An Unprecedented Set of High‐Resolution Earth System Simulations for Understanding Multiscale Interactions in Climate Variability and Change

TLDR

The study provides a 500‑year pre‑industrial and 250‑year historical/future high‑resolution climate simulation suite and compares it to standard‑resolution runs to evaluate the benefits of finer horizontal resolution. The simulations use CESM1.3 at 0.25° atmosphere/land and 0.1° ocean/sea‑ice, resolving tropical cyclones and mesoscale eddies and enabling interactions with large‑scale circulation. High‑resolution runs improve global mean temperature, seasonal SST and mixed‑layer depth, extreme events, and their links to climate modes, and reveal intermittent Weddell Sea polynyas coupled to the Interdecadal Pacific Oscillation.

Abstract

Abstract We present an unprecedented set of high‐resolution climate simulations, consisting of a 500‐year pre‐industrial control simulation and a 250‐year historical and future climate simulation from 1850 to 2100. A high‐resolution configuration of the Community Earth System Model version 1.3 (CESM1.3) is used for the simulations with a nominal horizontal resolution of 0.25° for the atmosphere and land models and 0.1° for the ocean and sea‐ice models. At these resolutions, the model permits tropical cyclones and ocean mesoscale eddies, allowing interactions between these synoptic and mesoscale phenomena with large‐scale circulations. An overview of the results from these simulations is provided with a focus on model drift, mean climate, internal modes of variability, representation of the historical and future climates, and extreme events. Comparisons are made to solutions from an identical set of simulations using the standard resolution (nominal 1°) CESM1.3 and to available observations for the historical period to address some key scientific questions concerning the impact and benefit of increasing model horizontal resolution in climate simulations. An emerging prominent feature of the high‐resolution pre‐industrial simulation is the intermittent occurrence of polynyas in the Weddell Sea and its interaction with an Interdecadal Pacific Oscillation. Overall, high‐resolution simulations show significant improvements in representing global mean temperature changes, seasonal cycle of sea‐surface temperature and mixed layer depth, extreme events and in relationships between extreme events and climate modes.