Local versus tropical diabatic heating and the winter North Atlantic Oscillation
In this paper, a version of the European Centre for Medium-Range Weather Forecasts (ECMWF) operational model is used to (i) diagnose the diabatic heating associated with the winter North Atlantic Oscillation (NAO) and (ii) assess the role of this heating in the dynamics of the NAO in the model. Over...
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ftoceanrep:oai:oceanrep.geomar.de:7423 2023-05-15T17:29:15+02:00 Local versus tropical diabatic heating and the winter North Atlantic Oscillation Greatbatch, Richard Jung, Thomas 2007 text https://oceanrep.geomar.de/id/eprint/7423/ https://oceanrep.geomar.de/id/eprint/7423/1/JCLI4125.pdf https://doi.org/10.1175/JCLI4125.1 en eng AMS (American Meteorological Society) https://oceanrep.geomar.de/id/eprint/7423/1/JCLI4125.pdf Greatbatch, R. and Jung, T. (2007) Local versus tropical diabatic heating and the winter North Atlantic Oscillation. Open Access Journal of Climate, 20 (10). pp. 2058-2075. DOI 10.1175/JCLI4125.1 <https://doi.org/10.1175/JCLI4125.1>. doi:10.1175/JCLI4125.1 info:eu-repo/semantics/openAccess Article PeerReviewed 2007 ftoceanrep https://doi.org/10.1175/JCLI4125.1 2023-04-07T14:54:44Z In this paper, a version of the European Centre for Medium-Range Weather Forecasts (ECMWF) operational model is used to (i) diagnose the diabatic heating associated with the winter North Atlantic Oscillation (NAO) and (ii) assess the role of this heating in the dynamics of the NAO in the model. Over the North Atlantic sector, the NAO-related diabatic heating is dominated above the planetary boundary layer by the latent heat release associated with precipitation, and within the boundary layer by vertical diffusion associated with sensible heat flux from the ocean. An association between La Niña–El Niño–type conditions in the tropical Pacific and the positive/negative NAO is found in model runs using initial conditions and sea surface temperature (SST) lower boundary conditions from the period 1982–2001, but not in a companion set of model runs for the period 1962–81. Model experiments are then described in which the NAO-related diabatic heating diagnosed from the 1982–2001 control run is applied as a constant forcing in the model temperature equation using both 1982–2001 and 1962–81 model setups. To assess the local feedback from the diabatic heating, the specified forcing is first restricted to the North Atlantic sector alone. In this case, the model response (in an ensemble mean sense) is suggestive of a weak negative feedback, but exhibits more baroclinic structure and has its centers of action shifted compared to those of the NAO. On the other hand, forcing with only the tropical Pacific part of the diabatic heating leads to a robust model response in both the 1982–2001 and 1962–81 model setups. The model response projects on to the NAO with the same sign as that used to diagnose the forcing, arguing that the link between the tropical Pacific and the NAO is real in the 1982–2001 control run. The missing link in the corresponding run for 1962–81 is a result of a change in the tropical forcing between the two periods, and not the extratropical flow regime. Article in Journal/Newspaper North Atlantic North Atlantic oscillation OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) Pacific Journal of Climate 20 10 2058 2075 |
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Open Polar |
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OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) |
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ftoceanrep |
language |
English |
description |
In this paper, a version of the European Centre for Medium-Range Weather Forecasts (ECMWF) operational model is used to (i) diagnose the diabatic heating associated with the winter North Atlantic Oscillation (NAO) and (ii) assess the role of this heating in the dynamics of the NAO in the model. Over the North Atlantic sector, the NAO-related diabatic heating is dominated above the planetary boundary layer by the latent heat release associated with precipitation, and within the boundary layer by vertical diffusion associated with sensible heat flux from the ocean. An association between La Niña–El Niño–type conditions in the tropical Pacific and the positive/negative NAO is found in model runs using initial conditions and sea surface temperature (SST) lower boundary conditions from the period 1982–2001, but not in a companion set of model runs for the period 1962–81. Model experiments are then described in which the NAO-related diabatic heating diagnosed from the 1982–2001 control run is applied as a constant forcing in the model temperature equation using both 1982–2001 and 1962–81 model setups. To assess the local feedback from the diabatic heating, the specified forcing is first restricted to the North Atlantic sector alone. In this case, the model response (in an ensemble mean sense) is suggestive of a weak negative feedback, but exhibits more baroclinic structure and has its centers of action shifted compared to those of the NAO. On the other hand, forcing with only the tropical Pacific part of the diabatic heating leads to a robust model response in both the 1982–2001 and 1962–81 model setups. The model response projects on to the NAO with the same sign as that used to diagnose the forcing, arguing that the link between the tropical Pacific and the NAO is real in the 1982–2001 control run. The missing link in the corresponding run for 1962–81 is a result of a change in the tropical forcing between the two periods, and not the extratropical flow regime. |
format |
Article in Journal/Newspaper |
author |
Greatbatch, Richard Jung, Thomas |
spellingShingle |
Greatbatch, Richard Jung, Thomas Local versus tropical diabatic heating and the winter North Atlantic Oscillation |
author_facet |
Greatbatch, Richard Jung, Thomas |
author_sort |
Greatbatch, Richard |
title |
Local versus tropical diabatic heating and the winter North Atlantic Oscillation |
title_short |
Local versus tropical diabatic heating and the winter North Atlantic Oscillation |
title_full |
Local versus tropical diabatic heating and the winter North Atlantic Oscillation |
title_fullStr |
Local versus tropical diabatic heating and the winter North Atlantic Oscillation |
title_full_unstemmed |
Local versus tropical diabatic heating and the winter North Atlantic Oscillation |
title_sort |
local versus tropical diabatic heating and the winter north atlantic oscillation |
publisher |
AMS (American Meteorological Society) |
publishDate |
2007 |
url |
https://oceanrep.geomar.de/id/eprint/7423/ https://oceanrep.geomar.de/id/eprint/7423/1/JCLI4125.pdf https://doi.org/10.1175/JCLI4125.1 |
geographic |
Pacific |
geographic_facet |
Pacific |
genre |
North Atlantic North Atlantic oscillation |
genre_facet |
North Atlantic North Atlantic oscillation |
op_relation |
https://oceanrep.geomar.de/id/eprint/7423/1/JCLI4125.pdf Greatbatch, R. and Jung, T. (2007) Local versus tropical diabatic heating and the winter North Atlantic Oscillation. Open Access Journal of Climate, 20 (10). pp. 2058-2075. DOI 10.1175/JCLI4125.1 <https://doi.org/10.1175/JCLI4125.1>. doi:10.1175/JCLI4125.1 |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1175/JCLI4125.1 |
container_title |
Journal of Climate |
container_volume |
20 |
container_issue |
10 |
container_start_page |
2058 |
op_container_end_page |
2075 |
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