Synoptic–Dynamic Patterns Affecting Iran’s Autumn Precipitation during ENSO Phase Transitions
We compared the effect on autumn (October, November, December) precipitation over Iran during two types of El Niño–Southern Oscillation (ENSO) phase transitions from the perspective of anomalies in wave activity flux and sea level pressure along the Atlantic–Mediterranean storm track, as well as pre...
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ftmdpi:oai:mdpi.com:/2225-1154/9/7/106/ 2023-08-20T04:07:31+02:00 Synoptic–Dynamic Patterns Affecting Iran’s Autumn Precipitation during ENSO Phase Transitions Faranak Bahrami Abbas Ranjbar Saadatabadi Nir Y. Krakauer Tayyebeh Mesbahzadeh Farshad Soleimani Sardoo agris 2021-06-28 application/pdf https://doi.org/10.3390/cli9070106 EN eng Multidisciplinary Digital Publishing Institute Climate Dynamics and Modelling https://dx.doi.org/10.3390/cli9070106 https://creativecommons.org/licenses/by/4.0/ Climate; Volume 9; Issue 7; Pages: 106 wave activity flux Mediterranean storm track Atlantic storm track sea level pressure precipitation anomaly ENSO Text 2021 ftmdpi https://doi.org/10.3390/cli9070106 2023-08-01T02:03:37Z We compared the effect on autumn (October, November, December) precipitation over Iran during two types of El Niño–Southern Oscillation (ENSO) phase transitions from the perspective of anomalies in wave activity flux and sea level pressure along the Atlantic–Mediterranean storm track, as well as precipitation. We used Oceanic Niño Index (ONI) to identify the transition phases of ENSO (El Niño to La Niña and also La Niña to El Niño, referred to as type 1 and type 2, respectively). Climate data during the period of 1950 to 2019 used in this study is derived from NCEP-NCAR reanalysis. In order to investigate the intensity and direction of Rossby wave trains in different ENSO transitions, we used the wave activity flux parameter, and to evaluate the statistical significance of values, we calculated Student’s t-test. The impact of the Atlantic storm track on the Mediterranean storm track was shown to be greater in type 2 transitions. Further, the existence of a stronger wave source region in the Mediterranean region during type 2 transitions was established. Results also showed the weakening of the Iceland low and Azores high pressure in type 1 transitions and the reinforcement of both in type 2, with the differences being significant at up to a 99% confidence level. Pressure values over Iran were at or below normal in type 1 years and below normal in type 2. Finally, the composite analysis of precipitation anomaly revealed that during ENSO type 1 transitions, most regions of Iran experienced low precipitation, while in type 2, the precipitation was more than average, statistically significant at 75% confidence level or higher over the northern half of the country. Text Iceland MDPI Open Access Publishing Climate 9 7 106 |
institution |
Open Polar |
collection |
MDPI Open Access Publishing |
op_collection_id |
ftmdpi |
language |
English |
topic |
wave activity flux Mediterranean storm track Atlantic storm track sea level pressure precipitation anomaly ENSO |
spellingShingle |
wave activity flux Mediterranean storm track Atlantic storm track sea level pressure precipitation anomaly ENSO Faranak Bahrami Abbas Ranjbar Saadatabadi Nir Y. Krakauer Tayyebeh Mesbahzadeh Farshad Soleimani Sardoo Synoptic–Dynamic Patterns Affecting Iran’s Autumn Precipitation during ENSO Phase Transitions |
topic_facet |
wave activity flux Mediterranean storm track Atlantic storm track sea level pressure precipitation anomaly ENSO |
description |
We compared the effect on autumn (October, November, December) precipitation over Iran during two types of El Niño–Southern Oscillation (ENSO) phase transitions from the perspective of anomalies in wave activity flux and sea level pressure along the Atlantic–Mediterranean storm track, as well as precipitation. We used Oceanic Niño Index (ONI) to identify the transition phases of ENSO (El Niño to La Niña and also La Niña to El Niño, referred to as type 1 and type 2, respectively). Climate data during the period of 1950 to 2019 used in this study is derived from NCEP-NCAR reanalysis. In order to investigate the intensity and direction of Rossby wave trains in different ENSO transitions, we used the wave activity flux parameter, and to evaluate the statistical significance of values, we calculated Student’s t-test. The impact of the Atlantic storm track on the Mediterranean storm track was shown to be greater in type 2 transitions. Further, the existence of a stronger wave source region in the Mediterranean region during type 2 transitions was established. Results also showed the weakening of the Iceland low and Azores high pressure in type 1 transitions and the reinforcement of both in type 2, with the differences being significant at up to a 99% confidence level. Pressure values over Iran were at or below normal in type 1 years and below normal in type 2. Finally, the composite analysis of precipitation anomaly revealed that during ENSO type 1 transitions, most regions of Iran experienced low precipitation, while in type 2, the precipitation was more than average, statistically significant at 75% confidence level or higher over the northern half of the country. |
format |
Text |
author |
Faranak Bahrami Abbas Ranjbar Saadatabadi Nir Y. Krakauer Tayyebeh Mesbahzadeh Farshad Soleimani Sardoo |
author_facet |
Faranak Bahrami Abbas Ranjbar Saadatabadi Nir Y. Krakauer Tayyebeh Mesbahzadeh Farshad Soleimani Sardoo |
author_sort |
Faranak Bahrami |
title |
Synoptic–Dynamic Patterns Affecting Iran’s Autumn Precipitation during ENSO Phase Transitions |
title_short |
Synoptic–Dynamic Patterns Affecting Iran’s Autumn Precipitation during ENSO Phase Transitions |
title_full |
Synoptic–Dynamic Patterns Affecting Iran’s Autumn Precipitation during ENSO Phase Transitions |
title_fullStr |
Synoptic–Dynamic Patterns Affecting Iran’s Autumn Precipitation during ENSO Phase Transitions |
title_full_unstemmed |
Synoptic–Dynamic Patterns Affecting Iran’s Autumn Precipitation during ENSO Phase Transitions |
title_sort |
synoptic–dynamic patterns affecting iran’s autumn precipitation during enso phase transitions |
publisher |
Multidisciplinary Digital Publishing Institute |
publishDate |
2021 |
url |
https://doi.org/10.3390/cli9070106 |
op_coverage |
agris |
genre |
Iceland |
genre_facet |
Iceland |
op_source |
Climate; Volume 9; Issue 7; Pages: 106 |
op_relation |
Climate Dynamics and Modelling https://dx.doi.org/10.3390/cli9070106 |
op_rights |
https://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.3390/cli9070106 |
container_title |
Climate |
container_volume |
9 |
container_issue |
7 |
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106 |
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1774719189996535808 |