Impact of Madden Julian oscillation (MJO) and other meteorological phenomena on the heavy rainfall event from 19th − 28th December, 2014 over Sri Lanka

Jayawardena, I. M. Shiromani; Sumathipala, W. L.; Basnayake, B.M.D.N.

doi:10.4038/jnsfsr.v45i2.8176

Cited by 2 publications

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“…Despite being prone to catastrophic floods and landslides every year, there has been a limited investigation of extreme precipitation events in Sri Lanka. Previous studies mainly focused on analyzing synoptic features during individual heavy rainfall events (e.g., Koralegedara et al., 2019; Warnasooriya et al., 2022) and the role of the Madden‐Julian Oscillation (MJO; Jayawardena et al., 2017) in triggering such events. As a result, there has not been any attempt to examine the association of extreme precipitation events with weather patterns in Sri Lanka, which could ultimately help in identifying periods with an increased likelihood of extreme precipitation and floods.…”

Section: Discussionmentioning

confidence: 99%

The Influence of Weather Patterns and the Madden‐Julian Oscillation on Extreme Precipitation Over Sri Lanka

Deoras

Turner

Hunt

et al. 2023

Geophysical Research Letters

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Sri Lanka is a compact island in the tropics which witnesses two monsoon seasons each year. The southwest monsoon brings rainfall between May and September, contributing to around 30% of the total annual rainfall, whereas the northeast monsoon (December-February) contributes around 26% of the total rainfall for the country as a whole (e.g., Jayawardena et al., 2020). The bimodal rainfall pattern (Figure 1b) is associated with the movement of the intertropical convergence zone over Sri Lanka (e.g., Suppiah, 1996), with the two rainfall peaks occurring in April and November. Sri Lanka receives around 14% and 30% of the total annual rainfall during the first (March-April) and second (October-November) intermonsoon seasons, respectively. The spatial distribution of rainfall is skewed since the mountainous region in the south-central part (Figure 1a) results in considerable orographic rainfall.Sri Lanka is vulnerable to devastating floods and landslides every year (Askman et al., 2018), particularly during the October-December period when the frequency of extreme precipitation events (here defined as the number of days on which daily rainfall averaged over the whole country exceeds the 95th percentile on all days between 1979 and 2016) is high (Figure 1b). For example, many parts of the country received over 200 mm rainfall on 15 May 2016, causing more than 200 fatalities and about USD 2 billion in economic losses (Koralegedara et al., 2019;Samantha, 2018). Jayawardena et al. (2020) found that rainfall in Sri Lanka is enhanced (suppressed) in phases 2-3 (6-7) of the Madden-Julian Oscillation (MJO), and the occurrence of extreme rainfall events is enhanced in MJO phases 2-3. Deoras et al. (2021) found that low-pressure systems forming over southern parts of the Bay of Bengal during June-September produce substantial rainfall in Sri Lanka, and the frequency of these Abstract Sri Lanka is affected by extreme precipitation events every year, which cause floods, landslides and tremendous economic losses. We use the ERA5 reanalysis data set to understand the association of extreme precipitation events with 30 weather patterns, which were originally derived to represent the variability of the Indian climate during January-December 1979-2016. We find that weather patterns that are most common during the northeast monsoon (December-February) and second intermonsoon (October-November) seasons produce the highest number of extreme precipitation events. Furthermore, extreme precipitation events occurring during these two seasons are more persistent than those during the southwest monsoon (May-September) and first intermonsoon (March-April) seasons. We analyze the modulation of extreme precipitation events by the Madden-Julian Oscillation, and find that their frequency is enhanced (suppressed) in phases 1-4 (5-8) for most weather patterns.Plain Language Summary Extreme rainfall events affect Sri Lanka every year, causing floods, landslides and tremendous losses. Thus, it is important to identify weather patterns that are associate...

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Section: Discussionmentioning

confidence: 99%

The Influence of Weather Patterns and the Madden‐Julian Oscillation on Extreme Precipitation Over Sri Lanka

Deoras

Turner

Hunt

et al. 2023

Geophysical Research Letters

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The impact of the Madden-Julian oscillation on spring and autumn afternoon diurnal convection in Sri Lanka

Huang,

Koralegedara,

Chiang

et al. 2024

npj Clim Atmos Sci

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This study examines the impact of strong Madden-Julian Oscillation (MJO) phases (P1–P8) on diurnal rainfall patterns focusing on Afternoon Diurnal Convection (ADC) events in Sri Lanka during 2001–2020 spring and autumn. Daily mean rainfall increases (decreases) during the P2-to-P3 (P6-to-P7) MJO phases in both seasons, while the diurnal rainfall amplitude peaks during the P2-to-P3 (P8-to-P1) MJO phases in spring (autumn). ADC events also occur more frequently and intensely during MJO P2-to-P3 (P8-to-P1) in spring (autumn). The MJO’s modulation of diurnal rainfall amplitude and ADC events is more apparent in autumn than in spring. Active MJO phases enhance the westward propagation of diurnal rainfall associated with ADC events, sustained by moisture flux convergence and enhanced upward motion. The prevailing mid-to-upper level easterly wind, combined with deep convection over Sri Lanka, contributes to a more pronounced westward propagation during the P2-to-P3 (P8-to-P1) phases for ADC events in spring (autumn).

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Impact of Madden Julian oscillation (MJO) and other meteorological phenomena on the heavy rainfall event from 19th − 28th December, 2014 over Sri Lanka

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Cited by 2 publications

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The Influence of Weather Patterns and the Madden‐Julian Oscillation on Extreme Precipitation Over Sri Lanka

The Influence of Weather Patterns and the Madden‐Julian Oscillation on Extreme Precipitation Over Sri Lanka

The impact of the Madden-Julian oscillation on spring and autumn afternoon diurnal convection in Sri Lanka

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