Interannual variability of isotopic composition in water vapor over western Africa and its relationship to ENSO
This study was performed to examine the relationship between isotopic composition in near-surface vapor (δ<sup>18</sup>O<sub>v</sub>) over western Africa during the monsoon season and El Niño–Southern Oscillation (ENSO) activity using the Isotope-incorporated Global Spectral...
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doaj-76a4262dd42c42c7b7def29736c0f7082020-11-25T00:35:03ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242015-03-011563193320410.5194/acp-15-3193-2015Interannual variability of isotopic composition in water vapor over western Africa and its relationship to ENSOA. Okazaki0Y. Satoh1G. Tremoy2F. Vimeux3R. Scheepmaker4K. Yoshimura5Institute of Industrial Science, University of Tokyo, Tokyo, JapanInstitute of Industrial Science, University of Tokyo, Tokyo, JapanLaboratoire des Sciences du Climat et de l'Environnement, UMR8212, Institut Pierre Simon Laplace, CEA-CNRS-UVSQ, Gif-sur-Yvette, FranceLaboratoire des Sciences du Climat et de l'Environnement, UMR8212, Institut Pierre Simon Laplace, CEA-CNRS-UVSQ, Gif-sur-Yvette, FranceSRON Netherlands Institute for Space Research, Utrecht, the NetherlandsInstitute of Industrial Science, University of Tokyo, Tokyo, JapanThis study was performed to examine the relationship between isotopic composition in near-surface vapor (δ<sup>18</sup>O<sub>v</sub>) over western Africa during the monsoon season and El Niño–Southern Oscillation (ENSO) activity using the Isotope-incorporated Global Spectral Model. The model was evaluated using a satellite and in situ observations at daily to interannual timescales. The model provided an accurate simulation of the spatial pattern and seasonal and interannual variations of isotopic composition in column and surface vapor and precipitation over western Africa. Encouraged by this result, we conducted a simulation stretching 34 years (1979–2012) to investigate the relationship between atmospheric environment and isotopic signature on an interannual timescale. The simulation indicated that the depletion in the monsoon season does not appear every year at Niamey. The major difference between the composite fields with and without depletion was in the amount of precipitation in the upstream area of Niamey. As the interannual variation of the precipitation amount is influenced by the ENSO, we regressed the monsoon season averaged δ<sup>18</sup>O<sub>v</sub> from the model and annually averaged NINO3 index and found a statistically significant correlation (<i>R =</i> 0.56, <i>P</i> < 0.01) at Niamey. This relationship suggests that there is a possibility of reconstructing past western African monsoon activity and ENSO using climate proxies.http://www.atmos-chem-phys.net/15/3193/2015/acp-15-3193-2015.pdf |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
A. Okazaki Y. Satoh G. Tremoy F. Vimeux R. Scheepmaker K. Yoshimura |
spellingShingle |
A. Okazaki Y. Satoh G. Tremoy F. Vimeux R. Scheepmaker K. Yoshimura Interannual variability of isotopic composition in water vapor over western Africa and its relationship to ENSO Atmospheric Chemistry and Physics |
author_facet |
A. Okazaki Y. Satoh G. Tremoy F. Vimeux R. Scheepmaker K. Yoshimura |
author_sort |
A. Okazaki |
title |
Interannual variability of isotopic composition in water vapor over western Africa and its relationship to ENSO |
title_short |
Interannual variability of isotopic composition in water vapor over western Africa and its relationship to ENSO |
title_full |
Interannual variability of isotopic composition in water vapor over western Africa and its relationship to ENSO |
title_fullStr |
Interannual variability of isotopic composition in water vapor over western Africa and its relationship to ENSO |
title_full_unstemmed |
Interannual variability of isotopic composition in water vapor over western Africa and its relationship to ENSO |
title_sort |
interannual variability of isotopic composition in water vapor over western africa and its relationship to enso |
publisher |
Copernicus Publications |
series |
Atmospheric Chemistry and Physics |
issn |
1680-7316 1680-7324 |
publishDate |
2015-03-01 |
description |
This study was performed to examine the relationship between
isotopic composition in near-surface vapor (δ<sup>18</sup>O<sub>v</sub>) over
western Africa during the monsoon season and El Niño–Southern
Oscillation (ENSO) activity using the Isotope-incorporated Global Spectral
Model. The model was evaluated using a satellite and in situ observations at
daily to interannual timescales. The model provided an accurate simulation of
the spatial pattern and seasonal and interannual variations of isotopic
composition in column and surface vapor and precipitation over western
Africa. Encouraged by this result, we conducted a simulation stretching 34
years (1979–2012) to investigate the relationship between atmospheric
environment and isotopic signature on an interannual timescale. The
simulation indicated that the depletion in the monsoon season does not appear
every year at Niamey. The major difference between the composite fields with
and without depletion was in the amount of precipitation in the upstream area
of Niamey. As the interannual variation of the precipitation amount is
influenced by the ENSO, we regressed the monsoon season averaged
δ<sup>18</sup>O<sub>v</sub> from the model and annually averaged
NINO3 index and
found a statistically significant correlation (<i>R =</i> 0.56,
<i>P</i> < 0.01) at Niamey. This relationship suggests that there is a
possibility of reconstructing past western African monsoon activity and ENSO
using climate proxies. |
url |
http://www.atmos-chem-phys.net/15/3193/2015/acp-15-3193-2015.pdf |
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