REGIONALIZATION OF DAILY MESOSCALE RAINFALL IN THE TROPICAL WET DRY CLIMATE OF THE TOWNSVILLE AREA OF NORTHEAST QUEENSLAND DURING THE 1988-1989 WET SEASON

This paper describes the use of unrotated principal component analysis (PCA), various oblique rotated principal component (PC) solutions, an d the VARIMAX orthogonal rotation scheme. One of the objectives is to determine which PC solution achieves the most satisfactory degree of ' simple structure' in the distribution of PC loadings, based on rainfal l data collected during the 1988-1989 wet season from a comparatively dense rain-gauge network (in excess of one gauge per 25 km2) in the To wnsville area of tropical north-east Queensland, Australia. The Harris -Kaiser Case II B(T)B rotation was subsequently judged to be the most appropriate PC solution for the total wet season record, and for subse ts based on the three most frequently occurring synoptic circulations. Daily isohyetal maps and radar imagery are used to show that the rota ted PCs could be physically interpreted. The PC loadings derived from the Harris-Kaiser II B(T)B rotation were then used as input to the War d clustering strategy for regionalization of the total wet season reco rd. The interactions between different synoptic circulations and chang es in the spatial patterns of mesoscale rainfall are discussed as a ba sis for understanding the regionalization of the 1988-1989 wet season. The analysis demonstrates the need for a longer period of record befo re precipitation affinity areas, or regions of relatively coherent rai nfall, can be used for forecasting purposes. None the less, the work s hows the inadequacy of using the official gauge site at the local mete orological office as representative of the region, and further highlig hts the importance of local topographical controls on the synoptic-sca le circulation for producing distinct spatial rainfall patterns. It is believed that this is one of the first studies attempting a regionali zation of rainfall at a mesoscale within the tropics.