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Modelling stable water isotopes in monsoon precipitation during the previous interglacial

Sjolte, Jesper LU and Hoffmann, Georg (2014) In Quaternary Science Reviews 85. p.119-135
Abstract
Changes in the tropical hydrological cycle have been recorded world wide in speleothem records dating back more than 200,000 years for some areas. Numerous empirical and modelling studies have demonstrated a strong link between the intensity of the northern hemisphere monsoon and the precessional insolation cycle (similar to 23 ka (thousand years)). Here we present simulations of the climate conditions of the previous interglacial, the Eemian (115-130 ka BP), using a general circulation model. We focus on changes in the tropical hydrological cycle and in the monsoon in particular. The model is equipped with a module for computing the water isotopic composition of all water reservoirs represented by the model. Our analysis of the simulated... (More)
Changes in the tropical hydrological cycle have been recorded world wide in speleothem records dating back more than 200,000 years for some areas. Numerous empirical and modelling studies have demonstrated a strong link between the intensity of the northern hemisphere monsoon and the precessional insolation cycle (similar to 23 ka (thousand years)). Here we present simulations of the climate conditions of the previous interglacial, the Eemian (115-130 ka BP), using a general circulation model. We focus on changes in the tropical hydrological cycle and in the monsoon in particular. The model is equipped with a module for computing the water isotopic composition of all water reservoirs represented by the model. Our analysis of the simulated water isotope signals indicates that this key palaeo-proxy, i.e. the O-18 or Deuterium signal in precipitation, is controlled by varying factors in different tropical areas: The main control on O-18 for the Indian summer monsoon is the local precipitation amount, in accordance with the traditional interpretation, while the main control of O-18 for East Asia is downwind depletion of O-18 in vapour along the transport path. Over Africa the model simulates a strong gradient in the O-18 anomalies during the Eemian climatic optimum, with depleted values in the east and relatively enriched O-18 content in the west. This pattern is the result of a combination of the local "amount effect" and an anomalous zonal moisture transport. The influence of the SSTs anomalies on the placement of the Intertropical Convergence Zone (ITCZ) is found to be of major importance for the precipitation amount in the coastal regions of tropical South America. For the western part of South America a decrease in precipitation is seen for the Eemian climatic optimum, while an increase is seen for the eastern part. Our results underline the importance of reviewing the mechanisms causing isotopic changes in proxy records and further investigating the causes for past shifts in the ITCZ. (C) 2013 Elsevier Ltd. All rights reserved. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Monsoon, Eemian interglacial, Stable water isotopes, Modelling
in
Quaternary Science Reviews
volume
85
pages
119 - 135
publisher
Elsevier
external identifiers
  • wos:000331412200008
  • scopus:84891453089
ISSN
0277-3791
DOI
10.1016/j.quascirev.2013.12.006
project
MERGE
language
English
LU publication?
yes
id
44ebb4ad-74ac-4aac-ba46-1ab87a34474f (old id 4368456)
date added to LUP
2014-04-16 12:55:57
date last changed
2017-11-05 03:05:11
@article{44ebb4ad-74ac-4aac-ba46-1ab87a34474f,
  abstract     = {Changes in the tropical hydrological cycle have been recorded world wide in speleothem records dating back more than 200,000 years for some areas. Numerous empirical and modelling studies have demonstrated a strong link between the intensity of the northern hemisphere monsoon and the precessional insolation cycle (similar to 23 ka (thousand years)). Here we present simulations of the climate conditions of the previous interglacial, the Eemian (115-130 ka BP), using a general circulation model. We focus on changes in the tropical hydrological cycle and in the monsoon in particular. The model is equipped with a module for computing the water isotopic composition of all water reservoirs represented by the model. Our analysis of the simulated water isotope signals indicates that this key palaeo-proxy, i.e. the O-18 or Deuterium signal in precipitation, is controlled by varying factors in different tropical areas: The main control on O-18 for the Indian summer monsoon is the local precipitation amount, in accordance with the traditional interpretation, while the main control of O-18 for East Asia is downwind depletion of O-18 in vapour along the transport path. Over Africa the model simulates a strong gradient in the O-18 anomalies during the Eemian climatic optimum, with depleted values in the east and relatively enriched O-18 content in the west. This pattern is the result of a combination of the local "amount effect" and an anomalous zonal moisture transport. The influence of the SSTs anomalies on the placement of the Intertropical Convergence Zone (ITCZ) is found to be of major importance for the precipitation amount in the coastal regions of tropical South America. For the western part of South America a decrease in precipitation is seen for the Eemian climatic optimum, while an increase is seen for the eastern part. Our results underline the importance of reviewing the mechanisms causing isotopic changes in proxy records and further investigating the causes for past shifts in the ITCZ. (C) 2013 Elsevier Ltd. All rights reserved.},
  author       = {Sjolte, Jesper and Hoffmann, Georg},
  issn         = {0277-3791},
  keyword      = {Monsoon,Eemian interglacial,Stable water isotopes,Modelling},
  language     = {eng},
  pages        = {119--135},
  publisher    = {Elsevier},
  series       = {Quaternary Science Reviews},
  title        = {Modelling stable water isotopes in monsoon precipitation during the previous interglacial},
  url          = {http://dx.doi.org/10.1016/j.quascirev.2013.12.006},
  volume       = {85},
  year         = {2014},
}