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Study of Boundary Layer Height over West Africa

Monthly means of boundary layer height (BLH) over West Africa are pre- sented based on 36 years (1979-2014) of six-hourly ERA-Interim reanalysis. In this region, we found that there is a link between the West Africa Monsoon (WAM) and the monthly means of BLH in the summer. The trend and em- pirical orthogonal function (EOF) of BLH are presented, including the mid July variability of BLH with the precipitation. The dominant EOF of BLH ac- counts for around 42% of the variance with slightly large amplitude in the north while relatively small in the equatorial band. The second EOF which accounts for 16.4%, describes a longitudinal contrast with a zonal gradient. The relationship between BLH and precipitation is found using the canonical correlation analysis (CCA). Significant trends of the first and second pairs of BLH with precipitation are shown. The first and second CCA pair has a cor- relation of 68% and 60% with 12.2 and 10.8 degrees of freedom respectively. The critical correlation coefficients at the 95% level are 0.21 and 0.65 for the first and second CCA pairs respectively. This first CCA pair mostly deter- mines the arid and semi-arid areas where the rate of explained regional va- riance is about 78% in the arid area and 73% in the semi-arid area. For the second pair of CCA, the rate of explained regional variance is more than 60% in the Guinea coast and wet equatorial area.


Auteur(s) : Semou Ndao, Djiondo Ngongang Rinelle, Daouda Badiane, Andre Lenouo, Saïdou Moustapha Sall
Pages : 179-194
Année de publication : 2019
Revue : Journal of Geoscience and Environment Protection
N° de volume : 7
Type : Article
Mise en ligne par : SALL Saïdou Moustapha