Interaction between the Madden–Julian Oscillation and Easterly Waves on Extreme Precipitation Events over Southeastern Mexico and Central America.
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| Title: | Interaction between the Madden–Julian Oscillation and Easterly Waves on Extreme Precipitation Events over Southeastern Mexico and Central America. |
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| Authors: | Torres, Victor M.1 (AUTHOR) victorm.torres@atmosfera.unam.mx, Raga, Graciela B.1 (AUTHOR) |
| Source: | Journal of Climate. Mar2026, Vol. 39 Issue 6, p1373-1389. 17p. |
| Subjects: | Madden-Julian oscillation, Atmospheric waves, Meteorological precipitation, Atmospheric physics, Cyclogenesis |
| Geographic Terms: | Southeast Mexico, Central America, Gulf of Tehuantepec (Mexico), Mexico, Pacific Ocean |
| Abstract: | This paper investigates the precursors of extreme precipitation events (EPE) over the tropical northeastern Pacific (EPAC), focusing on the coastal regions over southeastern Mexico and Central America. This area was selected given the social vulnerability of its population and its closeness to the second most cyclogenetic region in the world. The study indicates that EPE resulted mainly from the interaction between the westerly phase of the Madden–Julian oscillation (MJO) and easterly waves (EWs) present over the EPAC. Selected events had precipitation values above the 99th percentile from the gamma distribution fit during the rainy season from June to September over the period 1981–2022. From three different domains, results show that while EPE are more frequent in the region of the Isthmus of Tehuantepec over the EPAC (around 60 mm day−1), these are more intense over the Gulf of Mexico, reaching values of 120 mm day−1. Threshold values increased about 20% over the southern coast and about 79% over the northern coast due to orographic uplift. While most of these EPE occurred during the westerly phase of the MJO over the EPAC, further analyses showed that this is a necessary, but not sufficient, precursor for these events. The presence of EWs is also necessary. The interactions between the MJO and EWs over the EPAC showed that EWs intensify from barotropic energy conversions during EPE. While the total barotropic conversion terms are basic for this interaction, the term involving the meridional shear of the mean zonal wind is key during westerly MJO events. Significance Statement: The purpose of this study is to better understand the atmospheric conditions associated with extreme precipitation events along the coastal regions of southeastern Mexico and Central America. The study of extreme precipitation events in this region is important because of the high social vulnerability and its closeness to the second most cyclogenetic region in the world, as is the tropical northeastern Pacific. Our results show that extreme precipitation events result from the interaction of two tropical phenomena known as the Madden–Julian oscillation and easterly waves and are more frequent during the months of June and September. Monitoring and forecasting these atmospheric waves can lead to improved forecast of extreme events and increase resilience in the region. [ABSTRACT FROM AUTHOR] |
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| Database: | Engineering Source |
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| Abstract: | This paper investigates the precursors of extreme precipitation events (EPE) over the tropical northeastern Pacific (EPAC), focusing on the coastal regions over southeastern Mexico and Central America. This area was selected given the social vulnerability of its population and its closeness to the second most cyclogenetic region in the world. The study indicates that EPE resulted mainly from the interaction between the westerly phase of the Madden–Julian oscillation (MJO) and easterly waves (EWs) present over the EPAC. Selected events had precipitation values above the 99th percentile from the gamma distribution fit during the rainy season from June to September over the period 1981–2022. From three different domains, results show that while EPE are more frequent in the region of the Isthmus of Tehuantepec over the EPAC (around 60 mm day−1), these are more intense over the Gulf of Mexico, reaching values of 120 mm day−1. Threshold values increased about 20% over the southern coast and about 79% over the northern coast due to orographic uplift. While most of these EPE occurred during the westerly phase of the MJO over the EPAC, further analyses showed that this is a necessary, but not sufficient, precursor for these events. The presence of EWs is also necessary. The interactions between the MJO and EWs over the EPAC showed that EWs intensify from barotropic energy conversions during EPE. While the total barotropic conversion terms are basic for this interaction, the term involving the meridional shear of the mean zonal wind is key during westerly MJO events. Significance Statement: The purpose of this study is to better understand the atmospheric conditions associated with extreme precipitation events along the coastal regions of southeastern Mexico and Central America. The study of extreme precipitation events in this region is important because of the high social vulnerability and its closeness to the second most cyclogenetic region in the world, as is the tropical northeastern Pacific. Our results show that extreme precipitation events result from the interaction of two tropical phenomena known as the Madden–Julian oscillation and easterly waves and are more frequent during the months of June and September. Monitoring and forecasting these atmospheric waves can lead to improved forecast of extreme events and increase resilience in the region. [ABSTRACT FROM AUTHOR] |
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| ISSN: | 08948755 |
| DOI: | 10.1175/JCLI-D-24-0726.1 |
