PaleoWeather: An Accelerated Scientific Discovery Project (ASD)

An unprecedented set of fully coupled high-resolution (HR) paleoclimate simulations has been performed using the water isotope-enabled Community Earth System Model version 1.3 (iCESM1.3). The simulations include well-studied paleoclimate intervals with higher atmospheric CO2 of the Early Eocene Climatic Optimum (EECO, ~50 Ma) and mid-Pliocene Warm Period (mPWP, ~3 Ma), and lower CO2 of the Last Glacial Maximum (LGM, 21 ka), as well as a corresponding Preindustrial (PI, 1850 CE). The simulations complement historical (1850-2005), abrupt 4xCO2, and RCP8.5 future (2006-2100) simulations available from the iHESP/MESACLIP project to connect past and future climate changes.

The research goals are to study the characteristics and dynamics of extremes weather events in Earth's past and future climates, as well as the climatic impact from directly resolving fine-scale processes such as ocean eddies and tropical cyclones. The project was made possible by computing resources from an award from the NSF NCAR Accelerated Scientific Discovery (ASD). 

Project leads: Bette Otto-Bliesner (NSF NCAR) and Jessica Tierney (U of Arizona)

Project investigators and contributors:

• Jiang Zhu: Model development and testing; preindustrial and Eocene simulations; post-processing
• Ran Feng: Pliocene simulation; post-processing
• Clay Tabor: LGM simulation; post-processing
• Jesse Nusbaumer: Model development
• Jim Edwards: Model porting and engineering support
• Esther Brady: Simulation setup
• Sophia Macarewich: Data management

Ongoing research and lead PIs:

• Bette Otto-Bliesner & Esther Brady: Tropical cyclones in paleoclimates (* main reference for the set of simulations)
• Jiang Zhu: More equable past and future warm climates in unprecedented high-resolution simulations (analyzes regional and seasonal temperatures and links them to improved representation of atmospheric and oceanic weather events enabled by high resolution; PREPRINT)
• Jiang Zhu & Hui Li: Role of tropical cyclones on the sea-surface temperature in equable climates
• Ran Feng & Mary Grace Albright: Mesoscale convective systems in paleoclimates
• Sophia Macarewich: Atmospheric rivers in paleoclimates
• Claire Rubbelke & Tripti Bhattacharya: Ocean resolution influence on southern African rainfall during Pliocene
• Ingrid Romero & Scott Wing: Preindustrial climate as a predictor of historical forest distributions in the US
• Victoria Todd & Tim Shanahan: Evaluating S. Hemisphere atmospheric response to the LGM, Spatial patterns of precipitation during the Pliocene
• Abigail Buchan & Alan Haywood: Jet stream variability and impacts on extremes during the Pliocene
• Karandeep Singh & Axel Timmermann: AI driven downscaling of paleoclimate data
• Anta-Clarisse Sarr: Resolution influence on sea-ice, surface circulation, and continental seasonality in the Pliocene
• Dervla Meegan Kumar & Jane Baldwin: Impact of tropical cyclones on preindustrial mean precipitation isotopes
• Aaron Kruskie & Dan Chavas: Role of continents in expansion of tropical cyclone environments during warmer climates
• Emily Nigro & Sophia Macarewich: Using PI simulation to understand water cycle in the western US over the Holocene
• Maya Tessler & Jessica Tierney: Using PI simulation as part of an ensemble of priors for a multi-model mid-Holocene data assimilation
• Chijun Sun & Sara Wong: Behaviour of western boundary currents during different paleoclimate intervals to determine key drivers
• Isma Abdelkader Di Carlo & Anna von der Heydt: Sensitivity of Atlantic Meridional Overturning Circulation to grid resolution in LGM simulations
• Sandy Herho & Andrew J. Ridgwell: Indonesian Throughflow transport pathways and thermohaline circulation across the Maritime Continent

Model: iCESM1.3_hires

Resolution: ~0.25° (~25 km) for the atmosphere and land models, and ~0.1° (~10 km at the Equator down to ~4 km at high latitudes) for the ocean and sea-ice models.

Simulations:

* The first 22 years were run on a different machine, which was branched off from the iHESP/MESACLIP PI of 646 years.

Policy and Data Acquisition: At this stage (before the publish of the main paper, Otto-Bliesner et al.), we are releasing the monthly output for collaborative use. Users are encouraged to provide co-authorship of papers and presentations to those who performed the simulations (Zhu for PI and Eocene, Tabor for LGM, and Feng for Pliocene) and leads of the ASD proposal and model development (Otto-Bliesner, Tierney, and Zhu). Please submit your request here.