Simplistic models of a tidewater glacier, with application to Columbia Glacier, Alaska

Progress has been made in the understanding of calving and tidewater glacier retreat, but there is still much to be understood about the processes controlling calving. Ice thickness near the terminus, thinning due to melt and dynamic processes, and the thickness gradient have been identified as the primary controls on mean calving rate. Minimalistic, idealized models have been shown to capture much of the dynamic behavior of tidewater glaciers while being computationally inexpensive and easy to implement. Because of their minimal nature, such models do not account for time lags in mass loss and ice flow. A model is presented that captures the essential controls on mean calving already proposed, while keeping with the simple nature of minimal models. The model is based on a simple, one-dimensional flowline model for a glacier. Calving is parameterized in several different ways, with comparisons made between each method. The model is applied to Columbia Glacier, Alaska, a large tidewater glacier that began a rapid retreat ca. 1980, which continues today. It is one of the best-studied glaciers in the world, and so makes an excellent case study to test the proposed model.