Search results for "Mesoscale convective system"

2011

Abstract. In situ measurements of ice crystal size distributions in tropical upper troposphere/lower stratosphere (UT/LS) clouds were performed during the SCOUT-AMMA campaign over West Africa in August 2006. The cloud properties were measured with a Forward Scattering Spectrometer Probe (FSSP-100) and a Cloud Imaging Probe (CIP) operated aboard the Russian high altitude research aircraft M-55 Geophysica with the mission base in Ouagadougou, Burkina Faso. A total of 117 ice particle size distributions were obtained from the measurements in the vicinity of Mesoscale Convective Systems (MCS). Two to four modal lognormal size distributions were fitted to the average size distributions for diffe…

The impact of a mesoscale convective system cold pool on the northward propagation of the intertropical discontinuity over West Africa

2009

The interaction between a mesoscale convection system cold pool and the intertropical discontinuity (ITD) is investigated on two consecutive days (5 and 6 June 2006), in the framework of the African Monsoon Multidisciplinary Analysis Special Observing Period (SOP 1a). Satellite imagery and surface meteorological observations are used to track the movement of the ITD prior to and after its interaction with the cold pool. The impact of the northward propagating cold pool on the Sahelo-Saharan planetary boundary layer (PBL) thermodynamics and aerosol vertical distribution is analyzed by means of airborne and ground-based measurements over the two-day period. Complementary European Centre for M…

Dust emissions over the Sahel associated with the West African monsoon intertropical discontinuity region: A representative case-study

2008

Near-dawn airborne lidar and dropsonde observations acquired on 7 July 2006, during the African Monsoon Multidisciplinary Analysis (AMMA) Special Observing Period 2a1, were used to investigate dust mobilization, lifting and transport in the intertropical discontinuity (ITD) region over western Niger. Atmospheric reflectivity data from the LEANDRE 2 lidar system enabled us to analyse the structure of dust plumes in the context of wind and thermodynamic information provided by the WIND lidar system and dropsondes. Dust mobilization was mainly observed in two locations: (a) within the monsoon flow as the result of the passage of a density current originating from a mesoscale convective system …