Intraseasonal oscillation of the rainfall variability over Rwanda and evaluation of its subseasonal forecasting skill

Zhou, Xuan; Chen, Lin; Umuhoza, Janet; Cheng, Yifeng; Wang, Lu; Wang, Ran

doi:10.1016/j.aosl.2021.100099

Cited by 5 publications

(5 citation statements)

References 19 publications

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“…In SSA, the rainfed agricultural sector is the utmost principal source of livelihood for the human population [2][3][4]. Te spatial and temporal variability of the rainfall distribution in East Africa countries (EA) is more pronounced, and catastrophic events, such as destructive droughts and foods, occur more frequently leading to detrimental efects on socioeconomic sectors as well as human and animal deaths [5][6][7][8][9]. Te dynamics and evolution of the climate system, as well as the variability and predictability that go along with it, can all be better understood with an improved understanding of rainfall variability and trend [10,11].…”

Section: Introductionmentioning

confidence: 99%

“…On the internal climate forcing mechanisms, volcanoes, for example, have been found to afect climate and have the potential to afect the skill of certain seasonal forecasts made after large eruptions [20]. Te intraseasonal rainfall variability over the region are associated with equatorial Rossby waves which exhibit a dominant 10-30-day time scale periodicity [8,21], while a higher association between Madden-Julian oscillation (MJO) with rainfall was observed over the west of the region [22].…”

Section: Introductionmentioning

confidence: 99%

“…During the dry season, the climate of Rwanda is dry mainly in Eastern lowlands and is infuenced by dry anticyclones of Saint Helena and Azores, while the western highlands receive some rainfall resulting from Saint Helena anticyclones passing over lake Kivu from Atlantic Ocean [18]. Rainfall characteristics over Rwanda have been the subject of several recent studies [8,19,27,28,31,33,34]. Since the economy of the Kayonza District is heavily dependent on the agriculture industry, rainfall fuctuation will have a variety of consequences on farming activities and other sectors that support the district's economy.…”

Section: Introductionmentioning

confidence: 99%

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Spatial and Temporal Analysis of Rainfall Variability and Trends for Improved Climate Risk Management in Kayonza District, Eastern Rwanda

Sebaziga,

Twahirwa,

Kazora

et al. 2023

Advances in Meteorology

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The variability, intensity, and distribution of rainfall have drawn a lot of interest globally and especially in nations where rainfed agriculture is the norm. This article uses rainfall data from the Rwanda Meteorology Agency for the years 1981 to 2021 to delineate and analyze rainfall variability and trends in the Kayonza District. The time series were grouped using the K-means clustering technique based on computed Euclidean distance, the total within-cluster sum of squares, and the elbow plot technique to determine the optimal number of clusters. The coefficient of variation measures was employed to analyze rainfall variability, while Sen’s slope and the Mann–Kendall (MK) test were used, respectively, to find trends and changes in magnitude. The results indicated four near homogeneous zones named region one to four. The dry seasons indicated higher variability compared to rainy seasons and annual rainfall total with a variability of 128–142% over the southeastern part during June to August (JJA) season, while a variability of 16–48% was observed over most of the district during both annual and rainy seasons. It was further noted that the areas in the central part of the Kayonza District indicated a significant increasing trend at a significance level of 95% and above during January to February (JF), September to December (SOND), and on annual basis, while March to May (MAM) and JJA season exhibited no significant trend. The findings of this study are essential for creating adequate mitigation strategies to lessen climate change’s effects on agriculture as well as other socioeconomic sectors.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spatial and Temporal Analysis of Rainfall Variability and Trends for Improved Climate Risk Management in Kayonza District, Eastern Rwanda

Sebaziga,

Twahirwa,

Kazora

et al. 2023

Advances in Meteorology

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“…At a local scale like Rwanda, a few previous climate-related studies conducted have generally paid attention to assessing spatiotemporal variations in different climatic variables such as rainfall and temperature [44,[48][49][50], with no studies at present emphasizing the historical behavior of the characteristics of meteorological drought over Rwanda. Furthermore, the sustainability of water resources and the environment in EA is likely to be affected by an anticipated rise in temperature, more frequent and intense precipitation, and drought events.…”

