Age Models
It is important that we are consistent in our use of age models. For this reason please only use officially accepted age scales. Below existing age models are listed and described. So far we have accepted age models for:
- RICE17 covers the last 2,7ka based on the annual layer count and to 83ka based on the methane/d18Oatm records.
- 100 years - now superseded by RICE17
- 2,000 years - now superseded by RICE17
- RICE-2ka - now superseded by RICE17
RICE17 age model
This age model is a combination between the annual layer count 0-303.0m (Winstrup et al. in review) matched with the deep age scale (Lee et al. in prep) reaching back to 83ka. A full description can be found in www.clim-past-discuss.net/cp-2017-101/Winstrup et al. in review. James' deep age scale will be submitted to Climate of the Past soon.
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File Name: RICE17_dec2017
Content: RICE17 - Combined age model for the past 83ka Originators: Mai Winstrup, Paul Vallelonga, and James Lee Uploaded by Nancy Bertler Date uploaded: April 2017 File last modified: December 2017 |
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File Name: ice_2700-year_timescale_and_accumulation_updatedapr2018.xls
Content: Annual Layer Count for past 2.7ka Originators: Mai Winstrup, Paul Vallelonga Uploaded by Nancy Bertler Date uploaded: May 2017 File last modified: May 2017 |
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File Name: rice_2700-year_timescale_and_accumulation_updatedapr2018.xls
Content: Snow accumulation data for the past 2.7ka Originator: Mai Winstrup and Paul Vallelonga Uploaded by: Nancy Bertler Date uploaded: May 2017 File last modified: May 2018 |
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File Name: rice17_acps_20170810.txt / rice17_fcp_20180507.txt/rice17_interpolated_ages_20180530
Content: Methane Age Scale Originator: James Lee Uploaded by: Nancy Bertler Date uploaded: May 2017 File last modified: May 2018 |
RICE-2ka age model - now superseded - please use RICE17
This age model is based on the annual layer count of CFA data with discrete age benchmarks from volcanic eruptions (one tephra layer and 13 geochemical signals of eruptions linked with the WAIS Divide volcanic record_. The section 0-40m is dated using a manual layer count, The section between 40-300m is counted using an automated layer count. The count was conducted primarily on CFA data from black carbon, Ca, conductivity, pH and isotopes. Two cores were spliced to provide a continuous age scale from 0.58m to 303m depth. From 0.58m to 12.28m the firn core RICE-12/13-B was used and from 12.30-303.0m RICE Deep was used, using the section RICE_II_Deep for 12.30m to 40.0m (2014 processing campaign). The age scale derived from the methane data agree well for the past 1,500 years but suggest that annual layers are systematically and increasingly lost between 1,500-2,000 years before present. The age scale will be described in detail in the upcoming RICE 2ka community paper (to be submitted in Sep 2016 for inclusion in the Antarctic 2ka temperature reconstruction).
Annual Layer Count - Paul Vallelonga, Helle Kjaer, Mai Windstrup, Ross Edwards
Volcanic Ash - Andrei Kurbatov
Methane Ages - James Lee, Ed Brook, Thomas Blunier, Christo Buziert, Jeff Severinghaus
Annual Layer Thinning - T.J. Fudge
Vertical Velocity / Thinning - Jonny Kingslake, Howard Conway, Ed Waddington, Richard Hindmarsh
Stable Isotope Data - Nancy Bertler, Daniel Emanuelsson, Troy Baisden, Liz Keller, Rebecca Pyne
Annual Layer Count - Paul Vallelonga, Helle Kjaer, Mai Windstrup, Ross Edwards
Volcanic Ash - Andrei Kurbatov
Methane Ages - James Lee, Ed Brook, Thomas Blunier, Christo Buziert, Jeff Severinghaus
Annual Layer Thinning - T.J. Fudge
Vertical Velocity / Thinning - Jonny Kingslake, Howard Conway, Ed Waddington, Richard Hindmarsh
Stable Isotope Data - Nancy Bertler, Daniel Emanuelsson, Troy Baisden, Liz Keller, Rebecca Pyne
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File Name: rice_2ka_agescale_copenhagen.xlsx
Originator: Paul Vallelonga Uploaded by: Nancy Bertler Date uploaded: Jun 2016 File last modified: May 2016 |
Age Model for the past 100 years - now superseded - please use RICE17 instead
This age model is based on an agreed annual layer count by Peter Neff, Daniel Emanuelsson, Andrea Tuohy, Tom Beers, Nancy Bertler, Ross Edwards, Paul Vallelonga using major ion and trace element concentrations, and stable water isotope using the RICE deep core and the 12/13 RICE-A Firn core. Daniel then updated the annual layer count using a stacked record based on all available cores including the Danish drilled core from the 1970s.. This is the agreed age scale for the past 100 years. The word file explains the methodology. The excel spreadsheet includes the data.
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File Name: RICE_Age_Scale_100a_v1_1_March2015.docx
Originator: Daniel Emanelsson Uploaded by: Nancy Bertler Date uploaded: Sep, 2015 File last modified: Mar, 2015 File Name: RICE_Age_Scale_100a_v1_1_March2015.xls
Originator: Daniel Emanelsson Uploaded by: Nancy Bertler Date uploaded: Sep, 2015 File last modified: Mar, 2015 |
Age Model for the past 2000 years - now superseded - please use RICE17 instead
This age model is based on an methane data developed by James Lee, Ed Brook, Thomas Blunier, and T.J. Fudge. The methane data were correlated to the WAIS Divide ice core and agree well with the annual layer count above and one available volcanic marker developed by Andrei Kurbatov. The pdf file describes the methodology and contains the age benchmarks. The matlab file contains the algorithm used for the Nye interpolation.
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File Name: Methane_ACP_RICE_2kya_v1_2.pdf
Originator: James Lee Uploaded by: Nancy Bertler Date uploaded: Sep, 2015 File last modified: Aug, 2015 File Name: Nye_Interp.pdf
Originator: James Lee Uploaded by: Nancy Bertler Date uploaded: Sep, 2015 File last modified: Mar, 2015 |