Experiment title:
Testing the effect of Indo-Pacific SST variability on mid-latitude droughts
Summary:
Using ACCESS-ESM1.5 to test the effects of increasing or decreasing SST variability in the Indian and Pacific oceans affects the occurrence, length, and/or intensity of mid-latitude droughts.
Scientific motivation:
Palaeoclimate evidence suggests that in the first half of the past millennium, decreased ENSO and IOD variability co-occurred with increased megadrought occurrence across the mid-latitudes. This suggests a relationship between Indo-Pacific SST variability and mid-latitude hydroclimate variability.
We are testing this hypothesis by running ACCESS-ESM1.5 in pacemaker format where the magnitude of tropical Indian and Pacific Ocean SST variability is altered using 4 forcing scenarios: 60% reduction, 30% reduction, 30% enhancement, 60% enhancement. We have created SST forcing files by taking the 500 years from the existing 1000-year-long control run, altering the magnitude of SST variability, and using these as SST restoring files (with all other model components allowed to evolve freely).
In the first instance we will alter both Indian and Pacific ocean SST variability. In later experiments we will alter SST variability in the individual ocean basins, to aid in diagnosing the results.
Design and details
Experiment Name: m60/m30/p30/p60 (for Indo-Pacific SST variability plus/minus 60/30%)
People: @georgyfalster @spencerwong + Nerilie Abram
Model: ACCESS-ESM1.5
Configuration: release-preindustrial+concentrations
Link to experiment repo: GitHub - ACCESS-Community-Hub/access-esm1.5-sst-perturbation-indo-pacific: Magnitude of tropical Indian and Pacific ocean SST variability altered relative to ACCESS-ESM1.5 preindustrial control
Initial conditions: restart files for the 4 experiments in /scratch/zr75/gf6872/access-esm/archive/
Run plan: 500 model years for each forcing scenario = 2000 model years total
Simulation details: for each model year, SST variability is prescribed according to the experiment outlined above. All other fields evolve freely.
Total KSUs required: 2000 model years x 1.1 kSU per year = 2200 kSU
Time required: 4 parallel runs of 500 years @ 16 years/day = 32 days
Total storage required: ~3 TB
Storage lifetime: approx. 12 months - for analysis, write-up and review
Long term data plan: a very reduced set of relevant outputs to be permanently archived in a suitable repository
Outputs: ‘spin-up’ preset output profiles as per Preset output profiles for ESM1.5 - #2 by spencerwong
Restarts: Currently saving every 10 years
Related articles: TBA
Analysis:
[in-depth analysis to be provided on completion of simulations]
Example Nino 3.4 SST anomaly output from the first ~300-400 model years of each experiment
Example south-eastern Australian precipitation anomalies from the first ~300-400 model years of each experiment
Conclusion:
TBA