Section: Introductionmentioning

confidence: 99%

Observed Changes in Meteorological Drought Events during 1981–2020 over Rwanda, East Africa

Uwimbabazi

Jing²,

Iyakaremye

et al. 2022

Sustainability

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Drought is one of the most complex natural phenomena affecting the life and livelihood of people, especially in the current time of human-induced climate change. This research employs ground-based observations to assess the recent spatiotemporal characteristics of meteorological drought events over Rwanda. The drought is examined based on the Standardized Precipitation Evapotranspiration Index (SPEI) and Standardized Precipitation Index (SPI) at seasonal and annual time scales from 1981 to 2020. The Man–Kendal test was used to evaluate the trends in rainfall, temperature, and SPEI values at the annual scale and during the March to May (MAM) and October to December (OND) seasons. The analysis revealed nonsignificant trends in annual (8.4 mm/decade), MAM (−3.4 mm/decade), and OND (4.5 mm/decade) rainfall, while an apparent significant increasing trend in surface air temperature was obtained during the MAM (0.19 °C/decade), OND (0.2 °C/decade), and annual (0.23 °C/decade) time slices. Overall, the SPEI characteristics indicated that the country is more prone to moderate drought events than severe and extreme drought events during MAM and OND seasons. However, the intensity, duration, and frequency differ spatially among seasons. The findings of this study inform policy and decision-makers on the past experienced drought behavior, which can serve as a baseline for future drought mitigation and adaptation plans.

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“…Recently, Zhou et al (2021) studied the dominant intra-seasonal precipitation mode during the February-May rainy season, and evaluated the forecast skill for the intra-seasonal oscillation (ISO) over Rwanda and its surrounding regions. They found that the dominant intra-seasonal rainfall mode in Rwanda exhibits a significant variability on the 10-25-day time scale, and is associated with the anomalous westerly wind in Rwanda.…”

Section: Introductionmentioning

confidence: 99%

The influence of intraseasonal oscillations on rainfall over Central Africa: Case of the 25 - 70 days variability

Tchinda,

Sandjon,

Tchotchou

et al. 2023

Preprint

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The influence of intra-seasonal oscillations (ISO) on rainfall in Central Africa (CA) is assessed using the National Oceanic and Atmospheric Administration Climate Prediction Center daily gridded rainfall data. ISO indices are defined using the time series analysis of the first two principal components resulting from the empirical orthogonal function, applied to daily filtered outgoing longwave radiation. Based on these indices, a total of 71 strong Intraseasonal Events (SIEs) and 66 weak Intraseasonal Events (WIEs) were selected using threshold method. The results show that SIEs are associated with enhanced rainfall conditions over almost all the study area, while WIEs provide a meridional dipole-like rainfall pattern, consisting of increasing precipitation in the western part and decreasing in the eastern part of CA. The relationship with Madden-Julian Oscillation (MJO) was also examined. The positive rainfall anomalies associated with MJO phases progress eastward and are modulated by the 850 and 200 hPa horizontal wind. The circulation, linked to geopotential height anomalies at lower layers, tends to strengthen (reduce) the convective activity over the region. Uncentered pattern correlation was further used to assess the link between ISO and MJO phases. We found a correlation of 0.5 in precipitation anomalies between phases 1 and 2 of the MJO and the SIEs; -0.4 and -0.6 between phases 5 and 6 and the SIEs respectively. This result suggests a strong relationship between ISO events and MJO phases.

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Intraseasonal oscillation of the rainfall variability over Rwanda and evaluation of its subseasonal forecasting skill

Cited by 5 publications

References 19 publications

Spatial and Temporal Analysis of Rainfall Variability and Trends for Improved Climate Risk Management in Kayonza District, Eastern Rwanda

Spatial and Temporal Analysis of Rainfall Variability and Trends for Improved Climate Risk Management in Kayonza District, Eastern Rwanda

Observed Changes in Meteorological Drought Events during 1981–2020 over Rwanda, East Africa

The influence of intraseasonal oscillations on rainfall over Central Africa: Case of the 25 - 70 days variability

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