HR: 1340h
AN: A43B-0046 [Abstracts]
TI: The Atmospheric Dynamics of the West African Monsoon Onset and its Ocean Counterpart
AU: * Sultan, B
EM: benjamin.sultan@lodyc.jussieu.fr
AF: LODYC/IPSL, Universit‚ Pierre et Marie Curie, Tour 45/55, Boite 100, 4 Place Jussieu, Paris cedex 05,
75252
AU: Janicot, S
EM: serge.janicot@lodyc.jussieu.fr
AF: LODYC/IPSL, Universit‚ Pierre et Marie Curie, Tour 45/55, Boite 100, 4 Place Jussieu, Paris cedex 05,
75252
AU: lazar, a
EM: alban.lazar@lodyc.jussieu.fr
AF: LODYC/IPSL, Universit‚ Pierre et Marie Curie, Tour 45/55, Boite 100, 4 Place Jussieu, Paris cedex 05,
75252
AU: menkes, c
EM: christophe.menkes@lodyc.jussieu.fr
AF: LODYC/IPSL, Universit‚ Pierre et Marie Curie, Tour 45/55, Boite 100, 4 Place Jussieu, Paris cedex 05,
75252
AU: vialard, j
EM: jerome.vialard@lodyc.jussieu.fr
AF: LODYC/IPSL, Universit‚ Pierre et Marie Curie, Tour 45/55, Boite 100, 4 Place Jussieu, Paris cedex 05,
75252
AB:
Precipitation in the Sahel is produced by one rainy season during the northern summer monsoon over West Africa. The onset of
these rains, linked to the northward migration of the Inter-Tropical Convergence Zone (ITCZ), is an important parameter for a
large community of users like meteorologists, farmers, water resources managers... By using combined daily rainfall and OLR
data on the period 1968-2002, we show that this migration is characterized by an abrupt latitudinal shift of the ITCZ in late
June from a quasi-stationary location at 5N in May-June to another quasi-stationary location at 10N in July-August. A
composite analysis based on NCEP reanalyses shows that this northward shift is associated with an enhanced Saharan heat low
dynamics, increasing inland zonal moisture advection. The same composite analysis is applied on Reynolds and TMI SST data to
investigate the potential surface temperature changes around the monsoon onset. Preliminary results will also be shown on the
response to this onset of the oceanic model OPA/ORCA of LODYC/IPSL forced by ERS and QuikSCAT fields.
DE: 3322 Land/atmosphere interactions
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
DE: 3374 Tropical meteorology
DE: 4215 Climate and interannual variability (3309)
DE: 3309 Climatology (1620)
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting