Study of the global and regional climatic impacts of ENSO magnitude using SPEEDY AGCM

Handle URI:
http://hdl.handle.net/10754/622992
Title:
Study of the global and regional climatic impacts of ENSO magnitude using SPEEDY AGCM
Authors:
Dogar, Muhammad Mubashar; Kucharski, Fred; Azharuddin, Syed
Abstract:
ENSO is considered as a strong atmospheric teleconnection that has pronounced global and regional circulation effects. It modifies global monsoon system, especially, Asian and African monsoons. Previous studies suggest that both the frequency and magnitude of ENSO events have increased over the last few decades resulting in a need to study climatic impacts of ENSO magnitude both at global and regional scales. Hence, to better understand the impact of ENSO amplitude over the tropical and extratropical regions focussing on the Asian and African domains, ENSO sensitivity experiments are conducted using ICTPAGCM (‘SPEEDY’). It is anticipated that the tropical Pacific SST forcing will be enough to produce ENSO-induced teleconnection patterns; therefore, the model is forced using NINO3.4 regressed SST anomalies over the tropical Pacific only. SPEEDY reproduces the impact of ENSO over the Pacific, North and South America and African regions very well. However, it underestimates ENSO teleconnection patterns and associated changes over South Asia, particularly in the Indian region, which suggests that the tropical Pacific SST forcing is not sufficient to represent ENSO-induced teleconnection patterns over South Asia. Therefore, SST forcing over the tropical Indian Ocean together with air–sea coupling is also required for better representation of ENSO-induced changes in these regions. Moreover, results obtained by this pacemaker experiment show that ENSO impacts are relatively stronger over the Inter-Tropical Convergence Zone (ITCZ) compared to extratropics and high latitude regions. The positive phase of ENSO causes weakening in rainfall activity over African tropical rain belt, parts of South and Southeast Asia, whereas, the La Niña phase produces more rain over these regions during the summer season. Model results further reveal that ENSO magnitude has a stronger impact over African Sahel and South Asia, especially over the Indian region because of its significant impact over the tropical Atlantic and the Indian Ocean through Walker circulation. ENSO-induced negative (positive) NAO-like response and associated changes over Southern Europe and North Africa get significantly strong following increased intensity of El Niño (La Niña) in the northern (southern) hemisphere in the boreal winter (summer) season. We further find that ENSO magnitude significantly impacts Hadley and Walker circulations. The positive phase of ENSO (El Niño) overall strengthens Hadley cell and a reverse is true for the La Niña phase. ENSO-induced strengthening and weakening of Hadley cell induces significant impact over South Asian and African ITCZ convective regions through modification of ITCZ/monsoon circulation system.
KAUST Department:
Earth Science and Engineering Program
Citation:
Dogar MM, Kucharski F, Azharuddin S (2017) Study of the global and regional climatic impacts of ENSO magnitude using SPEEDY AGCM. Journal of Earth System Science 126. Available: http://dx.doi.org/10.1007/s12040-017-0804-4.
Publisher:
Springer Nature
Journal:
Journal of Earth System Science
Issue Date:
9-Mar-2017
DOI:
10.1007/s12040-017-0804-4
Type:
Article
ISSN:
0253-4126; 0973-774X
Sponsors:
We would like to thank the editor and two anonymous reviewers whose constructive suggestions and comments significantly improved the manuscript. We are also thankful to the Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy, for providing computational facilities and technical support to perform the experiments at ICTP computer lab. The first author is supported by King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia. The simulation results and figures are available from the authors on request.
Additional Links:
http://link.springer.com/article/10.1007/s12040-017-0804-4
Appears in Collections:
Articles; Earth Science and Engineering Program

