The thesis presents the development of a procedure for the automatic identification of modal reference properties and their application to modal tracking of an onshore wind turbine tower. The primary objective is the assessment of Automated Operational Modal Analysis (AOMA) performed using acceleration measurements collected at three different heights along the tower, together with an investigation of AOMA based on strain measurements acquired at the tower base and bending moments, derived from the strain data. The recorded data are segmented into ten-minute datasets, from which modal properties are extracted through the SSI-COV method. Various clustering algorithms are examined to identify the tower modes within each dataset and to define reliable modal references based on one week of measurements.