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A simple physics-based improvement to the positive degree day model

Tsai, Victor C. and Ruan, Xiaozhou (2018) A simple physics-based improvement to the positive degree day model. Journal of Glaciology, 64 (246). pp. 661-668. ISSN 0022-1430. https://resolver.caltech.edu/CaltechAUTHORS:20180912-135435614

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Abstract

Meltwater is important to understanding glacier health and dynamics. Since melt measurements are uncommon, ice ablation estimates are often based on models including the positive degree day (PDD) model. The PDD estimate is popular since it only requires air temperature as input, but suffers from the lack of physical motivation of an energy-balance model. We present a physics-based alternative to the PDD model that still only takes air/surface temperature as input. The model resembles the PDD model except accounting for time lags in ablation when cold ice needs to be warmed. The model is expressed as a differential equation with a single extra parameter related to the efficiency of heating a near-surface layer of ice. With zero thickness, the model reduces to the PDD model, providing a physical basis for the PDD model. Applying the model to data from Greenland, it improves modestly upon the PDD model, with the main improvement being better prediction of early season melting. This new model is a useful compromise, with some of the physics of more realistic models and the simplicity of a PDD model. The model should improve estimates of meltwater production and help constrain PDD parameters when empirical calibration is challenging.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1017/jog.2018.55DOIArticle
ORCID:
AuthorORCID
Tsai, Victor C.0000-0003-1809-6672
Ruan, Xiaozhou0000-0003-1240-1584
Additional Information:© The Author(s) 2018. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited. MS received 20 November 2017 and accepted in revised form 11 June 2018; first published online 6 July 2018. We thank three anonymous reviewers for their constructive comments. This work was partly supported by NSF grant OPP-1735715.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
NSFOPP-1735715
Subject Keywords:energy balance, glacier ablation phenomena, melt-surface
Issue or Number:246
Record Number:CaltechAUTHORS:20180912-135435614
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20180912-135435614
Official Citation:TSAI, V., & RUAN, X. (2018). A simple physics-based improvement to the positive degree day model. Journal of Glaciology, 64(246), 661-668. doi:10.1017/jog.2018.55
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:89583
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:12 Sep 2018 21:07
Last Modified:03 Oct 2019 20:17

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