TY JOUR TI Estimation of the altitude profile of atmospheric optical turbulence intensity using gradient boosting KW atmospheric optical turbulence KW refractive index structure constant KW machine learning KW gradient boosting KW random forest KW astronomical sites JO AU Driga, M.B. AU Shikhovtsev, A.Y. AU Kovadlo, P.G. AU Kopylov, E.A. AU Potanin, S.A. PY 2026 IS PB