Experiment Title 
: Role of Mean-state Atlantic SST Biases in the Trans-Basin Atlantic–Pacific Connections under Observed Atlantic SST Forcing
Summary : This experiment investigates how mean-state Atlantic SST biases in climate models affect the simulated tropical Pacific atmospheric response to tropical Atlantic SST anomalies. Many climate models fail to reproduce the observed relationship between the tropical Pacific and Atlantic. One leading hypothesis from previous studies is that systematic SST biases in the tropical oceans affect the simulated atmospheric response to Atlantic SST forcing, thereby weakening the simulated Atlantic–Pacific teleconnection. However, these studies generally are based on experiments with linear Atlantic SST trends imposed, whereas pacemaker experiments (e.g., ACCESS-CM2 Atlantic pacemaker experiments) with monthly varying SST anomalies imposed produce markedly different Atlantic precipitation responses. We expect these Atlantic precipitation response differences to influence the simulated connections between the tropical Atlantic and Pacific. Further to this, the precipitation discrepancy between simulations forced with Atlantic SST trends and monthly varying Atlantic SSTs may result from the nonlinear precipitation response and therefore needs to be investigated. To address this question, we propose conducting two sets of AGCM experiments imposing observed Atlantic SST anomalies on two background climatology: the observed SST climatology and the CMIP6 multi-model mean SST climatology.
Scientific motivation: The experiment aims to investigate how nonlinearity of precipitation under monthly-varying SST anomalies influences the atmospheric responses over tropical Pacific to tropical Atlantic SST anomalies, and whether the role of mean-state Atlantic SST biases still hold under more realistic monthly-varying SST forcing. The observed SST climatology is based on: /g/data/access/TIDS/CMIP6_ANCIL/data/ancils/n96e/timeseries_1870-2016/SstSeaIce; and the modeled SST climatology is based on outputs from 40 CMIP6 models.
Two groups of experiments (5 members each) are designed as follows:
Group 1 (observed climatology):
Observed SST climatology (1992–2011) + observed tropical Atlantic SST anomalies (1992–2011).
Group 2 (modeled climatology):
CMIP6 multi-model mean SST climatology (1992–2011) + observed tropical Atlantic SST anomalies (1992–2011).
This setup allows us to isolate the role of the Atlantic SST model biases in affecting the Pacific atmospheric response to Atlantic SST forcing.
Experiment Name : Role of Mean-state Atlantic SST Biases in the Trans-Basin Atlantic–Pacific Connections under Observed Atlantic SST Forcing
People : Hao Wang and Shayne McGregor
Model: ACCESS-CM2 atmospheric model (UM 10.6)
Configuration: Atmosphere only (suite cz934)
Initial conditions: /g/data/access/access-cm2/cmip6_restarts/bi889/restart/atm/bi889a.da09500101_00
Run plan: Forcing:
Observed SST climatology (1992–2011) or CMIP6 multi-model mean SST climatology (1992–2011), plus imposed observed tropical Atlantic SST anomalies (1992–2011);
Present-day control with fixed concentrations of GHGs, aerosols and ozone.
Simulation details: Run length: 20 years; Ensemble size: 2 groups Ă— 5 members = 10 simulations in total (4 members already completed)
Total KSUs required : 600 KSU (~5 KSU per simulated year)
Total storage required : 4 TB
Storage lifetime : 1 year
Long term data plan : Process and stored on k10