COMPARISON OF MULTIQUADRIC SURFACES FOR THE ESTIMATION OF AREAL RAINFALL

Multiquadric surfaces constructed from hyperboloids of two sheets, cones and paraboloids are considered for the representation of the spatial distribution of rainfall. The multiple cone surface is preferred since it is simple, objective and efficient, and gives estimates of areal rainfall which are usually as good as those obtained with multiquadric hyperboloids. Although the multiple hyperboloid surface may give a better representation of a simple rainfall surface especially if there are few raingauges, its integration is less efficient and its characteristics depend on the preselection of a suitable secondary parameter. The optimum secondary parameter is related to approximately half the scale of the horizontal coordinates, although if this parameter is set too high computational difficulties may occur. Computational difficulties prevent the use of the multiquadric paraboloids.