The influence of volcanic eruptions on the climate of tropical South America during the last millennium in an isotope-enabled general circulation model
Currently, little is known on how volcanic eruptions impact large-scale climate phenomena such as South American paleo-Intertropical Convergence Zone (ITCZ) position and summer monsoon behavior. In this paper, an analysis of observations and model simulations is employed to assess the influence of l...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2016-04-01
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| Series: | Climate of the Past |
| Online Access: | http://www.clim-past.net/12/961/2016/cp-12-961-2016.pdf |
| _version_ | 1819069601738129408 |
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| author | C. M. Colose A. N. LeGrande M. Vuille |
| author_facet | C. M. Colose A. N. LeGrande M. Vuille |
| author_sort | C. M. Colose |
| collection | DOAJ |
| description | Currently, little is known on how volcanic eruptions impact large-scale
climate phenomena such as South American paleo-Intertropical Convergence Zone (ITCZ) position and summer
monsoon behavior. In this paper, an analysis of observations and model
simulations is employed to assess the influence of large volcanic eruptions
on the climate of tropical South America. This problem is first considered
for historically recent volcanic episodes for which more observations are
available but where fewer events exist and the confounding effects of El Niño–Southern
Oscillation (ENSO) lead to inconclusive interpretation of the impact of volcanic eruptions at
the continental scale. Therefore, we also examine a greater number of
reconstructed volcanic events for the period 850 CE to present that are
incorporated into the NASA GISS ModelE2-R simulation of the last millennium.
<br><br>
An advantage of this model is its ability to explicitly track water
isotopologues throughout the hydrologic cycle and simulating the isotopic
imprint following a large eruption. This effectively removes a degree of
uncertainty associated with error-prone conversion of isotopic signals into
climate variables, and allows for a direct comparison between GISS
simulations and paleoclimate proxy records.
<br><br>
Our analysis reveals that both precipitation and oxygen isotope variability
respond with a distinct seasonal and spatial structure across tropical South
America following an eruption. During austral winter, the heavy oxygen
isotope in precipitation is enriched, likely due to reduced moisture
convergence in the ITCZ domain and reduced rainfall over northern South
America. During austral summer, however, more negative values of the
precipitation isotopic composition are simulated over Amazonia, despite
reductions in rainfall, suggesting that the isotopic response is not a
simple function of the "amount effect". During the South American monsoon
season, the amplitude of the temperature response to volcanic forcing is
larger than the rather weak and spatially less coherent precipitation
signal, complicating the isotopic response to changes in the hydrologic
cycle. |
| first_indexed | 2024-12-21T16:52:38Z |
| format | Article |
| id | doaj.art-6e5d3fdb0d6a4544a3fa959768d6608e |
| institution | Directory Open Access Journal |
| issn | 1814-9324 1814-9332 |
| language | English |
| last_indexed | 2024-12-21T16:52:38Z |
| publishDate | 2016-04-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Climate of the Past |
| spelling | doaj.art-6e5d3fdb0d6a4544a3fa959768d6608e2022-12-21T18:56:50ZengCopernicus PublicationsClimate of the Past1814-93241814-93322016-04-0112496197910.5194/cp-12-961-2016The influence of volcanic eruptions on the climate of tropical South America during the last millennium in an isotope-enabled general circulation modelC. M. Colose0A. N. LeGrande1M. Vuille2Dept. of Atmospheric & Environmental Sciences, University at Albany, SUNY, Albany, NY 12222, USANASA Goddard Institute for Space Studies, New York, NY 10025, USADept. of Atmospheric & Environmental Sciences, University at Albany, SUNY, Albany, NY 12222, USACurrently, little is known on how volcanic eruptions impact large-scale climate phenomena such as South American paleo-Intertropical Convergence Zone (ITCZ) position and summer monsoon behavior. In this paper, an analysis of observations and model simulations is employed to assess the influence of large volcanic eruptions on the climate of tropical South America. This problem is first considered for historically recent volcanic episodes for which more observations are available but where fewer events exist and the confounding effects of El Niño–Southern Oscillation (ENSO) lead to inconclusive interpretation of the impact of volcanic eruptions at the continental scale. Therefore, we also examine a greater number of reconstructed volcanic events for the period 850 CE to present that are incorporated into the NASA GISS ModelE2-R simulation of the last millennium. <br><br> An advantage of this model is its ability to explicitly track water isotopologues throughout the hydrologic cycle and simulating the isotopic imprint following a large eruption. This effectively removes a degree of uncertainty associated with error-prone conversion of isotopic signals into climate variables, and allows for a direct comparison between GISS simulations and paleoclimate proxy records. <br><br> Our analysis reveals that both precipitation and oxygen isotope variability respond with a distinct seasonal and spatial structure across tropical South America following an eruption. During austral winter, the heavy oxygen isotope in precipitation is enriched, likely due to reduced moisture convergence in the ITCZ domain and reduced rainfall over northern South America. During austral summer, however, more negative values of the precipitation isotopic composition are simulated over Amazonia, despite reductions in rainfall, suggesting that the isotopic response is not a simple function of the "amount effect". During the South American monsoon season, the amplitude of the temperature response to volcanic forcing is larger than the rather weak and spatially less coherent precipitation signal, complicating the isotopic response to changes in the hydrologic cycle.http://www.clim-past.net/12/961/2016/cp-12-961-2016.pdf |
| spellingShingle | C. M. Colose A. N. LeGrande M. Vuille The influence of volcanic eruptions on the climate of tropical South America during the last millennium in an isotope-enabled general circulation model Climate of the Past |
| title | The influence of volcanic eruptions on the climate of tropical South America during the last millennium in an isotope-enabled general circulation model |
| title_full | The influence of volcanic eruptions on the climate of tropical South America during the last millennium in an isotope-enabled general circulation model |
| title_fullStr | The influence of volcanic eruptions on the climate of tropical South America during the last millennium in an isotope-enabled general circulation model |
| title_full_unstemmed | The influence of volcanic eruptions on the climate of tropical South America during the last millennium in an isotope-enabled general circulation model |
| title_short | The influence of volcanic eruptions on the climate of tropical South America during the last millennium in an isotope-enabled general circulation model |
| title_sort | influence of volcanic eruptions on the climate of tropical south america during the last millennium in an isotope enabled general circulation model |
| url | http://www.clim-past.net/12/961/2016/cp-12-961-2016.pdf |
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