Skip to main content

Research Repository

Advanced Search

ATAT 1.1, the Automated Timing Accordance Tool for comparing ice-sheet model output with geochronological data

Ely, Jeremy C.; Clark, Chris D.; Small, David; Hindmarsh, Richard C.A.


Jeremy C. Ely

Chris D. Clark

Richard C.A. Hindmarsh


Earth's extant ice sheets are of great societal importance given their ongoing and potential future contributions to sea-level rise. Numerical models of ice sheets are designed to simulate ice-sheet behaviour in response to climate changes but to be improved require validation against observations. The direct observational record of extant ice sheets is limited to a few recent decades, but there is a large and growing body of geochronological evidence spanning millennia constraining the behaviour of palaeo-ice sheets. Hindcasts can be used to improve model formulations and study interactions between ice sheets, the climate system and landscape. However, ice-sheet modelling results have inherent quantitative errors stemming from parameter uncertainty and their internal dynamics, leading many modellers to perform ensemble simulations, while uncertainty in geochronological evidence necessitates expert interpretation. Quantitative tools are essential to examine which members of an ice-sheet model ensemble best fit the constraints provided by geochronological data. We present the Automated Timing Accordance Tool (ATAT version 1.1) used to quantify differences between model results and geochronological data on the timing of ice-sheet advance and/or retreat. To demonstrate its utility, we perform three simplified ice-sheet modelling experiments of the former British–Irish ice sheet. These illustrate how ATAT can be used to quantify model performance, either by using the discrete locations where the data originated together with dating constraints or by comparing model outputs with empirically derived reconstructions that have used these data along with wider expert knowledge. The ATAT code is made available and can be used by ice-sheet modellers to quantify the goodness of fit of hindcasts. ATAT may also be useful for highlighting data inconsistent with glaciological principles or reconstructions that cannot be replicated by an ice-sheet model.


Ely, J. C., Clark, C. D., Small, D., & Hindmarsh, R. C. (2019). ATAT 1.1, the Automated Timing Accordance Tool for comparing ice-sheet model output with geochronological data. Geoscientific Model Development, 12(3), 933-953.

Journal Article Type Article
Acceptance Date Feb 25, 2019
Online Publication Date Mar 12, 2019
Publication Date Mar 31, 2019
Deposit Date Mar 27, 2019
Publicly Available Date Mar 27, 2019
Journal Geoscientific Model Development
Print ISSN 1991-959X
Electronic ISSN 1991-9603
Publisher European Geosciences Union
Peer Reviewed Peer Reviewed
Volume 12
Issue 3
Pages 933-953


You might also like

Downloadable Citations