Introducing new climate indices for identifying wet/dry spells within an Madden‐Julian Oscillation phase
Abstract Daily values of precipitation in southwestern parts of Iran along with the corresponding Madden–Julian oscillation (MJO) phase are analysed to introduce some auxiliary indicators that can identify the wet and dry spells within a particular MJO phase. As a case study, the identification proc...
Published in: | International Journal of Climatology |
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crwiley:10.1002/joc.6799 2024-09-15T18:24:13+00:00 Introducing new climate indices for identifying wet/dry spells within an Madden‐Julian Oscillation phase Nazemosadat, Mohammad Jafar Shahgholian, Kokab Ghaedamini, Habiballah Nazemosadat, Elham 2020 http://dx.doi.org/10.1002/joc.6799 https://onlinelibrary.wiley.com/doi/pdf/10.1002/joc.6799 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/joc.6799 https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/joc.6799 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor International Journal of Climatology volume 41, issue S1 ISSN 0899-8418 1097-0088 journal-article 2020 crwiley https://doi.org/10.1002/joc.6799 2024-07-18T04:27:25Z Abstract Daily values of precipitation in southwestern parts of Iran along with the corresponding Madden–Julian oscillation (MJO) phase are analysed to introduce some auxiliary indicators that can identify the wet and dry spells within a particular MJO phase. As a case study, the identification procedure focuses on phase 1 during the rainy season (Nov–Apr). The study shows that this phase contains two opposite spells, referred to as spells with pervasive precipitation (SWPP) and spells with widespread dryness (SWWD). Although the precipitation characteristics are essentially different between SWPP and SWWD, their associated MJO indices are found statistically identical. Therefore, the MJO–precipitation relationship fails to identify the wet/dry spells within an MJO phase. To resolve this deficiency, other climate indicators, which behave differently between these two spells, are introduced. The westward moisture flux over equatorial parts of the Indian Ocean and the northeastward moisture flux over the North African tropics are up to seven times stronger in the SWPP compared to SWWD. The dominance of a strong cyclonic (anticyclonic) circulation over the eastern side of the Mediterranean Sea and the negative (positive) west–east temperature gradient over southern parts of Iran are introduced as SWPP (SWWD) indicators. The study reveals that the SWPP (SWWD) coincides with a strong (weak) convection dipole that resembles the positive Indian Ocean dipole. The intensified (weakened) wind speed in the subtropical jet stream and persistence of the jet‐exit‐regions above Iran (Egypt and Saudi Arabia) are other SWPP (SWWD) indicators. Negative (positive) anomalies of sea surface temperature over the North Atlantic Ocean, the Black, Mediterranean, and Caspian Seas, as well as the Persian Gulf, signify the prevalence of the SWPP (SWWD). To the best of our knowledge, this is the first time that auxiliary indices are utilized to improve the MJO–precipitation relationship in southwestern Iran. Article in Journal/Newspaper North Atlantic Wiley Online Library International Journal of Climatology 41 S1 |
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Open Polar |
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Wiley Online Library |
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English |
description |
Abstract Daily values of precipitation in southwestern parts of Iran along with the corresponding Madden–Julian oscillation (MJO) phase are analysed to introduce some auxiliary indicators that can identify the wet and dry spells within a particular MJO phase. As a case study, the identification procedure focuses on phase 1 during the rainy season (Nov–Apr). The study shows that this phase contains two opposite spells, referred to as spells with pervasive precipitation (SWPP) and spells with widespread dryness (SWWD). Although the precipitation characteristics are essentially different between SWPP and SWWD, their associated MJO indices are found statistically identical. Therefore, the MJO–precipitation relationship fails to identify the wet/dry spells within an MJO phase. To resolve this deficiency, other climate indicators, which behave differently between these two spells, are introduced. The westward moisture flux over equatorial parts of the Indian Ocean and the northeastward moisture flux over the North African tropics are up to seven times stronger in the SWPP compared to SWWD. The dominance of a strong cyclonic (anticyclonic) circulation over the eastern side of the Mediterranean Sea and the negative (positive) west–east temperature gradient over southern parts of Iran are introduced as SWPP (SWWD) indicators. The study reveals that the SWPP (SWWD) coincides with a strong (weak) convection dipole that resembles the positive Indian Ocean dipole. The intensified (weakened) wind speed in the subtropical jet stream and persistence of the jet‐exit‐regions above Iran (Egypt and Saudi Arabia) are other SWPP (SWWD) indicators. Negative (positive) anomalies of sea surface temperature over the North Atlantic Ocean, the Black, Mediterranean, and Caspian Seas, as well as the Persian Gulf, signify the prevalence of the SWPP (SWWD). To the best of our knowledge, this is the first time that auxiliary indices are utilized to improve the MJO–precipitation relationship in southwestern Iran. |
format |
Article in Journal/Newspaper |
author |
Nazemosadat, Mohammad Jafar Shahgholian, Kokab Ghaedamini, Habiballah Nazemosadat, Elham |
spellingShingle |
Nazemosadat, Mohammad Jafar Shahgholian, Kokab Ghaedamini, Habiballah Nazemosadat, Elham Introducing new climate indices for identifying wet/dry spells within an Madden‐Julian Oscillation phase |
author_facet |
Nazemosadat, Mohammad Jafar Shahgholian, Kokab Ghaedamini, Habiballah Nazemosadat, Elham |
author_sort |
Nazemosadat, Mohammad Jafar |
title |
Introducing new climate indices for identifying wet/dry spells within an Madden‐Julian Oscillation phase |
title_short |
Introducing new climate indices for identifying wet/dry spells within an Madden‐Julian Oscillation phase |
title_full |
Introducing new climate indices for identifying wet/dry spells within an Madden‐Julian Oscillation phase |
title_fullStr |
Introducing new climate indices for identifying wet/dry spells within an Madden‐Julian Oscillation phase |
title_full_unstemmed |
Introducing new climate indices for identifying wet/dry spells within an Madden‐Julian Oscillation phase |
title_sort |
introducing new climate indices for identifying wet/dry spells within an madden‐julian oscillation phase |
publisher |
Wiley |
publishDate |
2020 |
url |
http://dx.doi.org/10.1002/joc.6799 https://onlinelibrary.wiley.com/doi/pdf/10.1002/joc.6799 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/joc.6799 https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/joc.6799 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
International Journal of Climatology volume 41, issue S1 ISSN 0899-8418 1097-0088 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1002/joc.6799 |
container_title |
International Journal of Climatology |
container_volume |
41 |
container_issue |
S1 |
_version_ |
1810464525948813312 |