Assessment of uncertainties in reanalysis datasets in reproducing thermodynamic mechanisms in the moisture budget’s provision in the Congo Basin

Kenfack, Kevin; Tamoffo, Alain T.; Djiotang Tchotchou, Lucie A.; Vondou, Derbetini A.

doi:10.1007/s00704-023-04576-0

Cited by 2 publications

(1 citation statement)

References 67 publications

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“…Using rainfall fields from reanalysis requires a degree of caution, particularly considering that differences in resolution can significantly influence the results (Kenfack et al, 2023). In this context, we opted to use precipitation fields from the ERA5 reanalysis in the water balance analysis, given its hourly estimates of numerous atmospheric and terrestrial climate variables at a resolution of 0.25° (Hersbach et al, 2020).…”

Section: Assessment Of Era5 Rainfallmentioning

confidence: 99%

Processes behind the decrease in Congo Basin precipitation during the rainy seasons inferred from ERA‐5 reanalysis

Kenfack,

Tamoffo,

Tchotchou

et al. 2024

Intl Journal of Climatology

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The ongoing Congo Basin drying is linked to decreasing atmospheric water vapour. To comprehend the processes reducing precipitation, we analysed water and Moist Static Energy components, associated with heating sources using ERA5 reanalysis data over the period 1981–2022. The findings reveal that the precipitation deficit in the Congo Basin during March–April–May and September–October–November is primarily attributed to a decreasing trend in the vertical moisture advection anomaly induced by vertical velocity anomalies. Following this, a horizontal moisture advection anomaly induced by specific humidity anomalies plays a significant role. However, evaporation, horizontal moisture advection anomalies induced by wind anomalies, and vertical moisture advection anomalies induced by specific humidity anomalies do not appear to contribute significantly to the drying trend in the region. The horizontal propagation of MSE advection anomalies exhibits a similar pattern to that of moisture flux advection anomalies, both at different boundaries and within the basin itself. Conversely, the contribution of vertical advection of MSE anomalies remains weak. By integrating moisture and MSE budgets, we interpret the declining precipitation trend as a consequence of uplift driven by horizontal MSE advection. Furthermore, our analysis indicates a decreasing trend in the atmospheric heating source within the basin in association with reduced precipitation. This reduction could signify a decrease in moisture influx into the basin, thereby providing more explanations for the observed drying.

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Section: Assessment Of Era5 Rainfallmentioning

confidence: 99%

Processes behind the decrease in Congo Basin precipitation during the rainy seasons inferred from ERA‐5 reanalysis

Kenfack,

Tamoffo,

Tchotchou

et al. 2024

Intl Journal of Climatology

Self Cite

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Dynamic and thermodynamic contribution to the October 2019 exceptional rainfall in western central Africa

Kenfack,

Marra,

Djomou

et al. 2024

Weather Clim. Dynam.

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Abstract. Exceptional rainfall hit western central Africa in October 2019. To understand its underlying mechanisms, we examined the regional moisture and moist static energy (MSE) budgets, intending to highlight the importance of the dynamic and thermodynamic effects associated with this historic event. Analysis of the moisture budget reveals that the precipitation anomalies in October were mainly controlled by dynamic effects. Horizontal moisture advection induced by horizontal wind anomalies controls extreme precipitation north of western central Africa, while vertical moisture advection induced by vertical velocity anomalies controls extreme precipitation south of western central Africa. Changes in the thermodynamic effect, although not the key factor responsible for the events of October 2019, contribute up to 35 % of the total effect on the northern part and 15 % on the southern part of the domain. The residual term on the northern part is important and provides a caveat when estimating dynamic and thermodynamic processes. Diagnosis of the MSE balance averaged over the northern part of western central Africa shows that the anomalous vertical motion is dominated by the dynamic effect, i.e., the wet enthalpy advection induced by the horizontal wind anomalies. This is confirmed by the high spatial correlation (r=0.6) between the two terms compared to the other terms, whereas to the west of the Congo Basin, the increase in the net energy balance dominated the changes in vertical motion (r=0.51). The horizontal advection of the MSE induced by the anomalies of the wet enthalpy and the vertical advection of the MSE induced by the anomalies of the MSE seem less important (r=0.29 and −0.19 to the north and −0.17 and 0.03 to the south). The strong anomalies in the MSE balance in the north are linked to its meridional component, in particular the meridional wind anomalies in the dynamic effect and the meridional anomalies in latent heat in the thermodynamic effect. Our results suggest that dynamic and thermodynamic effects should be jointly considered for adequately anticipating this kind of extreme event. Understanding the associated mechanisms could help us improve our forecasts and projections and increase the region's population resilience to these extreme weather events.

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Assessment of uncertainties in reanalysis datasets in reproducing thermodynamic mechanisms in the moisture budget’s provision in the Congo Basin

Cited by 2 publications

References 67 publications

Processes behind the decrease in Congo Basin precipitation during the rainy seasons inferred from ERA‐5 reanalysis

Processes behind the decrease in Congo Basin precipitation during the rainy seasons inferred from ERA‐5 reanalysis

Dynamic and thermodynamic contribution to the October 2019 exceptional rainfall in western central Africa

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