Sahel droughts and Enso dynamics

Janicot, Serge; Moron, Vincent; Fontaine, Bernard

doi:10.1029/96gl00246

Cited by 244 publications

(185 citation statements)

References 14 publications

Supporting

Mentioning

163

Contrasting

Unclassified

Order By: Relevance

“…It also suggests that the good correlation between ENSO and Sahel rainfall (e.g. Janicot et al, 1996) has a strong component that derives from ENSO events that rapidly develop during boreal spring, with key SST developments for Sahel rainfall occurring from April/May to June.…”

Section: Discussionmentioning

confidence: 99%

“…The key SST regions identified include the tropical Atlantic (Lamb, 1978a;Hastenrath, 1990;Ward, 1998), the Pacific Ocean El Niño/southern oscillation (ENSO) region (e.g. Janicot et al, 1996;Ward, 1998) and an inter-hemispheric gradient of SST in the Atlantic, with components of the gradient present in the Indian and Pacific Oceans leading to its interpretation as a near-global inter-hemispheric contrast (Folland et al, 1986;Ward et al, 1993;Rowell et al, 1995). Some mechanisms relating the dynamics of Sahel rainfall and SST variability in different basins have been proposed.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Using regional wind fields to improve general circulation model forecasts of July–September Sahel rainfall

Ndiaye

Goddard²,

Ward³

2008

Intl Journal of Climatology

View full text Add to dashboard Cite

This study develops and applies a model output statistics (MOS) approach for correcting poor general circulation model (GCM) seasonal rainfall predictions over the Sahel region of West Africa. It illustrates a methodology for approaching the MOS prediction of regional rainfall, drawing on knowledge of the regional circulation system. The ECHAM4.5 GCM has very little skill in predicting July-September Sahel rainfall. However, the GCM is much more capable of reproducing the regional wind circulation at 925 hPa, especially over the tropical Atlantic. This is capitalized upon using a MOS approach that applies empirical orthogonal functions (EOFs) of the model's regional (tropical Atlantic and West Africa) 925 hPa wind as predictors in a regression with observed Sahel rainfall as the predictand.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Using regional wind fields to improve general circulation model forecasts of July–September Sahel rainfall

Ndiaye

Goddard²,

Ward³

2008

Intl Journal of Climatology

View full text Add to dashboard Cite

show abstract

“…We also considered the linear correlation r between observed and hindcast percentiles. The significance of the linear correlation is estimated with the random-phase test, first proposed by Janicot et al (1996), and then elaborated by Ebisuzaki (1997). This test resamples the original time series in the frequency domain.…”

Section: Methodsmentioning

confidence: 99%

Relationship between sea-level pressure and sea-level height in the Camargue (French Mediterranean coast)

Moron

Ullmann

2005

Int. J. Climatol.

View full text Add to dashboard Cite

A statistical study of daily maximum sea-level height at one station (Grau de la Dent) in the Camargue (Rhône delta, French Mediterranean coast) and daily sea-level pressure (SLP) at 12 h UTC over the eastern North Atlantic is used to identify the meteorological conditions associated with sea-level variations in the Camargue for the winters 1974-75 to 2000-01. Mean SLP composites during and 5 days before major surge events (defined as those with a daily maximum sea-level height >80 cm) suggest the dominant influence of storms, moving northwest to southeast across the North Atlantic and strengthening as they approach the Bay of Biscay. During such storms, strong onshore winds may persist for up to 4-5 days. These winds tend to strengthen from 3 days to 1 day before the surge events. The mean October-March correlation between daily maximum sea-level height in the Camargue and SLP averaged over the Bay of Biscay (10°W-0°, 40-50°N) is strong (r = 0.69). A methodology is developed for assessing the low-frequency SLP variability impact on sea-level height in the Camargue. A cross-validated linear regression is used to hindcast the interannual and intraseasonal variability of the monthly 75th and 90th percentiles of the daily maximum sea-level height from the monthly mean SLP over the Bay of Biscay. The linear correlation between the cross-validated hindcast and observed time series is 0.83 (0.77) for the 75th (90th) percentile on the 1974-75 to 2000-01 period. The mean bias error, reflecting systematic errors in predicting the monthly percentiles, is close to zero.

show abstract

“…In fact, several observational studies have shown that the most heavy precipitation in West Africa is associated with features generating rainfall that are embedded in the AEWs and organized along the AEJ, with the strength of the TEJ strongly contributing to the duration of their lifetime (Janicot et al, 1996;D'Amato and Lebel, 1998;Diedhiou et al, 1999;Redelsperger et al, 2002;Gaye et al, 2005;Mohr and Thorncroft, 2006). In addition, Nicholson et al (2008) suggested that the strength and the northward extend of the large core of ascent lying between the AEJ and TEJ can significantly affect the West African monsoon rainbelt over the Sahel.…”

Section: Intraseasonal Variabilitymentioning

confidence: 99%

Simulation of the intraseasonal and the interannual variability of rainfall over West Africa with RegCM3 during the monsoon period

Sylla

Dell’Aquila

Ruti

et al. 2009

Intl Journal of Climatology

View full text Add to dashboard Cite

Intraseasonal and interannual variability of rainfall is simulated using the International Centre for Theoretical Physics (ICTP) Regional Climate Model (RegCM3) over West Africa. The intraseasonal variability of rainfall showing three distinct phases and the monsoon jump is well reproduced in the simulation. In addition, the regional model shows that while the monsoon rainbelt moves to the Sahel, the African Easterly Jet (AEJ) undergoes a northward migration and a weakening from June to August, when the core is at its northernmost location. This coexists with the appearance and the strengthening of the Tropical Easterly Jet (TEJ), the development and increased activity of the African Easterly Waves (AEWs), and the intensification and northward shift of the ascent between the AEJ and the TEJ core levels and axis. Similarly, the simulated interannual variability of rainfall over West Africa, the Guinea region, and the Sahel, as well as the variability of atmospheric features during contrasting wet and dry years, is also well captured. In fact, in the simulation during dry years the AEWs activity is decreased while the AEJ is strengthened and migrates southward, the TEJ becomes weaker, and the ascent between the levels of the AEJ and the TEJ decreases. The simulated rainfall variability and the behavior of the related features during the rainy season and during contrasting wet and dry years are in line with previous studies that used observations and reanalysis. We conclude that this model performance is of sufficient quality for application to the study of climate processes and mechanisms over West Africa.

show abstract

Sahel droughts and Enso dynamics

Cited by 244 publications

References 14 publications

Using regional wind fields to improve general circulation model forecasts of July–September Sahel rainfall

Using regional wind fields to improve general circulation model forecasts of July–September Sahel rainfall

Relationship between sea-level pressure and sea-level height in the Camargue (French Mediterranean coast)

Simulation of the intraseasonal and the interannual variability of rainfall over West Africa with RegCM3 during the monsoon period

Contact Info

Product

Resources

About