Meridionally Extending Anomalous Wave Train over Asia During Breaks in the Indian Summer Monsoon

Anomalous interactions between the Indian summer monsoon (ISM) circulation and subtropical westerlies are known to trigger breaks in the ISM on subseasonal time-scales, characterised by a pattern of suppressed rainfall over central-north India, and enhanced rainfall over the foothills of the central...

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Published in:Earth Systems and Environment
Main Authors: Umakanth, Uppara, Vellore, Ramesh K., Krishnan, R., Choudhury, Ayantika Dey, Bisht, Jagat S. H., Di Capua, Giorgia, Coumou, Dim, Donner, Reik V.
Format: Article in Journal/Newspaper
Language:unknown
Published: Springer-Verlag 2019
Subjects:
Online Access:http://repository.ias.ac.in/123898/
https://doi.org/10.1007/s41748-019-00119-8
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spelling ftindianacasci:oai:repository.ias.ac.in:123898 2023-05-15T15:18:03+02:00 Meridionally Extending Anomalous Wave Train over Asia During Breaks in the Indian Summer Monsoon Umakanth, Uppara Vellore, Ramesh K. Krishnan, R. Choudhury, Ayantika Dey Bisht, Jagat S. H. Di Capua, Giorgia Coumou, Dim Donner, Reik V. 2019 http://repository.ias.ac.in/123898/ https://doi.org/10.1007/s41748-019-00119-8 unknown Springer-Verlag Umakanth, Uppara Vellore, Ramesh K. Krishnan, R. Choudhury, Ayantika Dey Bisht, Jagat S. H. Di Capua, Giorgia Coumou, Dim Donner, Reik V. (2019) Meridionally Extending Anomalous Wave Train over Asia During Breaks in the Indian Summer Monsoon Earth Systems and Environment, 3 (3). pp. 353-366. ISSN 2509-9426 QE Geology Article PeerReviewed 2019 ftindianacasci https://doi.org/10.1007/s41748-019-00119-8 2021-10-27T07:00:21Z Anomalous interactions between the Indian summer monsoon (ISM) circulation and subtropical westerlies are known to trigger breaks in the ISM on subseasonal time-scales, characterised by a pattern of suppressed rainfall over central-north India, and enhanced rainfall over the foothills of the central–eastern Himalayas (CEH). An intriguing feature during ISM breaks is the formation of a mid-tropospheric cyclonic circulation anomaly extending over the subtropical and mid-latitude areas of the Asian continent. This study investigates the mechanism of the aforesaid Asian continental mid-tropospheric cyclonic circulation (ACMCC) anomaly using observations and simplified model experiments. The results of our study indicate that the ACMCC during ISM breaks is part of a larger meridional wave train comprising of alternating anticyclonic and cyclonic anomalies that extend poleward from the monsoon region to the Arctic. A lead–lag analysis of mid-tropospheric circulation anomalies suggests that the meridional wave-train generation is linked to latent heating (LH) anomalies over the CEH foothills, Indo-China, and the Indian landmass during ISM breaks. By conducting sensitivity experiments using a simplified global atmospheric general circulation model forced with satellite-derived three-dimensional LH, it is demonstrated that the combined effects of the enhanced LH over the CEH foothills and Indo-China and decreased LH over the Indian landmass during ISM breaks are pivotal for generating the poleward extending meridional wave train and the ACMCC anomaly. At the same time, the spatial extent of the mid-latitude cyclonic anomaly over Far-East Asia is also influenced by the anomalous LH over central–eastern China. While the present findings provide interesting insights into the role of LH anomalies during ISM breaks on the poleward extending meridional wave train, the ACMCC anomaly is found to have important ramifications on the daily rainfall extremes over the Indo-China region. It is revealed from the present analysis that the frequency of extreme rainfall occurrences over Indo-China shows a twofold increase during ISM break periods as compared to active ISM conditions. Article in Journal/Newspaper Arctic Indian Academy of Sciences: Publication of Fellows Arctic Indian Earth Systems and Environment 3 3 353 366
institution Open Polar
collection Indian Academy of Sciences: Publication of Fellows
op_collection_id ftindianacasci
language unknown
topic QE Geology
spellingShingle QE Geology
Umakanth, Uppara
Vellore, Ramesh K.
