@brabasuthan-m If by"original data" you mean observed values (reported by meteo. stations) and by "assumed data" you mean forecasted values by weather models then [image: 1530815194276-a14dfc39-fdff-4873-9a5f-453663222132-%CE%B5%CE%B9%CE%BA%CF%8C%CE%BD%CE%B1-resized.png] Technically speaking, even forecasted data are original as they came from a known "origin" (ECMWF, NOAA etc)