0000000001248339
AUTHOR
A. Boone
Vegetation - atmosphere feedback in West Africa on time scales of weeks to months
Rainfall exerts a strong control on the seasonal evolution of vegetation across West Africa. In turn vegetation, and the root zone soil moisture which influences its growth, controls the fluxes of water and heat back into the atmosphere. This provides a mechanism for the land to feed back on the large-scale circulation over the course of the annual cycle. In this study, satellite data are combined with the outputs from land surface models and atmospheric reanalysis to develop an overview of where and when such feedbacks can occur in the region. The influence of rainfall on vegetation cover is re-examined using satellite data from the period 2000-8. MODIS Normalised Vegetation Difference Ind…
Assessment of water budgets from NWP model analyses and reanalyses over West Africa
International audience; Water budgets from ECMWF reanalysis ERA-Interim and NCEP reanalysis I and II are inter-compared and compared to GPS precipitable water and to a 6-yr so-called "hybrid" budget dataset composed of ALMIP (AMMA Land surface Model Intercomparison Project) offline simulations forced with TRMM precipitation data. Deficiencies are evidenced in the reanalyses which are the most pronounced over the Sahel. Results from operational models (ECMWF-IFS, NCEP-GFS, and ARPEGE-Tropiques) and the special ECMWF AMMA reanalysis confirm and help understand these findings. A bias (~1-2 mm day-1) in precipitation and evapotranspiration leads to an unrealistic view of West Africa as a moistu…
Investigation of the West African Monsoon water cycle from Numerical Weather Prediction models and elaborate products.
This study investigates the atmospheric water cycle over West Africa at seasonal and intra-seasonal timescales during AMMA Extended Observing Period (2005 to 2007). It aims at characterizing the scales of variability and inter-relations of atmospheric water budget terms and the underlying processes. The regional-scale moisture budget is examined using Numerical Weather Prediction (NWP) models and elaborate products. The latter are: TRMM 3B42v6 satellite precipitation estimates and evapo-transpiration estimates produced by land surface models (ALMIP project). These products allow for a comprehensive description of the water budget. NWP models provide also their own complete description of th…
West African Monsoon Water Cycle : Assessment of numerical weather prediction water budgets
This study investigates the atmospheric water cycle over West Africa at seasonal and intraseasonal timescales during AMMA Extended Observing Period (2005 to 2007). It aims at characterizing the scales of variability and inter-relations of atmospheric water budget terms and the underlying processes. The regional-scale moisture budget is examined using Numerical Weather Prediction (NWP) models and elaborate products. The latter are: TRMM 3B42v6 satellite precipitation estimates and evapo-transpiration estimates produced by land surface models (ALMIP project). These products allow for a comprehensive description of the water budget. NWP models provide also their own complete description of the…