|
|
 |
|
|
Ann. Geophys., 20, 575-582, 2002
www.ann-geophys.net/20/575/2002/
© European Geosciences Union 2002
The relationship between the Sahelian and previous 2nd Guinean rainy seasons: a monsoon regulation by soil wetness?
N. Philippon and B. Fontaine
Centre de Recherches de Climatologie, UMR 5080 CNRS, Université de Bourgogne, 6 blvd. Gabriel, BP 138, 21000 Dijon, France
Correspondence to: N. Philippon
(nphilipp@u-bourgogne.fr)
Abstract. The correlation of 0.61
found between observed July–September Sahelian rainfall in year 0 and
September–November Guinean rainfall in year - 1, led us to explore the
statistical relationships between precipitation, soil moisture and near surface
Moist Static Energy (MSE) gradients in West Africa. These analyses were
performed over successive 30-year periods and specifically, the most recent
period between 1968–1998. It is shown from observations, National Centers for
Environmental Predictions and National Center for Atmospheric Research (NCEP/NCAR)
reanalyses and from the Global Soil Wetness Project (GSWP) database, that wet
Sahelian rainy seasons are preceded by abnormally wet soils over the
Sudan-Guinean belt during northern winter. Such moisture anomalies tend to hold
during the dry season, then generate increasing MSE gradients just above the
continent by March–April. These gradients have been shown to be of prime
importance for monsoon dynamics and associated rainfall.
Key words. Hydrology (soil
moisture) – Meteorology and atmospheric dynamics (climatology)
Full Article in PDF (464 KB) |
|
|
