NEW PERMITTIVITY MEASUREMENTS OF SEAWATER

We have measured the permittivity of representative samples of natural seawater, synthetic seawater, and aqueous NaCl solutions over the fre quency range 3-20 GHz, in 0.1-GHz steps and over the temperature range -2 degrees-30 degrees C in 1 degrees steps. Additional measurements h ave been made at spot frequencies (23.8, 36.5, and 89 GHz) and at sele cted temperatures between -2 degrees and 30 degrees C. The data from t hese measurements have allowed us to deduce an interpolation function for epsilon(nu, t, S) in the ranges 2 less than or equal to nu less th an or equal to 20 GHz, -2 degrees less than or equal to t less than or equal to 30 degrees C, and 20 parts per thousand less than or equal t o S less than or equal to 40 parts per thousand with a precision of 1% . If the frequency range is extended up to 40 GHz, the precision of th e interpolation function is about 3%. The data have also allowed us to compare the permittivities of natural seawater, synthetic seawater, a nd aqueous NaCl solution with the same salinities. Natural and synthet ic seawater have the same permittivities within a 1% experimental erro r estimate. An aqueous NaCl solution has a significantly different per mittivity (up to about 6% difference, depending upon the frequency and temperature).