Comparing deep convective system evolution for Africa and the tropical Atlantic

Some of the strongest convection found anywhere occurs over the African continent in the summer months, while more weakly buoyant convection is often found over the tropical Atlantic convergence zone. Differences in the radiative, precipitation and lightning properties between these regimes will be investigated as a function of system evolution.

Broadband infra-red radiance data from the geostationary Meteosat-8 satellite are used to identify and track convective cloud systems. A multiple threshold detect and spread approach is used to capture all stages of development. The observed system evolution is then used to define the life-cycle stage at each time-step, providing a framework within which other, non-geostationary satellite or in situ data can be used to build up a composite picture of convective system evolution.

Initial results suggest that Atlantic systems are shallower and have lower albedos, but higher precipitating area fractions than their land based counterparts throughout their lifecycle. TRMM precipitation radar and lightning imager data will be used to further investigate and interpret differences in both the mean properties and system evolution for the two regions. We expect the results to provide valuable constraints for the testing of mesoscale updraft and stratiform anvil parameterizations that are currently absent or deficient in GCMs.