This is the 863rd most frequent Estonian word.
tänavu
"This year."
Here, 'tänavu' modifies 'suvel' ('in summer'), indicating that the warm weather is specific to the summer of this year.
Tänavu suvel oli ilm haruldaselt soe.
This summer, the weather was unusually warm.
In this sentence, 'tänavu' is again an adverb of time, referring to the participation occurring during the current year.
Tänavu osaleb maratonil palju uusi jooksjaid.
This year, many new runners are participating in the marathon.
Here, 'tänavu' means 'this year' and is used as a time indicator to specify which winter (the current year's) is being described.