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West African Monsoon water cycle: 1. A hybrid water budget data set / Rémi Meynadier in Journal of geophysical research : Atmospheres, vol 115 n° D19 (2010)

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inJournal of geophysical research : Atmospheres > vol 115 n° D19 (2010) . - 21 p.

Titre :	West African Monsoon water cycle: 1. A hybrid water budget data set
Type de document :	Article/Communication
Auteurs :	Rémi Meynadier, Auteur ; Olivier Bock , Auteur ; Françoise Guichard, Auteur ; Aaron Boone, Auteur ; Pascal Roucou, Auteur ; Jean-Luc Redelsperger, Auteur
Année de publication :	2010
Article en page(s) :	21 p.
Note générale :	bibliographie
Langues :	Anglais (eng)
Descripteur :	[Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] Afrique occidentale [Termes IGN] bilan hydrique [Termes IGN] coordonnées GPS [Termes IGN] données météorologiques [Termes IGN] évapotranspiration [Termes IGN] mousson [Termes IGN] précipitation [Termes IGN] teneur en vapeur d'eau [Termes IGN] variation saisonnière
Résumé :	(auteur) This study investigates the West African Monsoon water cycle with the help of a new hybrid water budget data set developed within the framework of the African Monsoon Multidisciplinary Analyses. Surface water and energy fluxes are estimated from an ensemble of land surface model simulations forced with elaborate precipitation and radiation products derived from satellite observations, while precipitable water tendencies are estimated from numerical weather prediction analyses. Vertically integrated atmospheric moisture flux convergence is estimated as a residual. This approach provides an advanced, comprehensive atmospheric water budget, including evapotranspiration, rainfall, and atmospheric moisture flux convergence, together with other surface fluxes such as runoff and net radiation. The annual mean and the seasonal cycle of the atmospheric water budget are presented and the couplings between budget terms are discussed for three climatologically distinct latitudinal bands between 6°N and 20°N. West Africa is shown to be alternatively a net source and sink region of atmospheric moisture, depending on the season (a source during the dry season and a sink during the wet season). Several limiting and controlling factors of the regional water cycle are highlighted, suggesting strong sensitivity to atmospheric dynamics and surface radiation. Some insight is also given into the underlying smaller‐scale processes. The relationship between evapotranspiration and precipitation is shown to be very different between the Sahel and the regions more to the south and partly controlled by net surface radiation. Strong correlations are found between precipitation and moisture flux convergence over the whole region from daily to interannual time scales. Causality is also established between monthly mean anomalies. Hence, precipitation anomalies are preceded by moisture flux convergence anomalies and followed by moisture flux divergence and evapotranspiration anomalies. The results are discussed in comparison to other studies.
Numéro de notice :	A2010-653
Affiliation des auteurs :	LAREG+Ext (1991-2011)
Thématique :	POSITIONNEMENT
Nature :	Article
nature-HAL :	ArtAvecCL-RevueIntern
DOI :	10.1029/2010JD013917
Date de publication en ligne :	01/10/2010
En ligne :	https://doi.org/10.1029/2010JD013917
Format de la ressource électronique :	URL article
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=91724

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West African Monsoon water cycle: 2. Assessment of numerical weather prediction water budgets / Rémi Meynadier in Journal of geophysical research : Atmospheres, vol 115 n° D19 (2010)

West African Monsoon water cycle 2 - pdf éditeur

Public

[article]
inJournal of geophysical research : Atmospheres > vol 115 n° D19 (2010) . - 24 p.

Titre :	West African Monsoon water cycle: 2. Assessment of numerical weather prediction water budgets
Type de document :	Article/Communication
Auteurs :	Rémi Meynadier, Auteur ; Olivier Bock , Auteur ; Sébastien Gervois, Auteur ; Françoise Guichard, Auteur ; Jean-Luc Redelsperger, Auteur ; Anna Agustí‐Panareda, Auteur ; Anton Beljaars, Auteur
Année de publication :	2010
Article en page(s) :	24 p.
Note générale :	bibliographie
Langues :	Anglais (eng)
Descripteur :	[Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] Afrique occidentale [Termes IGN] circulation atmosphérique [Termes IGN] coordonnées GPS [Termes IGN] données météorologiques [Termes IGN] évapotranspiration [Termes IGN] mousson [Termes IGN] prévision météorologique
Résumé :	(auteur) Water budgets from European Centre for Medium‐Range Weather Forecasts (ECMWF) Re‐Analysis (ERA)‐Interim and National Centers for Environmental Prediction (NCEP) Reanalysis I and II are intercompared and compared to GPS precipitable water and to the 6 year hybrid budget data set described in part 1 of this study. Deficiencies are evidenced in the reanalyses which are most pronounced over the Sahel. Results from operational models (ECMWF Integrated Forecast System, NCEP Global Forecast System, and ARPEGE‐Tropiques) and the special ECMWF African Monsoon Multidisciplinary Analyses reanalysis confirm and help understanding these findings. A bias (∼1–2 mm d−1) in precipitation and evapotranspiration leads to an unrealistic view of West Africa as a moisture source during the summer. North of the rainband (13°N–16°N), moisture flux convergence (MFC) shows a minimum in the NCEP models and divergence in the ECMWF models not consistent with the hybrid data set. This feature, added to presence of a deep layer of northerly dry air advected at midlevels (800–400 hPa), is thought to block the development of deep convection in the models and the northward propagation of the monsoonal rainband. The northerly flow is part of a shallow meridional circulation that is driven by the Saharan heat low. This circulation appears too strong in some of the models, a possible consequence of the too‐approximate representation of physical processes and land surface properties over the Sahel. In most of the models, evapotranspiration shows poor connection with precipitation. This is linked with large analysis increments in precipitable water, soil moisture, and MFC. Despite the large biases affecting the water budget components in the models, temporal variations (seasonal and interannual) might nevertheless be recovered with reasonable accuracy.
Numéro de notice :	A2010-654
Affiliation des auteurs :	LAREG+Ext (1991-2011)
Thématique :	POSITIONNEMENT
Nature :	Article
nature-HAL :	ArtAvecCL-RevueIntern
DOI :	10.1029/2010JD013919
En ligne :	https://doi.org/10.1029/2010JD013919
Format de la ressource électronique :	URL article
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=91725

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