An ensemble of convective systems on 11 February 1993 during TOGA COARE: Morphology, rainfall characteristics, and anvil cloud interactions

An active day during the Coupled Ocean-Atmosphere Response Experiment (COAR E) Intensive Observation Period (IOP) is examined in which nine convective systems evolved and moved eastward across the region of shipboard radar cov erage in the Intensive Flux Array (IFA) within westerly wind burst conditio ns. The detailed genesis, morphology, and interactions between these cloud systems are documented from a radar and satellite perspective. One of these systems was a large and complex elliptical cluster, among the largest obse rved during the Tropical Ocean Global Atmosphere COARE. Multiple, parallel deep convective lines spaced 20-30 km apart and embedded within this system were initially oriented from north-northwest to south-southeast, oblique t o the storm motion. Furthermore, the lines underwent counterclockwise reali gnment as the system moved eastward. The influence of strong lower-troposph eric directional and speed shear on these convective system properties is e xamined in the context of a dynamic, large-scale near-equatorial trough/tra nsequatorial flow regime. A daily analysis of flow conditions during the 11 9-day IOP revealed that this type of synoptic regime was present in the IFA at least 40% of the time. Radar-derived rainfall statistics are examined throughout the life cycles o f each individual convective system. Spatial mapping of accumulated rainfal l reveals long, linear swaths produced by the most intense cells embedded w ithin convective lines. The evolution of rainfall properties includes an in crease in the stratiform rainfall fraction and areal coverage in later gene rations of systems, with a peak in total rainfall production after local mi dnight. These trends can be explained by anvil cloud interactions originati ng within the sequence of closely spaced disturbances, including the effect s of both enhanced midtropospheric moisture and also strong reversing (east erly) shear. The issue of boundary layer recovery between the frequent, int ense convective systems on this day is also examined.