Global 4DVAR Assimilation and Forecast Experiments Using AMSU Observations over Land. Part II: Impacts of Assimilating Surface-Sensitive Channels on the African Monsoon during AMMA

• DOI: 10.1175/2009waf2222244.1
• Publication Date: 2009-08-01T01:05:51Z
• Authors: Fatima Karbou; Florence Rabier; Jean-Philippe Lafore; Jean-Luc Redelspe...; Olivier Bock
• Keywords: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere; [SDU.STU.ME] Sciences of the Universe [physics]/Earth Sciences/Meteorology; mousson; [SDU.OCEAN] Sciences of the Universe [physics]/Ocean, Atmosphere; observations de basse couche; influence de la surface de la terre; [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology; assimilation des données; 01 natural sciences; 13. Climate action; humidité; modèles numériques; 0105 earth and related environmental sciences

Abstract Observations from Advanced Microwave Sounding Unit-A and -B (AMSU-A -B) have been more intensively used over sea than land because of large uncertainties about the surface emissivity skin temperature. Several methods based on a direct estimation satellite observations found to be very useful for improving assimilation sounding channels land. Feasibility studies conducted within Météo-France global system in order examine possibility assimilating low-level atmospheric receiving contribution surface. The present study reports three 2-month forecast experiments, which include surface-sensitive AMSU-A together with control experiment, represents operational model. experiments compared control, important changes analyzed fields precipitation forecasts parts tropics, especially West Africa, noticed. seem emphasize moistening India, South America, drying Saudi Arabia northeast Africa. or atmosphere has successfully evaluated using independent measurements GPS African Monsoon Multidisciplinary Analysis (AMMA) network. Precipitation OLR also examined measurements. Physically, result better-organized monsoon stronger ITCZ terms ascent, vorticity, precipitation, but there is no northward shift system. Low-level humidity impacts analysis produce positive scores tropics.