We analyzed seasonal variations of lightning activity in continental tropical Africa using 10-day, monthly, and seasonal data observed by the Tropical Rainfall Measuring Mission (TRMM) satellite. The data collected were flash counts obtained with Lightning Imaging Sensor (LIS), and total rainfall, convective rainfall, and stratiform rainfall obtained with Precipitation Radar (PR) for the 10-year period 1998-2007.
The overall flash count migrates seasonally and meridionally following the solar angle, while it is abundant throughout the year at low latitudes near the equator. Flash count maximum areas generally occur over mountainous regions and the maximum frequency is observed in the Mitumba Mountains east of the Congo Basin. The flash count is also high in the central Congo Basin regardless of season. In the central region (7.5–12.5°N, along 20–22.5°E) of the African Continent, another maximum flash count area is observed during the period May–October. The maximum zone of total rainfall from May to August occurs between these two maxima of the flash count. The peak region of the flash count from December to March does not coincide with that of total rainfall. The maximum region of the flash count occurs from the equator to 2.5°S, while that of total rainfall occurs between 7.5° and 12.5°S. The maximum region of the flash count and total rainfall in January and March is separated by about 10° of latitude.
Along 22.5°E, in the central region of the African Continent, the flash count at 10°N is higher both at the beginning and final stages of the warm season rainfall. In contrast, the flash count is high only at the beginning of the warm season rainfall at 10°S. The beginning of warm season rainfall relative to the solar angle is 2 months earlier at 10°S.
