Measurements of UHF and L-Band Radar Clutter in the Central Pacific Ocean

Measurements of clutter with the TRADEX radar at UHF and L band are described. Clutter is shown to be due to sea return and returns from clouds. Sea clutter predominates at ranges less than 13 nmi, values of σ0 of -100 dB being typical at both frequencies. Coherent scattering from clouds is postulated, and the observed frequency independence of the cloud retums is offered as supporting evidence. Values of cloud cross section per unit volume are given. Below 15,000 ft altitude, values of -140 dB (reference m-1) are typical at both frequencies. Clutter spectra are presented.