Krishnan, R.
Choudhury, Ayantika Dey
Bisht, Jagat S. H.
Di Capua, Giorgia
Coumou, Dim
Donner, Reik V.
Meridionally Extending Anomalous Wave Train over Asia During Breaks in the Indian Summer Monsoon
topic_facet QE Geology
description Anomalous interactions between the Indian summer monsoon (ISM) circulation and subtropical westerlies are known to trigger breaks in the ISM on subseasonal time-scales, characterised by a pattern of suppressed rainfall over central-north India, and enhanced rainfall over the foothills of the central–eastern Himalayas (CEH). An intriguing feature during ISM breaks is the formation of a mid-tropospheric cyclonic circulation anomaly extending over the subtropical and mid-latitude areas of the Asian continent. This study investigates the mechanism of the aforesaid Asian continental mid-tropospheric cyclonic circulation (ACMCC) anomaly using observations and simplified model experiments. The results of our study indicate that the ACMCC during ISM breaks is part of a larger meridional wave train comprising of alternating anticyclonic and cyclonic anomalies that extend poleward from the monsoon region to the Arctic. A lead–lag analysis of mid-tropospheric circulation anomalies suggests that the meridional wave-train generation is linked to latent heating (LH) anomalies over the CEH foothills, Indo-China, and the Indian landmass during ISM breaks. By conducting sensitivity experiments using a simplified global atmospheric general circulation model forced with satellite-derived three-dimensional LH, it is demonstrated that the combined effects of the enhanced LH over the CEH foothills and Indo-China and decreased LH over the Indian landmass during ISM breaks are pivotal for generating the poleward extending meridional wave train and the ACMCC anomaly. At the same time, the spatial extent of the mid-latitude cyclonic anomaly over Far-East Asia is also influenced by the anomalous LH over central–eastern China. While the present findings provide interesting insights into the role of LH anomalies during ISM breaks on the poleward extending meridional wave train, the ACMCC anomaly is found to have important ramifications on the daily rainfall extremes over the Indo-China region. It is revealed from the present analysis that the frequency of extreme rainfall occurrences over Indo-China shows a twofold increase during ISM break periods as compared to active ISM conditions.
format Article in Journal/Newspaper
author Umakanth, Uppara
Vellore, Ramesh K.
Krishnan, R.
Choudhury, Ayantika Dey
Bisht, Jagat S. H.
Di Capua, Giorgia
Coumou, Dim
Donner, Reik V.
author_facet Umakanth, Uppara
Vellore, Ramesh K.
Krishnan, R.
Choudhury, Ayantika Dey
Bisht, Jagat S. H.
Di Capua, Giorgia
Coumou, Dim
Donner, Reik V.
author_sort Umakanth, Uppara
title Meridionally Extending Anomalous Wave Train over Asia During Breaks in the Indian Summer Monsoon
title_short Meridionally Extending Anomalous Wave Train over Asia During Breaks in the Indian Summer Monsoon
title_full Meridionally Extending Anomalous Wave Train over Asia During Breaks in the Indian Summer Monsoon
title_fullStr Meridionally Extending Anomalous Wave Train over Asia During Breaks in the Indian Summer Monsoon
title_full_unstemmed Meridionally Extending Anomalous Wave Train over Asia During Breaks in the Indian Summer Monsoon
title_sort meridionally extending anomalous wave train over asia during breaks in the indian summer monsoon
publisher Springer-Verlag
publishDate 2019
url http://repository.ias.ac.in/123898/
https://doi.org/10.1007/s41748-019-00119-8
geographic Arctic
Indian
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Indian
genre Arctic
genre_facet Arctic
op_relation Umakanth, Uppara
Vellore, Ramesh K.
Krishnan, R.
Choudhury, Ayantika Dey
Bisht, Jagat S. H.
Di Capua, Giorgia
Coumou, Dim
Donner, Reik V. (2019) Meridionally Extending Anomalous Wave Train over Asia During Breaks in the Indian Summer Monsoon Earth Systems and Environment, 3 (3). pp. 353-366. ISSN 2509-9426
op_doi https://doi.org/10.1007/s41748-019-00119-8
container_title Earth Systems and Environment
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container_start_page 353
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