Long base hydrostatic level

The measurement capabilities of the hydrostatic level with a base of 1–3 km are described. The paper presents physical assessments of the effects related to the influence of changes in the parameters of meteorological conditions (atmospheric pressure, temperature, and its gradients along a track). The dynamic characteristics of the instrument and its limiting resolution, determined by both its own thermal fluctuations and the influence of seismic noise, are considered. A new radiotechnical method for measuring variations if the fluid level in the measuring vessel is discussed, characterized by a simple and reliable design and a large dynamic measurement range while maintaining the high sensitivity necessary for constructing long base systems.