Record‐Breaking Precipitation in Indonesia's Capital of Jakarta in Early January 2020 Linked to the Northerly Surge, Equatorial Waves, and MJO

Abstract

Jakarta, the capital megacity of Indonesia located in the northwest of Java Island, Indonesia (Figure 1a), experienced an extraordinary heavy rainfall event in early January 2020. The highest amount reached up to 377 mm (14.83 inches) per day, making it a record-breaking number in observations since 1866. This extreme rainfall subsequently triggered widespread disastrous flooding in Jakarta and its surroundings in the early morning of 1 January 2020, leading to catastrophic losses. It is estimated that at least 173,000 people were evacuated, 66 people died, more than 60% of the residential areas were submerged, and the economic loss reached over US$700 million (Berlinger & Yee, 2020;Nisa, 2020). Because of the high vulnerability of Jakarta to rainfall extremes, a better understanding of the physical processes of heavy rainfall is needed to establish a reliable extended-range flood forecast system for this region.Numerous studies have examined the effects of large-scale atmospheric circulation on precipitation extremes and major floods in Jakarta. For example, the major flooding event in February 2007 (the second highest record-breaking precipitation event) was attributed to an intense and persistent cross-equatorial northerly surge (CENS) that created an intensive low-level wind convergence and favorable dynamic conditions for the

Mesoscale Convective Systems Modulated by Convectively Coupled Equatorial Waves

“…The MJO shows overall slight increases in probability but those increases are interspersed with decreases around the globe (Figure 3c). The most robust increase appears over the Indian Ocean and the equatorial Maritime Continent, consistent with strong MJO signals in the region and previous studies (Da Silva & Matthews, 2021; Lubis et al., 2022; Schreck III, 2021). The mixed probability over South America and Africa is somewhat similar to the noisy signal in Schreck III (2021) but slightly at odds with Vasconcelos Junior et al.…”

“…In fact, Kelvin waves and TDs are the two most effective modulators, followed by MRGs and ERs, and trailed by the MJO (Figure S2 in Supporting Information ). While numerous studies have highlighted the MJO as an important modulator of tropical rainfall and extreme events (e.g., Grimm, 2019; Jones et al., 2004; Schreck III, 2021; Vasconcelos Junior et al., 2021), these results suggest that synoptic‐scale CCEWs influence convective organization and precipitation even more strongly than the MJO (Ferrett et al., 2020; Fink & Reiner, 2003; Latos et al., 2021; Linden et al., 2016; Lubis et al., 2022; Schlueter et al., 2018).…”

Cross‐Equatorial Surges Boost MJO's Southward Detour Over the Maritime Continent

“…This study improves our understanding of the dynamics that govern the intensity and propagation of the MJO over the MC, which can ultimately improve our ability to forecast and mitigate the impacts of extreme weather events in the affected regions (Wu et al, 2013;Lubis et al, 2022). Furthermore, the diagnostics developed in this study can be useful for investigating the processes that lead to the moisture and circulation biases in simulating MJO in climate models or operational forecast models (e.g., Li et al, 2017), with an emphasis on the role of extratropical-tropical interaction through the CES.…”

Impacts of the boreal summer intraseasonal oscillation on precipitation extremes in Indonesia

“…On the other hand, the onset of the Indian Summer monsoon, which has a negative correlation with precipitation over the central and eastern parts of Indonesia (Kripalani and Kulkarni, 1997;Klingaman et al, 2008;Karmakar and Misra, 2019) can interfere with the modulation of the BSISO on precipitation over the regions (Lee et al, 2013). In addition, the effects of the diurnal cycle, topography, and large-scale atmospheric systems such as convectively coupled equatorial waves may also interact with BSISO and influence its regional impacts on extreme precipitation (Hsu and Lee, 2005;Wu and Hsu, 2009;Lubis and Jacobi, 2015;Lubis and Respati, 2021;Lubis et al, 2022). The interaction between El-Niño Southern Oscillation and BSISO can influence summertime extreme precipitation events in Indonesia and could partially (if not entirely) explain a recent wetting trend during the summer (Supari et al, 2017(Supari et al, , 2018.…”