GLOBAL OCEAN 4D Nitrate Reconstruction at Pacific Line P: Global-to-Regional Evaluation and External Comparison with Line P Nitrate+Nitrite Profiles

GLOBAL OCEAN is an independently developed, global-to-regional, four-dimensional ocean modelling, reconstruction, forecasting, environmental-risk, biological-exposure, and marine carbon-removal framework spanning longitude, latitude, depth, and time. Its scientific architecture integrates physical, chemical, biogeochemical, geochemical, biological, ecological, climatic, and spatiotemporal information within a common four-dimensional computational framework. This record documents a Pacific Line P regional application of the GLOBAL OCEAN four-dimensional nitrate (NO₃) reconstruction. The Line P application demonstrates how the same global longitude × latitude × depth × time architecture can represent regional and depth-resolved ocean biogeochemical structure along a major Pacific observational transect. The Line P NO₃ profiles contained in this work are generated by GLOBAL OCEAN. They represent the regional expression of the broader GLOBAL OCEAN reconstruction and are not generated from the Line P observational profiles used for external comparison. Over the model’s original 2022–2025 held-out test period, the Pacific Line P regional evaluation achieved: R² = 0.9948 Pearson r = 0.9979 RMSE = 1.12 MAE = 0.77 These statistics characterize a separate held-out regional evaluation of the GLOBAL OCEAN NO₃ reconstruction. They are not performance statistics calculated from the subsequent Line P observational comparison. As a distinct external evaluation layer, the model-generated GLOBAL OCEAN NO₃ profiles were subsequently examined alongside corresponding Pacific Line P nutrient profiles from five cruises represented between 2013 and 2015. This produced 113 station–month vertical-profile comparisons. A chemical-measurand distinction is retained explicitly throughout this comparison. GLOBAL OCEAN represents nitrate (NO₃⁻), whereas the observational quantity is reported as nitrate + nitrite (NO₃⁻ + NO₂⁻). The observational profiles are therefore treated as an external proxy comparator for reconstructed NO₃, rather than as an exactly identical chemical measurand. The observational profiles serve only as an external reference for examining correspondence in regional and vertical nutrient structure; they are not used to generate, train, define, or recalibrate the GLOBAL OCEAN NO₃ profiles documented here. This Pacific Line P record forms part of the continuing GLOBAL OCEAN research program previously documented and archived in Zenodo under: Heidari, Mehdi (2026). Four-dimensional assessment of oxygen–carbonate multistressor risk and biological co-occurrence in the global ocean. Zenodo. DOI: 10.5281/zenodo.20514721. The present deposit is a new standalone regional application and not a new version of that earlier record. The earlier Zenodo deposit establishes prior GLOBAL OCEAN scientific provenance, while this record documents the subsequent Pacific Line P nitrate application as a distinct citable research object. Upstream ocean data used within the GLOBAL OCEAN workflow include Copernicus Marine Service products. The original third-party Copernicus source data are not redistributed in this deposit. The scientific outputs documented here are GLOBAL OCEAN-generated products and associated evaluation materials. External Line P observations used for comparison likewise remain scientifically distinct from the GLOBAL OCEAN-generated reconstruction. The broader GLOBAL OCEAN framework extends beyond nitrate and supports multi-variable four-dimensional reconstruction and forecasting of ocean environmental and biogeochemical conditions, together with biological-exposure assessment, environmental-risk analysis, and four-dimensional modelling and evaluation of marine carbon-removal interventions, including their spatial, vertical, and temporal behaviour, environmental interactions, deployment assessment, and monitoring, reporting, and verification (MRV). The scope of this specific Zenodo record, however, is deliberately limited to the Pacific Line P NO₃ application, its regional held-out evaluation, and its external comparison with available nitrate+nitrite vertical profiles. The purpose of this deposit is to establish a persistent, citable, independently timestamped scientific record of the Pacific Line P application of GLOBAL OCEAN while preserving clear distinctions among: (1) GLOBAL OCEAN-generated model output,(2) the separate held-out regional model evaluation,(3) external Line P observational comparison, and(4) upstream third-party source data. This separation is maintained to support scientific provenance, reproducibility, interpretability, and transparent attribution of the different components of the analysis. Author and developer: Mehdi HeidariFramework: GLOBAL OCEANRecord scope: Pacific Line P 4D NO₃ regional applicationVersion: v1.0Publication year: 2026