Air-Sea interaction over West Africa

Air–Sea interaction over West Africa The effects of the sea on West African climate are studied with Era-Interim data, Dakar radiosonde and ground level data.Wind, temperature and humidity are used. We find a seasonal variation: during the dry season, winds are northerly or north-easterly over land and sea, however with a southward rotation about 40 ° at the coast. During the rainy season, the wind is north-easterly over the sea but becomes westerly off the coast north of the ITCZ whilst, in the South, the wind is south-easterly, i. e the monsoon circulation. Dakar temperatures display high correlations with grid-points over the ocean more than 300 km to the West and low correlations with Thies (70 km East of Dakar). Dakar is a very important station for models data assimilation; the nearest stations with two-daily radiosoundings are Sal, 600 km to the West, and Bamako, more than 1000 km to the East. We suggest that the solitary position of Dakar may influence the prediction quality: Dakar is probably more representative of an oceanic than a continental climate.