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Origin of cold bias over the Arabian Sea in Climate Models

Almost all climate models in Coupled Model Inter-comparison Project phase five (CMIP5) were found to have a cold bias in Sea Surface Temperature (SST) over the northern Arabian Sea, which is linked to the biases in the Indian Summer Monsoon (ISM). This cold SST bias was attributed to the anomalous c...

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Autores principales: Sandeep, S., Ajayamohan, R. S.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4165943/
https://www.ncbi.nlm.nih.gov/pubmed/25228235
http://dx.doi.org/10.1038/srep06403
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author Sandeep, S.
Ajayamohan, R. S.
author_facet Sandeep, S.
Ajayamohan, R. S.
author_sort Sandeep, S.
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description Almost all climate models in Coupled Model Inter-comparison Project phase five (CMIP5) were found to have a cold bias in Sea Surface Temperature (SST) over the northern Arabian Sea, which is linked to the biases in the Indian Summer Monsoon (ISM). This cold SST bias was attributed to the anomalous cold winds from the north-western part of south Asian landmass during boreal winter. However, the origin of the anomalously strong cold winds over the Arabian Sea and its association with the large-scale circulation is obscure. Here we show that an equatorward bias in subtropical Jetstream during boreal spring season anomalously cools down the northern Arabian Sea and adjoining land regions in CMIP5 models. The models with stronger equatorward bias in subtropical jet are also the ones with stronger cold SST bias over the Arabian Sea. The equatorward shift coupled with enhanced strength of the subtropical jet produce a stronger upper tropospheric convergence, leading to a subsidence and divergence at lower levels over the Arabian deserts. The low entropy air flowing from the Arabian land mass cools the northern Arabian Sea. The weaker meridional temperature gradients in the colder models substantially weaken ISM precipitation.
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spelling pubmed-41659432014-09-22 Origin of cold bias over the Arabian Sea in Climate Models Sandeep, S. Ajayamohan, R. S. Sci Rep Article Almost all climate models in Coupled Model Inter-comparison Project phase five (CMIP5) were found to have a cold bias in Sea Surface Temperature (SST) over the northern Arabian Sea, which is linked to the biases in the Indian Summer Monsoon (ISM). This cold SST bias was attributed to the anomalous cold winds from the north-western part of south Asian landmass during boreal winter. However, the origin of the anomalously strong cold winds over the Arabian Sea and its association with the large-scale circulation is obscure. Here we show that an equatorward bias in subtropical Jetstream during boreal spring season anomalously cools down the northern Arabian Sea and adjoining land regions in CMIP5 models. The models with stronger equatorward bias in subtropical jet are also the ones with stronger cold SST bias over the Arabian Sea. The equatorward shift coupled with enhanced strength of the subtropical jet produce a stronger upper tropospheric convergence, leading to a subsidence and divergence at lower levels over the Arabian deserts. The low entropy air flowing from the Arabian land mass cools the northern Arabian Sea. The weaker meridional temperature gradients in the colder models substantially weaken ISM precipitation. Nature Publishing Group 2014-09-17 /pmc/articles/PMC4165943/ /pubmed/25228235 http://dx.doi.org/10.1038/srep06403 Text en Copyright © 2014, Macmillan Publishers Limited. All rights reserved http://creativecommons.org/licenses/by-nc-nd/4.0/ This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder in order to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/4.0/
spellingShingle Article
Sandeep, S.
Ajayamohan, R. S.
Origin of cold bias over the Arabian Sea in Climate Models
title Origin of cold bias over the Arabian Sea in Climate Models
title_full Origin of cold bias over the Arabian Sea in Climate Models
title_fullStr Origin of cold bias over the Arabian Sea in Climate Models
title_full_unstemmed Origin of cold bias over the Arabian Sea in Climate Models
title_short Origin of cold bias over the Arabian Sea in Climate Models
title_sort origin of cold bias over the arabian sea in climate models
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4165943/
https://www.ncbi.nlm.nih.gov/pubmed/25228235
http://dx.doi.org/10.1038/srep06403
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