# Experiment proposal: ACCESS-AM3 N96 2007-2008, with reduced RHcrit (0.5), recompiled executables, and UKCM-like parameter changes

**URL:** <https://forum.access-hive.org.au/t/experiment-proposal-access-am3-n96-2007-2008-with-reduced-rhcrit-0-5-recompiled-executables-and-ukcm-like-parameter-changes/6604>\
**Category:** AM3\
**Tags:** access-am3\
**Created:** [9 July 2026 22:46 UTC](https://forum.access-hive.org.au/t/experiment-proposal-access-am3-n96-2007-2008-with-reduced-rhcrit-0-5-recompiled-executables-and-ukcm-like-parameter-changes/6604 "2026-07-09T22:46:17Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![qinggangg](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/qinggangg/32/4460_2.png) [@qinggangg](https://forum.access-hive.org.au/u/qinggangg)\
**Post date:** [9 July 2026 22:46 UTC](https://forum.access-hive.org.au/t/experiment-proposal-access-am3-n96-2007-2008-with-reduced-rhcrit-0-5-recompiled-executables-and-ukcm-like-parameter-changes/6604/1 "2026-07-09T22:46:17Z")

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**Experiment title 🔔:** ACCESS-AM3 N96 2-year simulations 2007-2008, with markedly reduced RHcrit (0.5) and recompiled executables

**Summary 🔔:** These are sensitivity experiments to a previous experiment [proposal](https://forum.access-hive.org.au/t/experiment-proposal-amip-style-access-am3-n96-1982-2025-with-prognostic-aerosol-and-cosp1/6006) and similar to these [ones](https://forum.access-hive.org.au/t/experiment-proposal-access-am3-n96-2007-2008-with-varying-rhcrit-and-cloud-erosion/6494). I have run a control simulation AM3-N96 and a SST+4K simulation from 1982-2012 to investigate cloud feedback. Here I would like to investigate the sensitivity of model output to markedly reduced RHcrit (one control and one SST+4K), UMCM2-like parameter changes (one control and one SST+4K), and recompiled executables (one control). The year 2007 will be used as a spin-up, and 2008 for analysis. 2008 is chosen because it is a common period among CMIP5, CMIP6, and CloudSat-CALIPSO datasets.

**Scientific motivation:** Cloud feedback remains the leading source of uncertainty in estimating equilibrium climate sensitivity (ECS). Given large ECS in ACCESS-CM3 and UK models employing the latest UM, it is instrumental to investigate cloud responses to evolving environmental conditions in these models. Here we aim to elucidate the role of clouds in the model responses to radiative forcing.

**Experiment Name 🔔:** am3-control   
**People 🔔:** Qinggang Gao   
**Model:** ACCESS-AM3   
**Configuration:** [https://github.com/ACCESS-NRI/access-am3-configs](https://github.com/ACCESS-NRI/access-am3-configs)  
**Initial conditions:** Default   
**Run plan:** 5 simulations, 2 years, N96 resolution   
**Simulation details:** 2007, global   
**Total KSUs required 🔔:** 22.5 KSU / year \* 2 years \* 5 simulations = 225 KSU   
**Total storage required 🔔:** 70 GB / year \* 2 years \* 5 simulations = 700 GB   
**Outputs:** /g/data/gx60/experiments/2026-03-04\_am3-control/cylc-run/   
**Restarts:** Default   
**Related articles:**  
**Analysis:**

**Conclusion:**