Paleo-ENSO revisited: Ecuadorian Lake Pallcacocha does not reveal a conclusive El Niño signal

Tobias Schneider , Henrietta Hampel , Pablo V. Mosquera , Wojciech Tylmann , Jeremy Grosjean

Abstract

Information about decadal to millennial variability of El Niño Southern Oscillation (ENSO) is fundamental for the assessment of ENSO responses to natural and anthropogenic forcings. Despite a growing number of ENSO reconstructions, the overall picture of Holocene ENSO variability is inconsistent. Here, we revisit the iconic Holocene ENSO sediment record of Lake Pallcacocha, Ecuador (Rodbell et al., 1999). We asked: (i) How coherent are the records of clastic layers (flood layers) in the sediments of Lake Pallcacocha and adjacent Lake Fondococha? (ii) What are the synoptic-scale atmospheric conditions that lead to intense precipitation and, potentially, to alluvial activity promoting the deposition of clastic layers in these lakes? (iii) Is intense precipitation in this area associated with El Niño, or not? We analyzed clastic layers in Late-Holocene sediments from multiple cores in Lakes Pallcacocha and Fondococha from Cajas National Park, southern Ecuadorian Andes. Additionally, we investigated precipitation data from 13 nearby meteorological stations to test if intense precipitation (percentiles P0.95, P0.99, P0.995) is predominantly related to El Niño conditions or not (based on 15 different ENSO indices). Our results show that the absolute flood frequencies (clastic layers per 100 years) differ substantially from lake to lake. This indicates that the frequency of clastic layers reflects different sensitivities (thresholds of precipitation) of the catchments to alluvial activity. 210Pb ages suggest that neither the 1982/83 nor the 1997/98 very strong El Niños produced clastic layers comparable to those found in the late Holocene. Daily precipitation records from meteorological stations close to Lake Pallcacocha including a high-altitude station from the western slope of the Andes did not show unusually high precipitation during the super El Niño 2015/16. We further find that intense precipitation in this area occurs at roughly equal probability under El Niño, La Niña and neutral conditions. Although the spectral properties of the late Holocene clastic layers in Lake Pallcacocha fall into the typical ENSO frequency band, we do not find evidence in the recent sediments and the meteorological data that would support a diagnostic link between alluvial activity in Lake Pallcacocha and strong El Niño events. Our data do not support the idea that the (late) Holocene flood record of Lake Pallcacocha is a conclusive paleo-El Niño record
Author Tobias Schneider
Tobias Schneider,,
-
, Henrietta Hampel
Henrietta Hampel,,
-
, Pablo V. Mosquera
Pablo V. Mosquera,,
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, Wojciech Tylmann KGiGCz
Wojciech Tylmann,,
- Department of Geomorphology and Quarternary Geology
, Jeremy Grosjean
Jeremy Grosjean,,
-
Journal seriesGlobal and Planetary Change, ISSN 0921-8181
Issue year2018
Vol168
Pages54-66
Publication size in sheets0.6
Keywords in EnglishHolocene, Andes, paleolimnology, Limnogeology, ENSO, climate change
DOIDOI:10.1016/j.gloplacha.2018.06.004
URL https://doi.org/10.1016/j.gloplacha.2018.06.004
Languageen angielski
Score (nominal)45
ScoreMinisterial score = 40.0, 27-06-2018, ArticleFromJournal
Ministerial score (2013-2016) = 45.0, 27-06-2018, ArticleFromJournal
Publication indicators WoS Impact Factor: 2016 = 3.915 (2) - 2016=4.28 (5)
Citation count*0 (2018-07-18)
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