Towards using radar data to understand changes in sub-daily rainfall extremes: An Australian case study

One expected impact of climate warming is an increase in sub-daily extreme rainfall. A simple thermodynamic argument suggests that  extremes should increase at a rate of about 7.5%/K of warming. Convective permitting models and some in situ gauge data  suggests sub-daily extreme intensity increases by more than 7.5%/K.  In situ gauge data is sparse and so will miss many small-scale extreme rainfall events. Radar rainfall can sample a large region with high space and time resolution but has its own problems.  Australian radar data has been homogenised through comparison with the Tropical Rainfall Measuring and Global Precipitation Missions. This gives 20+ year records for about ten sites in Eastern Australia. Radar reflectivity is converted to rainfall intensity using power-law behaviour estimates from distrometer data. Rainfall data is then averaged to 30 minute, 1hour, 2 hour and 4 hour accumulations and seasonal maxima extracted.  For each radar a GEV fit with covariates on local temperature was fit to samples from the seasonal maxima.  No strong evidence is found that extreme rainfall intensity increases by more than 7.5%/K.