General overview of the SSIRC ISA-MIP experiments

ExperimentFocusNumber of specific experimentsYears
Total yearsAKnowledge-gap to be addressed
Aerosol [BG]
Stratospheric sulphur budget in volcanically quiescent conditions 1 mandatory +

2 recommended


20 year climatology to understand sources and sinks of stratospheric background aerosol, assessment of sulfate aerosol load under volcanically quiescent conditions
Aerosol Record [TAR]
Transient stratospheric aerosol properties over the period 1998 to 2012 using different volcanic emission datasets4 mandatory +3 optional experiments

recommended are 5 (see also Table 4 )

Evaluate models over the period 1998-2012 with different volcanic emission data sets

Understand drivers and mechanisms for observed stratospheric aerosol changes since 1998
Historic Eruption SO2 Emission Assessment [HErSEA]Perturbation to stratospheric aerosol from SO2 emission appropriate for 1991 Pinatubo, 1982 El Chichón,1963, AgungfoBr each (x3) eruption (Control, median and 4 (2x2) of hi/lo deep/shallow (see also Table 6)4

recom. 6

Assess how injected SO2 propagates through to radiative effects for different historical major tropical eruptions in the different interactive stratospheric aerosol models

Use stratospheric aerosol measurements to constrain uncertainties in emissions and gain new observationally-constrained volcanic forcing and surface area density datasets

Explore the relationship between volcanic emission uncertainties and volcanic forcing uncertainties
Pinatubo Emulation in Multiple Models [PoEMS]BPerturbed parameter ensemble of runs to quantify uncertainty in each model’s predictionsEach model to vary , 5 or 3 of 8 parameters (7 per parameter = 56 35 or 21) 5 per parameter280, 175 or 105 (8, 5 or 3Intercompare Pinatubo perturbation to strat- aerosol properties with full uncertainty analysis over PPE run by each model.

Quantify sensitivity of predicted Pinatubo perturbation stratospheric aerosol properties and radiative effects to uncertainties in injection settings and model processes

Quantify and intercompare sources of uncertainty in simulated Pinatubo radiative forcing for the different complexity models.

A Each model will need to include an appropriate initialization and spin-up time for each ensemble member (~3-6 years depending on model configuration).

B Note, that we are aware that some of the structural parameter variations in PoEMS will introduce some inherent drift in stratospheric aerosol properties for the background control run. However, initial test runs suggest the effect will be much larger for the volcanic perturbation. We therefore expect the effect of the contgggrol-drift on derived radiative forcings to be small. Models running tropospheric and stratospheric aerosol interactively will need to restrict the parameter scaling to the stratosphere.

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