Global atmospheric hydrogen chemistry and source-sink budget equilibrium simulation with the EMAC v2.55 model

Key findings from this study

• The study found that EMAC model predictions achieved Pearson correlation coefficients exceeding 0.9 at eight remote stations in polar regions and high mid-latitude islands.
• The authors report that 23 additional stations yielded correlation coefficients between 0.7 and 0.9, predominantly at remote marine locations across all latitudes.
• The model accurately predicted magnitude, amplitude, and interhemispheric seasonality of the annual hydrogen cycle at most observational stations.

Overview

This study applies the EMAC v2.55.2 earth system model to simulate global atmospheric hydrogen dynamics at 1.9° horizontal resolution. The model incorporates detailed atmospheric chemistry with comprehensive hydrogen and methane flux boundary conditions. Sources and sinks of atmospheric hydrogen include a soil uptake scheme accounting for bacterial consumption. Model outputs are validated against observations from 56 stations in the NOAA Global Monitoring Laboratory Carbon Cycle Cooperative Global Air Sampling Network. The simulation aims to accurately reproduce magnitude, amplitude, and interhemispheric seasonality of the annual hydrogen cycle.

Methods and approach

The EMAC v2.55.2 earth system model conducted global equilibrium simulations with detailed atmospheric chemistry at 1.9° horizontal resolution. Hydrogen sources and sinks were introduced, including a soil uptake scheme representing bacterial consumption. The model incorporated detailed hydrogen and methane flux boundary conditions. Time series outputs were compared with observational data from 56 NOAA Global Monitoring Laboratory stations using Pearson correlation coefficients. The approach validated model accuracy in predicting spatial and temporal patterns of atmospheric hydrogen concentrations across diverse geographic locations and latitudes.

Results

The EMAC model accurately predicted magnitude, amplitude, and interhemispheric seasonality of the annual hydrogen cycle at most observational stations. Eight remote stations in polar regions and high mid-latitude islands produced Pearson correlation coefficients exceeding 0.9 between model outputs and observations. An additional 23 stations yielded correlation coefficients between 0.7 and 0.9. These stations were predominantly remote marine locations across all latitudes and polar regions.

The model successfully reproduced temporal patterns and geographic variability in atmospheric hydrogen concentrations. Strong correlations at remote and polar sites indicate the model captures large-scale atmospheric transport and chemical processes governing hydrogen distributions. Moderate to high correlations at marine stations across latitudes demonstrate the model's capability to simulate hydrogen dynamics in diverse environmental conditions. The comprehensive soil uptake scheme representing bacterial consumption contributed to accurate sink representation in the global hydrogen budget.

Implications

The validated EMAC model provides a robust tool for simulating global atmospheric hydrogen chemistry and source-sink budget equilibrium. Accurate representation of hydrogen dynamics becomes increasingly important as hydrogen emerges as a potential energy carrier in decarbonization strategies. The model's success in capturing seasonal cycles and interhemispheric gradients enables assessment of perturbations to the hydrogen budget from anthropogenic emissions. The soil uptake parameterization accounting for bacterial consumption represents a critical sink term that influences atmospheric residence time and accumulation rates.

The strong performance at remote and polar sites demonstrates the model captures fundamental atmospheric chemistry and transport processes. This capability supports investigation of hydrogen's role in atmospheric oxidation capacity and interactions with methane cycles. The comprehensive framework enables future scenario analysis of hydrogen leakage from production, storage, and transport infrastructure. Model validation against extensive observational networks establishes confidence for projecting atmospheric hydrogen responses to evolving energy systems and assessing environmental consequences of large-scale hydrogen deployment.

Scope and limitations

This summary is based on the study abstract and available metadata. It does not include a full analysis of the complete paper, supplementary materials, or underlying datasets unless explicitly stated. Findings should be interpreted in the context of the original publication.