Not much is known about the wave-number spectrum at the deep-water station. Some estimate of the likely scales can be made from the section made north from Oahu by Talley and deSzoeke (1985); they show in peaks in dynamic height at 22.5�, 26� and 29�N, which, if they were due to waves, would imply a north-south wave-length of about 300 km. Roden's (1985) data showed current widths of about 50 km. XBT data from the Hawaii Ocean Experiment show considerable variability with wave-lengths of about 100 km (Jim Price, pers. comm., 1990).
While these observations may well be aliased, they suggest that an IES array should be able to resolve wavelengths down to about 100 km. The IES array is an equilateral triangle with 50 km sides. If all IESs return complete data, the orientation is immaterial, since one can recover both components of k from the three measurements of D. The orientation, however, is chosen so that should any one IES fail, we can make an estimate of the zonal component of k.