The value of initialization on decadal timescales: State-dependent predictability in the CESM decadal prediction large ensemble
Information in decadal climate prediction arises from a well-initialized ocean state and from the predicted response to an external forcing. The length of time over which the initial conditions benefit the decadal forecast depends on the start date of the forecast. We characterize this state-depende...
Published in: | Journal of Climate |
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Language: | English |
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2020
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Online Access: | https://doi.org/10.1175/JCLI-D-19-0571.1 |
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ftncar:oai:drupal-site.org:articles_24104 2024-04-28T08:31:05+00:00 The value of initialization on decadal timescales: State-dependent predictability in the CESM decadal prediction large ensemble Christensen, H. M. (author) Berner, Judith (author) Yeager, Stephen (author) 2020-09-01 https://doi.org/10.1175/JCLI-D-19-0571.1 en eng Journal of Climate--0894-8755--1520-0442 articles:24104 ark:/85065/d7ww7n2k doi:10.1175/JCLI-D-19-0571.1 Copyright 2020 American Meteorological Society (AMS). article Text 2020 ftncar https://doi.org/10.1175/JCLI-D-19-0571.1 2024-04-04T17:34:52Z Information in decadal climate prediction arises from a well-initialized ocean state and from the predicted response to an external forcing. The length of time over which the initial conditions benefit the decadal forecast depends on the start date of the forecast. We characterize this state-dependent predictability for decadal forecasts of upper ocean heat content in the Community Earth System Model. We find regionally dependent initial condition predictability, with extended predictability generally observed in the extratropics. We also detect state-dependent predictability, with the year of loss of information from the initialization varying between start dates. The decadal forecasts in the North Atlantic show substantial information from the initial conditions beyond the 10-yr forecast window, and a high degree of state-dependent predictability. We find some evidence for state-dependent predictability in the ensemble spread in this region, similar to that seen in weather and subseasonal-to-seasonal forecasts. For some start dates, an increase of information with lead time is observed, for which the initialized forecasts predict a growing phase of the Atlantic multidecadal oscillation. Finally we consider the information in the forecast from the initial conditions relative to the forced response, and quantify the crossover time scale after which the forcing provides more information. We demonstrate that the climate change signal projects onto different patterns than the signal from the initial conditions. This means that even after the crossover time scale has been reached in a basin-averaged sense, the benefits of initialization can be felt locally on longer time scales. OCE1243015 1852977 Article in Journal/Newspaper North Atlantic OpenSky (NCAR/UCAR - National Center for Atmospheric Research/University Corporation for Atmospheric Research) Journal of Climate 33 17 7353 7370 |
institution |
Open Polar |
collection |
OpenSky (NCAR/UCAR - National Center for Atmospheric Research/University Corporation for Atmospheric Research) |
op_collection_id |
ftncar |
language |
English |
description |
Information in decadal climate prediction arises from a well-initialized ocean state and from the predicted response to an external forcing. The length of time over which the initial conditions benefit the decadal forecast depends on the start date of the forecast. We characterize this state-dependent predictability for decadal forecasts of upper ocean heat content in the Community Earth System Model. We find regionally dependent initial condition predictability, with extended predictability generally observed in the extratropics. We also detect state-dependent predictability, with the year of loss of information from the initialization varying between start dates. The decadal forecasts in the North Atlantic show substantial information from the initial conditions beyond the 10-yr forecast window, and a high degree of state-dependent predictability. We find some evidence for state-dependent predictability in the ensemble spread in this region, similar to that seen in weather and subseasonal-to-seasonal forecasts. For some start dates, an increase of information with lead time is observed, for which the initialized forecasts predict a growing phase of the Atlantic multidecadal oscillation. Finally we consider the information in the forecast from the initial conditions relative to the forced response, and quantify the crossover time scale after which the forcing provides more information. We demonstrate that the climate change signal projects onto different patterns than the signal from the initial conditions. This means that even after the crossover time scale has been reached in a basin-averaged sense, the benefits of initialization can be felt locally on longer time scales. OCE1243015 1852977 |
author2 |
Christensen, H. M. (author) Berner, Judith (author) Yeager, Stephen (author) |
format |
Article in Journal/Newspaper |
title |
The value of initialization on decadal timescales: State-dependent predictability in the CESM decadal prediction large ensemble |
spellingShingle |
The value of initialization on decadal timescales: State-dependent predictability in the CESM decadal prediction large ensemble |
title_short |
The value of initialization on decadal timescales: State-dependent predictability in the CESM decadal prediction large ensemble |
title_full |
The value of initialization on decadal timescales: State-dependent predictability in the CESM decadal prediction large ensemble |
title_fullStr |
The value of initialization on decadal timescales: State-dependent predictability in the CESM decadal prediction large ensemble |
title_full_unstemmed |
The value of initialization on decadal timescales: State-dependent predictability in the CESM decadal prediction large ensemble |
title_sort |
value of initialization on decadal timescales: state-dependent predictability in the cesm decadal prediction large ensemble |
publishDate |
2020 |
url |
https://doi.org/10.1175/JCLI-D-19-0571.1 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
Journal of Climate--0894-8755--1520-0442 articles:24104 ark:/85065/d7ww7n2k doi:10.1175/JCLI-D-19-0571.1 |
op_rights |
Copyright 2020 American Meteorological Society (AMS). |
op_doi |
https://doi.org/10.1175/JCLI-D-19-0571.1 |
container_title |
Journal of Climate |
container_volume |
33 |
container_issue |
17 |
container_start_page |
7353 |
op_container_end_page |
7370 |
_version_ |
1797588732278210560 |