A global climatology is presented of rainfall in tropical cyclones (TCs), averaged over cyclone-centred circles of different radii. The TRMM (TMPA-3B42) data is combined with TC data from IBTrACS over the period 1988-2014; with the requirement that the TC had to exceed a 10-min average wind speed of 34 kts at some stage during the lifecycle and that full TRMM satellite coverage existed for 90% of the track. Climatologies are determined for both instantaneous rainfall and rainfall accumulated over the lifetime of the cyclone.
The analysis strategy is to examine distributions and variability rather than mean values, producing robust statistics. For example it is shown that globally 60% of TCs in the 64 to 85 kts intensity range have 0-350 km average rainfall exceeding 1 mm/hr, whereas for TCs in the 34 to 63 kts intensity category, 1 mm/hr is exceeded in 42 % of cases. These distribution-based statistics are presented for differences between TC basins and intensity classes. Translation speed is also addressed, but presents a less robust signal.
Addressing the issue of extremes, the TCs with the highest 20 values of instantaneous and lifetime accumulated rainfall are listed and examined. The highest total-area rainfalls are generally found in the North Atlantic and North West Pacific basins. For accumulation over the cyclone lifetime the record rainfall is for Atlantic Hurricane Ivan in 2004 with a total rainfall volume of almost 300 km3 assuming a 350 km storm radius. This is almost a third larger than the next wettest TC analysed due to Ivan being so long-lived.
Knowing the magnitude of TC rainfall extremes in each basin is important in the context of contribution to annual mean and extreme rainfall. TC rainfall can have both positive effects on water availability as well as negative effects due to freshwater flooding.