TY JOUR TI Estimation of Parameters of Non-stationary Geophysical Signals Based on Two-Stage Approximations Using Local Models KW geophysical signals KW geomagnetic pulsations KW estimation KW non-stationary parameters KW two-stage approximation JO Russian Journal of Earth Sciences AU Getmanov, V.G. AU Gvishiani, A.D. AU Pilipenko, V.A. AU Stukov, D.A. PY 2025 IS 25 PB Geophysical Center of the Russian Academy of Sciences