A protocol for calculating basal melt rates in the ISMIP6 Antarctic ice sheet projections
Climate model projections have previously been used to compute ice shelf basal melt rates in ice sheet models, but the strategies employed – e.g., ocean input, parameterization, calibration technique, and corrections – have varied widely and are often ad hoc. Here, a methodology is proposed for the...
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ftdoajarticles:oai:doaj.org/article:dc8874c79aec4d5cae945531bcd2d295 2023-05-15T13:41:13+02:00 A protocol for calculating basal melt rates in the ISMIP6 Antarctic ice sheet projections N. C. Jourdain X. Asay-Davis T. Hattermann F. Straneo H. Seroussi C. M. Little S. Nowicki 2020-09-01T00:00:00Z https://doi.org/10.5194/tc-14-3111-2020 https://doaj.org/article/dc8874c79aec4d5cae945531bcd2d295 EN eng Copernicus Publications https://tc.copernicus.org/articles/14/3111/2020/tc-14-3111-2020.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-14-3111-2020 1994-0416 1994-0424 https://doaj.org/article/dc8874c79aec4d5cae945531bcd2d295 The Cryosphere, Vol 14, Pp 3111-3134 (2020) Environmental sciences GE1-350 Geology QE1-996.5 article 2020 ftdoajarticles https://doi.org/10.5194/tc-14-3111-2020 2022-12-31T03:37:35Z Climate model projections have previously been used to compute ice shelf basal melt rates in ice sheet models, but the strategies employed – e.g., ocean input, parameterization, calibration technique, and corrections – have varied widely and are often ad hoc. Here, a methodology is proposed for the calculation of circum-Antarctic basal melt rates for floating ice, based on climate models, that is suitable for ISMIP6, the Ice Sheet Model Intercomparison Project for CMIP6 (6th Coupled Model Intercomparison Project). The past and future evolution of ocean temperature and salinity is derived from a climate model by estimating anomalies with respect to the modern day, which are added to a present-day climatology constructed from existing observational datasets. Temperature and salinity are extrapolated to any position potentially occupied by a simulated ice shelf. A simple formulation is proposed for a basal melt parameterization in ISMIP6, constrained by the observed temperature climatology, with a quadratic dependency on either the nonlocal or local thermal forcing. Two calibration methods are proposed: (1) based on the mean Antarctic melt rate (MeanAnt) and (2) based on melt rates near Pine Island's deep grounding line (PIGL). Future Antarctic mean melt rates are an order of magnitude greater in PIGL than in MeanAnt. The PIGL calibration and the local parameterization result in more realistic melt rates near grounding lines. PIGL is also more consistent with observations of interannual melt rate variability underneath Pine Island and Dotson ice shelves. This work stresses the need for more physics and less calibration in the parameterizations and for more observations of hydrographic properties and melt rates at interannual and decadal timescales. Article in Journal/Newspaper Antarc* Antarctic Ice Sheet Ice Shelf Ice Shelves The Cryosphere Directory of Open Access Journals: DOAJ Articles Antarctic The Cryosphere 14 9 3111 3134 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Environmental sciences GE1-350 Geology QE1-996.5 |
spellingShingle |
Environmental sciences GE1-350 Geology QE1-996.5 N. C. Jourdain X. Asay-Davis T. Hattermann F. Straneo H. Seroussi C. M. Little S. Nowicki A protocol for calculating basal melt rates in the ISMIP6 Antarctic ice sheet projections |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
Climate model projections have previously been used to compute ice shelf basal melt rates in ice sheet models, but the strategies employed – e.g., ocean input, parameterization, calibration technique, and corrections – have varied widely and are often ad hoc. Here, a methodology is proposed for the calculation of circum-Antarctic basal melt rates for floating ice, based on climate models, that is suitable for ISMIP6, the Ice Sheet Model Intercomparison Project for CMIP6 (6th Coupled Model Intercomparison Project). The past and future evolution of ocean temperature and salinity is derived from a climate model by estimating anomalies with respect to the modern day, which are added to a present-day climatology constructed from existing observational datasets. Temperature and salinity are extrapolated to any position potentially occupied by a simulated ice shelf. A simple formulation is proposed for a basal melt parameterization in ISMIP6, constrained by the observed temperature climatology, with a quadratic dependency on either the nonlocal or local thermal forcing. Two calibration methods are proposed: (1) based on the mean Antarctic melt rate (MeanAnt) and (2) based on melt rates near Pine Island's deep grounding line (PIGL). Future Antarctic mean melt rates are an order of magnitude greater in PIGL than in MeanAnt. The PIGL calibration and the local parameterization result in more realistic melt rates near grounding lines. PIGL is also more consistent with observations of interannual melt rate variability underneath Pine Island and Dotson ice shelves. This work stresses the need for more physics and less calibration in the parameterizations and for more observations of hydrographic properties and melt rates at interannual and decadal timescales. |
format |
Article in Journal/Newspaper |
author |
N. C. Jourdain X. Asay-Davis T. Hattermann F. Straneo H. Seroussi C. M. Little S. Nowicki |
author_facet |
N. C. Jourdain X. Asay-Davis T. Hattermann F. Straneo H. Seroussi C. M. Little S. Nowicki |
author_sort |
N. C. Jourdain |
title |
A protocol for calculating basal melt rates in the ISMIP6 Antarctic ice sheet projections |
title_short |
A protocol for calculating basal melt rates in the ISMIP6 Antarctic ice sheet projections |
title_full |
A protocol for calculating basal melt rates in the ISMIP6 Antarctic ice sheet projections |
title_fullStr |
A protocol for calculating basal melt rates in the ISMIP6 Antarctic ice sheet projections |
title_full_unstemmed |
A protocol for calculating basal melt rates in the ISMIP6 Antarctic ice sheet projections |
title_sort |
protocol for calculating basal melt rates in the ismip6 antarctic ice sheet projections |
publisher |
Copernicus Publications |
publishDate |
2020 |
url |
https://doi.org/10.5194/tc-14-3111-2020 https://doaj.org/article/dc8874c79aec4d5cae945531bcd2d295 |
geographic |
Antarctic |
geographic_facet |
Antarctic |
genre |
Antarc* Antarctic Ice Sheet Ice Shelf Ice Shelves The Cryosphere |
genre_facet |
Antarc* Antarctic Ice Sheet Ice Shelf Ice Shelves The Cryosphere |
op_source |
The Cryosphere, Vol 14, Pp 3111-3134 (2020) |
op_relation |
https://tc.copernicus.org/articles/14/3111/2020/tc-14-3111-2020.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-14-3111-2020 1994-0416 1994-0424 https://doaj.org/article/dc8874c79aec4d5cae945531bcd2d295 |
op_doi |
https://doi.org/10.5194/tc-14-3111-2020 |
container_title |
The Cryosphere |
container_volume |
14 |
container_issue |
9 |
container_start_page |
3111 |
op_container_end_page |
3134 |
_version_ |
1766147236642684928 |