Abstract
Abstract. The continually evolving large ice sheets present in the Northern Hemisphere during the last glacial cycle caused significant changes to river pathways both through directly blocking rivers and through glacial isostatic adjustment. Studies have shown these river pathway changes had a significant impact on the ocean circulation through changing the pattern of freshwater discharge into the oceans. A coupled Earth system model (ESM) simulation of the last glacial cycle thus requires a hydrological discharge model that uses a set of river pathways that evolve with Earth's changing orography while being able to reproduce the known present-day river network given the present-day orography. Here, we present a method for dynamically modelling river pathways that meets such requirements by applying predefined corrections to an evolving fine-scale orography (accounting for the changing ice sheets and isostatic rebound) each time the river directions are recalculated. The corrected orography thus produced is then used to create a set of fine-scale river pathways and these are then upscaled to a coarser scale on which an existing present-day hydrological discharge model within the JSBACH land surface model simulates the river flow. Tests show that this procedure reproduces the known present-day river network to a sufficient degree of accuracy and is able to simulate plausible paleo-river networks. It has also been shown this procedure can be run successfully multiple times as part of a transient coupled climate model simulation.
Highlights
Results of ocean circulation models are very sensitive to freshwater flux (Maier-Reimer and Mikolajewicz, 1989; Schiller et al, 1997; Stouffer et al, 2006; IPCC, 2013)
During the last glacial cycle, the courses of rivers in North America, northern Europe and Siberia were significantly altered by a combination of the physical presence of the ice sheets directly blocking the flow of rivers and the effects of isostatic adjustments altering the orography of ice-free areas (Teller, 1990; Licciardi et al, 1999; Mangerud et al, 2004; Wickert, 2016)
We introduce a dynamical model of river pathways and hydrological discharge for the simulation of glacial cycles that accounts both for the physical presence of ice sheets and for isostatic adjustments
Summary
Results of ocean circulation models are very sensitive to freshwater flux (Maier-Reimer and Mikolajewicz, 1989; Schiller et al, 1997; Stouffer et al, 2006; IPCC, 2013). During the last glacial cycle, the courses of rivers in North America, northern Europe and Siberia were significantly altered by a combination of the physical presence of the ice sheets directly blocking the flow of rivers and the effects of isostatic adjustments altering the orography of ice-free areas (Teller, 1990; Licciardi et al, 1999; Mangerud et al, 2004; Wickert, 2016). Previous studies indicate that modelling of these alterations may play an important role in the success of a transient simulation of the last glacial cycle (Alkama et al, 2008; Bahadory and Tarasov, 2018). We introduce a dynamical model of river pathways and hydrological discharge for the simulation of glacial cycles that accounts both for the physical presence of ice sheets and for isostatic adjustments
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
