Late 21st Century Projected Changes in the Relationship between Precipitation, African Easterly Jet, and African Easterly Waves

Kebe, Ibourahima; Diallo, Ismaïla; Sylla, Mouhamadou Bamba; Sales, Fernando De; Diedhiou, Arona

doi:10.3390/atmos11040353

Cited by 16 publications

(11 citation statements)

References 72 publications

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“…The regional climate model version 4.5.0 (hereafter RegCM4; Giorgi et al 2012) was used in the present study. RegCM4 is a limited area model and has been used for numerous studies including process studies (Sylla et al 2015;Diallo et al 2016;Kébé et al 2020) and future climate projections (Diallo et al 2016;Sawadogo et al 2020;Ashfaq et al 2020;among others). Performance of the RegCM4 model has been examined in tropical Africa as in Ogwang et al (2016); Komkoua et al (2017) andN'Datchoh et al (2018).…”

Section: Model Descriptionmentioning

confidence: 99%

On the Influence of Vegetation Cover Changes and Vegetation-Runoff Systems on the Simulated Summer Potential Evapotranspiration of Tropical Africa Using RegCM4

Anwar¹,

Mamadou

Diallo

et al. 2021

Earth Syst Environ

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The community land model version 4.5 provides two ways for treating the vegetation cover changes (a static versus an interactive) and two runoff schemes for tracking the soil moisture changes. In this study, we examined the sensitivity of the simulated boreal summer potential evapotranspiration (PET) to the aforementioned options using a regional climate model. Three different experiments with each one covering 16 years have been performed. The two runoff schemes were designated as SIMTOP (TOP) and variable infiltration capacity (VIC). Both runoff schemes were coupled to the carbon–nitrogen (CN) module, thus the vegetation status can be influenced by soil moisture changes. Results show that vegetation cover changes alone affect considerably the simulated 2-m mean air temperature (T2M). However, they do not affect the global incident solar radiation (RSDS) and PET. Conversely to the vegetation cover changes alone, the vegetation-runoff systems affect both the T2M and RSDS. Therefore, they considerably affect the simulated PET. Also, the CN-VIC overestimates the PET more than the CN-TOP compared to the Climatic Research Unit observational dataset. In comparison with the static vegetation case and CN-VIC, the CN-TOP shows the least bias of the simulated PET. Overall, our results show that the vegetation-runoff system is relevant in constraining the PET, though the CN-TOP can be recommended for future studies concerning the PET of tropical Africa.

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Section: Model Descriptionmentioning

confidence: 99%

On the Influence of Vegetation Cover Changes and Vegetation-Runoff Systems on the Simulated Summer Potential Evapotranspiration of Tropical Africa Using RegCM4

Anwar¹,

Mamadou

Diallo

et al. 2021

Earth Syst Environ

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“…It is unclear how the frequency of AEWs will change in future, with studies projecting both increasing (Bercos‐Hickey & Patricola, 2021; Hannah & Aiyyer, 2017; Skinner & Diffenbaugh, 2014) and decreasing (Kebe et al., 2020) AEW activity. This is further complicated by a projected multi‐model average increase and decrease of the northern and southern AEW tracks respectively, albeit with a large spread among individual climate models (Brannan & Martin, 2019).…”

Section: Introductionmentioning

confidence: 99%

Influence of African Easterly Wave Suppression on Atlantic Tropical Cyclone Activity in a Convection‐Permitting Model

Danso

Patricola

Bercos‐Hickey

2022

Geophysical Research Letters

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Understanding the physical controls on tropical cyclone (TC) frequency represents a major challenge, as there is no theory to explain why the global annual number of TCs is relatively constant in historical observations and no consensus on future changes in TC frequency (Sobel et al., 2021). Pre-existing low-pressure disturbances, or TC "seeds," may trigger TC genesis, and have been identified as one possible factor in determining TC frequency. The typical Atlantic TC seed is provided by African easterly waves (AEWs), which are synoptic-scale disturbances that grow off of the baroclinic and barotropic instability of the African easterly jet (AEJ) (Burpee, 1972). AEWs generate between 5°N and 30°N over tropical northern Africa (Kiladis et al., 2006) and propagate westward over the tropical Atlantic Ocean.There is a strong connection between AEWs and Atlantic TCs on the synoptic time scale (Dieng et al., 2017;Landsea et al., 1998), with about 60%-80% of major Atlantic hurricanes originating from AEWs (Landsea, 1993;Russell et al., 2017). However, some studies have suggested that the relationship between TC frequency and AEWs may not be as straightforward as previously thought, especially on climate time scales. For instance, results from Hodges (2001) andHopsch et al. (2007) suggest that the relationship between AEWs and Atlantic TC activity could depend on the period considered, with the former finding them to be correlated for one period whereas the latter found them to be uncorrelated for a different period using the same data product. Moreover, Thorncroft and Hodges (2001) showed that only AEWs leaving the West African coast with significant low-level amplitudes, rather than the total number of AEWs, may influence the seasonal Atlantic

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“…A similar result was reported by Brannan and Martin (2019) in their study of AEW tracks. A contrasting result of reduction of AEW activity throughout the region was reported by Kebe et al (2020) in their study using Regional Climate Model 4 (RegCM4). Similarly Mariotti et al (2014) also reported a reduction in 6-9 day AEW activity by the end of the century.…”

Section: Introductionmentioning

confidence: 81%

Future projection of the African easterly waves in a high-resolution atmospheric general circulation model

Raj

Bangalath

Stenchikov

2022

Preprint

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Simulating the features of the African Easterly Waves (AEWs), such as their westward propagation off the coast, is challenging for coarseresolution climate models. In this study, we use High-Resolution Atmospheric Model (HiRAM) to simulate AEWs and analyze their future projections by the end of the 21 st century. The simulations are performed globally at a horizontal resolution of ∼ 25km. The model uses shallow convective parameterization for moist convection and stratiform cloudiness. Future projections are conducted using representative concentration pathway 8.5. The AEWs are separated with respect to their periods as 3–5- and 6–9-day AEWs, and bandpass filtering is used to filter the waves from the mean flow. HiRAM simulates structure and propagation of the waves well; however, it tends to overestimate the associated precipitation. In the future, the AEW activity and intensity of the circulation will considerably increase. The northward extent of the AEW track also shows a significant increase in the future. The increased wave activity can be translated as more Atlantic hurricanes in the future because AEWs are the seed disturbances for cyclogenesis in this region.

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Late 21st Century Projected Changes in the Relationship between Precipitation, African Easterly Jet, and African Easterly Waves

Cited by 16 publications

References 72 publications

On the Influence of Vegetation Cover Changes and Vegetation-Runoff Systems on the Simulated Summer Potential Evapotranspiration of Tropical Africa Using RegCM4

On the Influence of Vegetation Cover Changes and Vegetation-Runoff Systems on the Simulated Summer Potential Evapotranspiration of Tropical Africa Using RegCM4

Influence of African Easterly Wave Suppression on Atlantic Tropical Cyclone Activity in a Convection‐Permitting Model

Future projection of the African easterly waves in a high-resolution atmospheric general circulation model

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