Mikhail Molodenskii

Mikhail Sergeyevich Molodenskii (Russian: Михаил Сергеевич Молоденский, sometimes transliterated as M. S. Molodensky, 16 June [O.S.

[1] He graduated from Moscow State University (1936), since 1946 he worked for the Institute of Earth Physics (Институт Физики Земли АН СССР).

His aim was to develop hypothesis-free methods for determining both the gravity field and defining vertical datums for large areas.

The separation between points P and Q, i.e., between topographic and telluroid surfaces, is called the height anomaly, and is, contrary to the geoid undulation N (with respect to the reference ellipsoid), defined without requiring density information throughout space, not only at sea level.

As a compromise to traditional thinking, the concept of quasi-geoid has been introduced, being a surface separated from the reference ellipsoid by precisely an amount equal to the height anomaly evaluated on the topography.