Full metadata record

DC FieldValue Language
dc.contributor.authorDogar, Muhammad Mubasharen
dc.contributor.authorKucharski, Freden
dc.contributor.authorAzharuddin, Syeden
dc.date.accessioned2017-03-14T11:58:04Z-
dc.date.available2017-03-14T11:58:04Z-
dc.date.issued2017-03-09en
dc.identifier.citationDogar MM, Kucharski F, Azharuddin S (2017) Study of the global and regional climatic impacts of ENSO magnitude using SPEEDY AGCM. Journal of Earth System Science 126. Available: http://dx.doi.org/10.1007/s12040-017-0804-4.en
dc.identifier.issn0253-4126en
dc.identifier.issn0973-774Xen
dc.identifier.doi10.1007/s12040-017-0804-4en
dc.identifier.urihttp://hdl.handle.net/10754/622992-
dc.description.abstractENSO is considered as a strong atmospheric teleconnection that has pronounced global and regional circulation effects. It modifies global monsoon system, especially, Asian and African monsoons. Previous studies suggest that both the frequency and magnitude of ENSO events have increased over the last few decades resulting in a need to study climatic impacts of ENSO magnitude both at global and regional scales. Hence, to better understand the impact of ENSO amplitude over the tropical and extratropical regions focussing on the Asian and African domains, ENSO sensitivity experiments are conducted using ICTPAGCM (‘SPEEDY’). It is anticipated that the tropical Pacific SST forcing will be enough to produce ENSO-induced teleconnection patterns; therefore, the model is forced using NINO3.4 regressed SST anomalies over the tropical Pacific only. SPEEDY reproduces the impact of ENSO over the Pacific, North and South America and African regions very well. However, it underestimates ENSO teleconnection patterns and associated changes over South Asia, particularly in the Indian region, which suggests that the tropical Pacific SST forcing is not sufficient to represent ENSO-induced teleconnection patterns over South Asia. Therefore, SST forcing over the tropical Indian Ocean together with air–sea coupling is also required for better representation of ENSO-induced changes in these regions. Moreover, results obtained by this pacemaker experiment show that ENSO impacts are relatively stronger over the Inter-Tropical Convergence Zone (ITCZ) compared to extratropics and high latitude regions. The positive phase of ENSO causes weakening in rainfall activity over African tropical rain belt, parts of South and Southeast Asia, whereas, the La Niña phase produces more rain over these regions during the summer season. Model results further reveal that ENSO magnitude has a stronger impact over African Sahel and South Asia, especially over the Indian region because of its significant impact over the tropical Atlantic and the Indian Ocean through Walker circulation. ENSO-induced negative (positive) NAO-like response and associated changes over Southern Europe and North Africa get significantly strong following increased intensity of El Niño (La Niña) in the northern (southern) hemisphere in the boreal winter (summer) season. We further find that ENSO magnitude significantly impacts Hadley and Walker circulations. The positive phase of ENSO (El Niño) overall strengthens Hadley cell and a reverse is true for the La Niña phase. ENSO-induced strengthening and weakening of Hadley cell induces significant impact over South Asian and African ITCZ convective regions through modification of ITCZ/monsoon circulation system.en
dc.description.sponsorshipWe would like to thank the editor and two anonymous reviewers whose constructive suggestions and comments significantly improved the manuscript. We are also thankful to the Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy, for providing computational facilities and technical support to perform the experiments at ICTP computer lab. The first author is supported by King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia. The simulation results and figures are available from the authors on request.en
dc.publisherSpringer Natureen
dc.relation.urlhttp://link.springer.com/article/10.1007/s12040-017-0804-4en
dc.rightsThe final publication is available at Springer via http://dx.doi.org/10.1007/s12040-017-0804-4en
dc.subjectENSOen
dc.subjectNAOen
dc.subjectMENAen
dc.subjectHadley circulationen
dc.subjectITCZen
dc.subjectmonsoon systemen
dc.titleStudy of the global and regional climatic impacts of ENSO magnitude using SPEEDY AGCMen
dc.typeArticleen
dc.contributor.departmentEarth Science and Engineering Programen
dc.identifier.journalJournal of Earth System Scienceen
dc.eprint.versionPost-printen
dc.contributor.institutionGlobal Change Impact Studies Centre (GCISC), Ministry of Climate Change, Islamabad, Pakistanen
dc.contributor.institutionAbdus Salam International Centre for Theoretical Physics, Earth System Physics Section, Trieste, Italyen
dc.contributor.institutionBirbal Sahni Institute of Palaeosciences, Lucknow, Indiaen
kaust.authorDogar, Muhammad Mubasharen
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