last update: Apr. 2017
I am interested in the physics of the climate system with a focus on the Atlantic Ocean and Northern Hemisphere ice sheets and a keen interest in paleoclimate. I used, modified and developed numerical models across the entire range of complexity from box models to comprehensive coupled global climate models.
Ice Sheet Modeling
Together with some very talented students, I developed two ice sheet models and a sophisticated surface mass balance model from scratch. Each one of the models uses an unconventional approach to address otherwise infeasible research questions.
The first ice sheet model keeps track of individual layers of accumulation, isochrones, as they travel through the ice. This enables the simulation of finely layered records of proxy data such as the ones reconstructed from ice cores and ground-penetrating radar. Direct comparison with these data archives greatly improves the quality of simulations and therefore the simulation of past and future sea level. While such comparisons with reconstructed data are common to evaluate models of the ocean circulation, they were virtually impossible in existing ice sheet models. A proof of concept on a limited domain has recently been published (Born, 2017
). Development of a version for the Greenland ice sheet is ongoing with support from the Bergen Research Foundation
The second ice sheet model is a very efficient vertically integrated model (Neff et al., 2016
), coupled to a comprehensive surface mass balance model (Imhof, 2016
). The unusual combination of simplified ice dynamics with a physics-based yet very fast mass and energy balance scheme facilitates simulations over several glacial cycles and large ensembles of simulations for probabilistic analysis.
My research on paleoclimate concerns the last interglacial, the last glacial period and the last millennium. Most of this focuses on the role of the circulation of the North Atlantic Ocean in shaping climate events and providing key feedback mechanisms (Born et al., 2011
, Born and Levermann, 2010
, Lehner et al., 2013
, Moffa Sanchez et al., 2014
). However, we also investigated how differences in ice sheet topography and sea ice conditions changed temperature reconstructions and precipitation on the Greenland Ice Sheet during the previous interglacial, a prerequisite for robust simulations of past sea level rise (Merz et al., 2014a
, Merz et al., 2016
The dynamics of the North Atlantic Ocean and in particular of the Atlantic Subpolar Gyre have been one of my main activities since the beginning of my career. I described the nonlinear behavior and feedbacks of the Subpolar Gyre in an idealized framework (Born and Stocker, 2014
), confirmed that the same mechanisms are at play in comprehensive ocean models (Born et al., 2013
, Born et al., 2016
), relevant for decadal climate variability (Born et al., 2012
, Born et al., 2015
), and in several paleoclimate events (Born and Levermann, 2010
, Born et al., 2010
, Montoya et al, 2011
). The Subpolar Gyre acts as an important gatekeeper for heat and salt transport into the Arctic Ocean and is in turn strongly influenced by freshwater exports from this region, in particular Arctic sea ice.