Modeling Glacier Behavior Under Different Precipitation Seasonalities

Abstract

To understand the dependence of glacial features on precipitation, glacier behavior was simulated under different precipitation conditions using a glacier fluctuation model that combined a mass-balance model with a glacier flow model. The results reveal a strong dependence of glacier behavior on precipitation conditions. Glacier volume changes in accordance with both precipitation seasonality and annual precipitation amount. Glacier volume also fluctuates in response to changes in precipitation seasonality even if no change in annual precipitation amount occurs, because of changes in glacier albedo and the volume that is able to accumulate. Furthermore, the accumulation area ratio (AAR) depends not only on the annual precipitation amount, but also on precipitation seasonality. These relationships should be considered when the AAR method is used to reconstruct the past equilibrium line of glaciers. Glacier reactions to temperature change become more sensitive as the amount of annual precipitation increases. Response time is different for each glacier type defined by precipitation seasonality: the winter-precipitation-seasonality type had the longest response time, and the summer-precipitation-seasonality type had the shortest. The difference in the response time of glacier types is larger under arid conditions and smaller under humid conditions. The simulation results in this study underscore the importance of including glacier response to precipitation conditions when estimating glacier reactions to climate change.

Acknowledgments

We express our gratitude to A. Sakai for her helpful discussions when writing the first draft of this paper. Helpful comments and suggestions from two anonymous reviewers are greatly appreciated. This study was supported by a Grant-in-Aid for Scientific Research (No. 19253001) from the Ministry of Education, Culture, Sports, Science and Technology of Japan.