Reconstructing the subsurface ocean decadal variability using surface nudging in a perfect model framework
Initialising the ocean internal variability for decadal predictability studies is a new area of research and a variety of ad hoc methods are currently proposed. In this study, we explore how nudging with sea surface temperature (SST) and salinity (SSS) can reconstruct the three-dimensional variabili...
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Online Access: | https://oskar-bordeaux.fr/handle/20.500.12278/200342 https://hdl.handle.net/20.500.12278/200342 https://doi.org/10.1007/s00382-014-2184-7 |
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ftoskarbordeaux:oai:oskar-bordeaux.fr:20.500.12278/200342 2024-06-23T07:55:20+00:00 Reconstructing the subsurface ocean decadal variability using surface nudging in a perfect model framework SERVONNAT, Jérôme MIGNOT, Juliette GUILYARDI, Éric SWINGEDOUW, Didier SÉFÉRIAN, Roland LABETOULLE, Sonia 2015-01 https://oskar-bordeaux.fr/handle/20.500.12278/200342 https://hdl.handle.net/20.500.12278/200342 https://doi.org/10.1007/s00382-014-2184-7 EN eng 0930-7575 https://oskar-bordeaux.fr/handle/20.500.12278/200342 doi:10.1007/s00382-014-2184-7 open Pas de Licence CC Physique [physics]/Physique [physics]/Géophysique [physics.geo-ph] Article de revue 2015 ftoskarbordeaux https://doi.org/20.500.12278/20034210.1007/s00382-014-2184-7 2024-06-10T14:02:26Z Initialising the ocean internal variability for decadal predictability studies is a new area of research and a variety of ad hoc methods are currently proposed. In this study, we explore how nudging with sea surface temperature (SST) and salinity (SSS) can reconstruct the three-dimensional variability of the ocean in a perfect model framework. This approach builds on the hypothesis that oceanic processes themselves will transport the surface information into the ocean interior as seen in ocean-only simulations. Five nudged simulations are designed to reconstruct a 150 years “target” simulation, defined as a portion of a long control simulation. The nudged simulations differ by the variables restored to, SST or SST + SSS, and by the area where the nudging is applied. The strength of the heat flux feedback is diagnosed from observations and the restoring coefficients for SSS use the same time-scale. We observed that this choice prevents spurious convection at high latitudes and near sea-ice border when nudging both SST and SSS. In the tropics, nudging the SST is enough to reconstruct the tropical atmosphere circulation and the associated dynamical and thermodynamical impacts on the underlying ocean. In the tropical Pacific Ocean, the profiles for temperature show a significant correlation from the surface down to 2,000 m, due to dynamical adjustment of the isopycnals. At mid-to-high latitudes, SSS nudging is required to reconstruct both the temperature and the salinity below the seasonal thermocline. This is particularly true in the North Atlantic where adding SSS nudging enables to reconstruct the deep convection regions of the target. By initiating a previously documented 20-year cycle of the model, the SST + SSS nudging is also able to reproduce most of the AMOC variations, a key source of decadal predictability. Reconstruction at depth does not significantly improve with amount of time spent nudging and the efficiency of the surface nudging rather depends on the period/events considered. The joint SST + SSS ... Article in Journal/Newspaper North Atlantic Sea ice OSKAR Bordeaux (Open Science Knowledge ARchive) Pacific Climate Dynamics 44 1-2 315 338 |
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Open Polar |
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OSKAR Bordeaux (Open Science Knowledge ARchive) |
op_collection_id |
ftoskarbordeaux |
language |
English |
topic |
Physique [physics]/Physique [physics]/Géophysique [physics.geo-ph] |
spellingShingle |
