 |
| Titel |
IceChrono1: a probabilistic model to compute a common and optimal chronology for several ice cores |
| VerfasserIn |
F. Parrenin, L. Bazin, E. Capron, A. Landais, B. Lemieux-Dudon, V. Masson-Delmotte |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1991-959X
|
| Digitales Dokument |
URL |
| Erschienen |
In: Geoscientific Model Development ; 8, no. 5 ; Nr. 8, no. 5 (2015-05-21), S.1473-1492 |
| Datensatznummer |
250116345
|
| Publikation (Nr.) |
 copernicus.org/gmd-8-1473-2015.pdf |
|
|
|
|
|
| Zusammenfassung |
| Polar ice cores provide exceptional archives of past environmental
conditions. The dating of ice cores and the estimation of the age-scale
uncertainty are essential to interpret the climate and environmental records
that they contain. It is, however, a complex problem which involves different
methods. Here, we present IceChrono1, a new probabilistic model integrating
various sources of chronological information to produce a common and
optimized chronology for several ice cores, as well as its uncertainty.
IceChrono1 is based on the inversion of three quantities: the surface
accumulation rate, the lock-in depth (LID) of air bubbles and the thinning
function. The chronological information integrated into the model are
models of the sedimentation process (accumulation of snow, densification of
snow into ice and air trapping, ice flow), ice- and air-dated horizons, ice
and air depth intervals with known durations, Δdepth observations
(depth shift between synchronous events recorded in the ice and in the air)
and finally air and ice stratigraphic links in between ice cores. The
optimization is formulated as a least squares problem, implying that all
densities of probabilities are assumed to be Gaussian. It is numerically
solved using the Levenberg–Marquardt algorithm and a numerical evaluation of
the model's Jacobian. IceChrono follows an approach similar to that of the
Datice model which was recently used to produce the AICC2012 (Antarctic ice core chronology) for
four Antarctic ice cores and one Greenland ice core. IceChrono1 provides
improvements and simplifications with respect to Datice from the
mathematical, numerical and programming point of views. The capabilities of
IceChrono1 are demonstrated on a case study similar to the AICC2012 dating
experiment. We find results similar to those of Datice, within a few
centuries, which is a confirmation of both IceChrono1 and Datice codes. We
also test new functionalities with respect to the original version of
Datice: observations as ice intervals with known durations, correlated
observations, observations as air intervals with known durations and
observations as mixed ice–air stratigraphic links. IceChrono1 is freely
available under the General Public License v3 open source license. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|