Importance of Madden–Julian oscillation phase to the interannual variability of East African rainfall

Maybee, Ben; Ward, Martin; Hirons, Linda; Marsham, John H.

doi:10.1002/asl.1148

Cited by 8 publications

(12 citation statements)

References 62 publications

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“…As discussed by Maybee et al. (2022), phases 1‐to‐4 are associated with enhanced East African MAM rainfall. In 2018, as discussed in Kilavi et al.…”

Section: Resultsmentioning

confidence: 81%

“…The various regions of deep convection (or "phases") are identified with values from 1 to 8. As discussed byMaybee et al (2022), phases 1-to-4 are associated with enhanced East African MAM rainfall. In 2018, as discussed inKilavi et al (2018), MJO activity in phases 2, 3, and 4 combined with shorter term influences associated with tropical cyclones over the southwestern Indian Ocean to drive "an anomalous westerly low-level circulation over Kenya and the surrounding region", supporting enhanced moisture convergence and extreme rains.Through mid-May 2023 MJO index values also indicate enhanced MJO activity in March, April and early May (Figure S1b in Supporting Information S1).…”

mentioning

confidence: 90%

“…The MJO is the dominant source of sub-seasonal climate variability in the tropics (Zhang, 2005). The MJO is known to strongly modulate MAM rains in East Africa (Maybee et al, 2022;Pohl & Camberlin, 2006). The eastward propagation of the MJO can be quantified using two indices, based on the empirical orthogonal function (EOF) of three variables: 200 and 850 hPa equatorial zonal winds and outgoing longwave radiation (Wheeler & Hendon, 2004) In addition to sub-seasonal influences, in 2023 the Pacific climate system also transitioned rapidly from La Niña to El Niño conditions.…”

Section: Opportunities and Challenges For Seasonal Drought Predictionmentioning

confidence: 99%

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Frequent but Predictable Droughts in East Africa Driven by a Walker Circulation Intensification

Funk,

Fink,

Harrison

et al. 2023

Earth's Future

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During and after recent La Niña events, the decline of the eastern East African (EA) March‐April‐May (MAM) rains has set the stage for life‐threatening sequential October‐November‐December (OND) and MAM droughts. The MAM 2022 drought was the driest on record, preceded by three poor rainy seasons, and followed by widespread starvation. Connecting these dry seasons is an interaction between La Niña and climate change. This interaction provides important opportunities for long‐lead prediction and proactive disaster risk management, but needs exploration. Here, for the first time, we use observations, reanalyses, and climate change simulations to show that post‐1997 OND La Niña events are robust precursors of: (a) strong MAM “Western V sea surface temperature Gradients” in the Pacific, which (b) help produce large increases in moisture convergence and atmospheric heating near Indonesia, which in turn produce (c) regional shifts in moisture transports and vertical velocities, which (d) help explain the increased frequency of dry EA MAM rainy seasons. We also show that, at 20‐year time scales, increases in atmospheric heating in the Indo‐Pacific Warm Pool region are attributable to warming Western V SST, which is in turn largely attributable to climate change. As energy builds up in the oceans and atmosphere, during and after La Niña events, we see stronger heating and heat convergence over warm tropical waters near Indonesia. The result of this causal chain is that increased Warm Pool atmospheric heating and moisture convergence sets the stage for dangerous sequential droughts in EA. These factors link EA drying to a stronger Walker Circulation and explain the predictable risks associated with recent La Niña events.

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“…As discussed by Maybee et al. (2022), phases 1‐to‐4 are associated with enhanced East African MAM rainfall. In 2018, as discussed in Kilavi et al.…”

Section: Resultsmentioning

confidence: 81%

mentioning

confidence: 90%

Section: Opportunities and Challenges For Seasonal Drought Predictionmentioning

confidence: 99%

See 1 more Smart Citation

Frequent but Predictable Droughts in East Africa Driven by a Walker Circulation Intensification

Funk,

Fink,

Harrison

et al. 2023

Earth's Future

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“…In summary, we propose that accurate model representation of the U700C links to the Indo‐Pacific and Atlantic regions offers the prospect of much improved forecast skill for MAM EA rainfall. These linkages are a priority for further assessment in current models, including their interplay with intraseasonal variability via the Madden‐Julian Oscillation (e.g., Maybee et al, 2023; Vellinga & Milton, 2018). The work here also encourages further investigation of physically‐informed recalibration of current forecasts.…”