Physique [physics]/Physique [physics]/Géophysique [physics.geo-ph] SERVONNAT, Jérôme MIGNOT, Juliette GUILYARDI, Éric SWINGEDOUW, Didier SÉFÉRIAN, Roland LABETOULLE, Sonia Reconstructing the subsurface ocean decadal variability using surface nudging in a perfect model framework |
topic_facet |
Physique [physics]/Physique [physics]/Géophysique [physics.geo-ph] |
description |
Initialising the ocean internal variability for decadal predictability studies is a new area of research and a variety of ad hoc methods are currently proposed. In this study, we explore how nudging with sea surface temperature (SST) and salinity (SSS) can reconstruct the three-dimensional variability of the ocean in a perfect model framework. This approach builds on the hypothesis that oceanic processes themselves will transport the surface information into the ocean interior as seen in ocean-only simulations. Five nudged simulations are designed to reconstruct a 150 years “target” simulation, defined as a portion of a long control simulation. The nudged simulations differ by the variables restored to, SST or SST + SSS, and by the area where the nudging is applied. The strength of the heat flux feedback is diagnosed from observations and the restoring coefficients for SSS use the same time-scale. We observed that this choice prevents spurious convection at high latitudes and near sea-ice border when nudging both SST and SSS. In the tropics, nudging the SST is enough to reconstruct the tropical atmosphere circulation and the associated dynamical and thermodynamical impacts on the underlying ocean. In the tropical Pacific Ocean, the profiles for temperature show a significant correlation from the surface down to 2,000 m, due to dynamical adjustment of the isopycnals. At mid-to-high latitudes, SSS nudging is required to reconstruct both the temperature and the salinity below the seasonal thermocline. This is particularly true in the North Atlantic where adding SSS nudging enables to reconstruct the deep convection regions of the target. By initiating a previously documented 20-year cycle of the model, the SST + SSS nudging is also able to reproduce most of the AMOC variations, a key source of decadal predictability. Reconstruction at depth does not significantly improve with amount of time spent nudging and the efficiency of the surface nudging rather depends on the period/events considered. The joint SST + SSS ... |
format |
Article in Journal/Newspaper |
author |
SERVONNAT, Jérôme MIGNOT, Juliette GUILYARDI, Éric SWINGEDOUW, Didier SÉFÉRIAN, Roland LABETOULLE, Sonia |
author_facet |
SERVONNAT, Jérôme MIGNOT, Juliette GUILYARDI, Éric SWINGEDOUW, Didier SÉFÉRIAN, Roland LABETOULLE, Sonia |
author_sort |
SERVONNAT, Jérôme |
title |
Reconstructing the subsurface ocean decadal variability using surface nudging in a perfect model framework |
title_short |
Reconstructing the subsurface ocean decadal variability using surface nudging in a perfect model framework |
title_full |
Reconstructing the subsurface ocean decadal variability using surface nudging in a perfect model framework |
title_fullStr |
Reconstructing the subsurface ocean decadal variability using surface nudging in a perfect model framework |
title_full_unstemmed |
Reconstructing the subsurface ocean decadal variability using surface nudging in a perfect model framework |
title_sort |
reconstructing the subsurface ocean decadal variability using surface nudging in a perfect model framework |
publishDate |
2015 |
url |
https://oskar-bordeaux.fr/handle/20.500.12278/200342 https://hdl.handle.net/20.500.12278/200342 https://doi.org/10.1007/s00382-014-2184-7 |
geographic |
Pacific |
geographic_facet |
Pacific |
genre |
North Atlantic Sea ice |
genre_facet |
North Atlantic Sea ice |
op_relation |
0930-7575 https://oskar-bordeaux.fr/handle/20.500.12278/200342 doi:10.1007/s00382-014-2184-7 |
op_rights |
open Pas de Licence CC |
op_doi |
https://doi.org/20.500.12278/20034210.1007/s00382-014-2184-7 |
container_title |
Climate Dynamics |
container_volume |
44 |
container_issue |
1-2 |
container_start_page |
315 |
op_container_end_page |
338 |
_version_ |
1802647898962264064 |