Horizon / Plein textes La base de ressources documentaires de l'IRD

IRD

 

Publications des scientifiques de l'IRD

Kamsu-Tamo P. H., Janicot Serge, Monkam D., Lenouo A. (2014). Convection activity over the Guinean coast and Central Africa during northern spring from synoptic to intra-seasonal timescales. Climate Dynamics, 43 (12), 3377-3401. ISSN 0930-7575

Accès réservé (Intranet IRD) Demander le PDF

Lien direct chez l'éditeur doi:10.1007/s00382-014-2111-y

En Libre Accès sur HAL http://hal.upmc.fr/hal-01102836

Titre
Convection activity over the Guinean coast and Central Africa during northern spring from synoptic to intra-seasonal timescales
Année de publication2014
Type de documentArticle référencé dans le Web of Science WOS:000344861900011
AuteursKamsu-Tamo P. H., Janicot Serge, Monkam D., Lenouo A.
SourceClimate Dynamics, 2014, 43 (12), p. 3377-3401. ISSN 0930-7575
RésuméThis study proposes an overview of the main synoptic, medium-range and intraseasonal modes of convection and precipitation in northern spring (March-June 1979-2010) over West and Central Africa, and to understand their atmospheric dynamics. It is based on daily National Oceanic and Atmospheric Administration outgoing longwave radiation and Cloud Archive User Service Tb convection data, daily TRMM and Global Precipitation Climatology Project rainfall products and daily ERA-Interim reanalysis atmospheric fields. It is first shown that mesoscale convective systems can be modulated in terms of occurrences number and intensity at such time scales. Based on empirical orthogonal function analyses on the 2-90-day filtered data it is shown that the main mode of convective and rainfall variability is located along the Guinean coast with a moderate to weak extension over Central Africa. Corresponding regressed deseasonalised atmospheric fields highlight an eastward propagation of patterns consistent with convectively coupled equatorial Kelvin wave dynamics. Then a singular spectrum analysis combined with a Hierarchical Ascendant Classification enable to define objectively the main spectral bands of variability within the 2-90-day band, and highlight three main bands, 2-8-, 8-22- and 20-90-day. Within these three bands, space-time spectral decomposition is used to identify the relative impacts of convectively coupled equatorial Kelvin, Rossby and inertia-gravity waves, as well as Madden-Julian Oscillation (MJO) signal. It confirms that eastward propagating signals (convectively coupled equatorial Kelvin wave and MJO) are highly dominant in these convection and precipitation variability modes over the Guinean coast during northern spring. So, while rain-producing individual systems are moving westward, their activity are highly modulated by sub-regional and regional scales envelops moving to the east. This is a burning issue for operational forecasting centers to be able to monitor and predict such eastward propagating envelops of convective activity.
Plan de classementHydrologie [062] ; Limnologie physique / Océanographie physique [032]
Descr. géo.AFRIQUE DE L'OUEST ; AFRIQUE CENTRALE ; ZONE EQUATORIALE ; SAHARA ; GUINEE COTE
LocalisationFonds IRD [F B010062701]
Identifiant IRDfdi:010062701
Lien permanenthttp://www.documentation.ird.fr/hor/fdi:010062701

Export des données

Disponibilité des documents

Télechargment fichier PDF téléchargeable

Lien sur le Web lien chez l'éditeur

Accès réservé en accès réservé

HAL en libre accès sur HAL


Accès aux documents originaux :

Le FDI est labellisé CollEx

Accès direct

Bureau du chercheur

Site de la documentation

Espace intranet IST (accès réservé)

Suivi des publications IRD (accès réservé)

Mentions légales

Services Horizon

Poser une question

Consulter l'aide en ligne

Déposer une publication (accès réservé)

S'abonner au flux RSS

Voir les tableaux chronologiques et thématiques

Centres de documentation

Bondy

Montpellier (centre IRD)

Montpellier (MSE)

Cayenne

Nouméa

Papeete

Abidjan

Dakar

Niamey

Ouagadougou

Tunis

La Paz

Quito