Intraseasonal descriptors and extremes in South African rainfall. Part II : Summer teleconnections across multiple timescales
International audience Extreme events contribute significantly to rainfall variability in semi-arid regions like South Africa. Here, following the definition of a novel typology of rainfall extremes, disentangling large- and small-scale events in Part I, we use quality-controlled observational datab...
Published in: | International Journal of Climatology |
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Main Authors: | , , , , |
Other Authors: | , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
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HAL CCSD
2023
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Online Access: | https://hal.science/hal-04037468 https://hal.science/hal-04037468/document https://hal.science/hal-04037468/file/Intl%20Journal%20of%20Climatology%20-%202023%20-%20Ullah%20-%20Intraseasonal%20descriptors%20and%20extremes%20in%20South%20African%20rainfall%20%20Part%20II%20.pdf https://doi.org/10.1002/joc.8059 |
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Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
op_collection_id |
ftccsdartic |
language |
English |
topic |
atmospheric convection El Niño–Southern Oscillation Interdecadal Pacific Oscillation large-scale and small-scale extremes Madden–Julien Oscillation rainfall South Africa tropical temperate troughs [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere |
spellingShingle |
atmospheric convection El Niño–Southern Oscillation Interdecadal Pacific Oscillation large-scale and small-scale extremes Madden–Julien Oscillation rainfall South Africa tropical temperate troughs [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere Ullah, Asmat Pohl, Benjamin Pergaud, Julien Dieppois, Bastien Rouault, Mathieu Intraseasonal descriptors and extremes in South African rainfall. Part II : Summer teleconnections across multiple timescales |
topic_facet |
atmospheric convection El Niño–Southern Oscillation Interdecadal Pacific Oscillation large-scale and small-scale extremes Madden–Julien Oscillation rainfall South Africa tropical temperate troughs [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere |
description |
International audience Extreme events contribute significantly to rainfall variability in semi-arid regions like South Africa. Here, following the definition of a novel typology of rainfall extremes, disentangling large- and small-scale events in Part I, we use quality-controlled observational databases in South Africa, the ERA5 reanalysis and satellite estimates TRMM-3B42 to examine the relationship between these two types of rainfall extremes and different modes of climate variability at various timescales. At low frequencies, rainfall extremes are assessed at interannual (IV: 2–8 years) and quasi-decadal (QDV: 8–13 years) timescales, which are primarily associated with the El Niño–Southern Oscillation (ENSO) and the Interdecadal Pacific Oscillation (IPO), respectively. At subseasonal timescales, the typology of rainfall extremes is analysed depending on the synoptic configurations, as inferred by seven convective regimes including tropical temperate troughs (TTTs: 3–7 days), and the intraseasonal variability associated with the Madden–Julien Oscillation (MJO: 30–60 days). At the IV timescale, the occurrence of large-scale extremes is substantially higher during its wet phases thereby suggesting a 400% rise in the occurrence of large-scale extremes as compared to its dry phases. At the QDV timescale, variability mostly relates to the modulation of small-scale extremes during its wet phases. Teleconnections with global sea surface temperature (SST) confirm that La Niña conditions favour overall wet conditions and extremes in South Africa. The numbers of large-scale extremes are consistently related to warmer SSTs in the North Atlantic, while their link with warmer Indian and tropical South Atlantic oceans is found to be statistically independent of the state of ENSO. At the subseasonal timescales, large-scale extremes largely occur during three out of the seven convective regimes identified in the southern African region whereas small-scale extremes are nearly equiprobable during all convective regimes. The ... |
author2 |
Centre de Recherches de Climatologie UMR Biogéosciences (CRC) Biogéosciences UMR 6282 (BGS) Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS)-Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS) Centre for Agroecology, Water and Resilience (CAWR) Coventry University Nansen-Tutu Centre for Marine Environmental Research University of Cape Town I-SITE Bourgogne Franche-Comté Junior Fellowship IMVULA, Grant/Award Number: AAP2-JF-06 Alliance Programme 2020, Grant/Award Number: 608081922 |
format |
Article in Journal/Newspaper |
author |
Ullah, Asmat Pohl, Benjamin Pergaud, Julien Dieppois, Bastien Rouault, Mathieu |
author_facet |
Ullah, Asmat Pohl, Benjamin Pergaud, Julien Dieppois, Bastien Rouault, Mathieu |
author_sort |
Ullah, Asmat |
title |
Intraseasonal descriptors and extremes in South African rainfall. Part II : Summer teleconnections across multiple timescales |
title_short |
Intraseasonal descriptors and extremes in South African rainfall. Part II : Summer teleconnections across multiple timescales |
title_full |
Intraseasonal descriptors and extremes in South African rainfall. Part II : Summer teleconnections across multiple timescales |
title_fullStr |
Intraseasonal descriptors and extremes in South African rainfall. Part II : Summer teleconnections across multiple timescales |
title_full_unstemmed |
Intraseasonal descriptors and extremes in South African rainfall. Part II : Summer teleconnections across multiple timescales |
title_sort |
intraseasonal descriptors and extremes in south african rainfall. part ii : summer teleconnections across multiple timescales |
publisher |
HAL CCSD |
publishDate |
2023 |
url |
https://hal.science/hal-04037468 https://hal.science/hal-04037468/document https://hal.science/hal-04037468/file/Intl%20Journal%20of%20Climatology%20-%202023%20-%20Ullah%20-%20Intraseasonal%20descriptors%20and%20extremes%20in%20South%20African%20rainfall%20%20Part%20II%20.pdf https://doi.org/10.1002/joc.8059 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
ISSN: 0899-8418 EISSN: 1097-0088 International Journal of Climatology https://hal.science/hal-04037468 International Journal of Climatology, In press, 43 (8), pp.3799-3827. ⟨10.1002/joc.8059⟩ https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/joc.8059 |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1002/joc.8059 hal-04037468 https://hal.science/hal-04037468 https://hal.science/hal-04037468/document https://hal.science/hal-04037468/file/Intl%20Journal%20of%20Climatology%20-%202023%20-%20Ullah%20-%20Intraseasonal%20descriptors%20and%20extremes%20in%20South%20African%20rainfall%20%20Part%20II%20.pdf doi:10.1002/joc.8059 |
op_rights |
info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.1002/joc.8059 |
container_title |
International Journal of Climatology |
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1781703448571412480 |
spelling |
ftccsdartic:oai:HAL:hal-04037468v1 2023-11-05T03:44:11+01:00 Intraseasonal descriptors and extremes in South African rainfall. Part II : Summer teleconnections across multiple timescales Ullah, Asmat Pohl, Benjamin Pergaud, Julien Dieppois, Bastien Rouault, Mathieu Centre de Recherches de Climatologie UMR Biogéosciences (CRC) Biogéosciences UMR 6282 (BGS) Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS)-Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS) Centre for Agroecology, Water and Resilience (CAWR) Coventry University Nansen-Tutu Centre for Marine Environmental Research University of Cape Town I-SITE Bourgogne Franche-Comté Junior Fellowship IMVULA, Grant/Award Number: AAP2-JF-06 Alliance Programme 2020, Grant/Award Number: 608081922 2023 https://hal.science/hal-04037468 https://hal.science/hal-04037468/document https://hal.science/hal-04037468/file/Intl%20Journal%20of%20Climatology%20-%202023%20-%20Ullah%20-%20Intraseasonal%20descriptors%20and%20extremes%20in%20South%20African%20rainfall%20%20Part%20II%20.pdf https://doi.org/10.1002/joc.8059 en eng HAL CCSD Wiley info:eu-repo/semantics/altIdentifier/doi/10.1002/joc.8059 hal-04037468 https://hal.science/hal-04037468 https://hal.science/hal-04037468/document https://hal.science/hal-04037468/file/Intl%20Journal%20of%20Climatology%20-%202023%20-%20Ullah%20-%20Intraseasonal%20descriptors%20and%20extremes%20in%20South%20African%20rainfall%20%20Part%20II%20.pdf doi:10.1002/joc.8059 info:eu-repo/semantics/OpenAccess ISSN: 0899-8418 EISSN: 1097-0088 International Journal of Climatology https://hal.science/hal-04037468 International Journal of Climatology, In press, 43 (8), pp.3799-3827. ⟨10.1002/joc.8059⟩ https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/joc.8059 atmospheric convection El Niño–Southern Oscillation Interdecadal Pacific Oscillation large-scale and small-scale extremes Madden–Julien Oscillation rainfall South Africa tropical temperate troughs [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere info:eu-repo/semantics/article Journal articles 2023 ftccsdartic https://doi.org/10.1002/joc.8059 2023-10-07T22:37:10Z International audience Extreme events contribute significantly to rainfall variability in semi-arid regions like South Africa. Here, following the definition of a novel typology of rainfall extremes, disentangling large- and small-scale events in Part I, we use quality-controlled observational databases in South Africa, the ERA5 reanalysis and satellite estimates TRMM-3B42 to examine the relationship between these two types of rainfall extremes and different modes of climate variability at various timescales. At low frequencies, rainfall extremes are assessed at interannual (IV: 2–8 years) and quasi-decadal (QDV: 8–13 years) timescales, which are primarily associated with the El Niño–Southern Oscillation (ENSO) and the Interdecadal Pacific Oscillation (IPO), respectively. At subseasonal timescales, the typology of rainfall extremes is analysed depending on the synoptic configurations, as inferred by seven convective regimes including tropical temperate troughs (TTTs: 3–7 days), and the intraseasonal variability associated with the Madden–Julien Oscillation (MJO: 30–60 days). At the IV timescale, the occurrence of large-scale extremes is substantially higher during its wet phases thereby suggesting a 400% rise in the occurrence of large-scale extremes as compared to its dry phases. At the QDV timescale, variability mostly relates to the modulation of small-scale extremes during its wet phases. Teleconnections with global sea surface temperature (SST) confirm that La Niña conditions favour overall wet conditions and extremes in South Africa. The numbers of large-scale extremes are consistently related to warmer SSTs in the North Atlantic, while their link with warmer Indian and tropical South Atlantic oceans is found to be statistically independent of the state of ENSO. At the subseasonal timescales, large-scale extremes largely occur during three out of the seven convective regimes identified in the southern African region whereas small-scale extremes are nearly equiprobable during all convective regimes. The ... Article in Journal/Newspaper North Atlantic Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) International Journal of Climatology |