Synopsis

VolMIP is a protocol-driven international project aiming at coordinating the activities of different Research Institutes involved in numerical climate modelling focused on a multi-model assessment of climate models' performance under strong volcanic forcing conditions.

Synopsis

VolMIP is a protocol-driven international project aiming at coordinating the activities of different Research Institutes involved in numerical climate modelling focused on a multi-model assessment of climate models' performance under strong volcanic forcing conditions.
 

VolMIP is motivated by the large uncertainties regarding the climatic responses to strong volcanic eruptions identified in CMIP5 simulations with respect to, e.g., the radiative forcing during periods of strong volcanic activity (e.g., Santer et al., 2014; Marotzke and Forster, 2015), the Northern Hemisphere's winter response (e.g.,Zambri and Robock, 2016), the precipitation response (e.g., Iles and Hegerl, 2014; Zambri et al., 2017) and the response of the oceanic thermohaline circulation (e.g., Ding et al., 2014), and by the apparent mismatch between simulated and reconstructed post-eruption surface cooling for volcanic eruptions during the last millennium (Mann et al., 2012, 2013; Anchukaitis et al., 2012; D'Arrigo et al., 2013; Schurer et al., 2013). Inter-model differences are likely related to differences in the prescribed volcanic aerosol forcing data used by different models, or variations in implementation, which create differences in the radiative forcing produced by the volcanic aerosol forcing. The use by some modeling groups of coupled aerosol modules for the CMIP6 historical experiments, with volcanic forcing thereby explicitly simulated based on estimates of SO2 emissions will increase inter-model spread in volcanic forcing.

Therefore, VolMIP fills the need for a coordinated model intercomparison with volcanic forcing - in terms of aerosols optical properties - constrained across participating models. Specifically, VolMIP will assess to what extent responses of the coupled ocean-atmosphere system to the same applied strong volcanic forcing are robustly simulated across state-of-the-art coupled climate models and identify the causes that limit robust simulated behavior, especially differences in their treatment of physical processes.

The VolMIP protocol (Zanchettin et al., 2016) entails three main sets of experiments: the first focusing on the short-term (seasonal to interannual) atmospheric response, the second focusing on the long-term (interannual to decadal) response of the coupled ocean–atmosphere system, and the third focusing on the climatic response to close successions of volcanic eruptions (so-called volcanic clusters). Experiments are further prioritized into three tiers. Careful sampling of initial climate conditions and the opportunity to consider volcanic eruptions of different strengths will allow a better understanding of the relative role of internal and externally forced climate variability during periods of strong volcanic activity, hence improving both the evaluation of climate models and our ability to accurately simulate past and future climates

 
References

Anchukaitis K, et al. (2012) Tree-rings and volcanic cooling. Nature Geoscience, 5: 836-837, doi:10.1038/ngeo1645

D'Arrigo, R., Wilson, R., & Anchukaitis, K. J. (2013) Volcanic cooling signal in tree ring temperature records for the past millennium. J. Geophys. Res. Atmosph., 118(16), 9000-9010

Ding, Y., et al. (2014) Ocean response to volcanic eruptions in Coupled Model Intercomparison Project 5 (CMIP5) simulations. J. Geophys. Res., 119, 5622-5637, doi:10.1002/2013JC009780

Iles C. and Hegerl G.C. (2014) The global precipitation response to volcanic eruptions in the CMIP5 models. Environm. Res. Lett., 9, 104012

Mann, M.E., Fuentes, J.D., Rutherford, S. (2012) Underestimation of volcanic cooling in tree-ring based reconstructions of hemispheric temperatures. Nature Geosc., doi:10.1038/ngeo1394

Marotzke, J., and Forster, P. M. (2015) Forcing, feedback and internal variability in global temperature trends. Nature, 517, 565-570. doi:10.1038/nature14117

Santer, B. D. et al. (2014) Volcanic contribution to decadal changes in tropospheric temperature. Nature Geosc., 7(3), 185-189, doi:10.1038/ngeo2098

Schurer, A., Hegerl, G.C., Mann, M., Tett, S.F.B., Phipps, S (2013) Separating forced from chaotic variability over the last millennium. J. Climate, doi:10.1175/JCLI-D-12-00826.1

Zanchettin, D., et al. (2012), Bi-decadal variability excited in the coupled ocean–atmosphere system by strong tropical volcanic eruptions. Clim. Dyn., 39:1-2, 419-444

Zanchettin, D., Khodri, M., Timmreck, C., Toohey, M., Schmidt, A., Gerber, E. P., Hegerl, G., Robock, A., Pausata, F. S. R., Ball, W. T., Bauer, S. E., Bekki, S., Dhomse, S. S., LeGrande, A. N., Mann, G. W., Marshall, L., Mills, M., Marchand, M., Niemeier, U., Poulain, V., Rozanov, E., Rubino, A., Stenke, A., Tsigaridis, K., and Tummon, F.: The Model Intercomparison Project on the climatic response to Volcanic forcing (VolMIP): experimental design and forcing input data for CMIP6, Geosci. Model Dev., 9, 2701-2719, doi:10.5194/gmd-9-2701-2016, 2016.

Zambri, B., and A. Robock, 2016: Winter warming and summer monsoon reduction after volcanic eruptions in Coupled Model Intercomparison Project 5 (CMIP5) simulations. Geophys. Res. Lett., 43, 10,920-10,928, doi:10.1002/2016GL070460.

Zambri, B., A. N. LeGrande, A. Robock, and J. Slawinska, 2017: Northern Hemisphere winter warming and summer monsoon reduction after volcanic eruptions over the last millennium. J. Geophys. Res. Atmos., 122, 7971-7989, doi:10.1002/2017JD026728.
 

Published on  15.12.2017