Section: Concluding Discussionmentioning

confidence: 99%

Predictability of the East Africa long rains through Congo zonal winds

Ward,

Walker,

Keane

et al. 2023

Atmospheric Science Letters

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East Africa is highly vulnerable to extreme weather events, such as droughts and floods. Skillful seasonal forecasts exist for the October–November–December short rains, enabling informed decisions, whereas seasonal forecasts for the March–April–May (MAM) long rains have historically had low skill, limiting preparation capacity. Therefore, improved long rains prediction is a high priority and would contribute to climate change resilience in the region. Recent work has highlighted how lower‐troposphere Congo zonal winds in MAM strongly impact regional moisture fluxes and the long rains total precipitation. We therefore approach long rains predictability through the predictability of the Congo winds. We analyze a set of hindcasts from a dynamical prediction system that is able to reproduce the long rains—Congo winds relationship in its individual ensemble members. Encouragingly, in observations, the strength of MAM Congo zonal winds and East Africa rainfall show substantial correlation with the MAM Atlantic (including North Atlantic Oscillation, NAO) and Indo‐Pacific variability, suggestive of ocean influence and potential predictability. However, these features are replaced by different teleconnections in the hindcast ensemble mean fields. This is also true for NAO linkage to Congo winds, despite correct representation in individual members, and good skill in hindcasting the NAO itself. The net effect is strongly negative skill for the Congo winds. We explore statistical correction methods, including using the Congo zonal wind as an anchor index in a signal‐to‐noise calibration for the long rains. This is considered a demonstration of concept, for subsequent implementation using models with better Congo zonal wind skill. Indeed, the clear signals found in the Atlantic (including Mediterranean) and Indo‐Pacific, studied here both in observations and a dynamical prediction system, motivate evaluation of these features across other prediction systems, and offer the prospect of improved physically‐informed long rains dynamical predictions.

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“…representation in models can affect the accuracy (e.g., Funk et al, 2019;Gudoshava and Semazzi, 2019;Wainwright et al, 2019Wainwright et al, , 2021aKolstad et al, 2021;Lyon and DeWitt, 2012;Nicholson, 2014;Vellinga and Milton, 2018;Gudoshava et al, 2022b;Liu et al, 2022;Maybee et al, 2023;Mwanthi et al, 2023;Palmer et al, 2023).…”

Section: Figurementioning

confidence: 99%

Advances, gaps and way forward in provision of climate services over the Greater Horn of Africa

Gudoshava,

Otieno,

Koech

et al. 2024

Front. Clim.

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The Greater Horn of Africa is prone to extreme climatic conditions, thus, making climate services increasingly important in supporting decision-making processes across a range of climate sensitive sectors. This study aims to provide a comprehensive review of the recent advances, gaps and challenges in the provision of climate services over the region, for each of the components of the Global Framework for Climate Services. The study explores various milestones that have been achieved toward climate service delivery. The achievements include improvement of station network coverage, and enhancing the capacity of member states to utilize various tools in data analysis and generate routine climate products. The advancement in science, and availability of High-Performance Computing has made it possible for forecast information to be provided from nowcasting to seasonal timescales. Moreover, operationalizing of the objective forecasting method for monthly and seasonal forecasts has made it possible to translate tercile forecasts for applications models. Additionally, innovative approaches to user engagement through co-production, communication channels, user-friendly interfaces, and dissemination of climate information have also been developed. Despite the significant progress that has been made in the provision of climate services, there are still many challenges and gaps that need to be overcome in order to ensure that these services are effectively meeting the needs of users. The research of the science underpinning climate variability, capacity building and stakeholder engagement, as well as improved data management and quality control processes are some of the gaps that exist over the region. Additionally, communication and dissemination of climate information, including timely warnings and risk communication, require improvement to reach diverse user groups effectively. Addressing these challenges will require strengthened partnerships, increased investment in capacity building, enhanced collaboration between the climate information producers and stakeholders, and the development of user-friendly climate products. Bridging these gaps will foster greater resilience to climate-related hazards and disasters in the Greater Horn of Africa and support sustainable development in the region.

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Importance of Madden–Julian oscillation phase to the interannual variability of East African rainfall

Cited by 8 publications

References 62 publications

Frequent but Predictable Droughts in East Africa Driven by a Walker Circulation Intensification

Frequent but Predictable Droughts in East Africa Driven by a Walker Circulation Intensification

Predictability of the East Africa long rains through Congo zonal winds

Advances, gaps and way forward in provision of climate services over the Greater Horn of Africa

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