For some purposes, such as for accurate orbit prediction, it seems to be useful to replace the large fields of harmonic coefficients, in the Earth gravity field models by a limited set of the lumped geopotential coefficients, tailored to the individual orbits. The lumped values absorb the orbital information to a high degree for the particular order of the harmonics, and a small set of the lumped coefficients, written for various orders, should be sufficient to describe the orbit as perturbed by the Earth. Some problems and questions concerning the application of this method for orbits similar to those of SEASAT or TOPEX are discussed and answered.