The frequencies of the harmonics of standing Alfven waves depend on the distribution of mass along the magnetic field line that sustains the waves. This fact is the basis of the inversion techniques (normal mode magnetospheric seismology) to estimate the plasma mass density variation along the magnetic field from the frequencies of observed ULF waves. However, the technique has not been used extensively because it is difficult to accurately determine the frequencies. Wave observations from geostationary (e.g., GOES) or near-geostationary (e.g., CRRES) satellites provide the best chance of a successful implementation of the technique because the satellites accumulate the spectral information on the harmonics with minimal variations in frequency. By using the frequencies observed by these satellites in a numerical density modeling technique, we find an equatorial mass density enhancement and much milder density variations along the field line than previously thought