Publications des scientifiques de l'IRD

Lavaysse C., Flamant C., Evan A., Janicot Serge, Gaetani M. (2016). Recent climatological trend of the Saharan heat low and its impact on the West African climate. Climate Dynamics, 47 (11), p. 3479-3498. ISSN 0930-7575.

Titre du document
Recent climatological trend of the Saharan heat low and its impact on the West African climate
Année de publication
2016
Type de document
Article référencé dans le Web of Science WOS:000389349000006
Auteurs
Lavaysse C., Flamant C., Evan A., Janicot Serge, Gaetani M.
Source
Climate Dynamics, 2016, 47 (11), p. 3479-3498 ISSN 0930-7575
The Saharan heat low (SHL) plays a pivotal role in the West African monsoon system in spring and summer. The recent trend in SHL activity has been analysed using two sets of numerical weather prediction (NWP) model reanalyses and Atmospheric Models Intercomparison Project simulations from 15 climate models performed in the framework of the 5th Coupled Models Intercomparison Project (CMIP5) exercise. A local increase of temperature in the Sahara during the 90s is found in the two sets of NWP models temperature. This increase is stronger within the SHL region than over the surrounding areas. Using different temporal filters (under 25 days, 25-100 days and above 300 days), we show that this is accompanied by a slight but widespread increase of temperature, and a change in the filtered signal under 25 days during the transition period of the 90s. We also show that SHL pulsations occurring at different time scales impact the West Africa climate on a variety of spatial scales, from the regional scale (for the high band pass) to the synoptic scale (for the low band pass signal). Despite a large variability in the temporal trends for 15 climate models from the CMIP5 project, the warming trend in the 90s is observed in the models ensemble mean. Nevertheless, large discrepancies are found between the NWP models reanalyses and the climate model simulations regarding the spatial and temporal evolutions of the SHL as well as its impact on West African climate at the different time scales. These comparisons also reveal that climate models represent the West African monsoon interactions with SHL pulsations quite differently. We provide recommendations to use some of them depending on the time scales of the processes at play (synoptic, seasonal, interannual) and based on key SHL metrics (location, mean intensity, global trend, interaction with the West African monsoon dynamics).
Plan de classement
Sciences du milieu [021] ; Hydrologie [062]
Description Géographique
AFRIQUE DE L'OUEST ; SAHARA
Localisation
Fonds IRD [F B010068759]
Identifiant IRD
fdi:010068759
Contact