Tropical and mid-latitude teleconnections interacting with the Indian summer monsoon rainfall: a theory-guided causal effect network approach
The alternation of active and break phases in Indian summer monsoon (ISM) rainfall at intraseasonal timescales characterizes each ISM season. Both tropical and mid-latitude drivers influence this intraseasonal ISM variability. The circumglobal teleconnection observed in boreal summer drives intrasea...
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ftcopernicus:oai:publications.copernicus.org:esd78780 2023-05-15T17:34:56+02:00 Tropical and mid-latitude teleconnections interacting with the Indian summer monsoon rainfall: a theory-guided causal effect network approach Capua, Giorgia Kretschmer, Marlene Donner, Reik V. Hurk, Bart Vellore, Ramesh Krishnan, Raghavan Coumou, Dim 2020-02-10 application/pdf https://doi.org/10.5194/esd-11-17-2020 https://esd.copernicus.org/articles/11/17/2020/ eng eng doi:10.5194/esd-11-17-2020 https://esd.copernicus.org/articles/11/17/2020/ eISSN: 2190-4987 Text 2020 ftcopernicus https://doi.org/10.5194/esd-11-17-2020 2020-07-20T16:22:29Z The alternation of active and break phases in Indian summer monsoon (ISM) rainfall at intraseasonal timescales characterizes each ISM season. Both tropical and mid-latitude drivers influence this intraseasonal ISM variability. The circumglobal teleconnection observed in boreal summer drives intraseasonal variability across the mid-latitudes, and a two-way interaction between the ISM and the circumglobal teleconnection pattern has been hypothesized. We use causal discovery algorithms to test the ISM circumglobal teleconnection hypothesis in a causal framework. A robust causal link from the circumglobal teleconnection pattern and the North Atlantic region to ISM rainfall is identified, and we estimate the normalized causal effect (CE) of this link to be about 0.2 (a 1 standard deviation shift in the circumglobal teleconnection causes a 0.2 standard deviation shift in the ISM rainfall 1 week later). The ISM rainfall feeds back on the circumglobal teleconnection pattern, however weakly. Moreover, we identify a negative feedback between strong updraft located over India and the Bay of Bengal and the ISM rainfall acting at a biweekly timescale, with enhanced ISM rainfall following strong updraft by 1 week. This mechanism is possibly related to the boreal summer intraseasonal oscillation. The updraft has the strongest CE of 0.5, while the Madden–Julian oscillation variability has a CE of 0.2–0.3. Our results show that most of the ISM variability on weekly timescales comes from these tropical drivers, though the mid-latitude teleconnection also exerts a substantial influence. Identifying these local and remote drivers paves the way for improved subseasonal forecasts. Text North Atlantic Copernicus Publications: E-Journals Indian Earth System Dynamics 11 1 17 34 |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
The alternation of active and break phases in Indian summer monsoon (ISM) rainfall at intraseasonal timescales characterizes each ISM season. Both tropical and mid-latitude drivers influence this intraseasonal ISM variability. The circumglobal teleconnection observed in boreal summer drives intraseasonal variability across the mid-latitudes, and a two-way interaction between the ISM and the circumglobal teleconnection pattern has been hypothesized. We use causal discovery algorithms to test the ISM circumglobal teleconnection hypothesis in a causal framework. A robust causal link from the circumglobal teleconnection pattern and the North Atlantic region to ISM rainfall is identified, and we estimate the normalized causal effect (CE) of this link to be about 0.2 (a 1 standard deviation shift in the circumglobal teleconnection causes a 0.2 standard deviation shift in the ISM rainfall 1 week later). The ISM rainfall feeds back on the circumglobal teleconnection pattern, however weakly. Moreover, we identify a negative feedback between strong updraft located over India and the Bay of Bengal and the ISM rainfall acting at a biweekly timescale, with enhanced ISM rainfall following strong updraft by 1 week. This mechanism is possibly related to the boreal summer intraseasonal oscillation. The updraft has the strongest CE of 0.5, while the Madden–Julian oscillation variability has a CE of 0.2–0.3. Our results show that most of the ISM variability on weekly timescales comes from these tropical drivers, though the mid-latitude teleconnection also exerts a substantial influence. Identifying these local and remote drivers paves the way for improved subseasonal forecasts. |
format |
Text |
author |
Capua, Giorgia Kretschmer, Marlene Donner, Reik V. Hurk, Bart Vellore, Ramesh Krishnan, Raghavan Coumou, Dim |
spellingShingle |
Capua, Giorgia Kretschmer, Marlene Donner, Reik V. Hurk, Bart Vellore, Ramesh Krishnan, Raghavan Coumou, Dim Tropical and mid-latitude teleconnections interacting with the Indian summer monsoon rainfall: a theory-guided causal effect network approach |
author_facet |
Capua, Giorgia Kretschmer, Marlene Donner, Reik V. Hurk, Bart Vellore, Ramesh Krishnan, Raghavan Coumou, Dim |
author_sort |
Capua, Giorgia |
title |
Tropical and mid-latitude teleconnections interacting with the Indian summer monsoon rainfall: a theory-guided causal effect network approach |
title_short |
Tropical and mid-latitude teleconnections interacting with the Indian summer monsoon rainfall: a theory-guided causal effect network approach |
title_full |
Tropical and mid-latitude teleconnections interacting with the Indian summer monsoon rainfall: a theory-guided causal effect network approach |
title_fullStr |
Tropical and mid-latitude teleconnections interacting with the Indian summer monsoon rainfall: a theory-guided causal effect network approach |
title_full_unstemmed |
Tropical and mid-latitude teleconnections interacting with the Indian summer monsoon rainfall: a theory-guided causal effect network approach |
title_sort |
tropical and mid-latitude teleconnections interacting with the indian summer monsoon rainfall: a theory-guided causal effect network approach |
publishDate |
2020 |
url |
https://doi.org/10.5194/esd-11-17-2020 https://esd.copernicus.org/articles/11/17/2020/ |
geographic |
Indian |
geographic_facet |
Indian |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
eISSN: 2190-4987 |
op_relation |
doi:10.5194/esd-11-17-2020 https://esd.copernicus.org/articles/11/17/2020/ |
op_doi |
https://doi.org/10.5194/esd-11-17-2020 |
container_title |
Earth System Dynamics |
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11 |
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1 |
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17 |
op_container_end_page |
34 |
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1766133928915107840 |