Diverse hydrological responses to volcanic eruptions in CMIP5 multi-models
Abstract
It is well understood that explosive volcanic eruptions induce global-scale surface cooling and drying during a few years after eruptions by reflecting solar radiation with increased stratospheric aerosols. Global climate models can simulate the overall cooling and drying responses but there remains a large inter-model spread particularly in precipitation responses. Our recent study (Paik and Min 2018) showed that large inter-model differences in hydrological responses is associated with diverse atmospheric circulation responses among models. This study further investigates causes of the inter-model uncertainty in the dynamic responses to volcanic forcing focusing on El Niño occurrence using CMIP5 models. First, we show that El Niño affects monsoon regional precipitation through altering atmospheric circulations. Most of the CMIP5 models simulate El Niño occurrence after eruptions but with a large difference in its amplitude. When removing El Niño influences from each model, precipitation responses decrease with reduced inter-model difference, representing that the diverse El Niño response among models is partly responsible for the inter-model uncertainty in precipitation responses. Secondly, we demonstrate that large inter-model uncertainties of El Niño responses are in part due to different strength of the volcanic forcing implemented among models. Different volcanic forcing based on Sato et al. (1993) and Ammann et al. (2003) data is found to bring a systematic difference in the westerly winds over the equatorial Pacific (stronger winds under stronger Ammann forcing), which largely explains different El Niño responses among models. Further, ocean initial conditions, as indicated by the warm water volume intensity before eruptions, are also found to contribute to the diverse El Niño responses among the models simulated with identical volcanic forcing. Physical mechanisms associated with different El Niño developments will also be discussed.
References Ammann, C. M., G. A. Meehl, W. M. Washington, and C. S. Zender, 2003: Geophys. Res. Lett., 30, 1657. Paik, S., and S.-K. Min, 2018: Assessing the impact of volcanic eruptions on climate extremes using CMIP5 models. J. Climate, 31, 5333-5349. Sato, M., J. E. Hansen, M. P. McCormick, and J. B. Pollack, 1993: J. Geophys. Res., 98, 22 987-22 994.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMGC13E1055P
- Keywords:
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- 0370 Volcanic effects;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 4313 Extreme events;
- NATURAL HAZARDSDE: 8408 Volcano/climate interactions;
- VOLCANOLOGYDE: 8409 Atmospheric effects;
- VOLCANOLOGY