B-WP1 - ALARM-II: Alert for LARge volcanic eruptions in Medium term climate prediction II

Project aims

Including volcanic forcing in the MiKlip prediction system has increased the prediction skill for global surface temperature (Timmreck et al., 2016). However, the regional impacts of volcanic forcing in particular on Northern Hemisphere (NH) winter climate which are controlled largely by dynamical changes are neither fully understood nor well represented in the current prediction system. ALARM-II will therefore explore and improve the representation of the climate response to aerosol perturbations caused by volcanic eruptions in the MiKlip prediction system, in order to prepare for future events and be able to forecast their effects immediately after a potential future eruption.

Project structure

ALARM II consists of three workpackages and is coordinated by Dr. Claudia Timmreck (MPI-M). Dr. Hauke Schmidt (MPI-M) and Prof. Dr. Kirstin Krüger (UiO), as an external partner, contribute to the project.

Tasks of the projects

  1. ALARM-II studies all seasons but focusses on NH winter climate for which the highest  regional uncertainty in mid-term climate prediction for Europe exists after a large volcanic eruption. NH winter climate responses to external forcing presumably depend on the preconditioning of the polar vortex and the resolution of the prediction system.
  2. ALARM-II investigates if seasonal and decadal predictions after a large volcanic eruption can be improved if volcanically induced ozone changes are taken into account.
  3. The Coupled Model Inter Comparison Phase 6 (CMIP6) experiments investigate the impact of future volcanic eruptions on seasonal and decadal predictions. ALARM-II plays a leading role in the planning,analysis and interpretation of these building on experience gained in MiKlip.

Deliverables

  • Recommendation regarding the applied model configuration for post-volcanic studies.
  • Improved understanding of the impact of model background state and variability on response to volcanic forcing.
  • Assessment of the impact of volcanically induced ozone changes on NH climate predictability.
  • Synthesis of the seasonal and decadal post-volcanic response in a multi-model framework.
  • Updated version of the MiKlip volcanic impact recipe.

Progress so far

A multilinear regression analysis of five historical runs with the MPI-ESM-HR and CMIP5 forcing shows that the MPI-ESM-HR model reacts qualitatively similar, in the middle atmosphere to natural and anthropogenic forcings, to the MPI-ESM-LR and the MPI-ESM-MR model (see, Schmidt et al., 2013). The temperature response to volcanic eruptions shows the typical pattern of a tropospheric cooling and a warming in the low to mid-latitude lower stratosphere. The meridional temperature signal from volcanic forcing is reflected in the westerly wind anomalies in large parts of the stratospheric high-latitudes. It is however difficult to interpret the difference between the model versions as the volcanic signal is masked by the high interannual variability in NH winter. The large ensemble (≥25) of the planned VolMIP Pinatubo simulations (Zanchettin et al., 2016) with the MPI-ESM in LR and HR resolutions will offer a great possibility to study the effect of an increased model resolution with an ensemble sufficiently large to get a significant response.

Figure 1: Multi-model mean of the zonal mean zonal wind anomaly in the first winter after the nine strongest tropical eruptions since 1880 (left) and after the two strongest eruptions since 1880 – Krakatau and Pinatubo (right). Stippling indicates where at least 14 of 15 models agree on the sign of the anomaly. Figure from Bittner et al. (2016).

The MPI Grand Ensemble, a 100-member ensemble of historical (1850–2005) simulations with the MPI-ESM-LR, has been analyzed with the focus on the stratospheric temperature and wind response in the 1st post volcanic NH winter (Bittner et al., 2016). Approximately 15 ensemble members are needed to get a significant (95%) response of the NH polar vortex in DJF after the Pinatubo eruption. How many ensemble members are necessary for a significant response depends on the magnitude of the anomaly and the interannual variability. Including smaller eruptions to increase the sample size does not necessarily improve the detectability of the volcanic signal. Analyzing the dynamical response to volcanic eruptions in too small ensembles might therefore lead to false conclusions. Hence, the CMIP5 models do not generally fail to capture the dynamical response to tropical volcanic eruptions (Figure 1). Large uncertainties remain in the response of the real atmosphere to volcanic eruptions due to the small number of observed events.

References:

  • Bittner, M., H. Schmidt, C. Timmreck and F. Sienz (2016) Using a large ensemble of simulations to assess the Northern Hemisphere stratospheric dynamical response to tropical volcanic eruptions and its uncertainty, Geophys. Res. Lett., 43, doi:10.1002/2016GL070587.
  • Schmidt, H., S. Rast, F. Bunzel, M. Esch, M.A. Giorgetta, S. Kinne, T. Krismer, G. Stenchikov, C. Timmreck, L. Tomassini  and M. Walz (2013). The response of the middle atmosphere to anthropogenic and natural forcing in the CMIP5 simulations with the MPI-ESM., Journal of Advances in Modeling Earth Systems (JAMES), 5, 98-116, doi: 10.1002/jame.20014.
  • Timmreck, C., H. Pohlmann, S. Illing and C. Kadow (2016). The impact of stratospheric volcanic aerosol on decadal scale predictability. Geophys. Res. Lett, 43, doi: 10.1002/2015GL067431.
  • Zanchettin, D., M. Khodri, C. Timmreck, et al. (2016). The Model Intercomparison Project on the climatic response to Volcanic forcing (VolMIP): experimental design and forcing input data, Geosci. Model Dev., 9, 2701-2719, doi:10.5194/gmd-9-2701-2016.

 

Contact

MPI for Meteorology
Dr. Claudia Timmreck (PI)
claudia.timmreck(at)nospammpimet.mpg.de
040/41173384

Dr. Hauke Schmidt
hauke.schmidt(at)nospammpimet.mpg.de
040/41173405

University of Oslo
Prof. Dr. Kirstin Krüger
kkrueger(at)nospamgeo.uio.no
+4722855811

The Model Intercomparison Project on the climatic response to Volcanic forcing (VolMIP): experimental design and forcing input data

2016 - Geosci. Model Dev., Vol. 9, pp. 2701-2719

Zanchettin, D. | M. Khodri, C. Timmreck, et al.

Easy Volcanic Aerosol (EVA v1.0): An idealized forcing generator for climate simulations

2016 - Geosci. Model Dev., Vol. 9, pp. 4049-4070

Toohey, M. | B. Stevens, H. Schmidt and C. Timmreck

Tambora 1815 as a test case for high impact volcanic eruptions: Earth system effects

2016 - WIREs Clim Change 2016

Raible, C. C. | S. Brönnimann, R. Auchmann, P. Brohan, T.L. Frölicher, H.-F. Graf, P. Jones Phil, J. Luterbacher, S. Muthers, R. Neukom, A. Robock, S. Self, A. Sudrajat, C. Timmreck, and M. Wegmann

Stratospheric aerosol—Observations, processes, and impact on climate

2016 - Rev. Geophys., 54, 278–335

Kremser, S. L. W. | Thomason, M. von Hobe, M. Hermann T. Deshler, C. Timmreck, M. Toohey, A. Stenke, F. Prata, J. Schwarz, R. Weigel, S. Fueglistaler, J.-P. Vernier, B. Luo, H. Schlager, J. Barnes, J.-C. Antuna-Marrero, D. Fairlie, M. Palm, E. Mahieu, J. Notholt, M. Rex, R. Neely, C. Bingen, A. Bourassa, J. Plane, D. Klocke, S. Carn, C. Lieven, A. James, S. Borrmann, L. Rieger, T. Trickl, C. Wilson, and B. Meland