ExoCcycle v1.0.0: A Generalized Framework for Spherical Community Detection and its Application to Defining Global Ocean Basins from Multi-Field Data

Abstract. Ocean basins are fundamental units for modeling the Earth system, paleoceanography, and the global carbon cycle. However, their boundaries are often defined heuristically, limiting the robustness of reduced-order models and the interpretation of paleoproxy data, especially in data-limited paleo- or planetary contexts. We present ExoCcycle, an open-source Python library for objective, automated community detection on spherical grids. This framework implements novel composite algorithms (e.g., SB-Reduction) that couple efficient partitioning (Leiden/Louvain) with ensemble-based agglomerative clustering for robust boundary detection. A key technical innovation is our Difference Quantile Transformation Cumulative Density Function (DQT-CDF) edge-weighting scheme, enabling the principled analysis of single or multiple, non-normally distributed scalar fields in a large spherical domain. We validate the method using modern bathymetry and temperature/salinity fields, demonstrating that (1) a spatial resolution of 1–2 degrees is necessary to capture critical basin-defining features such as ridges and plateaus; (2) basin boundaries evolve significantly over geological time, underscoring the inadequacy of using static, modern boundaries for past climate simulations; and (3) the ocean's community structure is fundamentally layered – deep basins (defined by bathymetry) are distinct from shallow shelf partitions (shaped by sedimentation, sea-level changes, and riverine fluxes), and surface basins (driven by wind and temperature/precipitation). ExoCcycle provides a systematic tool for generating physically-grounded, time-evolving basin definitions, enabling the development of next-generation modular intermediate-complexity models for Earth and exoplanet habitability. As a generalized spherical community detection tool, our new framework is also broadly applicable to other non-ocean related domains, including ecology and land processes, atmospheric science, solid-Earth geophysics, and planetary science.