For our discussion, it is helpful to separate the LSL equation into a high-frequency and a low-frequency part. For studies of impacts, the combined effects of the high-frequency and low-frequency part of the LSL equation are important. Here we separate these two parts at the period of approximately two months, which is partly motivated by the fact that low-frequency LSL variations are conveniently studied on the basis of monthly mean LSL values.
We will not discuss the high-frequency part, but mention here that the high-frequency part accounts for waves, tides (up to monthly periods), seiches, tsunamis and atmospherically driven variations on time scales of hours to several weeks.
An equation summing up the contribution of a number of global, regional and local processes contributing to low-frequency LSL variations has to account for steric changes and ocean circulation, atmospheric forcing, mass exchanges in the large ice sheets, continental glaciers, and the terrestrial hydrosphere, postglacial rebound, secular and non-linear vertical land motion others than postglacial rebound. These processes interact with each other and LSL in a complex way and lead to LSL variations on a wide range of temporal and spatial scales.