The Python Energy Balance model for Snow and Ice (PEBSI): Application and tradeoff analysis on Gulkana Glacier, Alaska

Journal of Glaciology
By: , and 

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Abstract

Glacier energy-balance models offer mechanistic insights into glacier mass balance under a changing climate, yet their considerable data requirements hinder large-scale applications. Here we present the open-source Python Energy Balance model for Snow and Ice (PEBSI), which includes physically based albedo evolution using the Snow, Ice and Aerosol Radiative (SNICAR) model. PEBSI is calibrated and validated using robust in situ data from Gulkana Glacier, Alaska from 2000 to 2024. Simulations forced with original and bias-corrected climate reanalysis data show that statistically downscaling reanalysis data with in situ observations is necessary to reproduce summer mass balance (mean absolute error [MAE] = 0.75 m w.e. vs 0.22 m w.e., respectively). A grid search across two parameters, a precipitation factor and a densification parameter, reveals tradeoffs in performance compared to seasonal mass balance and end-of-winter snow density and depth. No single combination of parameters minimizes all errors, underscoring the inherent overparameterization of energy-balance models and challenges with translating coarse climate data to the glacier scale. The calibrated model successfully simulates the 2024 melt season, agreeing with surface-height change (MAE = 0.48 m) and albedo (MAE = 0.066) observations. Moving forward, PEBSI provides unique opportunities to quantify albedo feedbacks and their impact on present and future glacier mass loss.

Suggested Citation

Wilson, C.V., Rounce, D.R., Sass, L., Wells, A., Baker, E.H., Flanner, M., and Skiles, S.M., 2026, The Python Energy Balance model for Snow and Ice (PEBSI): Application and tradeoff analysis on Gulkana Glacier, Alaska: Journal of Glaciology, v. 72, e47, 14 p., https://doi.org/10.1017/jog.2026.10154.

Study Area

Publication type Article
Publication Subtype Journal Article
Title The Python Energy Balance model for Snow and Ice (PEBSI): Application and tradeoff analysis on Gulkana Glacier, Alaska
Series title Journal of Glaciology
DOI 10.1017/jog.2026.10154
Volume 72
Publication Date March 25, 2026
Year Published 2026
Language English
Publisher Cambridge University Press
Contributing office(s) Alaska Science Center Water
Description e47, 14 p.
Country United States
State Alaska
Other Geospatial Gulkana Glacier
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