nd) and carbon (C) isotope records, proxies of water-mass provenance and nutrient contents, respectively, from an equatorial Indian Ocean core (SK129−CR2) spanning the last 150 kyr. The Nd isotope record shows that an increased proportion of North Atlantic Deep Water (NADW) reached the Indian Ocean during interglacials (marine isotope stages, MIS 1 and 5), and a reduced proportion during glacials (MIS 2, 4, and 6), and also that changes occurred during

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“…[3] Variability in the strength of the monsoons at centennial and millennial scales has been reported in a number of studies [e.g., Anderson et al, 2002;Charles et al, 1997;Jung et al, 2002;Gupta et al, 2003;Ivanochko et al, 2005]. Whether it is the d 18 O changes from foraminifers or banded corals, the interpretation of cooling has been that strong monsoons drive stronger upwelling and evaporative cooling in the Arabian Sea.…”

Section: Introductionmentioning

confidence: 99%

“…While the role of the IO sea surface temperatures (SSTs) in monsoon variability may not be well resolved, the response of the Arabian Sea to monsoonal variability is fairly well understood with enhanced surface cooling during strong monsoons [Shukla and Misra, 1977;Weare, 1979]. While the meteorologists presumed an increase in evaporative cooling due to strengthened Findlater Jet, oceanographers have often invoked stronger coastal and open-ocean upwelling off the Arabian Peninsula as well as the open ocean evaporative cooling as a means to explain variabilities preserved in the sediment cores and the corals [e.g., Jung et al, 2002;Altabet et al, 2002;Anderson et al, 2002;Ivanochko et al, 2005]. Vinayachandran [2004] used satellite surface chlorophyll estimates to compare weak and strong monsoon years to argue that the strength and duration of the southwesterlies are more important for the Arabian Sea cooling rather than the amount of rainfall on the Indian subcontinent.…”

Section: Introductionmentioning

confidence: 99%

Arabian Sea response to monsoon variations

2007

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[1] This study aims to quantify the impact of strong monsoons on the mixed layer heat budget in the Arabian Sea by contrasting forced ocean general circulation model simulations with composite strong and weak monsoon winds. Strong (weak) monsoons are defined as years with zonal component of the Somali Jet being greater (smaller) by more than a standard deviation of the long-term mean of the National Centers for Environmental Prediction reanalysis winds. Coastal upwelling is shown to be demonstrably stronger for strong monsoons leading to significant surface cooling, shallower thermoclines, and deeper mixed layers. A coupled ecosystem model shows that surface chlorophyll, primary, and export production are indeed higher for strong monsoons compared to weak monsoons driven by the supply of colder, nutrient-rich waters from greater than 100 m depths. The surprising result is that a strong monsoon results in stronger negative wind stress curl away from the coasts and drives Ekman pumping that results in a deeper thermocline. The weaker stratification and larger turbulent kinetic energy from the winds drive deeper mixed layers leading entrainment cooling with some contribution from the advection of colder upwelled waters from the coastal upwelling regions. Thus the strong monsoons, in fact, enhance oceanic heat uptake indicating that ocean dynamics are cooling the surface and driving the lower atmosphere which has implications for the interpretation of monsoon variability from paleorecords.

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Variations in tropical convection as an amplifier of global climate change at the millennial scale

Cited by 192 publications

References 58 publications

Influence of the intertropical convergence zone on the East Asian monsoon

Influence of the intertropical convergence zone on the East Asian monsoon

Indian Ocean circulation and productivity during the last glacial cycle

Arabian Sea response to monsoon variations

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